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Thermal energy storage by agitated capsules of phase change material Sözen, Zeki Ziya 1985

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THERMAL  ENERGY  STORAGE  PHASE  BY A G I T A T E D  CHANGE  CAPSULES  OF  MATERIAL  by ZEKI  ZIYA  SOZEN  B . S c ,  Middle  East  Technical  University,  1978  M . S c ,  Middle  East  Technical  University,  1980  A  THESIS THE  SUBMITTED  IN  REQUIREMENTS DOCTOR  PARTIAL FOR  OF  THE  FULFILMENT DEGREE  OF  PHILOSOPHY  in THE  FACULTY  (Department  We  accept to  THE  OF  GRADUATE  of  Chemical  this  thesis  the required  UNIVERSITY  OF  Ziya  Engineering)  as  conforming  standard  B R I T I S H COLUMBIA  January,  o Zeki  STUDIES  1985  Stfzen,  1985  OF  In p r e s e n t i n g  t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f the  requirements f o r an advanced degree a t the U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make it  f r e e l y a v a i l a b l e f o r reference  and study.  I further  agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying o f t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the head o f my department o r by h i s o r her r e p r e s e n t a t i v e s .  It is  understood t h a t copying o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l gain  s h a l l not be allowed without my  permission.  Department o f  Chemical  Bopineertty  The U n i v e r s i t y o f B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3  DE-6  (3/81)  written  -  i i  -  ABSTRACT  Thermal change  materials  relatively systems. studied low  Glauber's phase  However, in  is  diameter  hollow  the  5%  were  air  by  under  Toss  of  space  agitation  with  water  was  cycles found  sodium  a pilot first  but  under  fluidization  to  improved  be  tube  by  sodium  its  heat. to  application  reduce  a  or  encapsulated  by  weight  containing  weight  sulfate  mm  25  including  to  The  in  of  excess  with  5%  25%,  15%  water  concentration  conditions.  the  possible,  of  of  leading  systems  Some c a p s u l e s  effect  latent  encapsulated  borax  10%  because  limited  efficiency.  and  and  melting-freezing  was  4%  density  extensively  behaviour  rotating  phase  storage  most  high  repeated  and  heat  systems  different  salt  storage  the  and  salt  and  sulfate  capacity  in  over  the  of  severely  in  capsules.  test  fluidizing  93  Glauber's  the  excess  decrease  agitated  heat  one  melting  Glauber's  storage  storage  theoretically  and  has  its  heat  a  which  suitable  energy  energy  upon  of  sensible  temperature  drum  in  is  incongruent  study  to  solar  rotating  The  showed  for  heat  higher  t  efficiency  96%  prepared, to  different  to  this  in  of  compared  change  problem  bed,  weight  also  due  spheres  consisted  volume  2  phase  In  latent  (Na S0i «10H20)  materials  serious  fluidized  mixture  and  a  the  advantages  storage  salt.  eliminate  by  change  heat  via  behaviour  segregation  Glauber's  liquid  the  salt  suitable  the  cycling  has  storage  isothermal  price,  loss  energy  by  there  of  5756  capsules,  plant  size  three  cycles  was  no  further  conditions. increasing  the  The  by  m diameter)  (0.34 to  agitated  about  60%  decrease  heat  storage  superficial  column,  of  that  over  the  next  efficiency  water  velocity  -  and  by  decreasing  effect. or  The  from  the  discharged  the  cooling  fluidized heat  in  about  transfer  and  may  by  encapsulated  liquid  fluidized  almost  negligible The  heat  theoretical system  bed  storage or  only  7  decreased  with  further  capacity  was  refluidi  zed.  cycles  Performances tested  horizontal rotating The  the  drum,  the  theoretical  the  The  rotating  rotations  around  force  a  had  the  heat  three  regular tube,  to  capacity  was  efficiencies for  the  not  capsules'  collisions  in  the  influence,  At  to  high  especially  of  the  costs  in  38.4%  are  the  a  storage-  tube the  were  capsules  fixed  and  addition  in  to  around  under  full  the rotation.  a  horizontal  recovery  vigorous  were  the  efficiency  capsules  around  of  (fluidized)  composition  However, even  to  heat  centers, in  rotating  subject  axis.  these  a capsule  possible,  energy  analysis  and  original  rotation  of  advantage  thermal  agitated  different  with  for  decreased  when  efficiency.  capsules  a horizontal  and  rotation  storage  of  or  outlet  operating  conditions,  cycles  the  due  full  bed  charged  to  costs.  capsules  97.5%  through  that  negative  fixed  within  impact  drum  the  no rates  important  that  corresponding  rotating  with  shows  capital  be  Economic  67%  of  to  applications  material.  or  transfer  and  an  of  under  passing  showed  improves  conditions. in  the  axis  results  axis  in  of  are  l i t t l e  heat  energy  efficiency  cycling.  recovered  of  system  fixed  had  inlet  rates  areas  change  to  the  realistic  storage  compared  capacity  new  phase  heat  in  were  open  rate  enhanced  enabling  heat  for  storage  medium, with  high  system  provide  hour  The  -  Heating  one  temperatures. the  rate.  capsules  storage  i i i  of  mixing  similar  to  those  same  number  of  rotation  speeds  centrifugal  the  rotating  tube.  On  the  -  basis  of  heat  material, optimal  47% for  Some relative  storage by  the  capacity  weight  sodium  rotating  drum  small  scale  importance  of  iv  per  -  unit  sulfate and  the  experiments different  volume  rotating  were  sulfate  concentration  different  thermal  cycling  h i s t o r i e s were  results  sulfate  is  not  the  systems  using  sulfate  beneath  showed  only  Glauber's a layer  that  bulk  in  the  found  to  by  heat  M i c r o e n c a p s u l a t i o n of crystals  heat  the  of  salt.  salt  found  change  to  be  the  storage  capsules  with  thermogravimetric  for  Glauber's  of  phase  determine of  in  segregation loss  was  loss  gradients  of  cases.  reason  of  the  tube  performed  factors  Sodium  The  weight  concentration  capacity.  analysis.  or  anhydrous  storage  is  capacity  anhydrous at  sodium  least  in  sodium as  important. Experiments another  factor  mixture  of  subcooling  in  to the  determine loss  96% G l a u b e r ' s of  about  crystallization  5 K  of  salt in  the  heat and  gently  temperatures  both  degree storage  4%  borax  agitated  of  subcooling, believed  capacity,  showed  by  undergoes  weight  capsules.  increase with  that  Nucleation  increased  to  a  and  agitation.  be  -  V  -  TABLE OF CONTENTS  Page ABSTRACT  i i  TABLE OF CONTENTS  ,  LIST OF TABLES  v viii  LIST OF FIGURES  x  ACKNOWLEDGMENTS  xiv  1.  INTRODUCTION  1  2.  PREVIOUS WORK  4  2.1  Phase Change Thermal Energy Storage Materials  4  2.2  Energy Storage Systems Using Phase Change M a t e r i a l s  9  3.  4.  PRELIMINARY WORK'.  21  3.1  Selection of Heat Storage Material  21  3.2  Proposed Heat Storage System Using Glauber's Salt  25  ENCAPSULATION OF GLAUBER'S SALT  29  4.1  Tabletting and Coating of Glauber's Salt  30  4.2  Encapsulation of Glauber's Salt in Hollow Polypropylene Capsules  32  Capsules Containing Mixtures of Different Compositions..  34  4.3 5.  FIXED AND FLUIDIZED BED STUDIES  36  5.1  Thermal Cycling of Capsules in the Liquid Fludized Bed..  36  5.1.1 5.1.2 5.1.3 5.1.4 5.1.5 5.1.6  36 43 50 52 54 55  Experimental System Experimental System C a l i b r a t i o n Theoretical Heat Storage Capacity Heat Transfer Resistances Observations and Parameters Varied Data and Data Processing  -  vi  -  Page  6.  5.2  Thermal  5.3  Recovery  SMALL SCALE 6.1  6.2  Cycling of  8.  Storage  Capacity  Experiments  HEAT  STORAGE  7.1  Fluidized  7.2  Rotating  to  Determine  and F i x e d Drum  Samples  Capsules  System  Varied  C A P A C I T I E S OF  from  the  Drum  Different  and R o t a t i n g  Tube  and P r o c e d u r e  and D a t a Degree  THE  with  of  83  Subcooling  86  CAPSULES  94  Bed C a s e s  and R o t a t i n g  HEAT  STORAGE  78 79  Analysis  94  Tube  Cases  I l l  Method f o r Comparing Systems w i t h Different Compositions E f f e c t o f Phase Change M a t e r i a l C o m p o s i t i o n  AFFECTING  CAPACITIES  121 126  138  8.1  Bulk  8.2  Microencapsulation Effect  143  8.3  Subcooling  148  8.3.1 8.3.2  148  8.3.3 8.3.4  9.  of  in the Rotating  Parameters  6.3  of  72  Experimental  FACTORS  63 66  Analysis  6.2.2  7.2.2  Bed  71  6.2.1  7.2.1  in a Fixed  STUDIES  Thermogravimetric Capsules Heat  Capsules  Efficiency  Compositions  7.  of  FUTURE  OF  Segregation  138  E f f e c t s of Subcooling I n f l u e n c e o f B o r a x C o n c e n t r a t i o n and Degree of A g i t a t i o n I n f l u e n c e o f Sodium S u l f a t e C o n c e n t r a t i o n Temperature V a r i a t i o n s Inside Capsules During Cooling  ENCAPSULATED  9.1  Economic  Analysis  9.2  Advantages  HEAT  STORAGE  Compared  154  159  and C o m p a r i s o n  and D i s a d v a n t a g e s  150 152  159 to  Other  Systems..  182  -  v i i  -  Page 10.  C O N C L U S I O N S AND  RECOMMENDATIONS  FOR  FUTURE  STUDIES  187  10.1  Conclusions  187  10.2  Recommendations  189  NOMENCLATURE  192  REFERENCES  196  APPENDICES  201  Appendix  1  Numerical  Values  in the Text Design of the Minimum Appendix  Appendix  Appendix  2  3  4  f o r Some  Computer System Raw D a t a  Velocity  Program to Analyze F l u i d i z e d Experimental Data from F l u i d i z e d Bed S t u d i e s  Raw D a t a :  Fixed  Appendix  6  Raw D a t a :  Refl uidi zation  Appendix  7  Computer  Program  Rotating  Appendix  9  (water).  Tube  213 Heat 220  Bed S t u d i e s  to  226  Studies  Analyze  Experimental  206  Bed  Computer Program to C a l c u l a t e Experimental Transfer Rates to/from the Capsules Rate of Heat T r a n s f e r Data  5  8  202  o f Heat T r a n s f e r Between t h e and t h e Heat T r a n s f e r Medium  Appendix  Appendix  Used  Distributor  Fluidization  Simulation Capsules  Parameters  Rotating  229 Drum  and  Data  232  I n i t i a l N u c l e a t i o n and C r y s t a l l i z a t i o n Temperatures in Capsules with Different Compositions  236  Computer Program t o C a l c u l a t e T h e o r e t i c a l Heat Storage C a p a c i t y of Sodium S u l f a t e - W a t e r Mixtures  238 241  Appendix  10  Material  and U t i l i t y  Cost  Data  Appendix  11  Computer Program to Perform Economic A n a l y s i s C a l c u l a t i o n s f o r t h e F l u i d i z e d Bed Heat Storage System  243  -  viii  -  L I S T OF TABLES Page Table  1  Table  2*  Table  3  P r o p e r t i e s of T y p i c a l Organic Change Thermal Energy Storage Temperature A p p l i c a t i o n s Physical Numerical the  Table  4  C h a r a c t e r i s t i c s of Values  Calibration  for  the  and I n o r g a n i c Materials for  Phase Low 6  an  Average  Parameters  Capsule  Evaluated  34 from  Experiments  49  S p e c i f i c Heat C a p a c i t i e s and T o t a l M a t e r i a l s i n 5756 C a p s u l e s Used i n  Weights of the Fluidized  System Table  5  Experimental Cooling  Table  Table  Table  Table  Table  Table  Table  Table  Table  6  7  8  9  10  11  12  13  14  51 Results  Period  on  the  Showing Heat  the  Effect  Storage  of  the ...  Efficiency  61  Experimental R e s u l t s Showing the E f f e c t of the H e a t i n g P e r i o d on t h e H e a t S t o r a g e E f f i c i e n c y  62  Experimental Results Superficial Velocity  64  Showing the on t h e H e a t  Effect of the Storage E f f i c i e n c y . . . .  Experimental R e s u l t s Showing the E f f e c t of the Number o f T h e r m a l C y c l e s U n d e r F i x e d Bed C o n d i t i o n s on t h e H e a t S t o r a g e E f f i c i e n c y o f t h e C a p s u l e s  67  Experimental Heat Storage  69  Results Samples Cycl ing Chemical Capsules Rotating  R e s u l t s Showing the Recovery E f f i c i e n c y of the Capsules  of  the  of the Thermogravimetric A n a l y s i s of the from the C a p s u l e s w i t h D i f f e r e n t Thermal Hi s t o r y  76  C o m p o s i t i o n s as Weight P e r c e n t a g e s f o r of D i f f e r e n t C o m p o s i t i o n s Used in t h e Drum and R o t a t i n g T u b e E x p e r i m e n t s  84  R o t a t i n g Drum E x p e r i m e n t a l E f f e c t s of C o m p o s i t i o n and Heat Storage E f f i c i e n c y of  R e s u l t s Showing the R o t a t i o n a l S p e e d on the Capsules  R o t a t i n g Tube E x p e r i m e n t a l E f f e c t s o f C o m p o s i t i o n and  R e s u l t s Showing the R o t a t i o n a l S p e e d on  Heat  the  Storage  Efficiency  of  R e s u l t s of the S u b c o o l i n g in Erlenmeyer F l a s k s  Capsules  Experiments  the 87  the 88  Performed 91  -  ix  -  Page Table  Table  15  16  I n i t i a l System Cost Components f o r a L i q u i d F l u i d i z e d Bed H e a t S t o r a g e U n i t U s i n g t h e E n c a p s u l a t e d Phase Change M a t e r i a l Estimated Bed  Heat  Change Table  Table  17  18  Operating Storage  Cost  Unit  for  Using  a the  Liquid  161  Fluidized  Encapsulated  Phase  Material  165  Heat S t o r a g e C a p a c i t y o f a L i q u i d F l u i d i z e d Bed Heat S t o r a g e U n i t Using the E n c a p s u l a t e d Phase Change M a t e r i a l S p e c i f i c a t i o n s and Available  Heat  Prices  Storage  of  Some  167  Commercially  Units  170  Table  Al  Experimental  Results  for  the  Fluidized  Bed  Runs  216  Table  A2  Heat  Balance  Results  for  the  Fluidized  Bed  Runs  218  Table  A3  Heat Heat  Transfer Transfer  Rates Fluid  Between t h e C a p s u l e s and During a Typical Cooling  the Run  223  Heat Heat  Transfer Transfer  Rates Fluid  B e t w e e n t h e C a p s u l e s and During a Typical Heating  the Run  224  Table  A4  Table  A5  Experimental  Results  for  the  Fixed  Bed  Runs  227  Table  A6  Heat  Balance Results  for  the  Fixed  Bed  Runs  228  Table  A7  Experimental  for  the  Recovery  Efficiency Table  Table  A8  A9  Results  of  Runs  Heat B a l a n c e R e s u l t s E f f i c i e n c y Runs  230 for  the  Recovery  of  I n i t i a l N u c l e a t i o n and C r y s t a l l i z a t i o n T e m p e r a t u r e s in Capsules with D i f f e r e n t Compositions  231  237  -  X  -  LIST OF FIGURES Page Figure  1  Partial  Figure  2  Heat  Figure  3  Changes Heat  Phase  Diagram  Transfer in  the  Rotating  Figure  5  Photograph  Figure  6  Schematic Diagram Balance  8  Drum  a  System  Rotating  Temperatures  8  Drum  13  with 13  Schematic  Figure  from  H20  Release  4  7  Na2S0i+ -  Coefficients  Figure  Figure  of  Diagram of  the  of  the  Experimental  Experimental of  the  System  System  System  38  Inside  Energy  Boundary  44  Temperature P r o f i l e s of the Storage Unit O u t l e t S t r e a m s f o r a T y p i c a l C o o l i n g Run  Inlet  Temperature  Inlet  Outlet  37  Profiles  Streams  for  a  of  the  Storage  Typical  Heating  Unit  and 56 and  Run  57  Figure  9a  Photograph  of  the  Rotating  Drum  80  Figure  9b  Photograph  of  the  Rotating  Tube  80  Figure  10  Rate  Figure  Figure  Figure  Figure  Figure  11  12  13  14  15  of  Heat  Transfer  Between  the  Capsules  and  t h e Heat T r a n s f e r F l u i d v e r s u s Time f o r a T y p i c a l C o o l i n g Run i n t h e F l u i d i z e d B e d G i v e n i n F i g u r e 7  95  R a t e o f H e a t T r a n s f e r B e t w e e n t h e C a p s u l e s and t h e Heat T r a n s f e r F l u i d v e r s u s Time f o r a T y p i c a l Heating Run i n t h e F l u i d i z e d B e d G i v e n i n F i g u r e 8  96  P e r c e n t T h e o r e t i c a l Heat Recovery from a Function of the F l u i d i z i n g V e l o c i t y P e r c e n t T h e o r e t i c a l Heat Function of the D u r a t i o n  G a i n by t h e of C o o l i n g  the  Capsules  102  C a p s u l e s as  P e r c e n t T h e o r e t i c a l Heat Recovery from the as a F u n c t i o n of the D u r a t i o n of Heating  as  a 105  Capsules  Decay and R e c o v e r y i n Heat S t o r a g e C a p a c i t y as a R e s u l t of H e a t i n g / C o o l i n g C y c l e s with the C a p s u l e s U n d e r F i x e d Bed and F l u i d i z e d Bed C o n d i t i o n s  107  108  -  xi  Page Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  16  17  18  19  20  21  22  23  24  25  P e r c e n t T h e o r e t i c a l H e a t G a i n by t h e C a p s u l e s o f D i f f e r e n t C o m p o s i t i o n s i n t h e R o t a t i n g Drum a s a F u n c t i o n of the R o t a t i o n Speed  112  P e r c e n t T h e o r e t i c a l Heat G a i n by t h e C a p s u l e s o f D i f f e r e n t C o m p o s i t i o n s i n t h e R o t a t i n g Drum a s a F u n c t i o n of Sodium S u l f a t e C o n c e n t r a t i o n  113  P e r c e n t T h e o r e t i c a l Heat G a i n by t h e C a p s u l e s o f D i f f e r e n t C o m p o s i t i o n s i n t h e R o t a t i n g Tube as a F u n c t i o n of the R o t a t i o n Speed  114  P e r c e n t T h e o r e t i c a l Heat G a i n by t h e C a p s u l e s o f D i f f e r e n t C o m p o s i t i o n s i n t h e R o t a t i n g Tube as a F u n c t i o n of Sodium S u l f a t e C o n c e n t r a t i o n  115  T h e o r e t i c a l Heat S t o r a g e C a p a c i t y per U n i t Volume o f Sodium S u l f a t e - W a t e r M i x t u r e s as a F u n c t i o n of Sodium S u l f a t e C o n c e n t r a t i o n over Different Temperature I n t e r v a l s  124  T h e o r e t i c a l Heat Storage C a p a c i t y per U n i t Weight of Sodium S u l f a t e - W a t e r M i x t u r e s as a F u n c t i o n of Sodium S u l f a t e C o n c e n t r a t i o n over Different Temperature I n t e r v a l s  125  T h e o r e t i c a l Heat S t o r a g e C a p a c i t y per U n i t Volume o f Sodium S u l f a t e - W a t e r M i x t u r e s w i t h o u t any A d d i t i v e and w i t h 4 w e i g h t % B o r a x A d d i t i o n as a F u n c t i o n o f Sodium S u l f a t e C o n c e n t r a t i o n  127  T h e o r e t i c a l Heat S t o r a g e C a p a c i t y per U n i t Weight o f Sodium S u l f a t e - W a t e r M i x t u r e s w i t h o u t any A d d i t i v e and w i t h 4 w e i g h t % B o r a x A d d i t i o n as a F u n c t i o n of Sodium S u l f a t e C o n c e n t r a t i o n  128  Heat S t o r a g e C a p a c i t y of the C a p s u l e s per U n i t Volume o f P h a s e Change M a t e r i a l as a F u n c t i o n of S o d i u m S u l f a t e C o n c e n t r a t i o n i n R o t a t i n g Drum a t D i f f e r e n t Speeds  130  Heat Storage C a p a c i t y of the C a p s u l e s per U n i t Volume of Phase Change M a t e r i a l as a F u n c t i o n of Sodium S u l f a t e C o n c e n t r a t i o n i n R o t a t i n g Tube a t D i f f e r e n t S p e e d s and U n d e r F i x e d Bed C o n d i t i o n s  133  -  xii  -  Page Figure  26  Heat S t o r a g e C a p a c i t y o f the C a p s u l e s per U n i t W e i g h t o f P h a s e Change M a t e r i a l as a F u n c t i o n of Sodium  Sulfate  Different Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  27  28  29  30  31  32  33  34  35  36  37  Concentration  in  Rotating  Drum  at  Speeds  135  Heat Storage C a p a c i t y of the C a p s u l e s per U n i t Weight Phase Change M a t e r i a l as a F u n c t i o n of Sodium S u l f a t e C o n c e n t r a t i o n i n R o t a t i n g Tube at D i f f e r e n t Speeds and U n d e r F i x e d Bed C o n d i t i o n s  of  136  C h a n g e s i n a C a p s u l e C o n t a i n i n g 96 W e i g h t % G l a u b e r ' s S a l t and 4 W e i g h t % B o r a x D u r i n g a Thermal C y c l e  139  Sodium S u l f a t e Axial Location with Different  145  C o n c e n t r a t i o n as a F u n c t i o n of from Top t o B o t t o m i n S a m p l e C a p s u l e s Thermal C y c l i n g H i s t o r i e s  A v e r a g e N u c l e a t i o n and C r y s t a l l i z a t i o n T e m p e r a t u r e s for Capsules with Different Compositions  153  Temperature Composition Water Bath  P r o f i l e s in a Fixed Capsule with D i n T a b l e 8 w h i l e C o o l e d i n a 25  155  Temperature Composition Water Bath  P r o f i l e s i n an A g i t a t e d C a p s u l e w i t h D i n T a b l e 8 w h i l e C o o l e d i n a 25 C  Temperature Composition Water Bath  P r o f i l e s i n an A g i t a t e d C a p s u l e w i t h B i n T a b l e 8 w h i l e C o o l e d i n a 25 C  156  157  I n i t i a l Cost of a L i q u i d F l u i d i z e d U n i t per M e g a j o u l e of Heat S t o r a g e F u n c t i o n of the Column Volume Initial U n i t as  C  Bed H e a t Capacity  171  C o s t o f a L i q u i d F l u i d i z e d Bed H e a t a F u n c t i o n of t h e Column D i a m e t e r  Annual Heat Recovery Heat S t o r a g e U n i t as  from a L i q u i d a Function of  A n n u a l O p e r a t i n g , F i x e d C a p i t a l and a L i q u i d F l u i d i z e d Bed Heat S t o r a g e F u n c t i o n o f the Column D i a m e t e r  Storage as a  Storage 173  F l u i d i z e d Bed Column D i a m e t e r Total Costs U n i t as a  174  for 176  -  xiii  -  Page Figure  Figure  38  39  Total Cost of F l u i d i z e d Bed Circumstances  Energy Recovered from a L i q u i d Heat S t o r a g e U n i t Under Different as a F u n c t i o n of the Column D i a m e t e r  Total Cost of F l u i d i z e d Bed  Energy Recovered from a L i q u i d Heat S t o r a g e U n i t as a F u n c t i o n  Superficial Figure  40  Total  Cost  of  Velocity of  Energy  177  178 Recovered  F l u i d i z e d Bed H e a t S t o r a g e U n i t Average F l u i d i z a t i o n Period  from as  a a  Liquid Function  of 181  -  xiv  ACKNOWLEDGMENTS  First Dr.  John  R.  of  Grace  supervision, for  I  wish  and  to  Special  me  thanks  are Mr.  and  department's  secretaries  University made  this  of work  Engineering None encouragement  of  and  many  gratitude  Pinder  for  suggestions,  the  members and  assistance.  for  their  made  to  for  their for  of  have  useful  Many  Natural  help  to  Prof.  their  invaluable  endless  patience  suggestions  for  their are  and  and  support  also  of  due  to  the  Engineering  and  to  the  Fellowship  Science  which  and  appreciated.  without  from  also  co-operation.  Doctoral  assistance  possible  department's  Sciences  University  is  the  thanks  financial  Turkey been  of  stores  friendly  the  Financial  Council would  deepest L.  and  Jarvis,  Columbia  possible.  this  Kenneth  to  Paddy  Canada  British  Research of  is  my  friendship.  due  invaluable  Acknowledgment Council  Dr.  warm  enthusiastic  Research  express  encouragement  and  especially  to  Prof.  constant  listening  workshop,  all  my  the  wife,  loving GUlgUn.  support,  -  current of  and  solar  energy future  energy  Consequently during  Many  is  solar  the  night  The  need  The  that  is  and for  energy  energy  storage.  thermal  of  form  energy  to  purposes,  storage  it  and is  energy  is  solar  unique  have  the  for  application  energy  resource.  provide  If  the  store  to  solar  developed  energy  energy  energy  storage  and  advantages  case,  the  methods  energy  is as  to  in be  heat  a  thermal  and  other  transformation results  proposed.  storage,  its  energy  applications. or  has  transformation  to  to  mechanical  methods energy  been  necessarily involve  desirable  source  limits  storage  not  storage,  these  1974).  which  time-dependent  gravitational  Each  Li  cyclic  energy  energy  of  factor  energy  periods.  storing  the  another.  (Grace  a  storage  storage,  alternative  main  require  energy  For  energy  it  overcast  Each  disadvantages.  important  usage.  include chemical  electrical  one  an  systems  p o s s i b l e ways  These  is  -  INTRODUCTION  1.  Solar  1  of  loss  used  than energy of  for  (thermal  from  available  heating  energy  storage). Probably heating  and  material any  inexpensive cases, and of  of  phase.  materials  these  is  stored  factors  hot  energy  s e n s i b l e heat  energy  easiest  domestic  absorbs  change  the  are  way  water by  needs  rocks  this  storage over  storing is  a  and  undesirable  for  as  large  broad  many  space  without  common  volumes  a  undergoing  and  economical  temperature  cases.  for  sensible heat;  are  Although  very  relatively  energy  temperature  concrete  purpose.  requires  thermal  storage  increasing its  Water, for  of  in  some  (Telkes interval.  1975) Both  -  •Thermal materials, higher  energy  in  addition  energy  relatively principle  or  for  for  usually  use any  greater  and t h e  are  generally  conducted, heat  but  storage  There  storage  segregation, after  following  50 C  problems Design  hot water  for  phase for  pressures (Grace  of  or  .  phase  mean  phase  prohibitively  Common  cycles.  have  While  the is  large  volume  liquid-gas  phase  changes  been  expensive  with  nucleation  Some  generally  the  change  solid-liquid  problems  with  of  of  1974).  identified  for  are  needs.  changes,  that  and L i  solid-solid  alternatives  heat  and  in  (vaporization/condensation)  solid-liquid  high  material for  of  materials either  (Busico  phase  these  studies  been  latent  et  1980).  a l .  thermal  materials to  have  low in  change  and f a i l u r e  published  a  study phase  low temperature  associated with  (4)  this  with  and c o n s t r u c t i o n  material.  changes  changes  of  volumes)  possible  high  and d o m e s t i c  objectives  change  25 C t o  with  suitable  advantages  smaller is  of  energy  are  cycle  properly  are discussed  in  the  sections.  The phase  It  heating  all materials  of  1975). change  heat)  has t h e  phase  difficulty  a number  heat,  considerably  phase  studies  materials  (giving  (latent  solid-liquid  capacity  a r e many  sensible  reversible  impractical  Several  change  but  than  need  phase  (Telkes  release, space  their  -  behavior  liquid-gas  gas  to  by  density  isothermal  absorptions  energy  storage  to  preferred  storage  2  it of  Experimental  were: change  energy  an e n e r g y  temperature  ways  storage of  Selection  storage.  and p o s s i b l e  testing  (1)  the  of  (2)  in  of the  proposed  promising range  Analysis  overcoming  system  a  using energy  of  them.  the  of the (3)  selected  storage  - 3 -  system.  (5) E v a l u a t i o n  design.  The  system  for  important was  findings  space to  of  may  heating  state  that  study  the  system  basis.  Thus  the  results  the  system  performance  present over solar  a  study broad  energy  of  was range  but  and  on  designed  storage  main an  a  no  system.  practical  aim  not  also  hot in  study means  solar  energy  needs,  in  and  the  storage it  is design  development  performance and  system  experimental assumed  system  system  designing  experimental  be  but  experimental  reflect  selected should  improved  research  helpful The  to  water  the  only  be  systems. to  leading  engineering  should  similar  by  to  domestic  should  and  results  lead  the  to  particular  the  to  be  of  the  predicting used  in  the  parameters the  optimum  -  4  -  2. PREVIOUS WORK Phase Change Thermal Energy Storage  2.1  The energy and  selection  storage  their  (TES)  storage  capability  considerations  Other  desirable  be  follows  (3)  Long-term  (4)  Safety  (5)  High  thermal  (6)  High  specific  heat  (7)  Small  volume  change  (8)  Low  heat  Although  of  have TES  lack  have  of  based  choice  phase  their  range.  cost  However,  considerably.  change  Christian  melting  on  thermal  TES  materials  1979):  point  behaviour repeated  cycling  toxicity  conductivity and  density  during  phase  transition  pressure.  (Lane  with  final  and  change  temperature  suitable  freezing  of  (Borucka been  materials.  lists  compounds  of  studies  data  desired the  phase  primarily  r e l i a b i l i t y during  already  fusion  the  (eutectic)  temperature  fusion of  and  vapor  number  selected of  congruent  candidate be  (Segaser  Dependability  change  most  as  (2)  phase  the  influence  A  1980)  of  in  (1)  Telkes  heat  also  of  should  c h a r a c t e r i s t i c s of  summarized  A  the  evaluation  materials  other  may  and  Materials  other  Compounds  high  have  a l .  costs,  phase  to  with  been  1976),  physical  possible  Lane  performed  ranges et  1975,  et  find  the  phase  also  properties change  TES them  1975 most  change  searched  and  w h i c h make  a l .  by  for  and  promising temperatures  their  using  (Tel kes materials  1976,  in  empirical  correlations 1980). are  ineligible.  extensive,  -  The  most  temperatures  in  some  phase  the  of  -  Organic  2  -  Inorganic  esters,  etc.  desirable  fusion  TES  materials,  phase  The  Telkes  1980.  Na+  degree  of  cheap  are their  appropriate  *For referred  to  have  have  range high  about  1978).  change  salts  consist  of  (Chahroudi of  1975).  fusion  The m a i n  their of  freezing  of  inorganic of (Mehalic  some  organic  TES  materials  are  hydrated  positive  of  ions,  and C I " . of The  per unit  water such  A  advantages and  are the  and s e g r e g a t i o n  as  "melting"  and " f r e e z i n g "  respectively  Ca  + +  high  the material  volume  by of  due  to  of  the  these  relatively need  for  to  s i m p l i c i t y , d e s o l i d i f i c a t i o n and s o l i d i f i c a t i o n w i l l as  heats  1.  disadvantages  subcooling  exhibit  s u p e r c o o l i n g and  those  a combination  point  =  fatty  i s discussed in detail  available k  on  Properties  the melting*  agent,  change as  conductivities  in Table  phase  no  are that  half  reduction  P0t+=  heats  listed  materials  melting,  a s S0 ,  conductivities. nucleating  These  low thermal  hydrated  such  phase  are paraffins,  disadvantages  are listed  readily  lowers  1978).  a volume  materials  ions,  materials  are only  inorganic  and  TES  hand,  and A b h a t  in  with  materials.  as congruent  basis  they  storage  hydration  thermal  thesis.  common  temperature  materials  they  materials  50 C a r e g e n e r a l l y  and A b h a t  the other volume  TES  materials,  change  such  materials  These  plus  (Heine  Heine  and n e g a t i v e  desired  high  most  Thermal  hydration and  TES  25 C t o  change  phase  and t h a t  1975,  change  salts.  On  that  15%,  Tweedie  phase  -  change  change  qualities,  on a u n i t  typically and  phase  organic  self-nucleation. of  range  1  Common acids,  promising  5  throughout  be this  an  Table  1.  Properties  of  Typical  Organic  Storage  Materials  for  Lane  a l .  Heine  et  1976,  Low  and  Inorganic  Temperature  and  Abhat  Phase  Change  Applications  1978,  Dow  Thermal  (Telkes  Chemical  Agent  Energy  1975, Retail  Prices  1984)  Vol u m e t r i c Chemical Organic  Compound TES  Mel t i n g Point (C)  Heat gf Fusion (10J kJ/m3)  (Melt  Density Form)(kg/m3)  Price (Can. $/kg)  Materials  Paraffin  (3%  oil)  68-66  156.9  830  0.65*  Paraffin  (5%  oil)  44-42  146.4  765  0.65*  44  154.8  870  2.0*  Calcium chloride hexahydrate, CaCl2*6H20  27  284.5  1630  Sodium  32.4  366.5  1460  0.12  Disodium phosphate dodecahydrate, Na2HP04*12H20  36.1  389.1  1520  0.84'  Sodium t h i o s u l f a t e pentahydrate, Na2S203*5H20  48  349  1670  0.96  Laurie  acid  (fatty  acid),  CHg(CH2)igC02H Inorganic  TES  Materials  sulfate  0.25** I  decahydrate,  **  Na2S01+'10H20 (Glauber's  salt)  •Commercial. **Technical ***Photo  grade  grade.  hydrated  price,  comes  in  anhydrous  salt  form.  ***  -  incongruent  melting  1975).  properties  The  materials  are  In lauric  given  this  acid,  some  change  for  phase  melting  given  in  anhydrous  anhydrous (Weast  1976)  density  "stratifies")  Figure  1,  at  blocking  diffusion  preventing  the  top  the  Tweedie  phase  change  TES  then  are  performed  Results  together  discussed in  chosen  with  phosphate  pentahydrate.  as  the  of  to  the water  C),  high of  most  Chapter  3.  promising  segregation  and  salt,  which  1460  to  solution  and  Na2S0n  cooling,  precipitate  anhydrous  reform  inner Na2S04  part  heat  (3.665  of  large  its  ^ S O ^  of  Glauber's the  a  H20  slurry  2680  difference ( i . e . ,  salt  The  kg/m3 in it  Na2S04 crystals,  precipitate  from  -  solution.  anhydrous  crystals  major  forms  crystals  the  of  to  the  sulfate  the  x  nucleating The  due  a density  due  During  price,  melting,  sodium  have  low  1955).  diagram  upon  its  kg/m3.  Hoffman  phase  phase  a suitable  salt  is  studied  latent  bottom  the  of  is  a .saturated  the  to  because  density  partial  crystals  1980).  remaining  (32.4  (Hodgins  in  extensively  systems  Glauber's  saturated  of  most  availability  Its  the  sulfate  sulfate  crystals  the  energy  behaviour  (Telkes  the  and  were  disodium  materials  was  Glauber's  from  the  of  1952).  precipitate  between  these H2O)  and  seen  sodium  sodium  inorganic  experiments  decahydrate,  temperature  1975)  (Telkes  be  well-known  (Mehalick  1.  one  solar  change  Telkes  can  salts  preliminary  10  is  associated with  As  some  thiosulfate  •  -  study.  for  incongruent  of  this  (borax)  system  (Na^SOit  materials  problem  some  sodium  salt  kJ/m3,  agent  Table  sulfate  Glauber's  suitable 105  salt  of  some  c h a r a c t e r i s t i c s of  Glauber's material  study,  and  of  in  sodium  dodecahydrate with  behaviour  7  and  rehydrating  to  - 8 -  Na S0 + 2  LIQUID  O j  4  LIQUID  UJ I D  o. CO  <  UJ  a.  o.  UJ  Na SO .10H O 2  4  2  LIQUID — i —  30 10 20 WEIGHT P E R C E N T Figure  1.  Partial  Phase  Diagram  of  Na S0  Na2S0)+-H20  2  System  4  (Biswas  1977),  -  Glauber's  salt  crystals.  efficiency  from  cycle  overcoming  this  problem  2.2  change  have  primarily  heat  for  cycle are  is  a loss  (Hodgins  discussed  broad  classified fit  application  of  (a)  Bulk  than phase  and in  in  thermal  Hoffman  the  next  storage  1955).  Ways  of  section.  more  Use  10 of  of  the  the  latent  and  developed  for  the  solar  energy  waste  one  of  the  than  10  Use  Use  mm a l o n g  material  PCMs  of  of  PCMs  latent  systems  systems  1982),  cover  a  are  Some  systems  (PCM)  storage  with  some  heat  unit. PCMs  in  the  containers  minor  capsules  major  axis.  by  having  a  dimension  axis. having  a dimension  a  suitable  thickener  heat  exchange  between  to  less  prevent  separation. contact  transfer  medium.  PCMs  of  (Michaels  characteristics.  in  thickened  direct  of  above  the  the  These  power  number  These  phase  categories:  mm a l o n g  of  A  of  decade,  cooling,  available  widely.  major  heat  past  recovery.  development.  differ  their  in  heating,  commercially  to  change  heat  under  and  surface  phase  heat (f)  are  Encapsulation  bulk (e)  utilize  Macro-encapsulation  than (d)  which  become  according  more  of (c)  have  applications  transfer (b)  and  prototypes  below  into  in  leveling  devices  other  range  systems  investigated  load  storage  and many  storage  been  generation,  Each  to  result  -  E n e r g y S t o r a g e Systems U s i n g Phase Change M a t e r i a l s Energy  may  The  9  in  construction  categories  may  use  the  PCM  and  the  materials.  a fixed  bed  system,  internal  mixing  - 10 -  of  the  PCM,  or  external  mixing  of  the  containers,  thus  mixing  the  PCM  itself. The reviewing using  in  this  heat  will  vessels  probably  the  most  economical  system.  Hoffman  1955).  storage  inside a  At  of  capacity  present  Glauber's not  work  tank  salt  to  Na2S0i+ of  and  the  filled  (1955) with  started  the  to  tubes  heat  the  surface  with  remove  the  crystal  mantle,  to  Glauber's capacity.  the  bottom  salt  system  Hodgins  without l i t t l e  stirred  by  internally  the  other  and  doubt  hand,  (Hodgins  salt.  respect  to to  results  surface the  The  to  Hoffman  suggested  that  moving  moving tanks  energy the that  mechanical filled  mechanical  studies  the  of  16.5%  using  of  saturated  prevent  tank.  and  heat  Their  transfer  the  making  resulting  a rotating  nor  of  crystals  dropped  internally  is  On  of  way  that  the  carried  heat  easiest  the  tested  the  work  tube  is  Systems  emphasized  and  Glauber's  upon  are  drawback  heat  there  efficiently.  and  for  materials.  internal  (tubes),  of  format  experimental  with  first  flow  Hoffman  the  (PCM)  of  be d e s i g n e d time,  for  surface  the  crystals  the  expected  exchangers  the  and  movement  nothing  theoretically heat  resists  Hodgins  coil;  did  segregation  then  transfer  crystallization  rotating  solution  heat  However,  change  material  into  mantle  that  change  phase  PCM  the  coil  phase  using  of  storage on  systems  a convenient  selected  filling is  provides  was  Bulk  transfer  as  substance  crystal  the  salt  study.  grow  showed  storage  this  exchangers a  classification  energy  Glauber's  because out  above  parts.  with  parts  congruent  would  -  melting and  PCMs  some  1981,  and  extended  systems  Michaels  of  this  mixing  fluid  There  commercially  Products  Inc. a  various  depths  is  cooled  flows  agitation,  discussed  This  is  Various study, was  a  the  promoted  by  by  using  show  promising  available  et  1982).  heat  results,  (MacCracken  lowest  are  no  mixing most  (1977  optimum  and and  an  first  bottom  direct  by  mixed  at  the  OEM by  at  a given  opening in  for  an  1981).  nozzles  freezing,  In  melting,  data  on  its  heat  the  possible  up.  contact  level  pressure  maximum  immiscible fluid  salt  performed  salt  unit  diameters rotating  external  1979)  Development  Glauber's  Glauber's drum  the  the  of  Thus,  quantitative  using  of  array.  array  and  nozzles with  or  it  is  thermal  provides transfer  a  very  systems  section.  Research of  nozzle from  of  air  marketed  PCM  arrays  valve,  highest  reported  of  as  of  Sherwood  tank,  salt  array  check  the  and  storage  out  Each  solution  a l .  an  to  injection  (Chadwick  Glauber's  the  this  problem  bulk  using  the  in  rotating and  from  in  Electric  segregation  surfaces  commercially  approach  available  lowest  used  later  Herrick General  the  Internal  sytem,  tank  spring-loaded  There  performance. similar  a  freezing  reverse.  are  water-immiscible oil  by  from  oil  another  (Michaels  increasing  the  Florida,  light,  controlled  the  is  of  pumping  transfer  nature  of  immiscible a  -  1982).  Internal  is  heat  11  using  with  were  Center  nucleating  was  at  detailed to  solve  rotating  external  used  speed  a  a  device.  at  system.  mechanical  mixing.  to The  be  stages 3  drum  the  the  drum  different  found  study  rpm. was  of  the  Nucleation 90%  filled  -  with  Glauber's  found  that  salt  individual  anhydrous  sodium  come  physical  into  causes until  layers all  of  the  by  the  cycles 1979)  was  .  storage  can  be  a  small  loss  it  area  during  of  unless  Inside  and  outside  Herrick  et  are  given  of  the  The  cylinder  rate  ance  of  a  PCMs  in  various  transfer  heat  area  of  heat  storage sizes  per  during  unit  buried  unit of  to  report  the  have  solar  2.  is  containers  inside  release  Nelson the  Depending  on  and  replace 150  drum  very  heat  low  outside  the rates  temperatures  (Duffie  and  and the  outside  lead  study  Figure  factor  in  the  size  and  high the  3.  perform-  Encapsulation a  by  tempera-  in  of  to  Beckman  appear  advantage  with  are  temperatures  from  heat  coefficient  transfer  1983).  the  to  to  Zarnoch  transfer  increased  important  has  due  heat  fluid  and  of  was  over  rotating  coefficients  heat  and  heat  inside  The  an  that  collectors  transfer  layer  sulfate  (Herrick  high  Such  adhesion  crystal a  performance  rates  transfer  latent  volume.  change  from  beneath  sodium  Repeatable  transfer  Figure  each  they  "microencapsulation",  anhydrous  phase  in  (Chen  is  called  (1978)  transfer  when  sulfate  period.  in  another  growing  heat  heat  one  was  and  on  Although  efficiency  decahydrate  accumulate  convection  heating  It  continues,  heat  high  to  analyzed.  process  he  possible  were  sulfate  freezing  excess  low  1980) .  tures  which  volume.  not  collection  a l .  sodium  forced  the  to  Ouden  from  is  the  complete  den  unit by  sodium  decahydrate.  with  and  per  drum,  types  percent  by  suffer  increased  provided a  Galen  area  rotating such  coated  media  transfer  25  reported  van  two  cycles  tenaciously  As  problem,  adding  of  adhere  anhydrous  This  crystals  crystals  contact.  the  -  melting/freezing  sulfate  of  decahydrate. overcome  and  12  of  heat properties  - 13 -  160  1  1  1  1  1  i  i  i  -  t 40  UJ Q  \  \VAAA A 1  100  '  tk.  o  8 0  N  60  C Y L I N D E R H  W\ \  E  A  T  I N S I D E  T R A N S F E R  C O E F F I C I E N T  -  to  -  a  -  X  N  -  40  D CD  C Y L I N D E R  20  HEAT  O U T S I D E  \  T R A N S F E R  V  C O E F F I C I E N T  0  i  e)  10  X  i  i  20  30  i .._  40  i  i  I  I  1  50  60  70  80  90  *  1  *~  108  PERCENT THEORETICAL LATENT HEAT  Figure  Figure  2.  3.  Heat Drum  Transfer Coefficients a t 3 RPM  Changes Heat  in the Rotating  Release at  3 RPM  Drum  from  a Rotating  Temperatures  with  -  of  the  capsules,  smaller of  the  degree  separation and  Lane  (1977)  in  Michigan  Containers  were  commercially  70  of  capsules,  Company  and  encapsulated  pillows mm a l o n g  container  on  from  materials,  The  axis.  change  for  different  applicable material  included  capacity  in  their  during  their  Glauber's  salt  shows  freezing/melting provided. bulk  The  Glauber's Chen  studied  and  the  was  salt  salt  into  thickness,  material,  (1983)  They  decay  of  and  with  tumbling  The in  to  a  rotating  tests  the  (Lane  the  same  as  different 8  to  12  concave  coated,  drum.  than  various and  density salt  in  heat  et  al.  was  storage 1975).  with  capsule for  the  is case  of  above. Pennsylvania,  phase PCM's  mm i n  change including  diameter  surfaces,  usually  Water  tetrahedra  economical  Corporation, of  are  greater  capacity  of  mixing  which  Glauber's  discussed  seven  were  high  a decay  encapsulation  and  most  film.  Pennwalt  tablets  convex  be  mixing  are  the  roll  tablets a  the  a  PCMs.  a p p l i c a b i l i t y of  storage  systems  pelletized  both  heat  sizes  usually  PCMs,  as,  Chemical  Cylinders,  were  showed  external  cylindrical  machine. by  its  storage  pelletization  Glauber's  tabletting  heat  the  it  selection  in  unless for  Nelson  (PCMs).  because  a decay  reasons  found  Dow  and  such  external  storage  stock.  combination  material  cycles  materials  6 mm i n  study  the  the  heat  shapes  containers  Although  advantages easier  at  of  manufacturers'  considered. minor  study  macro-encapsulation to  other  segregation,  a detailed  polyethylene/aluminum/polyester not  to  have  performed  materials  universally  may  transport.  available  the  due  -  cheaper  restricted  were  PCMs  14  with  and  using a  permeability  3  to  a  polymeric of  the  -  coating formed 0.5%  materials 12  16% at  mm t a b l e t s  calcium  material  C  was  by  a  presented in  storage  of  authors  days.  al.  difference Glauber's  beds  capsules  using  bulk  kWm"3 of  10  salt,  of Wax  of  as  and C.  450  numerical  capacity  of  capacity  PCMs as  no  with  Glauber's  PCM  average  salt.  was  made They  did  a  mixture  reliable  3000  capsules  and  the  cycles. energy  hollow heat  in  sealed.  particular,  polymers,  m3  offer  encapsulation  power  densities  on  of  temperature  performed  not  data  Cranfield  then  based  air  to  operating  were  in  thermal  into  per  attaining  were  the  the  were  and  calorimetric  activated $40  experiments  projections  than  processes,  below  an  of  at  mm w h i c h  temperature well  loss  due  temperatures  injected 20  4% a s p h a l t  melting-freezing  low  p o s s i b i l i t y of  Although  more  storage  encapsulation  kWm-3  of  and  coating  Although  numerical  of  and  glycol-water  dollars.  result  number  was  they  2% c l a y  release  addition  no  diameter  silica,  permeability  ethylene  1981  salt,  4.3% weight  water  encapsulated  ambient  mold  Cost  in  the  was  Glauber's  fumed  cycles,  the  encapsulation the  or  investigated  automatic  reported  storage  with  (1981)  packed  cents/kg  heat  4%  of  suffered  medium.  cooling the  of  Since  solution  reported  Technology.  for  150  55  and  believe  They  between  heat  was  encapsulation  potential  to  case  selected coating  coating  transfer  capacity  et  polypropylene  cost.  69  the  compacting,  The  this  of  showing  this  using  Institute  cold  45  heating  Wood  The  was  behaviour  accelerated  change  improve  and  heat  In  -  addition  properties.  period  as  encapsulation  were  to  the  a calcium chloride  suggested  cycling  problem.  with  weight,  over  problem,  a  stearate  adhesion  latex 40  was  15  the  with theoretical  mention  the  -  possible bed  decay  of  its  stabilize  heat  controversial find  many  discrete Marks that  cells  all  Swayne have  topic  number  1980,  capacity  due to  cycling  all  discrete  must  of  et  phase  under  fixed  decrease will  to  thus  closed  ideality  reliable  to  product high  achieve  1981). either  If  factors  have  1980, use of  the  of  in 1975, clear  Page  and  thickeners  separation  between  which suspension  cells,  the  as t h e  size to  nucleation to  to  an  is also  can lead  of  the  other  within  each  transform  relative  volume  the necessary amount  the wall  the chance  it  in "uniform"  approach  be r e q u i r e d  over  nucleators  this  a  possible  Chahroudi  (Marks  to  that  Both  hand,  tend  most  encapsulation  gross  are held  the  system  and t h e  including  be noted  increasing  of  to  i s the is  and 1 9 7 6 ,  cells  discrete  for  is decreased,  using  reliable  achieve  and Swayne  increase.  efficiency.  will  However,  also  Page  material  small,  It  salt  1975  thickeners  cycles  the other  process  in order  would  On  solids  hydrate  ability  should  a l . 1975,  will  of  decreases.  It  encapsulating  overall  a given  (Telkes  prevention  all  the case  be g u a r a n t e e d  encapsulating  cells  that  cycles  in d i s c r e t e  rehydration  e . g . the  reversibly.  cells  In  cells  drawbacks:  (Lane  the  times.  performance  cell  ensuring  use of  literature.  necessarily  in mind:  the  Glauber's  1981).  are not  purpose  in  storage  thickeners  and Swayne  or  freezing/melting  stable  Encapsulation  a common  participate  a  cells  freezing/melting  the claims  thus  over heat  claiming of  Page  PCMs  in the  and/or  1981).  phases,  in discrete  storage  studies  extensive  the  storage  -  conditions. Encapsulation  at  heat  16  a negative  the  stability  of  thickness  leakage  of  of  or the  impact  the size  on t h e  of  - 17 -  Telkes thickening cooling  agent  Swayne  and  found  (1981) that  capacity  of  cycles.  They  depends  on  believed  surface  thickening  increase  progressively  energy  1981).  phase  for  material  formation  of  inhibitor  and  and  on  (1975)  Glauber's  large a new  gel  be  information  on  the  agents  Researchers  in  the  Calor  are  for  formidable  stable  suspensions.  are  the  becomes  for  reported  The  decay  more  used  in  Group  in now  Ltd.,  the  and  achieving on  hydrogels  salt.  They  long-term a  range  by  the  may value bulk  as  life  of  from  Marks is  size  (1982)  no  final  Swayne  product. have  1981)  (including concluded  stability of  is  Swayne  crystal  There  (Page  U.K.,  Glauber's  reported  of  of  the  pulp  cycle  arise A  testing  and  % wood  to  cycles.  700  c o l l o i d s and  working  were  reduce  (Page  pulp.  very  size  crystals  to  effective  wood  over  equilibrium  weight  thought  150  inability  these an  Telkes  after  crystal  enough  5  the  the  than on  of  was  agent  nor  reach  by  ultimately  the  theoretical  and  crystals  of  Page  storage  unaltered  hydrate's  important  use  value  Also  size  curves.  heat  thickeners  c y c l i n g to  the  thickening  They  the  proposed  inorganic  problems  weakness;  thickening  to  attapulgite)  influence  of  Na2S0it  of  heating  1000  patented  The  ideal  solutions.  50%  salt  the  suitable  than  mixture  remaining  only  cycles.  300  candidate  to  of  50%  a  cooling  optimistic.  forces  thermal  cycle  claimed  studied  to  the  as  more  heating  stability  electrolyte  separation  per  as  the  underlying  Chahroudi  thickener the  an  turnover  that  particles  to  local  be  d e c l i n e d to  clay  reported  tested  overly  col 1oidal-type  strong  and  identical  (1980)  c l a i m s were  believed  where  Marks  attapulgite  salt  practically  mixture  in  proposed  Glauber's  and  the  the  periods  these  for  cycles with  and  long  (1975, 1976)  of  that  there  these  water-soluble  synthetic  - 18 -  polymers  which  agents  to  PCM  to  form  the  category  can  form a  inside  stable of  of  (50  gel  to  2000  encapsulated  including  Pennwalt  small  capsules Fouda  studied medium  the  by  This  weight  this  2  mixture  solvent  performed  column.  They  temperature Canadian 85  percent  and  the  weight  C)  the  a 0.30  not  mass  of  easily  cells  PCMs  the  fit  into  with  several  paraffins, agent  in  the  PCM  encapsulated  They  tested  the  companies  Company.  3M  percent  Although the  possibility  mixtures  by  Biswas  Research  Glauber's with  of  into  such  of  Canada  2  to  30%  at  diameter  by  the  transfer  fluid  maintain  above  a 6  Thermal 90  hour  and  It  in  the  rate  cycle,  to  be  and  a l .  70% 1,  used  1%  paraffinic  Experiments  flow  should  +  change  Figure  et  m liquid  e f f i c i e n c i e s were  percent.  2  fluid.  1.83  cooling  phase  Fouda  storage  percent  Na S0i  shown  C.  transfer  heat  the  weight  agent  m inside heat  as  As  32.4  nucleating  i m m i s c i b l e heat  by  as  weight  68.2  (1977).  melting  Council salt  mixture  H0  corresponds  conditions. often  the  by  National  2  to  and  exchange  congruent  controlled  winter  NCR  heat  2  in  (20  at  suggested  as  whole  does  capsules.  material  (Na B407«10H 0) a s  "Varsol"  cross-linking  question.  contact  undergoes  borax  studied  c h a r a c t e r i s t i c s of  31.8  the  discrete  salt-nucleating  composition as  H 0,  weight  were  direct and  a  (1984)  operating  salt  material.  a l .  forming  obtained  Glauber's  concept  diameter)  plastic  were  remains  et  using  Glauber's  by  the  in  in  penetrate  with  encapsulation.  (1975)  Corporation,  results  encapsulating  um  or by  Tweedie  solution  This  thickners  and  in  which  network.  encapsulation  paraffins  satisfactory  reacted  molecules"  either  Mehalick  small  further  "giant  Instead solution,  be  depth at  a  simulate  generally  noted  constant  that  above the  - 19 -  theoretical weight  percent  eutectic  20  C  heat  to  storage  H0  C  (see  Recently, building  1982, PCM  this  building  the  the  there  mixture  material,  stabilizing  compatibility  has  external  the  percent  60  phase salt  is  one  of  its  or  internal  At  certain  change  low  in  this  phase  of  the  cost.  this point,  change  building  materials  (Grodzka  et  al.  It thermal the  same  system  difficult  storage  basis.  performance  a  such  to  systems  Evaluation is  of  complex as  heat  stored  medium  transfer  coefficient,  storage  life-time. specific  The  needs  which  material, relative  in  develop  is  depends is  a l .  candidate  in  on  with  as  the  the  results  concentrated widely  combining  are  et  almost  PCM  PCMs  generally  of  on  used with  Although  1982).  each  the  importance At  the  reported  results  There per  unit  system  and of  of  are  it  is  an  a  heat  these  many  of  not  on  reported  or  per  affecting  unit  mass,  fluid-to-storage  costs  are  energy  factors  transfer  factors  there  performances  a thermal  volume  operating  present,  are  operates,  available  capital  case.  the  performance  problem.  over  heat  Lang  compare  the  interval  the  of  problems  because  temperature heat  a  nature.  usually  energy  storage the  is  a p p l i c a t i o n , the  the  materials  p o s s i b l e ways  1982,  to  to  it  research  on  science  70  between  likely  Since  field  also  materials  of  (Grodzka  most  mixing  and  of  that  and  t  interval  materials  materials  field  2  of  temperature  building  important  Na S0i  percent  a considerable effort  development  efforts. of  weight  about  for  been  because  the  30  7.2.1).  Glauber's  apply  of  only  containing  purpose  to  is  Section  1982).  impossible  of  salt  materials  Lang  for  mixture  2  Glauber's  40  capacity  and  area,  of  expected  depends two  cost  on  standard  the methods  -  for  testing  94-77 and  thermal  (1977)  and NBSIR  accuracy  tested and  of  these  that  because  theoretically loss  has  been  they  used  94-77 1.  in these  will  at  This  method,  the Argonne  be a d e q u a t e committee  As a  f o r comparing found  the  to  (1981)  storage  of  error  result  of  to  than  the  i s  heat  the  project  committee  Laboratory,  USA t o  latent  systems  following  unit  meaningless  or extracted  a standard  National  change  lead  the source  methods.  94-77  phase  ASHRAE  applicability  Marshall  c a n be s t o r e d  He a t t r i b u t e d  The  discussion.  paraffin-based  energy  performance,  1974).  a n d NBS p r o c e d u r e s  more  i n t h e ASHRAE  that  a  on t h e r m a l  and H i l l  a r e under  using  imply  -  based  (Kelly  methods  possible.  a l . 1983).  ASHRAE  74-634  by  established  standard  devices  t h e ASHRAE  expressions  inadequacies  et  these  methods  reported  values  storage  20  heat  inadequacies  devise  a  (Cole  with  the  method:  The t e m p e r a t u r e  range  of  the test  i s not  adequately  specified. 2.  The method not  3. (  4.  storage  to  calculating  the theoretical  storage  capacity  is  clear.  There  is  no s p e c i f i c a t i o n a s t o  prior  to  testing.  There  is  no t e s t  Although expected  of  lead  systems,  the to  study a  for  degradation  performed  new s t a n d a r d  n o new m e t h o d  how t h e u n i t  of  the  storage  by t h e S t a n d a r d method  has been  of  testing  published  should  at  cycled  devices.  Project  Committee  thermal this  be  energy  time.  is  -  3.  Although thermal  energy  materials clear  has  that  today's solve  i t i s clear storage  many  phase  world.  energy  storage In  2  +  2  heat  reliability  storage  thermal  performed  3.1  S e l e c t i o n o f Heat Storage  these  thiosulfate  material  with  i t s 48 C phase  of fusion  and  congruent  suitable  this  i s a promising  nucleating  material.  agent  No s o l i d  phase  sodium  and  were  change  dodecahydrate  heating  sulfate as the  and  storage  study.  (NaHP0\ 2  decahydrate most  domestic hot c a p a c i t i e s and  preliminary  making  to  thermal  forthis  sodium  Some  development  thiosulfate  chosen  heat  before  and  n o t commori i n  experiments  thefinal  selection.  Material  (TES)  of  costs,  are  motivation  phosphate  pentahydrate  (also  phase  change  melting  which  research  survey,  salt,  materials  systems  performance  cycling.  i n photography)  of a dihydrate  storage  f o r space  fixer  existence  i t i s also  sodium  of their  were  heat  heat,  theinitial  materials  on repeated  Sodium  of sensible  0  on t h e b a s i s  with  t h e use  f o rfurther  as Glauber's  that  change  ( C H 3 (CH 2 )i C0 2 H)  acid  2  phase  energy  was  i n Chapter  of suitable  of t h el i t e r a t u r e  (Na2S0i»10H0), k n o w n  needs  This  reviewed  heat  higher  (Na2S20V5H0), d i  2  water  thermal  develop  units.  • 12H0), 1 a u r i c  thestudies  over  i s a need  and  thelight  pentahydrate  promising  from  v i at h el a t e n t  change  t h eproblems  PRELIMINARY WORK  advantages  There  21 -  stores  called  change  thermal  temperature,  behaviour almost  when  (Telkes  no l a t e n t  a r et h e p r i n c i p a l  i s precipitated  "hypo"  problems  andused energy  349  x 10  3  1975). heat  and  storage kJ/m3  The the lack  associated  t h e pentahydrate  as a  with  melts,  - 22 -  but  the  excess  containing during  vessel  freezing  pentahydrate,  7-1  C,  water,  will  charcoal  et as  a l .  Na 2 S 0 «5H 0  and  2  tested  nucleation where  it  in  is  Na 2 S 03«5H 0 is  2  given.)  Na S0  no  nucleation  use  by  was  of  was  !+  action  Glauber's  C)  is  initiate of  In  Glauber's  this  the  agent  the  agent  for  they  do  was  over  a  20  for  case,  the  at  that  to  15%  as  salt  at  appear,  the and  only  addition (No  weight,  but  range.  temperature Glauber's  (borax) latter these  should  of  also  but  no  percentage  there  was idea  still is  to  for  Na2S203*5H0 2  salt,  temperature. should  agent,  Another agent  percentage  2  The  cases  to  +  Na S0i+  a nucleating  No  melting.  2  as  range.  mixtures  several  Na S0i  of  2 K  cooling.  for  6.5  of  about  complete  K.  activated  study,  and  to  by  (Telkes  charcoal  except  a nucleating  fusion  in  present  without  sodium  percent  heating  subcooling  temperature  Glauber's  should  the  agent  weight  subcooling,  tried K  the by  subcooling  +  crystallization salt  K  of  repeated  subcooling  20  resulting  percent  reported  the  weight  0.3  occurred  i+  fusion  that  phase  K  20  specify  agent,  for  Na S0  a  not  reported  increased  2  needed  nucleating  the  over  is  satisfactory  (Na S0i »10H20)  salt  above  nucleating  a  2  therefore  water  1981).  (1978)  weight  the  melts  cooling  reduce  of  which  within  observed  Na2S203*5H20. (48  Abhat  could  5%  nucleation  2  and  excess  top  dihydrate,  tubes  that  the  or  but  test  some  to  to  preliminary  observed  believed  Heine  2  ml  rise  conversion  0.2, 0.3, 0.4, 0.5  10  was  complete  nucleating  the  to  Since  necessary  (1978)  a good  During  were  report  pentahydrate,  acts  3  is  tends  1981).  give  (MacCracken  subcooling.  2  to  some m i x i n g  Stunic  1975).  order  studies  thiosulfate  lighter,  (MacCracken  in  form  Some  being  32.4  be  present  Then  nucleate  C.  The to  crystals  - 23 -  Na2S2 3*5rl20 c r y s t a l s  a t t h e same  n  investigated  with  Na S0i »10H 0  in  formation  Na2S0it• IOH2O  t  2  2  crystals  of  the presence of  unless  (71  a reduced  phase  temperature disodium having  above to  a bulk  change  389  of  system  n  71  above  during  each  case,  Na2S203*5H 0  b u t no  as a  2  phase  melts  in  flat  change  problem at a  plate  higher  which  solar  material  and b e c a u s e  melting/freezing  C, a t e m p e r a t u r e  cycles  would  lead  collectors  x  TES m a t e r i a l  10  3  kJ/m3  fusion  to  that  cooled,  which  of  C phase  hydrates.  stable  stable than  the  of  hydration  d e c r e a s e s t h e heat  involved  in this  system  accepted  e q u i l i b r i u m and c o n v e r s i o n this-study.  Since  and b e c a u s e rate  poses  of  data,  phase  should  to  hydrate and t h e  capability  of  Na HP0i »12H20 t  heated  dodecahydrate  i s more  the lack  2  is  a problem  storage  there  However, mixture  solid  but the rate  1975).  a  the dodecahydrate  C, t h e h e p t a h y d r a t e  (Simpson  change  If  36  to  another  1975).  (Telkes  the f i r s t  i s more  is  2  about  cooling  in  of  4  i t s 36.1  of different  equal  and t h e n  2  with  heat  has a number  appreciably  (Na HP0 »12H 0)  dodecahydrate  the heptahydrate  further  #  The l a t t e r  compound  considered  In  of the nucleation  efficiency  composition  With  weight  1980).  temperature  C.  65% b y  borax.  Na2S2 3 5H20  use  because  i s heated  the dodecahydrate,  presence the  study  i s the heptahydrate, 36  15% t o  from  K subcooling^  phosphate  phosphate  a high  appear  and  c o m b i n a t i o n was  by w e i g h t  a n d may a c c u m u l a t e  and Beckman  promising  5%  with  This  c r y s t a l s was o b s e r v e d ,  not to  collection  Disodium  varying  the dihydrate.  C)  the system  (Duffie  to  f o r 20  was d e c i d e d  temperature  to  2  2  in the present  (PCM) of  Na 2 S 03«5H 0  appeared  It  compositions  time.  than  of  one  widely was n o t  -  Laurie material  considered  temperature Abhat  acid,  of  1978).  melting, of  during  the  common  Laurie  were  which  c a n be s t o r e d  range  of  20 C t o area  ratio  volume)  even  occurs  disadvantage. 1),  it  where  absolute  1auric  further.  during  were  is  stores of  acid  that  the  water  is a  change  kJ/m3 such  with  of  as  1.6  and t h i s change is  relatively  A  acid  stated  acid  in  (in  fusion. times  the  energy  temperature a  higher  decreases (about  the  15%  by  another material  restricted  behaviour  congruent  1auric  expensive  is  and  1978).  1auric of  TES  (Heine  conductivity  and t h i s  r e l i a b i l i t y and i s o t h e r m a l  phase  in the  volume  its application  change  advantages  roughly  required,  freezing/melting,  i s concluded  performed of  phase  and Abhat  i t s low heat  A considerable  lauric  103  qualities  i t s low thermal is  x  disadvantage  volume  system  has a  (Heine  and a l l  acid  i n the. equal  Since  Table  cycles  materials)  exchange  154.8  nucleation  The main  Due t o  of  organic It  desirable  experiments,  that  only  work.  fusion  and s e l f  50 C .  heat  of  and f r e e z i n g  showed  was t h e  h a s some  organic  -  preliminary  observed.  other  Calculations  above  acid  preliminary  2.1  acid,  44 C and h e a t  melting  with  surface  in the  no s u b c o o l i n g  number  Section  a fatty  24  are  to  (see  systems  first  priorities. Glauber's TES  material.  Glauber's  discussed  in  (low p r i c e ,  a n d a known  salt  incongruent  (Na2S0i+«10H20)  As d i s c u s s e d  characteristics temperature  salt  is  in  melting. Section  Section  high  heat  nucleating  segregation Methods 2.2.  is  of  another 2.1,  of  anhydrous to  h a s many  fusion,  agent).  employed  it  promising  The  phase  desirable  suitable key problem  Na2S04 prevent  change  crystals  freezing with due  segregation  to are  -  Some 10  ml  initial  sample  several  experiments  tubes.  times  Tests  i n 75  ml  literature  (Chahroudi  media.  was f o u n d  the  It  medium  saturated Na2S04 Even  in a salt  could  be f o u n d ,  sharp  crystal  1980,  Page To  material found. that is  and Swayne  during  the  freezing  except  material  Since the  for  of  cycles  failure for  appears to  in  a  10  Glauber's  repeated  there  was c h o s e n  of  in  to  the  inject  medium.  the  suspension to  in  anhydrous  suspension  remains  salt the  melting  throughout  the  the  suspension  the Glauber's  incongruent from  as  in  repeated  as suggested  tried  crystals  problem  period,  experiments  crystallization complete  of  were  salt  matrix  matrix  be s o l v e d  by (Marks  1981).  segregation  Preliminary  the  a number  pulp,  was e a s y  destruction  the  maintained.  3.2  after  of  Glauber's  results  were  it  salt  with  replace  separate  the  solve  almost  salt  edges  While  almost  problem  to  the matrix,  distributing the  Wood  and a s b e s t o s  into  remained  a way o f  promising  tubes.  manner.  solution  -  performed  be d i f f i c u l t  uniform  crystals  if  1975), to  were  giving  sample  25  ml  a n d 75  salt i f  with  due t o  salt  physical ml  by m i x i n g process  sample  4 weight  sufficient  be no o t h e r  crystallize  this  Glauber's  suitable  cycles to  of  tubes percent  mixing  problem  must showed borax  is  with  segregation,  the  Glauber's  this  study.  Proposed Heat Storage System U s i n g G l a u b e r ' s S a l t The  system  desirable  c a n be s t a t e d 1.  Low  cost  2.  Complete  c h a r a c t e r i s t i c s of as of  a phase  change  heat  storage  follows: phase  phase  change  change  material  with  theoretical  latent  heat  release  be  - 26 -  3.  Reproducible  melting  4.  High  heat  rate  of  transfer Small  5.  temperature  use  7.  Low  capital  cost  8.  Low  cost  operation  of  of  storage of  hollow  polypropylene  liquid-solid  unit  fluidized  rotating  is  Glauber's  General  area  in  2.  precipitate  enormously:  the  the  compared  helps  alleviate  to  easier  more  to  a  the  Mechanical  and  Glauber's  fixed  bulk  increases  and  heat  has  solution  Glauber's  segregation of  than  advantages,  the  is  drum  is  about  with  salt  also  a  capsules the  much  expected  that  most  area m3 more  used  anhydrous larger unit,  thus  entire  type  drum  per  of heat  by  length-to-diameter  the  and  a  external  0.2  times  30  in  offer  transfer  the  storage and  to  sufficient  heat  of  in  rotating  containing  between  problem  mixing it  the  a  appears  when  capsules  area  investigated  salt  unit  1979)  encapsulated  system,  storage  Zarnoch  mixing  bed  above  rotating  salt  was  Glauber's  interfacial  efficient  these  and  saturated  recovery.  addition  storage  maintenance  spheres a  A  mm s p h e r i c a l  (Herric  capsules to  system,  a cylindrical  Since and  bed  by  Encapsulation  25  than  Electric  of  easy  characteristics listed  volume  salt  storage  Encapsulated  supplied.  storage  ratio  tube.  desirable  transfer  between  Safety.  mm d i a m e t e r  mixing  heat  volume  and  heat  the  and  equipment  study,  a  storage.material  medium  this  and  cycles  between  difference  Efficient  In  of  transfer  6.  9.  freezing  medium  transfer  25  and  t  in  the  encapsulation  gives  their  Na2S0t  improved  contents  storage  is  volume.  scale-up  of  the  heat also In heat  - 27 -  storage  unit  will  transportation  of  be  easier  the  salt  in is  the  case  easier  of  in  an  encapsulated  capsules  compared  PCM, to  and  bulk  transportation. Fluidized mixing  bed  systems  of  the  particles  collision  and  vibration.  therefore  reduce  it  might  be  theoretical transfer the  latent  area  and  in  Since  other  the  have  give  a  high  cycles  the  a  of  Glauber's  salt  Thus  it  to  heat to  time  the  with  rotation,  capsules  the  the  should  heat  surface  area  between  of  the  energy  recovery  in  Glauber's  the  that  complete  high  total  rapid  continuous  conjectured  transfer  have  if  was  time,  present  should  long  it  change  same  generally  and  undergo  equal  leading  agent,  over  of  uniform  particles  phase  rate  media,  nucleating  freezing-melting  At  system,  is  supply  The  complete  additive  to  problem.  release.  transfer no  them.  Fluidization  fluidized  should  delivery. than  to  heat  a  heat  within  known  segregation  possible  capsules,  storage  the  are  or salt  reproducible  segregation  can  be  prevented. For thermal  energy  fluidized between to  domestic  bed  the  recover  salt. since  all  combined equipment.  storage heat  water  total  one  at  could  system.  water almost  will the  necessary  (except  the  This  would  unit.  Rapid  needs,  medium  and  volume  components in  water  storage  capsules hot  The  hot  heat  transfer  the be  water  combined  Since be  the  very  phase for  tank, a  single  small,  it  purpose  will  collector)  also  reduce  the  storage  be  temperature  energy  the  tank  total  unit  also  and  using  difference  will  solar  in  exchanger  temperature  change  this  in  heat  be  possible  of  the  minimized  would cost  be  of  means  a  lower  a  -  temperature efficiency  in  used  as  the a  uniformity  of  particle  water  unsteady  state  operations  inside  study  of  fluidized heat  storage  medium,  leading  mixing  is  needed  freezing.  time. act  the  the the  When  as  a  only  Hence in  good  the  a higher  view,  another  However,  should  of  to  of  or  the  the  in  leading  collection  1980).  point  for  -  collector  temperature  advantage  fluidize  undergoing  Beckman  experimental  disadvantage  recirculate  all  and  energy  calorimeter  considerable A  solar  (Duffie  From be  the  28  is  insulator  leading  because  This  is  bed  that  is  is  fluid  at  increased heat  it a  sufficient  to  fluidize  (packed  bed)  state,  small  heat  to  rate  to  costs.  material  necessary  to  the  necessary  operating  storage  of  may  a  systems.  the  defluidized  system  storage  to  not  bed.  bed  energy  transfer  when  it  the  fluidized  is  the the  losses  to  system capsules the  surroundings. The  purpose  compare  the  studied  in  the  motion  speeds.  The  collision  of  a  to the  of  find  of  of  studying  with  rotating  influence  only  was  results  of  tube  different  the  drum  capsules to  Glauber's  optimum salt.  be  capsules  fluidized  and  in  modes  c a p s u l e s was  rotating  the  the  the  a of  bed  fixed  case.  The  drum  mixing.  For  the  around  combined  investigated.  speed  a  rotating  rotation  allowed  in  and mode o f  An  axes  effects  to  to  rotating  their  of  was  capsules order  the  aim  mixing  in  bed  of  at  to were  determine tube,  overcome  the  various  rotation  these  also  and  experiments segregation  -  29  -  4. ENCAPSULATION OF GLAUBER'S SALT  Encapsulation study the  because  whole  important  size,  transfer  shape  area  and h e n c e  capsules. volume  affects  per unit  larger  fraction  fluidized  fraction  the  capsule  no  phase  of  this  and e c o n o m i c s  beds  of  because tend  the  the  of  economic  important  result  i n a change  period  of  time,  of  important Spherical  be s m a l l e r  for  in  crystals of  have  any d i f f u s i o n  the composition the degree  the  within of  the  voidage by t h e PCM.  strength,  important edges  and c a n be material  Permeability  through  the  with The  the encapsulating  maintenance.  on  are  i s occupied  sharp  unit  the  compared  are  the  the  t h e bed and  material,  conductivity  by  capsules  which  encapsulating  higher  per  influence  volume  and e x t r a  affecting  occurs  storage  sulfate  because  occupied  and d e n s i t y .  Destruction  losses  volume  a  inside  encapsulation  volume  and thermal  1980).  of  change  gives  fluidization  same  the  three  segregation  the voidage  to  inertness Sodium  total  volume.  are  minimum  cost  h a s an  of  (Marks  is  of  the  selection  considerations.  to  total  velocity  particles  permeability,  lead  part  the capsule  and l e s s  of  i t s volume  per unit  fluidization  non-spherical  Since  of  a lower  higher  for  In  volume,  capsules  size  are the  capacity  the  the  Disadvantages  material,  abrasive  important  performance  the  costs  encapsulating  preferred  of  pumping  material.  affects  the e f f i c i e n c y ,  Decreasing  encapsulating  minimum  i s an  lower  and t h e  storage  salt  and m a t e r i a l  parameters.  velocity  Glauber's  system.  The  heat  it  of  of  the capsule  the capsules  crystallization  over  would  the would a  and hence  long the  - 30 -  efficiency the  of  the  encapsulating  keep  the  wall  should  this  turns  and  capsules have out  system.  Since  material  must  and  their  high  to  be  long  be  completely  contents  thermal a less  capsule  from  is  impermeable  deteriorating.  conductivity important  life-time  to  factor  promote than  required,  and  inert  The  capsule  heat  to  transfer  strength,  but  permeability  inertness. The  cost  of  encapsulating  governing  its  applicability.  saving  the  storage  in  transfer  surfaces,  encapsulation, to  a  be  and  a high  uneconomical.  analyzing  the  tank,  the  and  its  economics  the  encapsulation  time were of  because  of  Since  behaviour  circumstances,  Although  corrosion cost  there  there  caused  present  effort  limited.  Glauber's  salt  no  may a  the  large  for  is  factor  considerable internal  heat  eliminated the  salt  study  under  system  aimed  process  suggestions  quantities  are  at  different  encapsulation and  by  overall  research  information  in  a  cause  Glauber's on  be  PCM  is  a critical  need  the  work  spent Some  is  will  is  by  encapsulated  and  salt  encapsulation  the  of  Glauber's  for  outlined  below.  4.1  Tabletting and Coating of Glauber's Salt Tabletting  means  of  cheapest coating  then  encapsulation way are  of  conditions and  forming  highly  pharmaceutical  coating  and  the  considered separate  developed  industry  required  coating  to  choice  and  (Ridgway  the in  resultant  this  study.  This  capsules.  Although  automated  processes,  1982),  the  form  tablets  which  of  coating  material  a  tablets  additives  are  was  is  widely and  specific  first  probably  tabletting  sufficiently are  the  the  and  used  in  tabletting strong for  each  for  the  -  application; find  the  long  right  1983),  difficulties in  this  manual At  in  pressing  made  it  salt  was  salt  particles  finely  The  stearate Nelson  many  lower  the  been  Some  with than  nature  literature  is  often  30  At  required  of  this  to  hard  4%  around  were  using  of  silica,  overcome  to  32  being  temperature  fumed  to  enough  are  2% c l a y  tabletting  Chen  and  causes  tablets  hemispheres  temperature  this  salt  simple  near  mm. salt  when  the  Glauber's  the  harder  25  even  fine  and  a  Glauber's  coat,  C,  performed  diameter  i n c o m p r e s s i b i l i t y of  tablets  at  reported  the  1980,  experiments  salt  temperatures  sticky, formed  preliminary  hollowed  C,  (Schmok  Glauber's  Glauber's  two  produce  ground. were  and  loss  ethylene  selected weight  loss  was  rigid  uniform,  Nelson  in  (1983)  in  no  air  4% at  were  may  Pennwalt  melting  than  0.5%  necessary  calcium  difficulties  be  solved  mixture  40  C over a PVC  in  by  as  and  using  period  solution  water-impermeable  coating.  doubt  coating  the  case.  (Chen  and  by  of  Water Although  69  medium,  weight, days.  (commercially coating  permeability the  done  by  the  even  During  water  solution the  suffered  4.3%  our  available  material.  However, was  Pennsylvania,  a calcium chloride  transfer  latex  a water-impermeable  because  materials.  each  heat  16% a  Corporation,  coating  problems  asphalt  experiments, as  of  available  glycol-water  tried  and  air  problem  coating,  preliminary  a  device  commercially  weight  glue)  empirical  1983).  permeability or  in  spherical  Addition  has  Chen  and  make  tablets  coating.  an  i n c o m p r e s s i b i l i t y of  impossible to  point.  tried  studies  tabletting.  to  temperatures  for  to  the  study  of  -  parameters.  According Nelson  research  31  The  coating  hand.  Also  as  a  PVC  result  was  was the  not  -  strength  and  durability  Coating special  is  a  equipment  discontinue concern  of  the this  of  the  complex  (Clarkson  32  coating  process 1951,  experiments  study.  A  simpler  more  4.2  Encapsulation of Glauber's Salt method  polypropylene  spheres  10  20  35 mm a n d  mm,  mm,  available. were  25  a  reasonable  (1  mm);  flow  hence  fluidized  of  hollow of  the  capsule  sealing  job  more  A mixture injected,  polypropylene sphere. anhydrous  The  a  tedious  an  spheres mixture  for  water of  was  sulfate  2.1  had  fine  were  use  and  it  needs  decided  not  the  of  to  main  encapsulation  more  A  the  the  have  Denmark. are  considerations  ratio to  capsule  of  bed  obtain  1982).  same  a larger  storage  a The  thickness  volume  make  size  diameter  (2)  wall  capsules  size  available  of  spheres  larger  10  Grace  Small  for  fraction  the  unit.  injection  (4)  Larger  fluidization.  syringe,  salt  into  mm d i a m e t e r mixing  powder  (1)  than  almost  a given  Company  following  1953,  (3)  commercially  hollow  since  diameter  by  was  Euro-Matic  96% G l a u b e r ' s  prepared in  be  flow  automatic through  to  The  (Schwartz  smaller  consisting  using  sodium  should  It  they  selection:  material.  large  by  diameter  spheres  variables,  mm d i a m e t e r  size  distribution  was  chosen.  bed  (Dc/dp)  spheres  require  were  inadequate.  r e l i a b l e method  chosen  50  be  in Hollow Polypropylene Capsules  produced  capsule  by  capsules  was  the  diameter  sizes  occupied and  in  larger  particle  different  mm,  mm s p h e r e s  important  requires to  25  to  1976).  because  adopted.  hollow  many  Ranney  coating  encapsulation  appeared  with  was  The  -  form  25  and mm  holes,  4%  by  weight  hollow one  calculated (BDH  Borax  drilled  amounts  Chemicals,  in  each  of analytical  -  grade),  distilled  analytical  grade).  stoichiometric borax)  water  had  to  Since  amount be  used  through  a  uniform  suspension.  1  kg  each)  uniform to  small  and  which sealed  by  7.7  after  ml  fine  heat  freezing on  a  hot  sealing. density  capsule  density  in  kg/m3.  the  average,  volume.  The  The  observations  were  both  and  the  capsules  after  the  melting  capsule  of  the  capsules  the of  contents an  average  checked water. used  experiments  that  They it  over No  in  of  the  a  weight  The  showed  probably  wall of  The  of  were  given  material one was  from  ensure  each  sphere  observed were and  weight weight  changes  holes  was  were  about and  had of  an  the  was  the  on  capsule  runs.  the  for  (about  contributed,  Table  and  year  year  a 0.07%  in  a  allowing  experimental  are  as  deviation  % of  translucent  them  volume  capsules  17.6  and  to  filled  (polypropylene) and  in  volume  70  sulfate  stirrer  standard  system  one  results  capsule  the  inject  mm i n j e c t i o n  spheres  the  change  only  2.1  in  batches  the  were  lasted  small  for  experimental  which  in  soluble  mixture  a magnetic  sample  period  the  allow  capsule the  keep  to  to  weight  during  able  left  material  walls  be  Chemicals,  (sodium  was  kg/m3.  capsule  to  total  chosen  wall  completely  space  5800  the  cycles.  difference  The  1340  randomly  impermeability  capsules air  of  to  (BDH  air  melting.  plate.  form  materials  using  and  of  characteristics The  and  not  prepared  volume  13.8%  of  also  was  Altogether,  capsule  a  and  efficiency  average  17.3  5% b y  was  form  continuously A  powder  solid  powder  mixture  -  fine  the  needle  The  in  mixture  in  mixing  accompany  the  water,  stirred  the  borax  of  diameter  composition.  increase  and  33  Physical 2.  stability  capsules in  either  weighed  involved  of  stored  in  case.  Also  before 120  increase, measurement  the  and  freezing-  such  a  small  errors.  -  Table  2.  Physical  Total  volume  Total  weight  Weight  34 -  Characteristics  o f an A v e r a g e  7 . 7 ml 10.32  of capsule  Weight  of Glauber's  Weight  of  Volume  occupied  by a i r space  Volume  occupied  by phase  between  4.3  suggest  material  8.536  g  0.356  g  6 . 0 5 ml  capacity 2.61  20 C and 40 C  excess  literature  studies  t h e use o f excess  Glauber's  salt  water  anhydrous decrease  mixtures  sodium  hand,  excess  1979)  to replace  Glauber's  capacity  salt  sodium  crystals,  i n terms  sodium  the storage  kJ  segregated  has been  sodium  thus  eliminating  o f complete  of percent  from  t h e amount  Addition  and thus  due t o s e g r e g a t i o n . (Herrick  crystals the loss  based  made of  of  of  the solution  crystallization.  efficiency  in eutectic  efficiency.  reported  sulfate  and Zarnoch 1979)  sulfate  or decrease  of efficiency  sulfate  t h e anhydrous  1977, Herrick  or excess  crystals  the loss  due t o t h e l a c k  acceptable  water  to eliminate  sulfate  or eliminate  (Biswas  to increase  i s claimed  other  be  g  0 . 3 2 ml  change  storage  1.428  Capsules Containing Mixtures of Different Compositions Some  by  Salt  borax  heat  g  material  (polypropylene)  Theoretical  Capsule  On t h e  and Zarnoch inaccessible  storage  Both  claims  on t h e o r e t i c a l  might heat  -  storage excess heat  sodium  storage  change is  capacity  their  discussed In  15%  and  each  temperature  further  in  of  into  25  capsules  sulfate  and  storage  the  water.  capacity  and  total  was  to  Compositions  to  weight the  per  excess  filled  the  water  and  theoretical they  do  interest.  with  not  This  point  sodium  The  air  space was  having  excess  average  the  sodium  or  than  same  weight.  by  as  weight 100  10%  in  by were  the  in  weight  study  of  25%,  were  of  of  density  segregation  to  capsules  that  proportions  sulfate  decrease  Mixtures  these  capsule  particle more  water of  stoichiometric the  capsules,  sulfate.  excess  mass  different  described  10%  prevent  volume  on  excess  because of  and  considerable  unit  weight  interval  were  capsule  containing  effect  previously  sulfate  Maintaining  25% by due  the  capsules.  capsules  bed.  to  or  However,  7.  capsules  water  sodium  of  impractical  100  excess  volume  Chapter  addition  majority  than  in  study,  that  more  negative  the  in  so  or  a  phase  injected  fluidized  have unit  5% e x c e s s  previous  both  -  mixture.  per  adjusted  the  particular  capacity  compositions, effects  that  sulfate  this  the  of  35  the  was vast  sodium  the  same  as  the excess  considered  theoretical  water  to heat  be  -  5.  5.1  FIXED AND F L U I D I Z E D BED STUDIES  Experimental System A  cycling Figure  schematic of  diagram  the  capsules  A  photograph  4.  component  of  the  system  column  which  has  an  was  mm,  25  13.6,  the  bed  sufficient  distribution the  at  problem higher  system,  minimum  in  liquid  bed but  laboratory. windows 0.25  between  m high,  designed  to  fluidization transfer  on  to  to  to  top  the  distributor  a  pressure  conditions (water)  sides  and into  to the  size  0.34  to  diameter  1982).  was  the was  The  m.  would  and  the  the  drop  of  provide bed.  and  have  It  capsule  is  flow  height  is  1.37 and  most  cases  the  is  not  a  to  have  capacity  of  the  of  the  height of  each  50  mm w i d e  and  was  minimum  distribution of  had  viewing  distributor  holes  m  bed  better  mm H 2 O u n d e r  uniform  diameter  (Dc/dp)  3 pairs  The  79  fluidization  inlet  the  screen,  main  The  been  by  has  has  The  slugging  and  thermal  in  5.  reasonable  For  column.  a  ratio  Since  top  125  the  column  efficiency  PVC  for  given  Figure  screen.  restricted  of  of  a  height.  0.85 it  in  is  Since  obtain  m in  bed  used  cylindrical  m.  restraining  beds,  i s made  opposite  of  particle  0.25  height  appears  plant  bed  system  fluidized  system  Grace  increase  column  liquid  diamter  each  fluidized  experimental  pilot  fluidization  produce  fluid  a  the  overall  The  the  1953,  are  height the  the  of is  the  a particle  distributor  height  of  diameter  (Schwartz  compartments  in  inside  for  outlet  a  -  Thermal Cyclimig o f C a p s u l e s i n t h e L i q u i d F l u i d i z e d Bed  5.1.1  from  36  of  diameter  heat 9.5  mm  RECORDER  r~>->•i —  o  ro  •I  => .0 i-t-  -•• CL  o  rtc n> ->• 3 CL •o -<•  MULTIPLE SWITCH  O  fl> CL  M  ro  -J  Cu  CL  C o"5 rt> o  THERMOCOUPLE OUTLETS  IT>  CL  CU 3 CL  CU c Cu 7T  e  o  j5k  >  TO  i  o  "0  n  -n r  m m ^  -  TJ  >  Si o  DRAifcL^  m m m m o o  •z. m  O n 2:  ®  1/1  > —i m m -H > m —i > 5 2  - LZ -  Figure 5 .  Photograph of the E x p e r i m e n t a l  System.  -  arranged  in  an  described  in  openings,  used  equilateral  Appendix to  1.  prevent  39  triangular  -  pitch.  The  top  screen  is  the  entrainment  Distributor a wire  of  mesh  capsules  design  with  into  is  10  mm  the  outlet  stream. A closed velocity heating the  in or  than  the  globe  a  flow  the  valve  be  varied  water.  of  Water  by  60  without from  a 5 HP  m3/h.  The  pressure  piping  and  the  fittings,  and  a bypass  pressure  Inlet  outlet  diameter  recirculation  line  drop,  connections pipes  system  fully  changing  the  net  the  top  capable caused  pump  in  a  The  by an  pumped  providing  the  and  bed. a  adjustments)  capacity.  102  the  of  more  fluidized  pump by  into  pump c a p a b l e  flowrate  made  with  is  of  o r i f i c e meter,  (for  column  insulated  of  reduced  pump w e r e  flow  compartment  centrifugal  is  the  respectively. were  water  including  resulting the  superficial  drop  around  of  the  kW)  pump  the  allows  the  (3.73  to  the  inside  to  subject  increased and  r e c i r c u l a t i o n system  compartment  90 m / h  However,  bed  cooling  bottom  providing  water  nm  and  closed  76  mm  water  75  mm t h i c k  fibreglass  m  constant  head  insulation. Water storage energy  from  vessel storage  is  a  temperature  used  for  unit).  by  gravity  due  adjusted  by  a  valve  accumulated  globe  flow  paddle-wheel  flow  during sensor  accuracy.  During  the  was  to  water  heated  the  cooling  Water  pipeline  to  a  controlled and  enters  on run with  heating feed  the are  heating  the  a constant  accumulator  tank  column  through  a  difference.  The  measured  the  the  column  head  line.  runs,  0.5  water by  a  temperature  51  thermal  mm  The rate  ID  flowrate and  is  total  Cole-Palmer  which  outlet  flow  (the  water  was  calibrated  stream in  a  from  steam  the  heat  for  high  column exchanger  -  and  pumped  into  the  feed  tank  using  temperature  was  kept  around  40  was  used  the  feed  at  normal  Its  temperature  Heating inlet city  as  and  cooling  (feed) water  varied  flow  its  C  between  periods  rate  and  40  1/8  during  7  of  a  -  HP  the  C  and  the  15  C  column  temperature. by  runs.  Pipeline  connections  and  valves  can  be  operated  with  downflow  through  for  studies  light  capsules  or  of  packed  measured  at  the  copper-constantan digital and of  are  thermocouples  temperature  location  of  indicators  the  radial  and  heater  outlet  temperature,  outlet  temperature,  temperatures. are  Servagor mm/min  calculation as  for  from inlet  the  the and  in  through  Model  chart  axial  Outputs  connected  220  total  at  outlet  addition of  the  The  any  and  of time  input the  during  thermocouples  is  adjusting  so  during  that  rather  system upflow,  beds. shown by  0.1  in  Omega  Figure 410  4  by  series  K sensitivity.  The  in  the  column,  and  recirculation  temperature column  and  inlet  outlet  and  2  mV  digitized  output  to  transfer the  runs.  the  most  or rate  compensators  used  from  the  the  important  for  the  from  Since  steam pump  thermocouples  full-scale  and  monitoring  outlet  temperature  ice-point at  the  number  gradients  the  the  cooling  the  than  the  in  enable  were  heat  season.  to  recorded  or  by  runs.  chosen  tank to  water  variations  provided  points  have  the  flowrate  system,  electronic  curves  heat  the  were  inlet  Omega-CJ  calculation  water  which  feed  are  the  monitored  temperature  recorder  speed. of  and  thermocouples  the  changing  feed  cooling  to  changed  The  City  the  according  Temperature  for  pump.  runs.  during  were  compensated  Temperatures  kW)  heating  temperature  were  of  (0.09  to  range  a  and  10  the  system  as  capsules  accuracy  parameter  of for  well to the  or  -  reliable a  results,  digital  using  a  start  of  on  the  this  high  high  outputs  sensitivity  sensitivity  experiments.  recorder  is  calibration  temperature  to  digitize  on  the  chart  temperature  water  digitized  with  the  form  digital  all  the  digitizer. was  computer  outputs  to  of  program  was  the outputs  thermometer  output,  used  of  in  ice  the  using  digitizer  to  the  the point  corresponds  written  temperatures  2801A)  before  electronic  mm w h i c h  against  thermocouple  instruments  Sensitivity  0.05  Packard  bath  quartz  thermocouples,  output A  thermocouple  the  i . e .  and  recorder.  calibrated  constant  includes  recorder  were  (Helwelt  compared  process  thermocouples thermometer  Since  recorder  the  these  -  quartz  measurements,  compensators,  digitized  of  41  to  used  0.01  K  convert calibration  curves. The to  experimental  measure  heat  the  balance  be  from  the  including  all  was  on  based  were  placed  Since care  all was  confirmed system  In the  and  actual in  the  or  the  of  rather  measurements  during  used  the  to  heat  the  a  to  the  be  used  as  a  capsules  by  performing  the  this,  the  loss  from  heat heat  column  the  capacity balance  of  theoretical  based  calibration  this  and  calibration  with  less  the  than  had  heat  system Calibration the  capsules  calculations.  calibration,  experiments  This  calorimeter  on  system  boundary.  than  were  the  before  a  the  system,  obtained  on  and  calorimeter  experimental  results  experiments. as  do  sensible  inside  column  by  surrounding  order rate  designed  gained  experimental  repeated be  was  boundary  components  taken  could  for  pump  future  by  a  system.  calibrated  input  released  within  recirculation to  heat  system  the  results  assured ±0.1%  extreme  that  error  were the in  the  -  energy  storage  calibration are  given  5656  Section  system  contained  mixture Table  of  11  phase  Table  25  in  the  same  fluidization  5756 of  1).  contents  procedure given  in  inside  used  of  the  the  capacity Once any  the of  this system  51.2  weight The  The  Likewise,  we  have  using  Details  heat  of  aim  the of  it  is  of  balance  of  the  equation  these  density was  the  total  not  easy  to  the  B,  of  change  storage  C was  is  capacity  included  included  the  storage  was salt  The to  study  under  evaluate  Glauber's  reason  heat  because  the  capacity  14683  in  kJ.  to  The  this  water storage of  excluding  heat  is  the  by  capacity  for  different  the  salt  the  mm/s  inside  due  to  minimum  provided  not  spaces  calculation  only  was  in  varied  storage  capacity  capacity  E  58.8  material  heat 40  be  capsules  air  The  C and  storage  and  1340  to  a  100  The  kg/m3.  of  in  were  calculated  20  walls.  C  of D  other  A,  volume  compositions  theoretical  heat  study  Glauber's  of  (Comp:  compositions.  phase  between  heat  weight  volume  inside  consisting  compositions  pipelines  this  by  non-standard  of  The  volume  borax  with  column  encapsulated  capsules.  calculated  The the  found,  capsules.  resultant  inside  theoretical  in  main  the  5756  capsules  capsules  encapsulated  is  the  and  or  the  4%  each  with  kg.  the the  and  capsule  capsules.  capsules  that  of  5.1.3.  column  capacity. plastic  in  for  remaining  The  having  total  of  Section  contents  was  was  the  materials  average  The  as  with  salt  capsules  velocity  capsules  the  space,  6.2.2).  capsules 100  (Appendix  charged  change  these  maintain  was  Section  well  -  5.1.2.  5% a i r  contained  left  as  96% G l a u b e r ' s  in  11,  evaluations  experiments  in  The  capacity  42  the them  storage conditions.  storage  capacity  Glauber's  salt  of is  -  the  only  material  storing  heat  known.  The  on  the  way,  it  is  be for  salt  all  the  for  the  storage  in  in  the  other  materials  heats  which  are  efficiency  excluding  generalize  the  the  the  rest  in of  results  similar  size  reported  experimental  the  text  is  again In  systems  capsules.  If  and  may  system  well  system.  the  studied  the  generally  the  to  in  based  this  using  the  e f f i c i e n c i e s , those  set-up  of  capsules  was  this  study  Glauber's  salt  changes  for  thermal  performance. a suitable  for  the  in  interval  storage  especially  cycling  Since  constituting  rest  of  values  be  would  misleading  house  The  are  performed based  its  phase  c y c l i n g must  range  temperature  on  chosen  this at  32.4  C,  and  40  C  practical  the  C for  sufficiently  in  20  temperature  include 32.4  is  interval  between  high  broad,  uses  heating.  E x p e r i m e n t a l System C a l i b r a t i o n The  calorimeter used  to  evaluations  temperature  5.1.2  contents  phase,  -  cases.  interval.  heat  energy  included  Thermal and  sensible  their  encapsulated  was  only  other  by  possible  system true  its  thermal  capsules'  Glauber's the  only  changing  43  as  calibration was  an  the  important  calorimeter  recirculation  system  input,  and  output  of  includes as  experimental part the  shown  accumulation  of  this  system study.  fluidization  schematically terms  are:  in  to The  column Figure  be  used  part and 6.  of  the The  as  a  the water heat  system  - 44 -  HEAT OUTPUT BY WATER  2»  £  HEAT INPUT BY WATER  6.  HEAT INPUT DUE TO THE FRICTION IN THE PUMP  S c h e m a t i c Diagram o f t h e System I n s i d e E n e r g y Boundary.  Balance  - 45 -  Heat  Input:  Input  by t h e i n l e t  Input  by r e c i r c u l a t i o n  Heat  water  Output  by t h e o u t l e t  Losses  to  = QQ  = HQ mQ  the surroundings  = QL  =  due t o  Accumulation capsules  Q S C  =  = Q  = P At  A  (T^  - T  )  At  c  \  m  kCpkl>  than  <Tbf  sensible  ( T  c f -  3 2  '4>  due t o l a t e n t  =  of materials  the contents  -  in the  of  system  the capsules  V  heats  of  the contents  of the  =  ^55  +  m  heat  of  kCpks)  <  3 2  '  4  the contents  -  T  ci>  of the  ^GS  balance i s :  Ql  Throughout  "  Q  this  a r e assumed  o  +  % ' \  study  across  = %  t o be i n d e p e n d e n t  the  +  +  the specific  by t h e r e c i r c u l a t i o n  drop  b  heat  =  capsules  pressure  other  -  due t o  Accumulation  resulting  sensible  everything  %  input  friction  Accumulation:  including  heat  pump d u e t o  water  Accumulation  materials  = H^  Output:  Heat  The  =  system.  pump  heat  %l  capacities of a l l  of temperature,  i s assumed  to  and t h e r a t e  be i n d e p e n d e n t  of  of  =  -  Calibration placed must  inside  the column.  be m o d i f i e d  to  normally  occupied  included  in  Qh' b  = QK b  .  +  c  experiments  were  In  account  this  both  The m o d i f i e d  P., v . " pw w c  (Thf  -  c a s e Qc$  before  = QCL  the water  and f o r  T. . ) b i '  C  =  the °*  as Qt,',  V  o pwm  m  the  wall  were  % volume  material  i s :  n X c  wm  capsules Also  occupying  the capsule  expressed  Q5,  bf  -  performed  for  by t h e c a p s u l e s  m,  46  (T. . wm v b f  T..) bi (5.2)  If  Qb  QK' ^b  Since  is  replaced  =  all  by  v  (Ch b  + C  the  terms  n w  pw  C^CT^f  p„ Vr w c  the  V  where  C„' = C b  The before  heat  the capsules are  Qi  or,  in  .H  During  expanded  i m i  the  flowrates,  +  Eq.  -  P  for  W  the  V  n -  C  T  to  (Thf bf  -  v  are  TK,) b i '  C  <5-4>  p w m  the column,  + Qp  Q0  QL  (5.3) '  constants  P w m  V  C  n X ^  (5.5)  calibration experiments,  -  v  bi)  fed to  -  leads  n X ) wm'  parantheses  V  p w  (5.2)  C (m pllm V„ pwm wm c  first  =  + C  balance  T^-j),  n -  K  in  -  is  performed  therefore  = Qb'  (5.6)  form,  P At  -  HQ  mQ -  experiments, column  the  Ub  A  (T  b  column  temperature,  -  Ts)  inlet  At  ="Cb'(T  and o u t l e t  surrounding  air  b f  -  Tb1)  (5.7)  temperatures  temperature  and  and  time  -  interval " W '  are a l l measured  ^ b i ' ^s  parameters,  a  n  P,  d  A  Ub  ™  t  A  E c  -  parameters.  l'(5*7)  and C  47  b  ',  a  r  must  Therefore,  known  e  H..,  HQ,  parameters.  be e v a l u a t e d  m^, m Q ,  The  Tb,  remaining  by t h e c a l i b r a t i o n  experiments. In without  the  first  any water  entering  the  column  and t h e  the  system  by t h e  temperature,  c a l i b r a t i o n experiment,  rate,  repeated  times.  were and  for  each  average  differential column,  it  form takes  was r e c o r d e d  was 8 . 4 9 6  K/h.  for the  the column  (Ts)  Eq.(5.8)  of  these  the c a l c u l a t e d  the case of  rise  time.  If  the  heat  no  inlet  was  system  operated made  was c i r c u l a t e d  system  temperature  slopes in  the  against  column  Variation  P dt  When  The  Water  and t h e  throughout  r u n and t h e  calculated. their  uniform  equipment  the calorimeter  r e c i r c u l a t i o n pump,  recirculation  plotted  leaving  recirculation circuit.  almost  four  or  the  in the due t o  This  time  curves  at  slopes balance  and o u t l e t  of  within  column the  high  experiment  versus  up  data  room  was  were temperature  was l e s s  than  0.2%,  is written  in  water  the  from  form  -  Ub  A  (Tb  temperature  (T5)  -  Ts)  dt  i s equal  = Cb'dT  to  the  (5.8)  room  temperature  becomes  P dt  = Cb'dT  (5.9)  -  48  -  Hence  =  As  given  Slope  of  = 8.496  dt  Since  the  to  evaluate  Tb  versus  time  very  l i t t l e  Therefore to  cool  Ub  it  down  loss  were  leading  in  is  terms  curve  at  change  make  used  to  slight  is  the  within  heat  than  system  in  by  at  =  T$  (5.10)  in  terms  other  of  the  the  system  up  for  brief  uniform.  evaluate  the  Ub  possible  of  the  However,  45  there  temperature. -  without of  is  slope  with  to  periods  temperature  it  Ts.  curve  temperatures  to  Cb' .  than  the  Eq.(5.8)  of  c a l c u l a t i n g the  slope  monitoring  the  known  Cb'  the  time The  50 C  and  leave  operating at  A term  the  regular  resulting in  it  time  heat  terms  of  to  Ub  when  curve  temperature  in  decided  now of  a  pump o t h e r  to  data  A  while  intervals  A  time  K/h  P term  was  recirculation  Cb'  versus  above,  dT  was  Tb  increase bed the  is  in  the  A  = 2.3  overall  fluidized,  experimental  but  heat  due  error  x TO"2  to  range  Cb'  transfer the in  coefficient  heavy the  insulation  reported  is  expected  this  value.  increase Also,  as  -  shown was  in  less  pump.  Appendix  3,  than  percent  Therefore When  the  one  the  it  heat  is  P and  loss of  not %  to  the  49  the  -  surroundings  stored  a critical  A  terms  are  -  x  heat  or  during  the  heat  a cooling input  by  run  the  factor. inserted  in  Eq.(5.7),  it  takes  form:  H^-  + 8.496  Cb'  At  -  HQm0  2.3  10~2  C^'f^  -  T$)  At  = C  b  '(T  b f  -  Tb-)  (5.11) All  terms  run.  A  in  Eq.(5.11)  total  heating  or  of  12  cooling  temperature  range  heating  system.  of a  the  the 12  standard Cb  capsules the  can in  the  the  1.  performed  to  water  flow  rate,  time  result  Table  3.  of  the  The  be  Cb'  of  kJ/K.  calculated (n)  for  is  evaluate  value  was  fond  to  for  regular  as 8 5 7 . 2  in  experiments  Values  for  the  are  Cb'  =  1028.1  kJ/K  P  = 8734.4  kJ/h  =  23.65  kJ/K  kJ/h-K  as  number  are  bed  a  summarized  Evaluated  and  result  kJ/K  with  of runs  given  parameters  the  the  cooling  1028.1  fluidized  Parameters  = 857.2  A  The  The  Experiments  Cb  Ub  be  Eq.(5.5)  kJ/K.  run,  between  evaluated  Eq.(5.5).  varying  the  were  parameters  Calibration  of  experimental by  Cb'  period  alternating  an  Cb'  using  calibration  Numerical  by  during  for  5756  other  calculated  the  the  values  4.8  the  and  average  column  is  column  Twelve  values Cb  measured  were  in  now  are  Cb'  runs  deviation  numerical  Appendix as  runs.  except  and  in  evaluated in  Table  from  3.  -  Using terms  of  Himi  m  H0mQ +  C  p k l  The  last  the  contents  column.  this  components their  was  -  m  GS  X  Eq.(5.1)  parameters  23.65  +  (Tb  GS  -  the  T$)  C  amount  was  their  in  which  adjusted  system  this  '  T  bi)  The  i n  = 857.2  pks)  of  as 8 9 9 . 6 there  <  heat  kJ/K  were  accordingly  theoretical the  C to  the  heats,  written  3 2  '  (Tbf  "  4  T  in  -  Tb1)  +  c1>  stored  for  only  for  heat one  C.  or  some  4328  heat  (5--12)  released  by  high  capsules  storage  can  in  the  evaluations  than  storage  capacity  capsules  Since  the  heat  the  capsules  storage  capacity.  the  )  the  heat  easily  t n  of  of  actual  storage  other  sensible  40  (Q  heat  contents  contents  their  study,  k J  on  20  than  components  evaluated  the  based  theoretical  in  be  velocities.  interval other  can  as  At  ( \ \  +  re-evaluated  runs  study,  are  sensible  system  (Tbf  At  3,  T h e o r e t i c a l Heat S t o r a g e C a p a c i t y  temperature  the  Table  measurable  constitute  velocity  efficiencies  by  term  in  -  capsules.  superficial  In  to  given  '4>  3 2  the  Eq.(5.12)  high  5.1.3  "  terms  of  CD  superficial  8734.4  c f  ) ( T  three  The  at  values  experimentally  -  k  the  50  contents  heat  storage  term  of  heat  storage  capacity  of  storage store  capacity  For  calculate  for  the  the the  and the system  energy is  always  fluidized  sensible capsules  Eq. ( 5 . 1 2 ) ,  i . e . ,  by  (Qth)  includes  equal  stored using  857.2  the  via  bed  heat  -  theoretical  only  x  -  sensible  heat  20  40  C and  32.4  C.  and  stored  C and  Since  solid  sensible parts,  above  For  components  at  30  k  C is  between  ( 4  C  was  total  weights  phase  change  below  °  as  and  "  3  2  32.4  *  the  40  )  of  +  m  of  of  X  fusion)  more  the  GS  between  for. G l a u b e r ' s  Glauber's  convenient  contents  +  4  m  I  for  storage shows  in for  k  salt,  value  heat  materials  change  capsules  of  to  the  salt  salt  in  liquid  evaluate  capsules  at  the  in  two  Hence  GS  Table  phase  is  Glauber's  The  i n s i d e the  c a p a c i t i e s of it  C.  average  C.  the  (heat  4  than  neglected. of  heat  capacity  -  components  different,  other  used  20  capsules  p k l  C  the  s e n s i b l e heat  are  and  =  m  the  all  latent  storage  Qth  I  the  phases heat  by  51  the  W  3  their the  '  2  4  5756  Glauber's  20)  specific  temperature  capacity  the  -  of  specific capsules. salt  is  air heat  (5.13)  heat  capacity  interval inside  the  capacities  The  latent  251.03  and  heat  kJ/kg  (Telkes  1975).  Table  4.  S p e c i f i c Heat in  5756  Capacities  Capsules  Used  Material  Cp  Glauber's salt (Na2S0H«10H20 )  E x t r a sodium (Na2S04) Borax Extra  sulfate  (Na2B40yl0H20) water  in  (H20)  and  Total  the  Fluidized  Weights  of  Materials  System  (kJ/kg-K)  Weight  1i q u i d  3.307  (Tel kes  1975)\  sol i d  1.758  (Telkes  1975))  0.967  (Perry  1973)  0.100  1.613  (Perry  1973)  2.048  4.178  (Weast  1976)  0.011  49.045  of  (kg)  -  The  theoretical  contents the  of  values  salt  were  heat  noted  4328  of  system  and  4  calculated and  the  to  20  be  latent  C and  14683  heat  of  kJ  40  C for  by  the  substituting  fusion  for  Glauber's  after  some  about  experiments 25% o f  of  the  the  at  capsules  capsules  contents  higher  of  in  superficial  were  the  these  taken  bed.  out  The  capsules  velocities of  the  bed  theoretical  was  calculated  kJ.  rate  heat has  the  the  is  transfer an  area  Although of  provided of  makes  high by  capsules,  it  to  improve  (1)  Resistance  from  wall.  related  c a l c u l a t i o n s are  given  to  heat  transfer  resistance  to  calculate  and more  the  the  magnitude  accurate  in  across the  the  due  to  to  or  inside  these  the  of  (2) the  The  the  capsule  internal  source  the  heat  three Resistance  capsule.  resistances  2.  large  further.  composed  capsule.  the  salt  the  from  and  performance  Glauber's  system  is  from  Appendix  than  the  the  of  medium  understanding  transfer  Resistance  used  rates  transfer  outside  methods  and  estimate  (3)  heat  estimating  transfer  heat  possible  storage  encapsulated  to  to  to  the  heat  in  resistances  resistance  capsule  the  factor  heat  the  total  components:  between  important  unit.  advantage  medium  the  heat  storage  magnitude  The  to  of  fluid  transfer  storage  due  above,  capacity  transfer  any  heat  Table  between  Heat T r a n s f e r R e s i s t a n c e s The  heat  was  regular-composition  11065  5.1.4  in  capacity  -  Eq.(5.13).  storage  be  storage  capsules  performed  leaving  to  the given  into As  heat  52  external wall  resistance.  and  The the  resistance are  easier  The  added  -  complexity  comes  behaviour  from  inside  simplifying  the  the  transfer resistance  Resistance degree 0,  of  1.29,  to  Appendix  is  to  wall heat  crystals  on  resistance  was  results,  across  the  inside  22.7  K/W  for  0,  external  capsule  some  contents 50,  of  is  and 75  resistance 0.11  wall  capsule  the  with  2.  velocity  25,  inside  crystallization  treated  the  the  capsule  salt  and  Appendix  the  due  change  the  the  material  volume  resistance due  decreased  conductivity  by  to  to  the the  is  beginning  inner to  that  transfer  resistance  resistance  show  transfer  the  crystallized  be  in  of  compared  heat at  internal  dominant  problem  superficial  from  Glauber's  results small  resistance  internal  and  pattern  is  m/s, 4.02  and K/W.  dependent was  and  on  the  calculated  100%  capsule,  to  by  as  volume  respectively  (see  2).  These  phase  of  a  transfer  crystallization  crystallization  capsule  calculated  transfer  6.96  The  at  -  mixing  outlined  K/W  heat  heat  as  the  0.247  to  3.21,  capsules  to  is  unknown  capsules.  assumptions  According heat  the  53  of  the  of  capsule  wall  the  towards  the  capsules end  capsule  wall,  using  another  wall  a thinner  wall.  more  the  until  the  is  than  than  the  and  the  of is  of  smaller  57%  and  by  it  the with  fluidized the  the  solid  than  the of  of  the The  the  becomes  higher  to The  volume.  total  total  due  process.  crystallization  thus  material  6%  94%  percentage  increases of  the  crystallization  reaches as  of  deposition  capsules  salt)  the  and/or  to  sharply  the  and  Less  crystallization  due  surface  resistance  two.  external  (Glauber's  in  other  resistance  increases  external  the  process.  resistance, thermal  The could  -  5.1.5  (Grace was  Varied  The  fluidized  c a p s u l e s were  1982)  minimum  observed  capsule the  bed.  to or  top Full  uniform  non-uniformities.  anhydrous  to  the  i n s i d e the  that  sign  flowrate around  and  30 The  cooling  and  to  of  in  45  the  The  inlet  seconds;  were  at  the  bed  the  this  period  velocity  in  independent  is  is  the  could  in  not  the  be  However,  However,  there The  was  the  some  amount  capsules did  of  not  show  during  to  in  than  adjust a  variables  the  in  heating for  0.1  steady  included  column,  the  observable  less  reach  not  present  axes.  points  required to  adhered  inter-particle  cycle  difference  temperature  any  conditions.  different  time  observe  axis  and  the  observable  capsules  capsules. of  no  capsules.  top,  c y c l e to  fluidized  to  some  gentle  the  r e c i r c u l a t i o n system  superficial  period  from  Fluidization  with  possible  vertical  bottom  calculated  c a p s u l e s were  some  of  temperature  conditions. for  the  volume,  horizontal  at  the  mm/s).  which  around  bottom  under  not  a  about  i n s i d e the  stayed  at  bed  5756  rocking,  measurements  the  all  at  (58.8  above  gradient  the  maximum  was  around  increasing  cycles  the  bed  when  capsules at  It  rotation  precipitate  Temperature  fluidized  and  precipitate  Na2S0it  column  density  vibrations  freezing-melting  the  of  the  < 2.1,  back-and-forth  observable  revealed  U/Umf  capsules  collisions,  observable  for  velocity  throughout  rotation  some  bubble  fluidization  screen  there  was  initially  restraining  due  any  be  segregation  obtained,  air  -  O b s e r v a t i o n s and P a r a m e t e r s  channelling  to  54  the  system anywhere K  under  inlet  value the  in  was  run  period  periods.  and  experiments  under  -  fluidized 68  and  bed  130  capsules  (1.16  Umf  the  bed.  Because  in  out  screen  of  superficial Umf  and  unit 36  and  40  to  the  the  121 20  \i f  records  of  final  the  information, also  some  capsules  between  and  153  from  20  to  period  over  which  12  135  for  inlet  each  and  40  of  the  C was  the  bed  the  top  were The mm/s  (2.21  storage  varied was  between  cooled  from  minutes.  and  at  duration  date,  run  fluidized  outlet the  flow-accumulator  the  mm/s  period  to  capsules bed.  heating  5756  adhere  the  130  and  to  between  all  in  between  The  with  the  capsules  varied  Processing  temperature  line  started  25% o f  regular  increase  the  respectively)  about  varied  was  number  run  included  temperatures, beginning  readings, of  bed  the and  orifice  run. any  and  In  initial at  the  column end,  pressure  addition  extraordinary  continuous  initial  drop  to  on  the  this  observations  noted.  Water for  to  while  water  water  Umf  4328  then  recorded  room  recirculation  time  was  velocity  2.21  > 2.1,  leaving  varied  data  temperature,  U/Umf  temperature  C was  and  -  superficial  respectively).  m  minutes,  The  were  bed  D a t a and Data  5.1.6  and  for  velocity  2.60  for  The  rnrn/s  restraining taken  conditions.  55  inlet  typical  respectively. input  and  these  results,  Eq.(5.12),  outlet  cooling  These  output  to  and  from  and  curves the  together calculate  temperatures heating  are  column  with the  the heat  runs  integrated by  the  other stored  are in to  heat  plotted  Figures  functions  7  and  8  evaluate  the  total  transfer  measured or  as  fluid  parameters  released  by  the  heat  (water) are  of  used  contents  and with of  o  o CO  OUTPUT  < LU  INPUT  O J  30 40 TIME (minutes) Figure  7.  Temperature Cooling  Run.  Profiles  of  the Storage  Unit  Inlet  and O u t l e t  Streams  for  a Typical  Figure  8.  Temperature Heating  Run.  Profiles  of  the  Storage  Unit  Inlet  and  Outlet  Streams  for  a  Typical  -  the  capsules.  interval and  40  have  It  over  C.  was  which  the  storage  therefore  been  corrected  Experimental At  heat  around  temperature  interval  capacity  of  the  includes  some  is  some  with  c a l c u l a t e d as  temperature  166  data  143.2 at  both  according  to  the  in  For  first  the  the  heat  of  storage  and  heat  the  previous  by  a cooling  cycle.  run.  The  the  C  for  was  for  from  the  cycle  experimental  was  in  the  case  there  is  (cold  end),  solubility  for  a  small  C  the runs  temperature  adjusted which  40  small  representative  in  of  around  integrating  were  runs  storage  the  linearly number  of  5756.  that  c o n d i t i o n s may  Each  range  both  small  capacity  several  at  capacity  C  the  capacity  c o n d i t i o n s two  thought  20  capacities for  temperature  experimental  in  by  a  because  around  change  estimated  19  capsules  at  C  these  heat  storage  s e n s i b l e heat  storage  of  of  sensible  recovery)  storage  C was  C  the  to  heat  set  changed  (or  The  each  under  the  for  in  s e n s i b l e heat  was d i f f e r e n t  cycle  capacity  the  bed  It  used  to  20  of  to  been  20  capsules  differences  addition  around  performed.  storage  between  the  heat  the  were  temperature  of  the  The  These  exactly  contents  c a p s u l e s , even  21  heated  temperature  C,  kJ/K.  number  the  the  20  heat  in  ends  or  keep  c a p a c i t i e s have  around  in  between  kJ/K.  intervals  cycles  C,  of  small  temperature.  interval  experimental  capsules  for  c r y s t a l l i z a t i o n o c c u r s due  sulfate  give  cooled  capacity  At  heat  liquid  was  p r a c t i c a l l y equal  system.  latent  saturated  sodium  to  40  -  p o s s i b l e to  storage  less-than-theoretical  some  is  system  heat  corrections.  and  always  The  ends.  of  not  58  be  the  storage  affected  started  heat  melting-freezing  by  storage  by  capacity the  a melting  of  the  conditions run  followed  capacities reported  in  -  this  text  were  except  for  It  thought  was  the  cases  measured  because  all  the  heat run  the  cycle  the  caused runs for  and  high  The released  as  a  the was  function from  performed storage  latter as  a  of  the  in  cooling  to  the in  or  period.  The  for  show  the  of out  and  were  was  small  the  inlet  of  capsules  time  and  program  each  to  analysing its  change  also  by  under no  Odd  heat  study.  problem  stored  to  for  heat the  corrects  program,  the  rate  the  With  the  of  the  a  were  heat slight  integration  inside  the  this  temperatures  yield  during  during  equation,  calculations  range.  perform  are  or  balance  integration  run  heating  runs.  outlet  The  for  numbers  written  increments of  rates  results  was  (heat  and  temperature  possible  in  an  run  cooling  library.  accumulation  useful  computer  program  using  end  the  influence  differentiate  numbers: to  may  cooling  variable there  cycle,  variable.  minimized  capacity  the  Center  corresponding it  the  correspond  computer  carried  program  time,  from  a  was  or  heating  via  second  independent  easily  run  the  experiments  used,  storage  Computing  the  was  can  of  heating  the  capsules)  beginning  which  of  the  using  was  calculations  function  of  heat  Integration  U.B.C.  the  results,  transfer  3). time  between  capacity  all  the  performed  the  modification  of  from  the  numbers  the  problem  One at  run  the  high  period  runs.  even  is  generally  looking  contents  (Appendix  QINT4P,  and  while  evaluation  Eq.(5.12), purpose  by  for This  cooling  rate  cooling  during  capacity  were  -  period  effects  small.  data  runs  the  capacity  is  heating  runs  by  end  the  run  from  cooling  storage  when  cooling  heating  the  storage  heat  cooling  by  the  period  the  Since  where  that  evaluating second  evaluated  59  run.  the  The  capsules  heat heating  calculated  or heat  -  storage  capacity  to  the  60  temperature  -  interval  20  and  40  C as  discussed  above. The the  amounts  corrected  presented Appendix  3.  heat the  Each  3.  heat  stored  for  with term  This  storage as  capsules,  "specific  heat  separately  Appendix  overall  values  together  calculated in  of  heat  the the  in  contents  of  the  temperature  interval  20  to  by  experimental heat  each  run  conditions  balance  analyzed,  and  can  also  capacity  of  the  experimental  of  the  heat  heats  term  be  capsules 40  Table  to  evaluate  transfer  insulation  to  "heat  stored  by  Al  appear  fluid etc.,  in is  in  Table  including  by  A2  the  (water),  capsule  and  are  Eq.(5.12),  system,  pump,  C  they  used  pipes, the  in  equation  information  column,  gain"  the  the  for  sensible PVC  stored  the  all  adding  of  the  contents"  term. A modified  form  integration  and  all  analyze  rate  of  the  Appendix  4.  calculated  temperatures. reported and  in  heating The  the  save  Tables runs  A3  rates  space and  heating  period  and  storage  efficiency,  storage  capacity  in  A4  in  in  Appendix  superficial defined  recovered  due  the  as  program  for  to  heat  Figures  the  only  and  8,  the  of are  the  given in  in  to  in  the the  each minute sample  are  cooling  respectively.  effects  velocity  experimentally,  for  for  the  intervals  is  errors  rates  4  percent  time  fluctuations  transfer  7  performs  capsules  digitizing  showing  water  which  minute  the  caused  Appendix  3  one  to/from  increments  presented  results  computer  transfer  time  transfer To  the  calculations  heat  Shorter heat  of  on the  the  of  cooling  percent  theoretical  given  in  Tables  period,  heat heat 5,  6  and  T a b l e 5. E x p e r i m e n t a l R e s u l t s Showing t h e E f f e c t o f t h e C o o l i n g P e r i o d on t h e Heat S t o r a g e E f f i c i e n c y  RUN NO:  HEATING PERIOD (MIN »)  COOLING PERIOD (MIN.)  SUPERFICIAL VELOCITY (mm/s)  HEAT STORAGE CAPACITY (kj)  THEORETICAL CAPACITY (kJ)  PERCENT EFFICIENCY  21  67 .0  1 35.0  96. 1  941 4  1 4683  64. 1  71  70.0  96.0  96.0  9571  1 4683  65.2  25  67.0  81.0  96. 1  9173  1 4683  62.5  75  66.0  62.0  96. 1  8992  1 4683  61.2  79  64 . 0  52.0  96. 1  8748  1 4683  59.6  83  65. 0  41.0  96. 1  8701  1 468 3  59.3  95  63.0  27.0  96. 1  8629  1 4683  58 .8  91  64.0  18.0  96. 1  8725  1 4683  59.4  87  65. 0  12.0  96. 1  8592  1 4683  58.5  T a b l e 6. E x p e r i m e n t a l R e s u l t s Showing t h e E f f e c t o f t h e H e a t i n g P e r i o d on t h e Heat S t o r a g e E f f i c i e n c y  RUN NO:  HEATING PERIOD (MIN.)  COOLING PERIOD (MIN.)  SUPERFICIAL VELOCITY (mm/s)  HEAT STORAGE CAPACITY (kJ)  THEORETICAL CAPACITY (kJ)  PERCENT EFFICIENCY  •1 00  36.0  64.0  95.3  841 6  14683  57.3  1 04  47.0  61 .0  95.3  841 8  1 4683  57.3  1 08  63.0  65.0 .  95.3  8350  1 4683  56.9  40  65.0  71.0  96.2  8485  1 4683  57.8  11 2  68.0  64.0  95.3  8369  1 4683  57.0  4.4  73.0  76.0  96.2  84 1 9  1 4683  57.3  116  78.0  60.0  95.3  8387  1 4683  57 . 1  48  102.0  71.0  96.4  8354  1 4683  56.9  1 20  12 1.0  64.0  95.3  8253  14683  56.2  -  7  respectively.  The  A  decline  heat  cycling  is  traversed run  and  in of by  the which  easily  be  may  c a l c u l a t e d by  the  same  of  Therefore be  cooling  capsules  are  -  capacity  concern.  material  the  of  run)  went  those  Glauber's number  interest.  Since  make  the  one  cycle,  before  run  any  number  in  salt  the  through  dividing  as  of  with  runs  by  cycles (heating  number  reported  3.  thermal  thermal  two  the  Appendix  of  run  thermal  can  2.  Thermal C y c l i n g o f C a p s u l e s i n a F i x e d Bed After  fluidized  the  bed  conditions. a  special the  numbers  storage  following  cycles  5.2  the  run  63  fixed  fluidized  and  assign  aim to  state  was  the  as  a dollar  fluidization  to  to  test the  heat  value come  to to  the  the  in  the  same  efficiency  due  to  bed  improved  of  is  It  should  sound  and  fixed  then the  comparison  bed  capsules  cycling.  capsules  a measure  efficiency  economically  the  under  under  of  efficiency fixed  times  continued  performance  fluidization.  the  c y c l e d 96  c y c l i n g was  change  to  to  an  thermally  storage  compared  attributable  been  thermal  observe  between  improvement  had  conditions, The  bed  difference  capsules  in  The  a  of  the  be  possible  added of  cost  the  in  to  of  two  processes. The Section  5.1.1)  operation minimum  experimental  was  was  also  that  the  fluidization  direction  of  fixed  condition  bed  flow  set-up  in  used  used  as  fixed  superficial  velocity. the at  a  the  liquid  bed.  water  Although  column,  higher  for  thereby  velocities,  The  only  velocity it  was  was  the  was  bed  difference less  possible  keeping this  fluidized  to  than  to  in the  reverse  capsules  found  (see  be  under  the  -"64  Table  RUN NO:  -  7. E x p e r i m e n t a l R e s u l t s S h o w i n g t h e E f f e c t o f t h e S u p e r f i c i a l V e l o c i t y on t h e H e a t S t o r a g e E f f i c i e n c y  HEATING PERIOD (MIN.)  COOLING PERIOD (MIN.)  SUPERFICIAL VELOCITY (mm/s)  HEAT STORAGE CAPACITY (kJ)  THEORETICAL CAPACITY (kJ)  PERCENT . EFFICIENCY  124  64. 0  68 .0  67. 9  7244  14683  49.3  60  65. 0  60 .0  73. 1  7731  1 4683  52.7  1 28  65. 0  67 .0  75. 6  6906  1 4683  47.0  1 32  62 .0  76 .0  82. 6  7733  14683  52.7  136  64 .0  74 .0  89. 2  7856  14683  53.5  1 40  64 .0  74 .0  95. 3  8253  1 4683  56.2  144  64 .0  76 .0  1.01 .0  8 598  1 4683  58.6  56  66. 0  66 .0  105. 0  8846  1 4683  60.3  148  66. 0  75 .0  106. 5  8698  1 4683  59.2  1 52  66. 0.  71 .0  111. 7  8804  14683  60.0  1 56  66. 0  62 .0  116. 7  8775  1 4683  59.8  52  64 .0  68 .0  117. 8  8859  14683  60.3  1 60  64 .0  63 .0  12 1. 5  9193  1 4683  62.6  1 64  63 .0  62 .0  1 26.1  8732  1 4683  59.5  1 68  66. 0  61 .0  1 30.5  8599  14683  58.6  172  63. 0  56 .0  130. 6  6444  1 1 065  58.2  176  62 .0  57 .0  134. 9  6572  1 1065  59.4  180  62 . 0  52 .0  1 39 .2  6787  1 1 065  61.4  184  63 .0  51 .0  143. 2  6852  1 1 065  61.9  188  63. 0  50 .0  147. 2  6432  1 1 065  58. 1  1 92  64. 0  50 .0  152. 9  6458  1 1 065  58.4  -  unnecessary. the  recirculation  much U  lower  < Umf.  52  Tests  close  to  temperature  of  the  analysis  the  remaining column  during  were  was  for  bed  use  as  runs and  in  high  at  and a  15  the  as  superficial  of  those  the time  the  and  runs  velocity in  column  were  even  of  order  and  for  about to  keep  possible.  regular  tests  in  any  velocity,  100  for  had  runs,  85  of  were  them  taken  thermogravimetric  gradient  which  velocity  capsules,  composition,  and  concentration  including  K at  end  started,  of  future  0.2  superficial  uniform were  variations  than  fluidization  sulfate  capsules, the  more  operated  system  sodium  temperature  not  minimum  the  -  beginning  composition  the  5656  that  the  fixed  column  of  at  the  in  non-standard  out  K)  system  Before of  system  0.1  The  mm/s,  the  (<  showed  65  within  been were  them.  removed put  back  The  from  the  into  the  column. Since for  the  calculate However, changed  is  to  in  the  in  Section  fixed  A The first  heat value  860.2  The  bed  runs,  independent  the the  column.  the  experimental  fluidized  derivation  bed.  the  kJ/K  Cb  the  of  storage of  system heat  the  capacity  to  the  the  capsules  were  balance  equation  (Eq.5.12),  configuration,  (sensible  due  and  of heat  heat  bed  c a l c u l a t e d as  is  storage  capsules  capacity  removal  theoretical runs  the  was  of  100  capacity 14453  of  also in  used  the  the  kJ  the  using  from  5656 the  same  as  whose  to  fixed  system)  capsules of  the  bed. was  the  capsules  used  same m e t h o d  as  5.1.3.  total sharp 7  of  12  melting-freezing  decline  cycles  in  became  the more  heat  cycles  storage  gradual  after  were  performed  capacity the  of  eighth  the  in  the  fixed  capsules  cycle.  The  in  -  superficial almost  water  constant  minutes  program  data  used  analyze in  heat  storage  the  The in  Appendix  of  the  plotted  times  factors  heat  the  fixed  cycling  which  C to bed  in  Section the  efficiency  of  the  fixed  present  in  in in  the  and  same 4,  mode  given the  for  heat  heat  of  with  These curve been  cycling  bed  used  the  A5  Cj-, the  and  A6  efficiency data is  are  discussed  cycled  96  efficiency  observed  operation  fluidized  computer  correcting  storage  the  for  storage  resultant  the  of  program  Tables  8.  already  65  interval.  in  Table  that  The  as t h e  kept  and  method  except  had  capsules  the  the  runs.  constants  are  evident  bed  and  C temperature  capsules  is  also  40  and  conditions  the  the  runs  7.1  the  were  65 m i n u t e s  bed  Appendix  presented  it  to  is  change  cycling,  due are  20  is  fluidized  in  and  mm/s,  period  decrease  under  rather  fixed  than  had in bed  other  case.  Recovery of Efficiency  capsules storage  system were  the  bed  was  After the  for  fluidized  storage  given  52  cooling  procedure  balance  equation  Since  with  heat  and  about  the  corresponding  15  period  at  to  runs,  section.  stable  heat  of  with  Figure  under  the  bed  -  experimental  identical  balance  The  cycles  The  capacity  5.  heating  12  perform  results  in  conditions  5.3  to  heat  same  become the  were  capsules  the  all  fluidized  term  in  for  respectively.  processing  to  velocity,  66  after  then  12  cycles  between capacity 96  20  and  (or  cycles).  refluidized  in  to  the  fixed  bed  40  C was  down  63% o f The test  that  same  of  the to the  capsules,  whether  it  was  heat 37.5%  storage of  capacity  their  corresponding after  the  possible  fixed to  of  theoretical fluidized bed  recover  cycles, the  'Table 8  E x p e r i m e n t a l R e s u l t s S h o w i n g t h e E f f e c t o f t h e Number Thermal C y c l e s Under F i x e d Bed C o n d i t i o n on t h e Heat S t o r a g e E f f i c i e n c y of the C a p s u l e s  CYCLE NO:  RUN NO:  HEATING PERIOD (MIN.)  COOLING PERIOD (MIN.)  1  194  70.0  72.0  3  198  66,0  5  202  7  SUPERFICIAL VELOCITY (mm/s)  of  HEAT STORAGE CAPACITY (kJ)  THEORETICAL CAPACITY (kU)  PERCENT EFFICIENCY  52.4  7683  14453  53.2  67.0  52.4  6545  14453  45.3  62.0  63.0  52.4  5832  14453  40.4  206  61.0  62.0  52.5  554 1  14453  38.3  9  210  63.0  61.0  52.5  5555  14453  38.4  10  212  60.0  63.0  52.4  5572  14453  38.6  11  214  60.0  61.0  52.4  5386  14453  37.3  12  216  62.0  62.0  52.4  5412  14453  37.5  CD  -  lost of  efficiency.  encapsulated  the  expected  These  a  should  permanently  the  cooling  life  during  this  failure, capsules  performed Indeed, may  be  the  while  the  the  analysis  the  heating  Table  9).  The  The  fluidized  and  runs  used  were  equation fixed  bed  heat are  of  9.  also  lost  capacity in  of  data  the are  the  due  other  will  the  optimum  pattern  of  that and  fixed  used  of  for  fluidized  water  were  each same  capsules  runs.  storage  in  around as  for  used  capacity  performed  within  in  about  refluidization  were  with  the  Figure  occur. cycling  6.  in  fixed mm/s  bed and  60 m i n u t e s the  (see  previous  the  the  of  performed  and 123  for  fixed  heat  bed  balance  capsules  for  the  runs. observe of  cycles.  number 15  to  97.5%  three  Appendix  cycles  was  bed  Therefore,  efficiency.  capsules  was  5656  the  A8  efficiency  the  cycles  plotted  the  if  cycles.  were  heat for  lost  of  periods  bed  of  to  hand,  problem  All  and  efficiency On  during  capsules  serious  recovered  A7  the  use  fluidize  no  storage  was  Tables  efficiency These  heat  storage  If  to  capsules,  velocity  valid  fail  failure.  practical.  recovery  the  may  because,  number  refluidization  calculate  was  the  presented  Table  the  system  system  power  practical  a small  bed  runs.  bed  the  in  followed  melting-freezing  storage  storage  to  runs  Five recovery  for  bed  for  efficiency  cooling  procedures  the  heat  be  show  the  a  their  system  and  critical  fluidized  to  not  the  superficial  fixed  used  of  fluidized  periods  are  a  due  may  for  -  capsules,  lost  experimental  experiments.  in  would  fluidizing  alternate  same  part  system  Refluidization in  the  e.g.,  lose  recover  salt  of  cycle,  economic to  experiments  Glauber's  long  68  the  the  original  The  results  The  change  in  of  cycles  appears  Section  7.1  the  where  heat in the  Table 9  E x p e r i m e n t a l R e s u l t s Showing the Recovery of the Heat S t o r a g e E f f i c i e n c y o f t h e C a p s u l e s When T h e y a r e R e f 1 u i d i z e d A f t e r t h e Thermal C y c l e s Under F i x e d Bed C o n d i t i o n  CYCLE NO :  RUN NO:  HEATING PERIOD (MIN.)  COOLING PERIOD (MIN.)  1  218  59 . 0  55 . 0  2  220  6 1.0  3  222  4 5  SUPERFICIAL VELOCITY (mm/s)  HEAT STORAGE CAPACITY (kj)  THEORETICAL CAPACITY Ckd)  PERCENT EFFICIENCY  122 . 8  7042  14453  48 . 7  63 . 0  122 . 7  7756  14453  53 . 7  63 . 0  61.0  122 . 7  8057-  14453  55 . 8  224  64 . 0  62 . 0  122 . 7  7967  14453  55 . 1  226  62 . 0  60.0  118.8  7986  14453  55 . 3  -  importance recovery cycles  of  was  of  the  97.5% an  recovery of  the  encouraging  of  70  -  the  lost  efficiency  original  heat  storage  finding.  is  discussed.  capacity  within  The three  -  6.  From  the  understanding salt was  behaves  of  to  undertaken.  2.2)  have  is  used  melting  Most  in  When  a  heat  storage  to  capacity.  Although  why or  less  fully  than  the  recovered,  relative  are  to  Glauber's liquid  (see the  5).  capsules  was  capacity. Glauber's  This salt  clearly  be  100%  the  change  no  the  be  bed,  reasons,have possible  studies  encapsulated gave  the  heat  about  system  might  be  storage improve  theoretically  in  improved  only  to  studies  are  number field  reason  of  capsules  (see  advantages  have  of  found  possible been  heat  possible  this  Section •  the  system  especially Glauber's  theoretically  still  better  and  capsules  heat  proposed  storage  which  causes  is  storage to  concentrate  if  it  explain  capacity  under  critical  that  salt,  is on  stored the  different  heat  storage  improved.  However,  heat  storage  Glauber's  inside  For  small  investigators  previous  Such  heat  a  an  which  results.  material,  system,  different  salt,  fluidized  Chapter  of  of  conditions.  efficiencies  a  are  the  in  that  (freezing)  or  performance  qualitative  there  realized  manner  bed  capsules  in  theoretically  magnitude  operating  the  was  the  fluidized  single  utilize  it  crystallizing  studies on  work  affecting  and  a phase  impossible  this  the  on  concentrated  study.  of  explain  -  SHALL SCALE STUDIES  factors  experiments  were  under  the  while  necessary  controlled  begining  71  mm OD  heat  in  heat  possible  its  heat  of  present  than  in  form,  capacity.  in  general  contents  of  possible  other  efficiency  storage  agitated  the  theoretically  better  storage  and  results  capacity  the  performing  spheres  storage  storage  60% of  systems the  25  but from In  proposed it  would  60% this  to phase  -  of  our work,  cycled the  a small  during  loss  of  number  previous  of  the  experiments  efficiency  and t o  72  -  capsules which  had been  thermally  were  identify  reasons  evaluate  tested the  to  relative  magnitudes  of  for the  inefficiencies.  6.1  T h e r m o g r a v i m e t r i c A n a l y s i s o f Samples from t h e C a p s u l e s Thermogravimetric  segregation, efficiency, melting)  and t h u s in  salt  formation  of  complete,  the  a mixture  C;  borax H20  of  salt  the  investigate loss  thermal  of  the degree  heat  cycling  of  storage  (freezing/  crystals  in the at  anhydrous  i t s H2O  samples.  the  c a l c u l a t e the weight loss.  Since  percent  and i t  mixture  chemically  above  the  at  to  in a small  at  capsules  200 C a t  sulfate  be r e l e a s e d  the  of  borax  If  analyze  to  C,  in the  25 m g ) ,  from  should  is  a borax-anhydrous  (20  heated  the water  150  concentration  and  release  samples  below  the water  never  crystals  and b o r a x .  consist  atmospheric  water salt  the  should  for  to  of  necessarily  were  32.4 C,  sample  Since  i s not  sodium  a mixture  capsules  a temperature  average  with  The  water  percentage  is difficult  in the  Glauber's  sulfate,  sample  cooling  anhydrous  molecules  1973).  At  upon  borax,  filled  2  anywhere  was no c h a n c e  3 2 . 4 C.  sodium  from  salt,  were  (Na B407*10H20).  and b o r a x  from  and C h i l t o n there  4.2)  crystals  taken  releases  therefore  weight  (see Section  Glauber's  (Perry  evaporated to  different  (Na2S(V10H20)  samples  molecules  only  capsules  Glauber's  Borax  pressure 70  to  to  histories.  Glauber's  water.  was u s e d  its contribution  capsules with  Regular  of  analysis  it  it  above the  their  contain is  is  possible  sample  from  only  weight  4  sodium  the  sulfate  was a s s u m e d  that  -  the  concentration  concentration constituent  of  in  without  capsules.  Since  their  were  center  and  crayon  by  The  into  electrically  heated  wire.  of  the  material  along  hemispheres  capsule the  path  because  samples  were  of  then  where  the  and  where  Xs  is  the  and  dp  is  of  the  capsule  sampled a  capsules  boundary  sampling Xs/d  p  with  an  position  = 0.65,  Xs/dp  the  to  in  the  capsules  the  to  was  the  (shell with then shell  air  and  to  two  evaporation  is  each  from  diameter.  anhydrous  sodium  in  of  about  a large  whether  by  approximately distance  the  0.65.  was  then  A  was  from  sliced  that  sharp  marked of  knife  top  center  the  difference  had in  concentration  taken  from  at  0.65  precipitate  small  of  layer.  0.35,  most  layer  both  0.05,  in  a  frozen  A  a  sulfate  top  the  using  For  in  diameter)  in  the  difference sample  the  remove  water  be  with  and  mm  discarded  capsule  low  the  hemispheres.  of  the  at  marked  contents)  possible  be  contents  after  bubble  (0.3  was  even  the  been  a thin  as  wire  had  to  capsules to  performed  capsules of  the  freeze  capsule  ratio  result  according  inside  hot  the  each  gradient  vertical the  of  concentration  from  ratio  bottom  Xs/dp may  the  taken  of  nitrogen  the  percent  to  had  was  possible  locations 0.95,  of  ratio  capsules  portions  of  weight  same  the  location  from  the  evaluated.  freezing  It  in  crystallization,  capsule  equal  is  the  liquid  liquid  the  frozen  be  some  center  to  capsule Thus  the  The  two  contents  Four  bottom  reference  precipitate.  in  -  sections  incomplete  position.  the  vertically  was  immersed  relative  could  disturbing  to  the  different  there  due  in  sulfate.  sample  from  performed  analyzed  borax  sodium  the  Sampling  temperatures  of  73  the  near  -  precipitate in  or  from  concentration The  is  of  20 t o  25  mg.  by  occasional  The  C to  the  s a m p l e s was  was  continued  to  be  sure  analyzer stored  by  analyzer C at  for  at  all  were  of  computer  Theoretically Glauber's crystals the  salt,  and  were  the  As  mentioned  sodium  sodium  weight  of  by  a  sodium  capsules with  had  from  frozen  until  90  minutes  and  were  the  but  without  the  the of  range  analysis  The  the any  The  TGS-2  time  temperature  evaporation C,  fluctuation  in  i n c r e a s e the  The  about  Model  nitrogen. to  a  level.  samples  evaporated.  should these  be  of  water  heating change  from  process  in  weight  thermogravimetric  weight  loss  data  the  data  mixture  in  different  the  In  Glauber's percent  percent for  the  the  were  The  results,  cycling  two  Glauber's  from  runs  in  salt  sulfate. taken  sodium  From  from  sulfate  excluding  showing  test  sulfate  c a l c u l a t e d as  samples taken  thermal  of  different  crystals.  sodium  sodium  samples  was  salt  samples  percentages in  addition,  analytical  percentage  concentration.  sulfate  on  weight  weight  borax  pure  weight  runs  loss  representing 5  analyzed.  44.1  44.7  weight  capsules  grade  test  and  7  were  analytical  sulfate-water  sulfate  the  C/min. at  that  Perkin-Elmer  liquid  computer  c a l c u l a t e d the  above,  1  Therefore  automatically.  indicated 44.6  on  the  there  of  more  water  cycling  thermogravimetric  capsules  the  with  sizes  at  programmed  of  10  samples  thermal  performed  a  kept  complete  least  data  using  with  was  rate  the  Twenty-eight histories  a  controlled  the  The  contact  usually  that  was  analyzed  -  precipitate.  the  samples were  indirect  150  the  for  analyzer.  thermogravimetric 25  above  expected  samples were  thermogravimetric  from  just  74  the  a  the  ratio  the based borax. of  percentage  different  (melting/freezing)  sections  of  histories  -  are  given  and  also  history  in in  of  Table Figure  the  they  filled  at  capsules means during  were  84  All  then  5  cycles  96  in  times  Heat in  the  3,  5  the in  6  sodium Figure  (filling)  in  the  bed:  in  Table  sulfate 29,  again  plant  in  column  which  went as  Table  thermal  not  thermally  10  cycling  capsules  crystallized were  through  represents  the  cycled were  while  stored. one  the  This  thermal  cycle  the  bed  capsules  which  went  system.  capsules  which  went  through  12  are  of  12  through  in  bed,  known  the  cycles all  for  as  the  above,  fixed  cycles  concentration  calculation  capsules  cycles  fluidized  plus  under  "all  12  the  the  which fixed  i . e . ,  all  went bed  the  and  thermal  column.  efficiencies and  bed,  explained  container  10)  in  the  the  they  represents  scale  the  bed"  used  conditions.  column,  storage  that  went  represents  fluidized  small  were  were  fluidized  the  a  noted  before  bed:  in  scale  is  process.  cycles  in  be  which  capsules  column:  fluidized  and  the  the  pilot  system  summarize  contents  in  cycles  to  mixed  fluidized  bed  capsules  in  their  of  a fixed  cycles  plant  should  cycles  the  represents  12  and  cycles  fixed  recovery  All  pilot  in  code  capsules  vigorously  the  thermal  under  through  C  the It  contents  in  8.2  -  capsules.  encapsulation  Cycled cycles  being  the  Cycled through  32.4  following  Section  filled.  above  the  in  represents  were  that  29  The  related  Fresh; after  10.  75  the in  in  bed:  performed  afterwards  in  were  the cycled  conditions.  capsules the  fixed  cycles and  bed  a  coded  column"  reported  in  data  in  Table  loss  in  the  10  heat  "fresh",  (capsule  Chapter which  is  storage  5.  "cycled  No's By  also  1,  2,  using plotted  efficiency  due  Table  10.  R e s u l t s of the with Different  Thermogravimetric Analysis Thermal C y c l i n g H i s t o r i e s  Weight  Capsule No.  Thermal of  Cycling History the„Capsule  1  Fresh  2  Cycled  in  the  fluidized  3  Cycled  in  the  fluidized  4  Cycled  in  a  5  All  cycles  in  6  All  cycles  7  All  cycles  plus  12  0.05  %  of  the  Na2S04 at  0.35  Samples  Given  0.65  s  from  the  Capsules  p  0.95  Theoretically Expected Efficiency (%)  43.4  43.8  45.9  47.5  99  bed  38.6  38.8  47.3  42.9  91  bed  38.5  38.8  52.0  42.6  88  bed  17.1  35.2  54.2  52.9  -  the  column  34.7  36.4  53.4  46.7  83  in  the  column  35.7  36.9  49.9  46.1  87  in  the  12.8  31.1  70.9  64.9  -  fixed  cycles  in  column a  fixed  bed  -  to  segregation  sudden layer of  change and  enough  to  solution  in  the  samples  are at  sodium  by  triangles  sulfate  capsule  is  (at  some  Xs/dp  concentration  layer  the  Na2S0i+  anhydrous  microencapsulation accurate,  making  precipitate in The  the  compared Section cycles  are  with 8.2.  in  the  of  difficulties,  was  the  diamonds in  decrease  of  limited the  solution  the  solution  and  the  experimentally  For  the  capsules plus  composition  in  significant  concentration  12  solution  not  gradient.  in  a  the  bottom this  8.2, water  of  low  could  reach  any  by  the  storage  reasonably solution  calculated.  discussed  and  storage  efficiencies  a  bed"  fixed  are  and  assuming  because no  there  and  efficiencies  were  are  bed",  there  evaluation,  uniform.  at  results  in  measured by  29  therefore  heat  fixed  reasonable Also  layers  be  are  of  precipitate  segregation  "cycled  volumes  has  almost  not  heat  not  segregation  under  the  number  The  Figure  occupied  These  recovered  cycles is  would  of  samples,  Section  expected  10.  coded  in  Otherwise  amounts  Table  in  volumes  Theoretically  in  is  the  compositions  cases  assumptions  of  the  concentration  there  These  measured  three  discussed thin.  and  a  precipitate  Exact  after  shown  the  the  the  four  sulfate  As  probably  unknown.  efficiency  for  as  to  is  boundary.  therefore  sodium  in  probably  included  the  sampling  the  calculation  the  column  to  respectively.  crystals  possible.  presence  results  with  problem.  the  between  are  that  = 0.95)  is  boundary  storage  concentration  there  the  Due  layers  heat  0.65 and  there  position  assuming  and  at  -  However,  capsule  exact  themselves  = 0.35  Although the  the  each  expected  in  possible.  layer.  precipitate  uniform  circles,  from  locate  estimated  Xs/dp  be  concentration  taken  and  to  solution  theoretically been  seems  77  is  in  "all  uniform a  experimental  heat  -  storage in  the  efficiency column.  the  the  and  capsules  give  their  are  not  results  gradient  Collision a  of  Chapter  crystals adhere  2,  of  because  included are  used  they  in in  were  not  segregation Section  sodium  sodium  decahydrate  as  the  et  when  sulfate  the  in  they  "microencapsulation".  excess  anhydrous  The  8.2  1979)  cycled effect  to  predict  coated  by  Addition  of  et  added  a l .  necessary excess  claimed to  water  to  designed centre  to of  rotation As  explained  sulfate  Therefore a layer  phenomenon that  replace was  the  individual  contact.  This  the  motion.  sodium  beneath  to  the  drum.  that  in  was  other  anhydrous  buried  due  in  a  mixing  tube  rotating  physical  effects  As  around  through  is  the  concentration  system  any  continues.  Herrick is  to  the  capsules.  good  reported  and  remains  process  for  axis  the  study  capsules  surface  of  into  the  rotating  capsules  case  to  sulfate  fluidized  fixed  come  sulfate  of  horizontal  (1977,  usually  called  decahydrate.  the  the a  of  critical  decahydrate  freezing  sodium  in  the  a l .  sulfate  be  fixed  with  sodium  rotation  to  exposing  axis  the  capsules.  a  designed  efficiency  full  obtained  were  and  storage  around  Herrick  tenaciously  anhydrous  mixing  capsules  horizontal  part  appears  be  without the  of  inside  rotation  capsules,  this  5.1.5,  which not  in  heat  Section  could  full  around  the  axis,  capsules, density  degree  on  in  horizontal  in  they  capsules  behaviour.  experiments  type  explained  the  these  -  Heat Storage C a p a c i t y o f Capsules o f D i f f e r e n t Compositions i n R o t a t i n g Drum a n d R o t a t i n g T u b e The  of  Instead,  crystallization  6.2  for  Therefore  calculations. the  data  78  25%  the  also  some  of  the  may  by  weight  crystals  claimed  be  to  -  increase  the  Experiments different indicate  in  storage  this  sodium  and  part  excess  if  it  Experimental The of  constant  temperature shown  compartments, compartment capsule is  at  the  rotating  pin  bottom held  of  the  together  rotating  drum  rectangular around motor  10 by  possible  a  C  and  by  shaft  to  with  the  the  of  the  ice  which the  by  results or  mixing  1977).  in  five  should  excess is  to  a 0.3  at  the drum  water  each  45  C.  the  motor,  rotating  drum  to  0.45  is  case.  the  x  keep  was m o u n t e d hole  between  water  on  baths  32  top  box,  two  chart of  eight  mm l o n g .  Each  contact  while  again.  the  the  drum  While  rotates  compartments  the  the  a  will  flanges.  m inside  the  at  the  are The  dimensioned  air  temperature  at  a 0.186  kW v a r i a b l e  speed  in  0.5  and  capsule  Eight  0.3  cold  it  bottom the  experiments  consists  the  through  to  a  a  and  that  up t o  drum.  bottom  speed  The  it  passing x  so  bottom,  the  drum  calorimeter  located  through  temperature at  small  bring  of  in  motor  rotating  speed  gravity,  rods  passed  the  mm i n s i d e d i a m e t e r  speed  metal  for  the  drum,  top  rotating  other  effect  inside,  drop  placed  constant  the  it  at  adjust  the  sulfate  a  9a,  146  pin  of  three  The  (Biswas  capsules containing  Hence  variable  baths,  which  from  was  box  C.  Two 20  let  drum  salt  sodium  used  a  Figure  fixed  is travelling  the  set-up drum,  in  bottom  and  what  water  each of  has a  with  compositions.  i s ,  rotating  As  Glauber's  System and P r o c e d u r e  consists  recorder.  of  -  performed  anhydrous  experimental a  capacity were  sulfate  whether  necessary,  6.2.1  heat  79  the and  box. 1750  It  was  r.p.m.  were  used.  One  was  held  capsules, after  being  kept  for  at  at  least  Figure  9b.  Photograph  of  the  Rotating  Tube  -  5  hours  in  desired drum  the  speed  after  45 for  before  betwen  C and  experiments.  for  mixing  the  The 75  carefully  C for The  to  mass  and  the the  the  be  for  same  experiments. which  the  through 220 mV  During at  care  about to  produce  establish  the  capsules,  with  is  with  the  kept  at  while a 0.5  of  were  made  calorimeter  The  at  the  10  point  mm/min  a  placed  uniform  temperature contents  fluidized  in  the  in  crystallized  were  in  thermos  and and  the the  a  longer  a melted bottle  coefficient  was to  from  the  Since  temperature,  surroundings  the the  must  calorimetric  for  the  the  state.  calibrated  itself.  temperature  of  time  insulated  or  the  outputs  range  calibration.  surrounding  to  were  were  connected  a Servagor recorded  The  air  thermocouples,  for  on  Model the  2  speed. 0.4  liters  calorimeter  temperature  gradient  allow  calorimeter  as  c a l o r i m e t r i c measurements C were  the  compensators  chart  bath  of  calorimeter  that  the  results  keep  thermocouple  C water  calorimeter  same  from  the  capsules  copper-constantan  ice  removed  at  the  The  to  20  drum  of  liter  the  and  rotating  capacity  calorimeter  taken  the  they  the  at  the  45 C t o  transfer  not  the  calibrated  range  50  heat  was  electronic  the  of  in  c a l i b r a t i o n experiments  recorder.  scale  minutes  two  drum  capacity  between  i n s i d e the  using  two-pen  water  heat  Special  Omega-CJ  full  overall  measurements  temperature measured  the  storage  insulation.  insulation  gradient  heat  was  in  c a p s u l e s were  placed  was made  fiberglass  temperature the  the  placed The  comparison  capsules in  find  of  the  -  were  warm b a t h  calorimeter  surroundings whole  measuring  mm t h i c k  were  crystallization.  40  bed  with  bath,  c r y s t a l l i z a t i o n and  overnight 20  C water  81  inside  and  the  the  insulation  while  rotating  of  distilled  held  for  calorimeter layer. in  the  45 and  Then, rotating  to eight drum  -  and  having  been  the  calorimeter.  temperature frequently decrease loss.  in  heat The  of  adjusted  small  difference  could  be  C.  The  water were  between using  obtain  bath  until  reported storage  to  at  The  of  were  except  the  that  cylindrical  mounted  on  given  in  allow  the  the  Figure  rotate  same 9b.  filling  of  relative  the  calorimeter  when  the  were  digitized  and  used  the  and  s e n s i b l e heat  its  storage  would  heat  for  be  capacity capacity  of  the  calorimeter  used  in  the  next  only  the  s e c o n d one  run.  the  around  of  the  between and  40  C.  and  40  to  the  The C  contents  of  20  40  held  C and  in  Two  thermal  was  evaluated  conditions  the  45  C  cycles  on  and  the  procedure  the  and the  with  replaced  by  a 2 5 mm i n s i d e d i a m e t e r  variable  placed  speed  in  the  motor.  A  rotating  rotating  as  was  the  for  same  which  same  drum  heat  by  rectangular  photograph  of  the  2 6 0 mm box  of  the  tube  was  large  the  tube,  enough  that  the  capsules  the  tube.  tight  and  tube  inside diameter but  tube  experiments  The  to  the  temperature  temperature  previous  the  of  crystallization.  initial  out  the  rate  c a p s u l e s , equal  capsules during  the  set-up  was  tube  of  by  calorimeter  of  ambient  for  final  effect  the  stopped  of  into  and  accounted  temperature  heat  dropped  was  contents the  were  capsules.  exactly drum  of  bath,  contents  were  the  the  experimental  experiments  the  speed;  the  the  calorimeter  their  each  curves  final  were  eliminate  capacity  by  taken  they  C water  temperature  temperature  the  the  c a p s u l e s were  performed  long  that  corrected  capsules to  in  20  measurements  contents  water  so  the  The  stored  the  the  while mixing  temperature  heat  of  in  -  calorimeter  calorimeter  r e l e a s e d by  were  not  recorded  recorded  quantity  the  shaking.  the  calculation  overnight  Both  were by  The  kept  82  is  enough  to  could  -  6.2.2  P a r a m e t e r s V a r i e d and D a t a Rotational  the  independent  tube  pond  25%,  corresponds 10  heat  15% to  weight  obtained  at  by  weight  in  the  than  beyond  effect  of  produce  a  concentration  of  44.1  corresponding  capsules  heat  that  of  eutectic  fluidized  error. each  bed  unit  B and  The  theoretical  maximum  corresponds  sulfate  Glauber's the  quite  volume.  to  and  The  sodium  lead  could  salt.  efficiency may  concentration  D  E  sodium  or  corres-  Composition  weight  salt  C  in  Composition  basis,  when  used  was  55.9%  decrease  sulfate sharp  at a  (see  compositions lower  Therefore,  range  be  not  absolute  as  extended  above. of  each  composition which  temperature  before  The  experiments  rpm  for  were  rotating  were  which these  had  and  used  exist in  been  at 3.5,  to  minimize  the  between  capsules  and  the  randomly  were  rotational 10.5  calorimeter  selected  cycled  experiments  performed drum  may  were  difference  capsules  composition  the  A,  were  rotating  were  volume  percentage  weight  the  sulfate.  decreased' is  Glauber's  studied  The  system  or  and  a  capacity  higher  difference  reasonable  of  per  capsules small  a  while  and  capsules  compositions  capsules.  by  drum  sodium  eutectic  increased  so  the  to  storage  either  specified  experimental  Salt,  a weight  is  any  excess  Glauber's  the  Compositions  on  capacity  Eight  11.  both  before,  that  Table  the  that  storage  25  weight  different  in  7.2.1),  mentioned  and  5% b y  theoretical  Section  heat  and  inside  rotating  water  water  concentration  other  in  capacity, a  the  five  given  eutectic  Analysis  both  of  -  composition  as  % excess  storage  the  for  Capsules  experiments to  and  variables  experiments.  these  to  speed  83  and  84  from  times  to  reduce  the  in  to  25  the  started. speeds 17.5  rpm  of  1,3,  for  the  5,  10  Table  11.  Chemical of  -  84  -  Compositions  as  Percentage  Different  Rotating  Tube  Compositions  Used  in  Weights  the  for  Rotating  Capsules Drum  and  Experiments  Phase-Change  Material  Sodium  Sulfate-Water Mixture  Designation % Na2S04  % H20  % Borax  % Na2S04  %  H20  Comp.  A  56.3  39.7  4.0  58.7  41.3  Comp.  B  50.7  45.3  4.0  52.8  47.2  Comp.  C  45.1  50.9  4.0  47.0  53.0  Comp.  D  42.3  53.7  4.0  44.1  55.9  Comp.  E  37.9  58.1  4.0  39.5  60.5  .  -  rotating 25  rpm  were may  tube.  because  usually have  seemed drum  The  be  after  around  very  gains  at  high  its  speeds.  horizontal  of  from  for  each  was  not  increased  e f f i c i e n c i e s above  higher  Theoretically  drum  effect  rotating  fallen  axis  the  storage  for  than  had  -  negative  mixing  rather  capsules  speed  energy  The  added  sliding  the  in  small.  countered  to  turning  the  rotational  85  of  the  speeds. during  the  top  rotation  Also  the  half  when  in  the  drum  of  the  was  3.5  drum.  force  capsules  turn  undergoes the  rpm  centrifugal  the  a capsule  10  above  rotations  The  S rotational speeds the  speed  to  make  effect  of  efficiency. efficiency not  used  under  results  The  negative obvious  bed  conditions  the  same  program  given  and  in  calculations  for  fitted  Density a  on  the  centrifugal  rpm,  and  therefore  same  their  capsules  heat  drum  determination  of  storage  force  higher  were  storage  rotating  heat  of  The  the  the  the  were  analyzed  compositions  7,  was  written  for  on  the  speeds  also  were  crystallized  capacities  and to  the  density  weight data third  of  the  the  phase  results  and for  heat  volume sodium  order  heat  speeds.  were  storage A  integrate  theoretical  both  to  allow  the  Therefore  were  to drum  times  c a l o r i m e t r i c c a l c u l a t i o n s as  composition.  material.  3.5  the  The  of  data  different  composition.  basis  tube.  Appendix  perform  rotating  17.5  and  and  to  calorimeter.  experimental at  the  at  fixed  capsules  adjusted  influence  rotating  in  was  comparable  in  the  the  the  tube  collisions  became  The  data  the  the  in  measured  of  of  computer  the  temperature  well  as  the  storage  capacity  at  that  change  material  depends  were  calculated  occupied  by  sulfate-water  polynominal  the  and  are  phase  mixtures  expression  capacity  using  on  its  reported  on  change (Weast the  1976)  -  subroutine  OLSF  expression  i s :  p  The  = 997.16  m  densities  phase for  change  the  Tables are  included  Replications in  the  in  Tables  capacity about the in  at  the  used  to  check It  a n d 13  capsules compare  rotating Fixed  be n o t e d  rotation  material  that  the  rotation  percent  they  evaluate  heat  and t h u s  on t h e  physical  7.2.  The  the results  are given the  same  are also  in  capsules  included  efficiences possible  give  (6.1)  speed.  results  on t h e  storage  to  with  theoretically  Section  kg/m3  experiments  speed  heat  X3 s s  resulting  compositions.  the  Therefore  as d i s c u s s e d i n actual  zero  The  % borax  bed r e s u l t s  as  on t h e  composition. of  tube  r e l i a b i l i t y of  a r e based  library.  X2 + 918.64 ss  different  and marked  should  Center  the 4 weight at  respectively.  the  effect  276.14  for  and t h e  to  encapsulated the  drum  13  that  -  c c  ss  densities  in Table  tables. 12  X  corrected  material  and 13  -  t h e UBC C o m p u t i n g  + 985.5  were  rotating 12  from  86  heat  valuable  storage  storage  information  performance  changes  However,  reported  which  they  capacities obtainable  occur  cannot  at  of  be  different  compositions.  6.3  Experiments t o Determine Degree o f There  i s an  abrupt  change  temperature  versus  time  This  change  indicates  abrupt  temperature  and t h u s  the  The  water.  curves  also  in  for  the the  a sudden  Subcooling slope cooling  of  the water  runs,  increase  in  e . g . ,  the  outlet Figure  7.  capsule  in the  heat  transfer  rate  from  the  capsules  capsule-to-water  heat  transfer  rate  as a f u n c t i o n  of  to  Table  - 87 12. R o t a t i n g Drum E x p e r i m e n t a l R e s u l t s S h o w i n g t h e E f f e c t s o f C o m p o s i t i o n a n d R o t a t i o n a l S p e e d on the Heat S t o r a g e E f f i c i e n c y of t h e C a p s u l e s  SODIUM SULFATE (% WT)  ROT. SPEED' (RPM)  DENSITY OF PCM (kg/m ) 3  HEAT STORAGE CAPACITY (kJ/kg)  HEAT STORAGE CAPACITY ( I0 kj/m?)  PERCENT EFFICIEN  3  58 . 7  25. 0  1681.  216.4  363 . 9  99.4  58.7  25. 0  1 681 .  217.5  365.6  99.9  58.7  10. 0  1681.  215.5  362.3  99.0  58.7  5. 0  1 68 1 .  204 . 4  343 .5  93.8  58 . 7  3.0  1 681..  201 .4  338 . 6  92 . 5  58.7  1 .0  1 681 .  198. 1  333 .0  91 .0  52.8  25. 0  1 591 .  231 .4  368.3  94.2  52.8  10. 0  1 591 .  227. 1  361.4  92.4  52.8  5. 0  1591.  219.0  348.5  89. 1  52.8  3 .0  1 591 .  215.8  343 .5  87.9  52.8  1 .0  1 591 .  211.6  336.7  86. 1  52.8  1 .0  1 591 .  212.4  338.0  86. 5  47 . 0  25. 0  1510.  240.5  363. 1  87.9  47.0  10. 0  1510.  237 . 1  357 .9  86.7  47.0  5. 0  1510.  233.6  352 .7  85.4  47 . 0  3. 0  1510.  224 .8  339.4  82.2  47.0 .  1 .0  1510.  221 .6  334 .6  81.0  44 . 1  25 . 0  1472.  239. 1  351.9  83.2  44 . 1  25. 0  1 472.  2 38.0  350.2  82.8  44.1  10. 0  1472.  237 . 1  349.0  82.5  44 . 1  5. 0  1472.  232.6  342 .4  80.9  44 . 1  3.0  1 472. '  228 . 9  336.9  79.6  44 . 1  1 .0  1 472.  225.4  331 .8  78.4  39. 5  25. 0  14 15.  221 . 1  312.8  87. 1  39.5  10. 0  1415.  220.5  312.0  86.9  39.5  5 .0  1415.  213.8  302 . 4  84.2  39 . 5  3.0  1415.  211.9  299.7  83.5  3 9.5  1 .0  1415.  208.2  294 .5  82.0  39. 5  1 .0  14 15.  206. 1  291.6  81.2  - 88 Table  13. R o t a t i n g T u b e E x p e r i m e n t a l R e s u l t s S h o w i n g t h e E f f e c t s o f C o m p o s i t i o n a n d R o t a t i o n a l S p e e d on t h e Heat S t o r a g e E f f i c i e n c y of t h e C a p s u l e s .  SODIUM SULFATE  ROT. SPEED  % WT)  (RPM)  DENSITY OP PCM (kg/m )  58 . 7  17.5  1 681 .  193.7  325.6  88.9  58.7  10.5  1681 .  • 195.8"  329.2  89.9  58 . 7  3.5  1681 .  187. 1  314.5  85.9  58 . 7  3.5  1 68 1 .  188.3  316.5  8 6.5  58.7  0.0  1 681 .  1 55.8  261.9  71.5  52.8  17.5  1591.  2 12.5  338.2  86.5  52.8  10.5  1 591 .  212.7  338.4  86.6  3  H E A T STORAGE CAPACITY (kJ/kg)  HEAT STORAGE CAPACITY ( 1 0 kJ/m ) 3  PERCENT EFFICIENCY  3  52 . 8  3. 5  1591.  205.3  326.1'  83.6  52.8  0.0  1591.  170.4  271 . 2  69.4  47 . 0  17.5  1510.  224.6  339. 1  82. 1  47.0  10.5  1510.  223.4  337 .2  47 . 0  3.5  1510.  217.8  328.9  79.6  47 . 0  0.0  15 1 0 .  179.4  270.8  65.6  4 4.1  17.5  1472 .  227.7  335. 1  79.2  44 . 1  10.5  .1472.  222 . 8  327.8  77 . 5  .  81.7  44 . 1  3. 5  1472.  214.6  315.8  74.6  44 . 1  0.0  1472.  177.9  261 .8  61 .9  39.5  17.5  14 15.  211.8  299.6  83.5  39.5  10.5  1415.  210.9 .  298.3  83. 1  39.5  3.5  14 15.  203.9  288.5  80.4  39.5  0.0  14 15.  181.8  257.2  71.6  -  time  for  the  Appendix  4  increase  in  during  and  the  transfer  same  The  must  subcooling  which  nucleating  agent.  of  of  factors  the  of  induce  and  the  an  the  sulfate  and  the  the  location  capsule  bed  in The  part, of  two  phase  0.3  to  the in  a  in  given  in  at  the  to  since  7.1.  A  exactly  of  presence led  Table  capsule  initiation  run  in  Section  present  the  in  by  In  4%  same  the  time  temperature  by  subcooling  in  considerable  nucleation  of  in  A3  the  to  is  and  after  weight  experiments  a decrease  heat  heat  some  borax  as  determine  believed  but  these  which  liter  degree  was  the  to  be  one  storage  is  between of  after  studied  the  both  the  in  the  simulating  factors  or  tend the  to  by to  the be  effects  concentration degree  nucleation  starts by  molecules  analyzing  (borax),  many  possible  initiation  to  on  on  is  of  of  subcooling  initiated.  capsules the  of  motion  Also  under of  the  bed.  were  the  sometimes  mixing  crystallization  of  1.59  it  limited  agent  of  performed  Erlenmeyer  (OMEGA,  depends  types  temperature  material  Initially,  were  nucleating  the  which  collisions  Experiments of  process  addition,  causing  fluidized  change  is  complex  1976).  experiments  thermocouple flask.  a  conditions  the  10  observation  crystallization  fluidized  is  increase  results  is  and  at  7,  -  system.  concentration  sodium  rate  even  impurity,  unreproducible.  Figure  Figure  during  which  Smith  of  due  The  nucleation  presence  be  occurs  Nucleation (McCabe  in  sudden  subcooling  efficiency  in  transfer  run.  degree  as  plotted  heat  rate  run  89  flasks  identical  mm s h i e l d  phase  change  in  three  were  parts.  used,  each  composition.  diameter) material  was was  In  the  filled  A  with  0.2  kg  copper-constantan  inserted heated  first  into  above  each its  -  melting the  point  output  chart  then  the  thermocouple  recorder  Recorder data  of  and  at  output  using  the  temperature  the  nucleating  was  temperature, gives  using  two  flasks  under  the  same  and  The  %  the  borax,  liquid  average  initial  three  borax  the  and  mixing  part  mm/min  converted  to  temperature  the  initiation the  of  maximum  the  the  same m i x i n g  data  points  our  in  to  the  the  the  studied the  for  in  parallel  possibility was  with  condition.  Glauber's  without  disturbing  the  liquid  listed  each  of  in  experiments the  five  4%  studied the  believed  fluidized  Table  4%  borax.  for  bed.  c r y s t a l l i z a t i o n temperatures are  3%,  of  mixed  in  5  Glauber's  also  is  range  3 to  0%,  contribution  mixing  both  is  of  studied.  by  The  salt  compositions  the  of  increased  was  of  gives  reason  mixture  subcooling  from  the  in  The  salt  magnitute  capsules  and  minimum  of  conditions  the  time  initiation  them  tests  were  versus  c r y s t a l l i z a t i o n temperatures  gently  the  salt  evaluate  Glauber's  was  the  test  each  for  experiments,  used  sample c a p s u l e s  agent  Glauber's  and  at  220  speed.  The  temperature.  the  while  crystallization  after  to  Model  chart  thermocouples.  of  and  of  10  Reliability  nucleation  second  and  for  temperature  Servagor  always  was  condition  a  is  In  in  on  because there  weight  type  recorded  nucleating  (lignant)  The  to  using  a  room  c o m p o s i t i o n was  four  borax  96% by  similar  The  as  subcooling  part  precipitate.  composition  of  any  of  are  at  crystallization  under  1952).  weight  degree  weight  borax  (Telkes  without  and  the  same  test  there  for  5% b y  salt  same  so t h a t  weight  the  in  range  while  nucleation.  the  suggested  of  the  conditions  unusual  flasks  before  -  air  was  full-scale  digitized  curve  crystallization  repeating  2 mV  slowly  c a l i b r a t i o n curve  the  having  cooled  90  for  by when  bottom to  be  The each  14. was  performed  different  by  compositions  -  Table  14.  Results  of  the  Erlenmeyer  Composition  and  Mixing  G l a u b e r ' s s a l t , no v i g o r o u s l y mixed  91  -  Subcooling  Experiments  Performed  in  Flasks  Pattern  Nucleation Temp. (C)  Borax,  C r y s t a l 1i  zation  Temp.  (C)  16.6  32.4  3 wt. salt,  % B o r a x , 97 w t . % v i g o r o u s l y mixed  Glauber's  29.0  31.8  4 wt. salt,  % B o r a x , 96 w t . % v i g o r o u s l y mixed  Glauber's  30.4  31.8  4 wt. salt,  % B o r a x , 96 w t . % G l a u b e r ' s l i q u i d part gently mixed  28.3  30.4  5 wt. salt,  1 B o r a x , 95 w t . % v i g o r o u s l y mixed  30.3  31.7  listed  in  Table  which  had  been  fluidized  bed.  11.  The  The A  shield  diameter)  was  located  in  distance was  the  of  The constant  gently  anhydrous  be  s i n c e the  segregation  any  of  the borax  borax  capsules,  in  1  leakage.  mostly  times 40  in  C to  thermocouple  each  capsule  The  sulfate  mm f r o m  to  selected  the  likely  concentration  the melt  thermocouple  for  will  be  the  phase  1.59  mm  a drilled junction  in  the  capsule's inner place  those  liquid  (Omega,  through  precipitate  from  was  capsule  surface.  nucleation higher  hole,  to  there  at  a  This  be  due  to  the  crystals. together  temperature  agitated  heated  into  sodium  randomly  eighty-four  were  inserted  prevent  to  were  copper-constantan  approximately  considered  initiated  a  to  cycled  capsules  material.  enough  capsules  thermally  change  tight  Glauber's  the  with  the  water  bath  at  water  bath  with  thermocouples,  25 C one  at  a motion  a  were  time.  similar  to  immersed  into  They  were  that  of  a  -  stirring  rod  appeared  to  bed.  The  in be  in  crystallization in  The  Table  second  part,  at  the  center  of  of  these  happening  in  wished  find  to  temperature the  effect  the  temperature  %  while  is  was  was  recorded  repeated  for  composition  each  they in  the  that  The  third  second  in  the  the  was  to  a  on  the  crystallization  Three  c a p s u l e s were  (Comp.  in  given  in  Figure  subjected  to  the  0  (Comp. the  The  type  Table  bath  The  results  are  and  plotted  in  subcooling  than  in  time the  better  In to  while  11).  One  without  any  two  magnitude  of  capsule  was  of  for  The  what  and  to on  having  the  third the  the 44.1 had  44.1  c a p s u l e s were as  we  the  52.8  weight  agitation.  mixing  is  determine  two  of  both  particular,  and  as  located  estimate  temperature  11),  the  capsules.  idea  that  One  curves  times,  analyzed,  except  one.  junction  occurs,  remaining  and  of  various  Table  B in  water  31.  same  in  into  crystallization  part,  process.  nucleation  capsules  the  position  cooling  cooling  at  fluidized  nucleation  second  versus  obtain  the  and  studied  of  thermocouple  the  liquid  times.  rather  same  Temperature  during  mixing  converted  average  part  capsule  at  the  discussed.  used  each  located the  are  and  three  8.  of  the  nucleation  the  cooled  in  Appendix  initial  sulfate  magnitude  capsules  in  sulfate  sodium  was  during  the  the  determine  capsule.  gradient.  weight  result  was  capsule  mixing  % sodium  of  in  experiments  where  weight  % capsules  used  recorded  gradient of  in  with  while  the  were  mixing  to  followed  were  the  and  where  identical  in  purpose  A9  8.3  junction  thermocouples  data  temperatures  thermocouples  thermocouple  the  -  type  experiment  Section  is  The  thermocouple  time  procedure  experiments two  the  Each  tabulated  30  of  versus  temperatures.  Figure  liquid.  s i m i l a r to  output  temperature  are  a  92  The cooled  used  in  the  -  second  type  and  for  33  of 44.1  respectively.  subcooling and These  52.8  experiment. weight  %  experimental  93  -  Results  sodium results  are  sulfate are  given  in  Figures  concentration  discussed  in  32  capsules  Section  8.3.  -  F l u i d i z e d and F i x e d Bed Cases Heat  material are  transfer  (PCM)  plotted  runs the  (see  The  few  sharp due  in  in  to  rates  inside  the  Figures  Figures  first  increase  is  -  HEAT STORAGE PERFORMANCE OF THE CAPSULES  7.  7.1  94  7  and  minutes  the  10  in  and  11  increase  at  around  a  increase  and  for  the  cooling  21 in  the  PCM  The  continuous  which  follows  the  combined  internal the In  decrease Figure  rate on,  heat  transfer in  11,  after  to  temperature  the  the  slight  first  suggesting  resistance  that  but  few the  PCM  temperature  while  increasing  with  time.  of  difference  would  coefficient  due  melting  which  in  heat  transfer  to  be  and  due  the  to  water  be to  the  rate  probably toward  the  in  cooling  run  (Figure  increase  solid  PCM  in  between  the  PCM  increase  in  surrounding  the  from of  in  the  end  the  temperature process  the  is  water  the  the  in  10)  nucleation  in  rate the  capsules the  heat  and  water. transfer  process  constant  at  is  about  temperature  going the is  temperature in  the  heat  transfer  capsule  with  further  capsule run  and  the  water.  transfer  the  the  decrease  gradient  to  melting  almost  in  to  the  an  is  due  and  of  the  within  PCM  heat  the  melting  the  (water) heating  are  in  that  by  away  cycles  change  rates  decrease  increase  for  temperature  decrease  after  the  compensated  occurs,  the  Part  the  transfer  due  temperature  crystallization  and  temperature  continuous shows  phase  fluid  cooling  heat  the  the  transfer  heating  in  the  difference  minutes  the  effects  of  between  heat  between  minutes  some.subcooling. due  in  difference  bed  typical  and  after  is  the  Increases  both  temperature  sudden  fluidized  capsules  8).  of  the  wall.  Figure  difference  complete.  11  The  decrease  is  believed  between  The  the  average  PCM  I  10  Figure  10.  Rate Time  I  20  i  1  30 40 TIME (minutes)  —  i  50  I  60  o f Heat T r a n s f e r Between t h e C a p s u l e s and t h e Heat T r a n s f e r F l u i d f o r a T y p i c a l C o o l i n g Run i n t h e F l u i d i z e d B e d G i v e n i n F i g u r e 7.  versus  5  •  i  10 Figure  11.  20  Rate  of  Time  for a Typical  Heat  Transfer  i  u  —  30 40 TIME (minutes) Between  Heating  —  —  i  —  50  t h e C a p s u l e s and t h e Heat  Run i n t h e F l u i d i z e d  r~  60 Transfer  Bed G i v e n  in  Fluid  Figure  8.  versus  -  volumetric kW/m  heat  (where  maximum  transfer  the  heat  volume  transfer  rate is  corresponding  rates  for  kW/m3.  rates  enable  about in  These  65 m i n u t e s ,  Figures  heating  7  are  and 8 .  The  solar  collectors  today  (Duffie  40 C  gradient  value  between  that  city High  between system  at the  will  temperature heat  heat  collectors  storage  unit  rates  also  work  will  be  area  and  during the  during  winter.  more  closer storage  critical  especially  and  for  the  It  be  the  50 C  parts, is  or  discharged  the  therefore  the  to  at  the  most  water  for  an  important  High  unit  heat  Canadian  length  of  outlet  in  use of  in  cooling  they  of  even  runs  was  heat  transfer  inland  removal fluid  than  rates  variations  day  be  gradient  The  heat  this  can  temperature  necessary to  of  instead  advantage  fluid.  the  and  many a p p l i c a t i o n s .  transfer  high  cooling  resulting  the  since  the  given  temperature  smaller temperature transfer  in  as  equipment  fluid, for  91  real  temperature  of  sunny  for  compared  for  and  variations  increase the  storage  units.  For  charged  forces  the  The kW/m3  inlet  since  60  63  transfer  efficiently  is  are  temperature  a  run  capsules), while  kW/m3.  temperature  50 C  heat  the  the  run  efficiently  with  cooling  temperature  applications with  day.  northern  are  more  to  is  driving  heat  source  work  to  would  inlet  temperatures  especially  the  a common  181  than A  the  The  run  fluid  study  and  transfer  lower  transfer  demand  PCM  of  conservative,  higher  this  volume  outlet  1980).  periods.  water,  solar  operated  the  and  transfer  Beckman in  energy  even  usually  used  heating  system:  is  the  typical  heating  temperature  or  heat  and  shorter of  The  the  typical  inlet  realistic,  applications.  the  with  this  inside  during  the  -  during  the  rate  97  in  low  are  in  heat  supply  provinces, is  store  very the  short  solar  energy  -  at  a  high  also  rate  when  fluctuate.  morning  when Heat  using  For  the  thermal  heat  -  theoretically. transfer  crystallization resistance  which  time  heat  capsule  wall.  experimental and  heating  unknown. before  and  three  demand  the  PCM may  be  and/or  another  capsule  such  main  as  of  to  estimation,  cooling  until  is  The 57%  wall  of  was  overall  PCM  the  indicate  for  the  capsule a  coefficient  nucleation,  the  heat  could  be  were the  inside  transfer  the  50% o f  to  to  the at  become increase  more  in  conductive in  the  typical  capsule  cooling  was  coefficients, by  to  estimated  change  calculated  the  crystallizes,  or  the  6.1.4,  using  just  nucleation  * S o m e a t t e m p t s w e r e made t o f i n d h o l l o w m e t a l c a p s u l e s . I n d u s t r i a l T e c t o n i c s , I n c . M i c h i g a n m a k e s a l u m i n u m and s t e e l hollow p r e c i s i o n b a l l s of d i f f e r e n t s i z e s . T h e y w e r e t o o e x p e n s i v e ( a b o u t $1 f o r e a c h 1 9 mm d i a m e t e r b a l l ) f o r t h i s p u r p o s e . No o t h e r h o l l o w m e t a l c a p s u l e s were f o u n d . We a r e his e f f o r t s to help us.  grateful  to  Dr.  Peter  a  before  starts  for  with  resistance  than  the  by  resistance  wall  a thinner  transfer  overall  use  material  considerable  heat  hand,  of  more  calculate  temperature  -  capsule  to  other  in  increased  total  capsule  that  with  94%  possible  the  high  section  internal  the  in  inside  possible  household  wall  In  the  not  because  the  be  to  and  accounts  the  from  calculations would  due  is  further  aluminum.*  components  this  for  up.  According  It  after  energy  wall  rate  the  demands  capsule  resistance  runs  On  from  wall  warmed  Energy  external,  These  transfer  or  begins.  total  dominant.  the  during  the  be  conductivity, of  heat  thermal  must  to  -  available.  example,  capsule  contributions transfer  is  house  transfer  a thinner  higher  it  98  McGeer  of  Alcan  for  -  and  crystallization  transfer 21  min  fluid in  (Comp.  D in  (Figure  temperature  Figure  temperatures  for  An  in  7)  was  96  weight  Table  30).  temperatures  11)  25.7  were  overall  -  found  the C,  99  bed  in at  while  Section the  the  6.3.  time  of  salt  and  4  found  27.1  and  31.8  heat  to  be  transfer  and  (at  time  crystallization  weight  coefficient,  heat  nucleation  nucleation  % Glauber's  The  % borax  C,  mixture  respectively  U0,  can  be  defined  from  q = ^  The  total  using  the  sudden U0  outside heat  were  nucleation Section  this  that  there  predicted  is  no  the  temperature  On  is  capsules,  and  29.8  heat  the  starts.  capsule  other in  the the  attributed  to  76%  total  the  after  It  the  hand,  capsule  the  is  not  before  transfer  resistance  to  is  and of  before  m2.  after  By  the  nucleation, and  after  performed  the  in  be  since  it  was  assumed  inside  the  capsules  from  to  inner  remembered  obtain  compared  to  a higher  heat  before  surface  of  to  crystallization  near  p o s s i b l e to  predicted  and  resistance  the  avoid  crystallization  heat  45.2  should  side  temperature  theoretically heat  It  reasonable  on  time  estimation  nucleation,  it  the  transfer  wall  before  W/m2-K  high  is  capsules,  just  24.1  the  crystallization  inside  10  W/m2-K.  to  just  5756  theoretical  resistance  between  of  as  the  indicates  on  gradient  difference  19.6  The  AT  Figure  be  because  bring  in  of  which  as  U0  A,  should  coefficient  temperature.  values  rate,  calculated  estimation  nucleation,  the  the  crystallization  transfer  should  in  area,  rates  respectively.  5.1.4  that  before  transfer  increase  values  surface  U„ Ar o c  a  starts.  experimental  inside  transfer  capsule  at  the  If U0  the moment  of  -  crystallization These  still  calculations  increase  the  material  by  during as  is  heat  The  heat  the  first  90.9%  of  calculated  support  a  or  run  theoretical  be  more  heat  the  the  (melting  and  freezing)  There  was  no  further  decrease  conditions  (before  any  the  reduced  anhydrous of  the  efficiencies  sodium  capsules  sulfate around (see  of  the  during  differentiate of  each  Chapter  the  performed  were  These  the  of  during  the  (Hodgins  others,  anhydrous  first  to  few  of  small  discussed  has  observations  in  study  led  the  crystal  requires  decreases  the  rate  of  to  agitation  Marks same  to  (4)  crystallization  The  major  of  due  to  the  size  difficult the  8.  An  in  three  increase  salt in  to  magnitute  reported  in  crystals  some  studies  Visual An  increase  crystals the  in  first  1980).  the  rotation  the  observed  reasons  (3)  is  Glauber's  under  of  full  because  result.  keep  and  cycles  of  it  Section  theoretically  Change  Chapter  been  in  presence  lack  bed  measured  93  experiments,  and  was  that  Subcooling;  in  sulfate  cycles  The  effects  change  fluidized  heating  next  the  further  phase  filled  tests).  factors  to  calculated  Although  the  the  60% of  8.2);  scale  1975,  more  to  in  three  (1)  (2)  these  Telkes  size  be:  of  wall.  material.  were  the  bed  and  1955,  this  over  cycles.  sodium  thermal  2.2  analyze  are  about  due  Hoffman  and  and  the  experiments  the  few  contributions  6,  points. size  first  on  to  axes;  Sections  depends  to  precipitate,  wall  first  fixed  appear  horizontal  Microencapsulation crystals  cycles  possible  capsules  the  capsule  capsules  capacity,  cooling  for  over  the is  capsules  The  fluidization  it  conductive  storge  decreased  to  fluidized  of  after  due  that  5.1.3.  possible.  efficiency  from  efficiency  heating  to  -  argument  rate  thinner  storage  the  the  transfer  using  100  in  decreased  in  the  suspension surface  -  area  available  increased  crystal  efficiency of  the  it  formation  has  5%  toward  was  water  sodium the  found  than  the of  sulfate  run due  after to  the  structure  amount  cooling  run  minutes)  gain  gain  normal  the  the  for  4  2%  waiting of  thermal  The  change  rate  are  outside  the  change  factors, storage in  the  in  this  of  nuclei  the in  the  size  study  scope  which a  rate  of  controlled  of  crystal  reach  increase  in  the  (a  water  at  into  This the  heating  of  between  diffusion anhydrous  anhydrous  measured  sodium  that cooling end  run.  of  about  capsule, are  during  a  45  which believed  heat  to  release  efficiencies. The  increasing increase  in  performance the  of  superficial  efficiency  is  the  system  water more  was  velocity  gradual  at  found as  to  be  improved  shown  in  Figure  higher  4  holiday),  the  crystallization,  5% d i f f e r e n c e  or  (usually  the  always  efficiency  each  between  run  inside  the  the  the  indicates  end  occurred  gradient  weekend  was  crystallization by  to  period.  of  The  efficiency  salt  more  continuing  to  two  the  as  release  period  continuing  temperature  the  heat  probably  to  longer  the  of  these  analyzed  such  which  Glauber's  a 1  beginning  of  is  of  diffusion  still  of  not  efficiency.  runs  layers  a  was  variables  growth,  crystallization  because  reasons  heat  long  to  literature.  the  a  loss  predictions  that  over  was  and  and  increased the  of  many  the  was  the  cycling  crystal  There  crystallization The  of  cooling  addition  microencapsulation.  thermal  in  the  sulfate.  probably  of  -  In  increase  quantitative  through  first  may  function  found  end  growth.  increased  rate  been  the  sizes  during  No  less  crystal  to  a  and  It  of  is  study.  sizes  to  due  crystals  because  this  for  101  velocities,  by  12.  The  probably  be and  m  Figure  12.  Percent  Theoretical  Fluidizing  Velocity.  (Triangles);  Heat  Recovery  Number  Temperature  of  Range:  from  the  Capsules: 40 t o  20  Capsules as 5756  C.  a Function  (Diamonds)  and  4328  of  the  -  due  to  a  reduction  resulting of  about  space this  from 120  the  the  velocity  velocities capsules above  for  were  capsules  present  shown  Figure  of  in  about  space, again  145  even  mm/s, with  observed inside  rotation  even  never  of  the  at  on  the  higher  the  pumping  anhydrous  power  operating (and  at  with  75%  space  number  sodium  at  of  for  the bed  was of  to  At  this have  a  to  there  to  velocities  The  fill  of results  the  some  available  The  were  density capsule  therefore, the  are  velocity  capsules  full  in  as  the  number  prevented  crystals  Above  superficial  and  and  the  superficial  be due  velocity.  velocities, sulfate  high  expansion.  capsules,  above  at  to  velocity  f i l l s  remained  original  enough  mixing)  screen.  superficial  symbols.  appears  thus  high  the  above  a certain  velocities  below  about  term  thermal the  Experiments  superficial  system  long  believed  screen  capsules  and  is  expansion  reduced  completely  restraining screen  in  complete  solution  was  obtained. Since  the  the  the  triangular  bed  top  bed  hence  superficial  present  more  the  the  fixed  gradient  suspension  by  to  the  a  efficiency  screen.  allow  the  At  in  performed  to 12  and  that  (and  decrease  capsules  the  expansion.  stuck  slight  -  collisions  observed  capsules  The  on  mm/s  was  bed  distributor  5756  fixed  130  it  some  capsules.  inter-capsule  increased  mm/s,  between  fixed  in  103  operation.  cycling  first  difficult  few to  95  cycles, claim  the  cost),  mm/s  some  study  further  at  it  velocity  This  without  superficial  for  would  (see  not  shows loss  lower  that  in  be  Section  detrimental  superficial  same  velocities  heat  the  beneficial  9.1).  At  effects capsules  recovery  velocities  increases  above  velocities.  It  may go  the  to  operate  superficial occur  during  through  efficiency, 95  mm/s.  It  is  reasonable  after is to  -  assume will  that,  not  during  be  resulted  a certain  sufficient  thermal As  allows  below  shown  in  time  sulfate  precipitate.  loss  efficiency crystals  period.  influence  of  resistance parts  different  materials  rather  whether  some  whether  the  transfer  also  affect  the  in  the  rate  of  a  is  the  the  heat  degree  recovery  is  resistance  salt  slower  mixture crystal  and  thus  growth,  by  nuclei  more  grow  the  a complex is  of  mixing  efficiency  surface  the  use  and  there after  only  on  area the  resulting  of in  a  by  the  to  case,  and  since with bubble). agent on  nucleation  crystals.  These  the  the  For  rate  may  direction  of  self-nucleating  less  nucleation  is  small  larger  or  non-uniform  cooling  to  but  heat  initial  leads  fewer  the  air  propagation  capsules.  the  information  of  the  many  predict  contact  no  and  sodium  with  nucleating  the  capsule,  size  cooling  capsule  in  is  borax  the  sodium  our  Because  and  anhydrous  anhydrous  solution  form  generally  rate  are  gain period  easy  the  heat  cooling  process,  In  of  in  crystal  of  not  1976).  the  inside  rate  It  difficult.  formation  the  the  influenced  saturated  throughout  cooling  longer  into  throughout  capsule  to  crystals  be  Smith  nucleation,  start  nuclei  to  uniform  initiated  salt  A  subcooling,  result. and  inner  self  water  generally  not  improvement  microencapsulation  final  predictions  the  of  (precipitate,  than  Glauber's  systems,  the  crystals  heat  in  period.  of  expected  (McCabe  Glauber's  make  velocity,  considerable  cooling  any  also  was  nucleation  (borax)  unknowns  of  a  degree  to  the  changes  different  the  loss  diffusion  The  are  affecting  Also  for  due  variables  13, the  Crystallization  transfer  superficial  prevent  Figure  increasing  a longer  sulfate  -  cycling.  from  of  to  104  supersaturation compared  crystals  to  the  (McCabe  00  0 Figure  13.  30  60 90 COOLING PERIOD (minutes)  Percent  Theoretical  Cooling  Run.  40  C.  Number  Heat of  Gain  by t h e C a p s u l e s a s a  Capsules:  5756;  Function  U = 96 mni/s;  150  120 of  the Duration  Temperature  Range:  of  20 t o  and  Smith  borax  1976).  crystals  crystal  In  present,  growth.  different  Since  sodium of  either  the  of  crystal  capsule  and  this  shown  the  in  or  melting  the  internal  have  importance  phase  transition  believed  to  The recovery by  the  of  because  storage  of  the  circles  the in  of  first part  cannot  be  of  the  of  for  no  on  15.  cycles After  the  This  rate  in  the  melting  to  be  parameter  could  precipitate  precipitate  may  not  fixed  cycles  go  decrease  period  of  121  form  the  the  a heating  through in  the  min.  is  error.  bed  the  in  their  heat  conditions  heat  is  from  when  apparent  heat  subsequent  appear  rate.  experimental  7  the  c r y s t a l s which  would  cycle  The  under  found  incongruently  a considerable decrease 7  in  Heating  the  sulfate  in  in  proven.  crystallization been  of  have  change  change  rate.  rate  mass  gradients  this  rate  heating  A  of  crystals  melting  salt,  amount  has  sodium  cycles.  range  showed first  other  the  efficiency  the  Figure  or  the  the  solution  the  heating  heating  salt  by  future  the  information  anhydrous  a major  within  in  saturated  or  were  only  necessary.  on  subsequent  salt  affected  during  capsules  during  No  Glauber's  (recovery) be  the  effect  the  during  forms  heat  the  change  first  on  was  nuclei  affect  concentration  influence  changes  Glauber's  size  only  is  l i t t l e  to  of  Glauber's  there  regarding  during  from  14,  mixtures.  The  the  the  Figure  effect  mixtures.  and  data  no  of  would  available  to  crystallization  period  sulfate  changes some  sources  the  expected  literature  only  With  due  melting  sodium  have  efficiency  congruent  the  concentrations  recovery  have  if  -  precipitate  growth  might  106  cooling  the  water  microencapsulation. As  case,  sulfate  transfer rate  our  -  recovery  as  shown  a  o  T  25 Figure  14.  50 75 HEATING PERIOD (minutes) Percent  Theoretical  Duration Range:  of  Heating  40 t o 2 0  C.  Heat  Recovery  Run.  Number  from of  the Capsules  Capsules:  5756;  as a Function U = 96 m m / s ;  of  the  Temperature  Conditions '  Figure  15.  I  3  I  j  l  6 9 12 NUMBER OF CYCLES  |  15  '  Decay and R e c o v e r y i n H e a t S t o r a g e C a p a c i t y (shown a s P e r c e n t T h e o r e t i c a l Heat Recovery) as a R e s u l t of M e l t i n g / F r e e z i n g C y c l e s w i t h the C a p s u l e s Under Fixed Bed and F l u i d i z e d Bed C o n d i t i o n s . S u p e r f i c i a l V e l o c i t y - 52 mm/s a n d 1 2 3 mm/s, r e s p e c t i v e l y . Number o f C a p s u l e s = 5 6 5 6 .  -  efficiency 38.4%  of  of  the  the  capsules  theoretical  corresponding  agitated  decrease  with  further  capacity  during  well-known  studies of  thermal  storage as  which  low  capacity as  given). heat the  cycles.  16.5% For  a  storage  change.  change unit  after  volume  sodium  the  the  in  between  sulfate of  capsule  inside wall  is  greater  reasonable fixed  bed  the  thermal  to  the  expect  but  for  the  Section  salt  system, 40  the  higher  16%  (1955)  that  in  and  (see  Section  heat  is  range  an  e f f i c i e n c i e s under  heat fell  to  not  theoretical  of  or  no  phase  phase area  and  per  the  tank  along the  of  that  filled  8.2).  storage  This  of  number  contact  water  bottom  the  tray)  precipitate  of  few  the  heat  the  a bulk  are  s e n s i b l e heat  l i t t l e  case,  sulfate  of  indicates  undergoes  a  have  the  the  the  to  is  that  of  latent  diffusion  capsules.  recorded  about  only  storage  shallow  the  sides  parts  (a  to  than  the  reported  (temperature  our  for  function  due  In  that  there  to  probably  to  2.2),  due  Hoffman  C was  studies  is  and  Also,  heat  C  is  cycles.  of  20  continued  of  a  system  84%  larger  as  capacity  and  67%  many  (1955)  and  conditions  (see  is  somewhat  bed  and  sodium  middle  loss  salt  anhydrous  surface  conditions  encapsulation,  tank  encapsulation.  than to  20  Hodgins  the  the  fixed  Hoffman  salt  remaining  solution  because  and  (or  40  performance  quantitatively  between  repeated  between  capacity  the  Glauber's  fixed  bed  Although  theoretical  of  a  and  problem  Glauber's  result  salt  storage  loss  their  pure  and  The  Glauber's  of  fixed  Glauber's  this  the  capacity  material  of  Hodgins  of  -  c y c l i n g under  solving  report  heat  cycling.  thermal  on  the  system),  disadvantage  concentrated  in  109  the  precipitate  Therefore  c a p a c i t i e s even  it  is  under  advantage  of  fixed  conditions,  bed  -  especially operation  after (see  About the were  fixed  is  replaced  also  to  of  cycles  a  system  thickened  due  97.5%  bed  very  over  the  viable  system  could  fluidized  considered  in  Capsules  transported, turned  fluidization  and  there for  for  breakdowns,  for  economical  with  fixed  makes  use  not  have  stored  and  loaded  during  will the  be heat  the  cost  bed  the  to  savings  malfunctioning  unit of  the  systems has  to  of  This  transfer  is  cycles  output.  ability  system.  be  cycles  not of  view.  interspersed This  to  is  recover  lost  Glauber's  above In  32.4  salt C  addition,  months  or  when  the  system  in  control  and  safety  the  because pump,  and  result  point  encapsulated  the  to  storage  be m a i n t a i n e d in  rapid  advantage  salt  system  thermal  before  capsules  This  a number  heat  the  the  storage  after  for  The of  15.  economic  heat  energy  summer  storage  an  when  capacity.  of  9.1.  the  Figure  available  Glauber's  a heat  do  off  the  storage  from  cycles  salt  fluidization  Section  needed  requi red.  heat  necessary  also  in  container)  in  equipment power  its  of of  which  detail  are  needed,  in  more  they  low  capacity  gives  Glauber's  optimize  practical:  be  loss  It  to  more  can  bed  with  operated  capacity  too  three  triangles  result.  systems  continuous nor  the  cycles  storage  not  fixed  salt  be  still  storage  within  bed  heat  system  by  applicability  economically  with  shown  together  where  are  heat  recovered  unrecoverable  shows  cycles,  initial  promising  applications  The  the  other  (usually  few  -  9.1).  was  as  Glauber's  the  first  Section  refluidized,  recovery this  the  110  special etc.,  are  when the is  precautions not  - Ill  R o t a t i n g Drum a n d R o t a t i n g T u b e C a s e s  7.2  The results shows  percent  obtained  the  plotted  in  The  results  are  discussed one  around  a  from  can in  collision  was  drum  in  and  at  5.2.2,  the  to  capsules  the  after  the  drum the  obvious rotation  drum  at  were  had  and  centrifugal  that is  the such  rotating  be  with to  and  18,  with of  and the  at  rotate from  falling  altered  will  that  centrifugal  in  the  seems  and  6.2  rpm  10.5  in  and of  mentioned  Also,  was  is  a  turn  the  is  in  stronger  the more  than  at  rpm  the  25  to  drum  between  higher  speed  the  Section 25  of  trajectory. if  in  impact at  of  limit  above  the  smaller  falling all  both  As  the  top.  efficiency  approach  half  force  5  effect  to  during  at  19.  times  efficiency  speeds  fall  3.5,  speed,  rotational  the  and  Section  3 and  the  for  similar  3.5  1,  storage  rotational  capsule,  not  heat  tube.  the  are  about  for  18  are  rotation.  increase  in  observed  of  the  the  speeds rpm  results  results  from  for  which  composition  tube  differentiate  influence  rate  than  the  12  Figures  remembered  results  capsules the  the  should  Table  and  in  the  16  force  plotted  Therefore,  fallen  the  are  and  in  efficiency)  Corresponding  capsules  the  17.5  speed  the  The  rather  capsules surface  It  rotational  the  drum  increase  tube.  and  13)  storage  tabulated  rotational  compared  from  and  (heat  rotates  Figures  found  in  respectively,  drum in  drum  Table  drum  axis.  storage  respectively.  here.  the  tube,  higher  17  (see  directly  the  the  changes  rotating  of  heat  rotating  and  case  drum  in  since  16  the  slide  the  be  shown  capsules  in  of  together  the  in  As  rpm  the  horizontal  rpm  gradual  tube  rotation  drum  17.5  in  Figures  rotating  that  theoretical  influence  the  the  -  speeds  It of  is the  that  of  o  N  Figure  '  I  0  5  16.  T  — " ~  10 ROTATION  P  15 SPEED  —  —  (rpm)  1  T-  20  P e r c e n t T h e o r e t i c a l H e a t G a i n by t h e C a p s u l e s o f D i f f e r e n t R o t a t i n g Drum as a F u n c t i o n o f t h e R o t a t i o n S p e e d . Number each C o m p o s i t i o n ; Temperature Range: 20 t o 40 C .  25 Compositions of C a p s u l e s :  in the 8 at  m s  1  Fi g u r e 17.  i  r  —  T  !  1—  40 45 50 55 WEIGHT PERCENT SODIUM SULFATE  r—  60  P e r c e n t T h e o r e t i c a l Heat G a i n by t h e C a p s u l e s o f D i f f e r e n t Compositions R o t a t i n g Drum a s a F u n c t i o n o f S o d i u m S u l f a t e C o n c e n t r a t i o n . Number o f C a p s u l e s : 8 a t e a c h C o m p o s i t i o n ; T e m p e r a t u r e Range: 20 t o 40 C .  in  the  Na S04(wt%) 2  58.7 52.8 39.5 47.0 44.1  T  5 ROTATION Figure  18.  T  10 15 SPEED (rpm)  P e r c e n t T h e o r e t i c a l Heat G a i n by t h e C a p s u l e s o f D i f f e r e n t R o t a t i n g Tube as a F u n c t i o n o f t h e R o t a t i o n S p e e d . Number each C o m p o s i t i o n ; Temperature Range: 20 t o 40 C .  20 Compositions of Capsules:  in th 8 at  WEIGHT PERCENT SODIUM SULFATE Figure  19.  P e r c e n t T h e o r e t i c a l Heat G a i n by t h e C a p s u l e s o f D i f f e r e n t C o m p o s i t i o n s R o t a t i n g Tube as a F u n c t i o n o f Sodium S u l f a t e C o n c e n t r a t i o n . Number o f C a p s u l e s : 8 a t e a c h C o m p o s i t i o n ; T e m p e r a t u r e R a n g e : 20 t o 40 C .  in  the  -  gravity,  calculated  observations, contents The at  of  it  the  agitation high  surface lifted heat  to  is  happen  believed  capsules  of  speeds,  crystals  to  the  minimizing  from  to  the  storage  the  to  any  the  sodium  sul fate-water  mixture  mixing  conditions  probably  drum.  It  possible thus  seems by  that  creating  affecting  degree  of  period  above  the  hours,  is  of  the  drum.  weight  reached  at  about  turbulence anhydrous  by  sodium  increasing  something  which  the  would  sulfate  and  the  drum  possible  an  rpm  in  external  the  could  rotating only  entire  sulfate of  are  encapsulated under  the  be  rpm.  maximum  length  not  25  capsules  borax)  mixing  the  while  with  25  of  especially  sodium  efficiency  by  these  near  capsule  The  by  in  or  settle  attained  increase  of  vigorous,  anhydrous  which  the  at  quite  between  be  light  possible mixing  4%  the  and/or  can  (with  internal of  drum  of  the  developed  crystals  top  further  size  subcooling 2  a  was  the  In  maximum  tendency  e f f i c i e n c i e s which  is  the  collision  redisperse bottom  -  rpm.  drum  in  the  The  108  that  capsules  segregate.  helps  in  at  116  made  volume,  crystals the  be  and  the  cooling  practical  for  many  applications. In on  the  lower that  of  the  rotating  tube,  the  sodium  sulfate  crystals  rotational  speeds  than  in  the  drum.  fixed  in  the  tube  capsules  the  direction would  case  anhydrous  the  around  the  same and  allow  possible increases  horizontal  around  the  the  axis same  centrifugal  distance with  were  an  from  the  increase  as  the  in  effect  a capsule The  and  axis  to  move  the  center  of  rotation.  in  mass,  the  were  Rotation  force  the  reason  thus  tube.  horizontal  of  without crystals Since  effect  of  centrifugal became was  force  evident  most  likely  forced  to  in  same  any to  the  at  rotate  disturbances, the  greatest  centrifugal  force  centrifugal  force  -  will  be m o r e  for  higher  higher  percentages  is  reason  the  efficiency percent  in  low  as  not  behave  to  like  a  the  helping  to The  with the  at  10.5  rpm  the  l i f t  by  mixing  Glauber's  salt  sulfate.  At  25  drum in  mixture rpm  in  plus  and the  the  top  of  heat  for  storage  the  not  lower  at  by  in  is  a  drum,  and the  17.5 drum  minimum which and  likely  be  possible  rotation,  to  reach  the  during  inner  the  capsule  rotation,  thus  crystals.  experiments possible  showed  to  from  weight  efficiency  they  moved  gravitational  shaping  of  not  speeds,  10.5  rpm  the  did  recovery  3.5, 5  as  did  force  heat  would  pure  speeds  crystals  at  of  capacity  44.1  at  the  in  capsules  tube  was  contains  drum,  It  suspension  it  rpm  weight  precipitate  difference  effects  speeds.  rotating drum  which the  the  3  storage  sulfate  even  3 and  The  and  52.8  this  the  the  tube 1,  collision,  uniform  expected  at  efficiencies  to  a more  rotating  theoretically  tube  high  and  rotation  produce  the  at  crystals  rotating  heat  centrifugal  this,  5% s m a l l e r .  about  storage  because,  of  efficiencies  in  other  contains  Probably  sodium  hand,  the  which  the  and  therefore  speeds,  the  in  58.7  each  other  Inspite in  to  low  and  the  discussion  heat  the  vigorous  the  to  capsules  higher  capsules  1%  forces  the  for  18)  Anhydrous  stick  On  sulfate  crystals.  (Figure  speed  tube,  wall.  only  obtained  to  in  at  with  above  not  mass.  are  values  improve  wall  while  the  decrease  rotating  single  compared  the  did  sodium  sulfate  concentrations.  capsule  of  of  sodium  rotational  suspension  the  centrifugal  levels  the  settle,  when  observed  capsules in  toward  supports  to  highest  rpm  respectively, for  the  the  efficiencies rpm,  the  a uniform  tended them  3.5  anhydrous  sulfate  -  concentrations  for  sodium  crystals  form  at  of  117  a  recover  even  100%  of  eutectic  percent  was  that  83.2%.  sodium This  is  the  -  maximum that  a  value  found  uniform  maintained sodium  in  system.  the  the  Even  all  suspension  sulfate  completely  for  drum  theoretical  heat  if  the  crystals  sulfate  Glauber's  salt.  A  attributed  2.2).  Also  cycled  that  segregation  for  bulk  reduced  in  versus the  (eutectic the  shown  sodium  drum  the  and  tube  44.1  sodium  weight  sulfate  Although Glauber's  part salt  transformation which buried  was as  the  are  salt  present  in  anhydrous  bed  and  will  at  result  initial  sodium  salt  some  be  a  buried  reached  by  samples (see  more of  weight  is  not  heat  the  the  storage  be  amount  of  is  also  available  on  higher  mixture.  part  mixture,  in  anhydrous  sulfate  replacing  8.  based  sulfate  the  salt  the  sulfate  found  of  remaining  and  reason  speeds  sodium  sodium  only  efficiency  rotational  of  indicate  Chapter  melting  molecules  all  6.1),  in  can  a l .  capsules  results  percent  et  of  (Section  the  detail  larger  sodium  If  effect"  Section  explanation  a  a layer  Herrick  analysis  in  under  from  sulfate  Glauber's  sulfate.  recover  suspension,  incongruent  anhydrous  to  of  of  form  different  in  prevention  the  plots  An  was  salt  sodium  44.1  crystals  a Glauber's  of  at  the  believed  from  Concentrations  upon  that  sufficient  system  19,  is  capacity  was  discussed  Glauber's  the  not  still  crystallization,  form  evident  it  sulfate  "microencapsulation  mixture).  added  during to  can  analysis  effect.  percent  the  17  minima  precipitate of  in  concentration  show  Glauber's  remain  Since  sodium  Thermogravimetric  Figures  sulfate  is  storage  anhydrous  effect  in  mixing  fluidized  of  microencapsulation  than  to  efficiences.  microencapsulation As  it  now  conclusion  thermogravimetric  thermally  is  probably  similar  studied.  anhydrous  it  by  -  cases  the  segregation  sodium  who  of  tests,  anhydrous  (1979)  the  118  buried  under  undergoes sodium but  water  sulfate  became forms  -  Glauber's possible less  salt, heat  than  A  smaller  crystals  sulfate  which  water in  to  this  water heat  the  anhydrous  salt, 27  C  in (see  Although  the  the  storage  capacity  congruently  storage  during  use  of  salt  per  sodium  prevent  weight  by  weight  When  crystals  the  not  cycling  salt  heat  or  mean to  crystals  mixture  will  the  settle  is as  a  recover settle  warmed,  anhydrous  to  sodium  be  at  absolute  addition, no  need  gravity by  the  a  theoretical  15%  at  Figure  seems  is  under  about  about  capacity  there the  some  water  problems,  In  a  of  at  (see  smaller  as  Glauber's  in  sulfate  weight. that  of  starts  storage in  weight  undergoes  sulfate  above  and stated  formation  compositions  results  volume  does  thermal  Glauber's  to  theoretical  mixture  sodium  sulfate  by  nucleation  sodium  melting  concentrations  repeated  of  (1977)  composition  the  usually  sodium  problems  66.4%  this  upon  sodium  Biswas  the  mixture  The  borax,  solubility  storage  the  borax.  e f f i c i e n c i e s due  unit  sulfate,  to  of  of  sodium  as  sufficient  24.5%  the  well  Using  because  anhydrous  amount  of  containing  precipitate  crystals.  mixture as  mixtures  fewer  smaller salt  theoretically  less  C.  congruent  in  form  32.4  by  The  about  melting  crystallization.  4%  6.3). is  at  the  hand,  means  a  melting  crystals  of  thus  weight  not  sulfate  segregation  presence  sulfate  capacity.  Glauber's  the  decrease  sodium  mixing  is  reduced  reduced  by  of  other  Glauber's  congruently  presence  Section  considerable  33.4%  sulfate in  by  sulfate  material  1).  a  A  melts  temperature  to  and  a congruent  this  answer  medium  of  sodium  the  precipitate  use  even  the  of  -  recovery  sodium  buried  sodium  subcooling  the  On  be  section.  storage  100%  can  avoid  mixture  percent  amount  in  be  capacity.  weight  sulfate  suggested  should  storage  44.1  melting.  there  119  weight  sulfate  heat  use  of  for heat  upon of  the  -  crystals enough  due  to  to  dissolve  (less  than  by  external  an  presence the  10  of  reasons  increases to  The experiments  amount  further, results shown  tested  by  in  all  were  cases.  concentration 100%  fixed  Figures with  12  16,  (99.9% 25  under  heat  18  and  19  efficiency  rpm  would  in  the  five  an  for  cycling expected  7.1.  self-consistent (rotation of  and  speed  the  results  conditions. efficiency  conditions  is  less  than  0.6%  e f f i c i e n c i e s of  up  to  almost  100%  58.7  weight  drum),  error  heat  the  tube  different  in  and  storage  rotating  indicate  at  time  mixed  is  Section  rotating are  of  not  efficiencies  reproducibility  same  for  in  is  Unless  repeated  variables  difference  storage  period  efficiency  discussed the  the  storage  storage  independent  the  sulfate  unsaturated  Since  and  experiments  13,  heat  drum  The  short  remain  section.  beds,  sodium  applications).  would  heat  17,  the  the  and  Although  which  this  rotating  performed  at  in  of  relatively  reduced  concentration).  Tables  recorded,  beyond  causes  for  repeating  runs  layers  as  the  a  storage  precipitate,  trends  was  two  upper  -  Diffusion  in  of  of in  sulfate  between  the  daily  discussed earlier  sodium  in  most  precipitate  reasonable  shown  melting.  precipitate  in  force,  and  As  the  hours  the  the  decrease  show  incongruent  120  in  percent  none  the  of  sodium  the  sulfate  results  went  calorimetric  measurements. Results drum in  and  Table  of  rotating 13  and  in  They  are  included  tube  measurements.  the tube  first  bed  experiments  Figures for  fixed  18  and  comparison  During  cycles,  with 19,  with  comparisons  the  with the it  following  same the  capsules  rotating  rotating should  the  drum  always  rotating  are  tube  included results.  and  rotating  be  remembered  -  that,  although  repeatable not  the  for a large  repeatable  fixed  7.2.1  cycling  is difficult  studies  If  bed r e s u l t s  the capsules  efficiency  (Marshall  for the  resulting variety  units  from  differed  1981),  comparing  several  were  declined  heat  reaching  a maximum  94-77  have  (1977)  been  have  points  studies  storage at  are  used  under  rapidly  with  on t h e  et  be l o n g  to  heat  74-634  develop  (Kelly a  a l . 1983)  comparing  and  standard  (see  and complex of  storage  Section  because  the problem. heat  of It  storage  interest.  (Biswas  from  and NBSIR  for  heat  reported  for testing  (Cole  methods  1977,  sulfate-water  also  be  t h e a p p l i c a b i l i t y and t h e  and t h e c o m p l e x i t y  simple of  are not  conducted  probably  applications  they  available  will  (see also  possible  ASHRAE  from  about  methods  in composition  1983)  questions  systems  to  were  because  methods  studies  results  heat  sodium  additives  the  latent  of  specific  a l . 1984),  compare  standard  Although  be d e s i r a b l e  In  to  to  15).  are serious  t h e two  1974).  Nelson  storage  in the literature  There  of  great  Some  heat  (see Figure  would  et  one c y c l e .  fixed  different  devices  the  cycles,  are believed  It  accuracy  2.2),  thermal  experiments  Compositions  basis.  method  their  and tube  of  than  -  Method f o r Comparing Systems w i t h D i f f e r e n t  storage  Hill  drum  number  f o r more  bed c o n d i t i o n s  thermal  same  rotating  121  that  present  Sections capacity  Herrick  mixtures of  in 2.2  used  in  stoichiometric some  cases  and 7 . 2 ) .  is different  the eutectic  and Zarnoch  Glauber's  1982, the  different  salt  storage  Glauber's  (Marks Since  at  heat  1979,  Fouda studies  salt.  Chen  and  theoretically compositions,  composition,  i t  is  difficult capacity and/or  to or  to  sodium  of  The  against  the to  unit  usually weight  plot  is  different  weight the  the  determining  storage  against  capacity  theoretically  factor  possible  determined  performance  the  storage over  a  capacity range  capacity of  the  at  0%  the  sodium or  performance  of  system  as  the  storage  be  prepared  heat  in  any  a  comparison  weight  medium.  the  over  The  storage percentages  the  shows  the  water,  Results  for  the  is  easy  one  storage  heat to  salt of  in  possible  and  the of  the  the  real  storage  storage  using  hydrate  capacity the  only  water  systems  results for  but  the  compare  systems  is  interval  storage  the  a  heat  measure  heat  system  other  as  unit  The  between  is  unit,  theoretical  to  Superposition heat  the  variation  a corresponding  well  theoretically  theoretical  it  of  are  it  storage  composition  the  of  mixture.  as  cost.  provides the  the  temperature  the  that  with  in  the  the  and  intervals  basis  of  difference at  simple  capacities  weight  of  with  compared  alternative  is  composition,  volume  a given  capacity  plot  with  volume  than  capacity  s i m i l a r manner. of  unit  corresponds  with  storage  changes  together  of  study  sulfate  Since  sulfate  heat  calculation  The  composition.  this  sodium  per  24).  system  volume  direct  same  of  of  a  storage  system.  crystallization  of  system  storage  experimentally of  the  Figure  heat  temperature  rather  composition  (see  overall  different  also  on  a given  of  in  possible  practice,  in  the  adopted  mixture  important  basis  compositions.  percent  In  -  at  over  curves  basis.  c a p a c i t i e s of  plotted  the  comparision  of  all  also  on  looking  mixtures  the  weight  by  122  theoretically  density  the  storage are  method  at  sul fate-water  useful per  performance  use.  plotted Since  comparisions  efficiences The  easy  make  -  the  can  allows same  -  temperature It from range heat  of  also  be n o t e d  storage  mixtures  between  respectively. heat  storage  The  density  the  phase  storage  against  of  the  crystallization  33.4  percent  curve  for  sulfate and  sodium  sulfate  concentrations  order  a  Center.  polynomial  Computing  50,  volume  Center  function  of  systems  other  factors  area,  system  cost  works  only  temperature such of  as t h e  the  e t c . ,  The  should  sodium  sulfate  for  to  the by  using  congruent  concentration  Section As  with  0LSF  solubility  expression  than  solubility  about  to  from  the  sodium  at  fitted  in  1,  less  The  percent  5.1.3.  shown  the d i g i t i z e r  were  in  basis  see Figure  solubilities  the subroutine  fitted  in  15 C  theoretical  3 2 . 4 C.  and 3 3 . 4 w e i g h t  1  sulfate  Eq.(6.1)..  system,  than  between  weight  compositions  solubilities  using The  using  i s lower  Figure  sodium  explained  sulfate-water  resulting  library.  that  temperature  from  of  a n d on a u n i t  was p r e d i c t e d  11  sulfate-water  in c a l c u l a t i n g the  to  corresponding  expression  percent  basis  sulfate  sodium  55 a n d 60 C a n d a l s o  followed  between  3 2 . 4 C was d i g i t i z e d  Computing  as  sodium  the  the  a certain  transfer  the weight  sodium  theoretical weight  for  c a p a c i t i e s of  45,  procedure  the mixtures  diagram  view  which  c a p a c i t i e s was s i m i l a r of  compares  compared.  on a u n i t  The  of  heat  over  20 C and 4 0 ,  2 0 a n d 21  method  comparisons,  available  heat  60 C a r e p l o t t e d  Figures  point  interval  and  this  detailed  the  temperature  Theoretical  and  In  rate,  be e v a l u a t e d  that  capacity  operation.  transfer  system,  -  interval.  should  a heat  123  15 C  in the a  UBC  third  t h e UBC temperature  was:  CO  >-  20-40 C — - 80 46 C 20-60 C 20-66 C 20-60 C - - - 16-60 C  <  o u < u or o, I— LU  O  15 30 45 WEIGHT PERCENT Figure  20.  Theoretical M i x t u r e s as Temperature  60 SODIUM  75 SULFATE  90  H e a t S t o r a g e C a p a c i t y p e r U n i t V o l u m e o f Sod.ium. S u l f a t e - W a t e r a F u n c t i o n o f Sodium S u l f a t e C o n c e n t r a t i o n o v e r Different Intervals.  1  •~ 1  I  m  15 30 45 WEIGHT PERCENT  Figure  21.  Theoretical Mixtures  Heat  as a  Temperature  Storage  Function  Intervals.  of  Capacity Sodium  i  ' — — T  ••  60 75 SODIUM SULFATE per  Unit  Sulfate  Weight  of  Sodium  Concentration  over  P0  90  Sul f a t e - W a t e r Different  Tm  = -5.4292  + 249.45  Xgs  -  126  -  -  652.8  X2,.  +  725.47  X3g  (  7.1)  where  Both  Tm  = Congruent  Xss  = Weight  the  at  which  the  heat  calculate  A  the  a n d on a  sulfate  is  stored  computer  results  the  curves  performing  were  the  were  The  temperature  cold  given  0.1  in  with  0  show  the  the  help  9,  and 100  on  is also of  interval this  a unit  weight  increments  presence  of  of  was w r i t t e n  both  t h e maxima  program  amount  temperature  Appendix  percent  to  and t h e  the  capacity,  between  computer  calculations  end o f  in  storage  enough  (C)  sulfate  calculated  using  sensitive  same  the  basis,  By  accurately.  at  heat  weight  concentration.  the  sodium  program,  theoretical unit  of  temperature  crystallization  crystallization  expression.  basis  fraction  theoretical  theoretical  solubility  %  in  to volume  sodium  composition,  and t h e minima capable  in  of  an a d d i t i v e  such  as  borax. The sodium borax and  theoretical  sulfate-water as  nucleating  23 on a u n i t  These  figures  rotating  drum  are  heat  storage  mixtures agent  volume used  and t h e  are  basis for  capacities  between  without  any a d d i t i v e  plotted  in  the  and on a u n i t  comparison  rotating  tube  and  same  20 C and 40 C  and w i t h manner  weight  basis  in  4 weight Figures  results  in  the  Section  7.2.2.  7.2.2  E f f e c t o f Phase Change M a t e r i a l C o m p o s i t i o n In  Section  7.2,  rotating  drum  and  rotating  tube  % 22  respectively.  in the d i s c u s s i o n of  experimental  for  experimental  I  T  I  15 30 45 WEIGHT PERCENT Figure  22.  Theoretical Mixtures of  Sodium  Heat  without Sulfate  Storage any  Capacity  Additive  and  Concentration.  T—  1  T  !  60 75 SODIUM SULFATE per with  Unit  Volume  4 weight  Temperature  of  Sodium  % Borax  Range:  20  90  Sul  Addition to  40  C.  -  fate-Water as  a  Function  Figure  23.  Theoretical  Heat  Storage  Capacity  M i x t u r e s w i t h o u t any A d d i t i v e and o f Sodium S u l f a t e C o n c e n t r a t i o n .  per  Unit  Weight  of  Sodium  Sulfate-Water  with 4 weight % Borax A d d i t i o n T e m p e r a t u r e R a n g e : 20 t o 40 C .  as  a  Function  -  results  were  discussed  efficiencies. about at  the  different  conditions,  point  of  weight  phase  change  of  composition storage of  the  have  material.  in  The material Figures  storage  this  heat  and  composition  was  65  only  As all of  by  capacity rpm  the  concentrations  in  Figure  part  in  to  the  c a p s u l e s and  storage  storage  the  parameter capacity  heat  do  or  is  their  from  storage  behaviour  a  system  unit  volume  or  different capacities,  not  give  weight  the  heat  conclusions  per  of  storage  volume  capacity  in  important  compositions unit  per  presented  in  capacity between  of  Figure  speeds  unit  in  Above at  the  volume  Tables  12  with  of  main  curves  a a  heat  clear phase  idea change  parameter  theoretical  heat  24, the  HSCPUV drum  this  up  was to  a  plotted  in  corresponding  by  concentration,  different  22.  Since  weight  rotational  weight.  However,  must  curve  decline  the  sodium  curves  the  improved  sulfate in  between  35  it  sodium is  solid  At.  heat 25  almost  rpm  storage and  10  sulfate  obvious curve  sodium  at  concentration the  speeds.  for  (the if  be  changes  by  capacity  to  sodium  above  HSCPUV  are  storage  found  slowly  that  13  change  plotted.  increase  storage  phase  Figure  58.7%  to  47%  and  from  3 9 . 5 % and  of  the  continued  heat  24)  per  capacity  is  different  HSCPUV  theoretical  heat  led  Since mixtures  different  storage  weight. are  heat  theoretical  capacity  percent  rotational 47%  at  changed  shown  the  changes  important  respectively together  the  weight  most  material.  data  25  heat  sulfate,  is  storage  theoretical  the  in  the  section.  (HSCPUV) 24  discussion  occurring  different  Therefore  discussed  and  view  efficiencies heat  that  changes  economics  -  considering only  Although  physical  129  from  without  sulfate  the points  WEIGHT PERCENT SODIUM SULFATE Figure  24.  Heat S t o r a g e C a p a c i t y of the C a p s u l e s per U n i t Volume of Phase Change M a t e r i a l a s a F u n c t i o n o f S o d i u m S u l f a t e C o n c e n t r a t i o n i n R o t a t i n g Drum a t Different Speeds. T h e o r e t i c a l Heat S t o r a g e C a p a c i t y C u r v e s a r e from F i g u r e 2 2 . Number o f C a p s u l e s : 8 a t e a c h C o m p o s i t i o n ; T e m p e r a t u r e R a n g e : 20 t o 40 C .  -  concentration theoretical At  heat  rotational  gradual  is  concentration. indicate higher  that  sodium  probably amount  available  an  sulfate  of  space  to  concentration  speeds.  The  the of  be  showed  reduced,  weight  of  more  where  to  anhydrous  (2)  with  the As  the  density  of  vigorous  in  16).  in  is a  in  at  is larger  a more  uniform  sulfate  formation  sodium  a  general,  This  sodium  stated  or  effective  there  remain  the  sulfate  i s more  Figure  if  of  a  larger  Section  4.3,  sulfate  the  capsules  equal.  Hence  with  higher  sodium  mixing  in'the  capsules  sodium  sulfate  sulfate at  speeds.  speeds  % sodium  below  and the  44.1  heat  indicate  probably  heat  increased  a considerable  respectively,  rotational  case  in the capsules  caused  efficiency  theoretical  44.1  space  % sodium  speed  even  no c h a n g e  experiments,  allowing  varied  average  was d e c r e a s e d  HSCPUV  should  air  area  crystals.  capsules the  drum  crystals  thus  the e f f i c i e n c y  absolute  and 2 4 ,  surface  salt  weight  the  %,  experimentally.  was e i t h e r  (see also  In  the  diffusion,  keep  rotational  47  rotational  (1)  forcing  the  which  Although  rotating  in the  59 w e i g h t recovered  5 rpm, there  of  the  about  was t o t a l l y  above  reasons:  in the  above  concentrations  Glauber's  concentrations,  17  two  than  -  HSCPUV  increase  was a l a r g e r  higher  lower  in the  f o r water  concentration there  capacity  increases  proportion air  storage  precipitate,  suspension  the  increased  Results  due t o  of  further  speeds  decrease  131  to  storage studied. sulfate  On  weight  storage the  below  capacity  % (see Figure  in  to  at  all  capacity  sodium  the  or  higher  curves  in  the  drum  HSCPUV than  Figures  concentration  percent,  rotating hand,  17),  rotational  sulfate  35 w e i g h t  the other  i s equal  the  decrease  that  well  when  at the  to  in  approach  the  and  range  above  theoretical  -  heat  storage  unit  volume.  capacity Thus  concentrations drum  over  the  As  sodium at  of  rpm f o r  the  precipitate 17.5  the  rpm.  Centrifugal  sulfate  concentration  than  the  The  rotating  in the  capsules  a decrease  amount  of  conditions rotating HSCPUV to  versus  sodium  function  only  there a  mixtures  salt  in  a  with  rotating  the  below is  of  weight  this  sodium  at  of  when  %  mixing  at  sulfate  in  the  concentration  sodium (see  sodium  % i s more  uniform  uniform  force  precipitate  since  for  concentration  higher  the  weight  a less  those  the centrifugal  HSCPUV  a  47  to  insufficient  reasonable  having  sulfate  above  mass  44.1  sulfate  around  influence  produce of  per  the  gradual type  of  suspension  in  suspension  decreases  due t o  decreased  the  present. sodium  sulfate  concentration  first  thermal  cycle  experiments  where  conditions  the  will  importance  in the  during  tube  as a  cases  tube  in  This  at  effect  increased  decrease  mixture  similar  anyhydrous  has more  case.  are very  due t o  negative  the  using  sodium  decreases  extra  i s decreased  precipitate  HSCPUV  the  of  rotating and t h e  the  for  versus  tube  rpm, probably of  sulfate  Glauber's  a maximum  gradually  force  drum  reason  HSCPUV  reach  sodium  studied.  rotating  due t o  rate  range the  also  and due t o  7.2).  with  25,  utilization  Section  the  eutectic  and 17.5  concentrations  mixing  of  HSCPUV  sulfate  in  that  the  They  The  3.5  be no  speed  for  percent  to  Figure  drum.  weight  -  seems  than  curves  3.5  at  in  sulfate.  speeds  there  lower  shown  rotating  37  rotational  concentration the  of  132  are  presented  in  of  sodium  is  agitation.  This  fraction  the  small  sulfate  of  after  data  the  Figure  rotating  25.  concentration indicates anhydrous  under  The is  that sodium  fixed drum  bed and  variation  reduced under  relative  fixed  sulfate  in  in  bed the  m CM  *  35  Figure  25.  i • « « 40 45 50 55 WEIGHT PERCENT SODIUM SULFATE  • 60  Heat S t o r a g e C a p a c i t y of the C a p s u l e s per U n i t Volume of Phase Change M a t e r i a l as a F u n c t i o n o f Sodium S u l f a t e C o n c e n t r a t i o n i n R o t a t i n g Tube at Different S p e e d s and U n d e r F i x e d Bed C o n d i t i o n s . T h e o r e t i c a l Heat Storage Capacity Curves are from F i g u r e 22. Number o f C a p s u l e s : 8 a t e a c h C o m p o s i t i o n ; T e m p e r a t u r e R a n g e : 20 t o 40 C .  -  precipitate  undergoes  hydration  Addition  anhydrous  sodium  mixture  of  has the  fraction the  of  added  salt  anhydrous  volume.  Addition  the  the  extra  disadvantage water  The phase  has t h e  at  heat  change  theoretical  are  the  included  increases has  and t h e  in  with  a negative  positive HSCPUV  an  effect  curves.  the  47  to  weight  maximum rotating  higher  sulfate side  lower  around  at  of  i s more  curves.  the  weight  in  the  case  was s t i l l  at  about  t h e maximum  47  In  speeds percent  of  HSCPUW  (1  is  solubility  per  case  percent obtained  weight  26 a n d 27  of  gradual the  sulfate at  25,  sodium at  in  material This  and a with sodium  maximum  and t h e  decline  compared  to  rotating  drum  the  HSCPUW  HSCPUV  maximum  concentration 10  the  results  compared  the  of  for  HSCPUW v e r s u s  sharper  of  but  together  bed  change  and 3 r p m ) ,  but  unit  Fixed  side  is  sodium  HSCPUV,  weight  its  concentrations  hand  side)  Glauber's  concentration.  in the  of  precipitate  on HSCPUW w h e n  right  disadvantage  respectively,  sulfate  t h e maximum  rotational  44.1  the  small  process.  phase  sulfate  this  salt  of  Figures  the  the decline  concentrations  percent  tube,  sodium  words,  curves  storage  curves.  of  sodium  other  hand  at  density  in the  volume  experiments  In  concentration  experiments shifted  at  The  of  eutectic  capsules  capacity  Glauber's  due t o  in  crystals.  has t h e  the  the  plotted  concentrations  sodium  versus  tube  the  lower  (higher  left  rotating  27.  to  heat  at  concentration  the  of  are  but  sulfate  the  (HSCPUW)  increase  effect  end of  storage  hydration  reducing  capacities  heat  Figure  sulfate  at  sodium  losing  the  water  of  material  with  extra  salt  the eutectic  sulfate,  of  storage  drum  of  Glauber's  to  allowing sodium  cold  -  form  advantage  the  rotating  to  sulfate  of  added  mixture  has  advantage  134  and 5  sulfate.  approximately  from  rpm,  the  For  the  44.1  T O  •  no borax with borax^  o, <0  >-  EXPERIMENTAL  THEORETICAL  25 10 5 3 1  rpm rpm rpm rpm rpm  N  U  < LU  o < o CO  00 ^  < LU I  35 Figure  26.  —T  1  \  T~  "  40 45 50 55 WEIGHT PERCENT SODIUM SULFATE  60  Heat S t o r a g e C a p a c i t y o f the C a p s u l e s per U n i t Weight o f Phase Change M a t e r i a l a s a F u n c t i o n o f S o d i u m S u l f a t e C o n c e n t r a t i o n i n R o t a t i n g Drum a t Different Speeds. T h e o r e t i c a l Heat S t o r a g e C a p a c i t y C u r v e s a r e from F i g u r e 2 3 . Number o f C a p s u l e s : 8 a t e a c h C o m p o s i t i o n ; T e m p e r a t u r e R a n g e : 20 t o 40 C .  35 Figure  27.  40 45 50 55 WEIGHT PERCENT SODIUM SULFATE  60  Heat Storage C a p a c i t y o f the C a p s u l e s per U n i t Weight o f Phase Change M a t e r i a l as a F u n c t i o n of Sodium S u l f a t e C o n c e n t r a t i o n i n R o t a t i n g Tube at Different S p e e d s and U n d e r F i x e d Bed C o n d i t i o n s . T h e o r e t i c a l Heat Storage C a p a c i t y Curves are from F i g u r e 2 3 . Number o f C a p s u l e s : 8 a t e a c h C o m p o s i t i o n ; T e m p e r a t u r e R a n g e : 20 t o 40 C.  -  weight for  percent  sodium  sulfate  at  rotational  speeds  of  and  As  shown  decreased Although  the  must  to  the  as  gradual due  reach  maximum m u s t sulfate  Figure  gradually  concentrations curve  in  be  because  10.5  the  to  the  the  experimental  a  17.5  under  is  added at  sulfate  concentration  HSCPUW  at  39.5  bed  conditions  to  of  about  29 at  weight  continue  extra  sodium  above  HSCPUW  at  47  concentration  expected weight  and  weight  percent  rpm.  fixed  a lower  theoretical  -  rpm  3.5  sodium  decrease  a maximum at  27,  137  weight this  higher  sulfate,  the  concentration.  percent  sodium  The  sodium  concentration  percent  HSCPUW  increased.  at  sodium  sulfate  the  is  sulfate.  equal  -  Bulk melting  of  segregation Glauber's  Glauber's  (Hodgins  salt  and  as  Hoffman  of  salt a  of  studies  been  a  of  attempts  suspension.  however, sodium  Some  indicated sulfate  of  known  particular,  keep  this  and  is  total  not  of  the  initial  reduce  size  of  the  crystals.  the  anhydrous The  storage crystals Section  28.  effects  of  under 7.2.  borax  on  containing during  segregation storage  the  the  conditions  96 w e i g h t  a thermal  of  of  percent  cycle  are  crystals 1980),  part  have  of  the  proposed  the  of  additives  use  not  appear  different can in  be  to  exist  circumstances  recovered  segregation  on  the  sodium  discussed  Glauber's  to  the  if  suspension.  segregation,  shown  have  replace  anhydrous  were  there  to  kept  sulfate  have  sulfate  do  under  be  behaviour  effects  data  capacity  can  sodium  or  there  because  use  systems  Marks  authors  sodium  sulfate  crystals  mixing  summarize  excess  the  sulfate  1979,  solution  These  However,  heat  anhydrous  different To  the  of  sodium  bulk  sulfate  e f f i c i e n c i e s and  a capsule  percent  sodium  of  a  2.2,  sodium  Zarnoch  unhydrated.  part  much  anhydrous  (Herrick  unhydrated  how  the  to  storage  In  addition  showing  energy  problem.  the  nor  in  this  to  of  material  deterrent  Section  remains  importance  serious  incongruent  in  as  the  a  upon  summarized  such  showing  be  sulfate  As  solutions,  the  sodium  to  change  studies  that  still  is  1955).  a number number  anhydrous  phase  been  in  CAPACITIES  Bulk Segregation  8.1  in  -  FACTORS A F F E C T I N G HEAT STORAGE  8.  of  138  sulfate  indirectly  possible  salt  heat  and  schematically  4 in  in  changes weight Figure  a) At 32.4 C (1st  stage)  b) At - 2 7 C (before (2nd  nucleation)  c) At 2 0 C (3rd  stage)  stage)  d) At 32.4 C (4th  stage)  Figure  28.  C h a n g e s i n a C a p s u l e C o n t a i n i n g 96 W e i g h t % G l a u b e r ' s and 4 W e i g h t % B o r a x D u r i n g a t h e r m a l Cycle.  Salt  -  Figure  28a  denotes  the  sulfate  crystals  between  the  32.4  C  shows  saturated and  the  crystals.  sulfate  the  The  weight  percent.  Glauber's  salt  in  capsule  of  the  32.4  borax)  included below  at  in  32.4  and  the C,  subcooling.  C.  Borax  in  the  nucleation the  temperature,  form.  The  solubility  weight  percent.  capsule  C.  In  is  Figure  the  28b,  Ls  is  solution;  in  1;  Ssb  in  solubility  Stage  decrease saturated stages  1  separate  and  2,  from  During Glauber's the  Ssa  salt  efficiency.  water  percent  anhydrous saturated the  of  sodium (24.3  sodium i . e . ,  place. process Two  between  sulfate the  from The is  voids  a  extreme  form  2  of  critical  to the  3,  about  C  the  possibilities  in are  is  Glauber's  were  27  sodium  to  is  also  the  the  crystals.  in  in  at  present  due  24.3  salt  crystals  percent  are  is  with  27  Lsv  the  to  crystals  assumed  In to  both be  particulate  form.  crystallization  precipitate  factor  part  sulfate  formed  crystals  precipitate  stage  C due  decreases  which  temperature;  the  27  sulfate  decreasing  (soluble  cooled  the  with  sulfate  is  at  crystals  in  sodium  capsule  weight  crystals  the  not  sodium  additional  transition  takes  in  of  is  sulfate  anhydrous  at  it  about  the  other,  crystallization  release)  the  anhydrous  the  of  present  each  sodium  water  percent  simplicity,  until  in  solution  the  sodium  interstices  anhydrous  the  L-j  anhydrous  sulfate  of  When  sulfate  represents  denoted  solution  of  heating.  the  weight  in  for  start  26 w e i g h t  form  sulfate)  not  sodium  Therefore in  both  but  additional  of  form  presentation. does  16  the  in  sodium  the  present  solubility  decreasing  the  in  crystals,  schematic  Since  is  of  first  S-j  solution  Therefore, is  the  solution,  solubility  33.4  crystals  after  saturated  is  the  -  conditions  sodium L-jv  140  the a  crystals heat  uniform  of before  storage  (or  suspension  -  of  crystals  bottom.  in  As  suspension  the  discussed in of  25  the  rpm  of  those  c a p s u l e s was  than  bulk  heat  storage  the  sodium cycle  loss,  sulfate after  the  bottom,  but  tion not  20  solid  (100% the  case,  suspension, different sodium to  from  saturated  sodium  sulfate  Lfv  also  stage  which  2 which  form  be  S  liquid  (Ls  than  by  3),  of  been in  during solid  Stage  sodium  sulfate hydrate  form  2,  Lf  of  fixed  of  and  as to  a  at  the  block.  61.9%. be  a  crystallizathis  is  uniform having  partially  the  part  hydrated  precipitated saturated  sulfate)  precipitate.  an  anhydrous  salt  sodium the  bed  provides  medium  denotes  solution,  anhydrous  Since  storage  Glauber's  percent  the  complete  other  involved  crystalline  have  for  theoretical  the  measured  crystals  2);  the  precipitated  achieved.  Stage  causes  experiments  if  heat  the  efficiency  first  would  the  uniform  rotational  of  single  salt,  the  represents  the  a  the  indirectly  The  there  are  a  keeping  c a p s u l e s was  had  weight  to  be  crystals  (15.2  unable  17%  with  crystals  in  must  solely  Glauber's  is  g s  about  tube  Stage  at  a  indicates that  of  all  at  that  storage  rotating  such  present  heat  impossible.  portions Sf  were  solution  was  and  obtained  melting  rather  for  the  salt;  saturated  and  believed  This  loss  efficiency)  when must  seems  only  compositions.  Glauber's  the  is  storage  there  sulfate  form  containing  even  a  extremes,  28c  is  The  recovery  drum  efficiency  c r y s t a l l i n e block  it  drum.  for  complete  (Figure  heat  7.2,  Incongruent  particulate  C  single  as 8 3 . 2 % .  account  two  -  c a p s u l e s was  rotating  rotating  storage  At uniform  in  in  suspension  the  a  Section  measured  but  in  between  heat  the  capacity.  example  The  in  segregation  17%  and  crystals  speed  in  capsule  141  of  at  Lsv  Depending  20  C;  in on  the  -  mixing  in  capsule almost  the  will  capsule, change.  uniform  similar  to  the  melting  bed  conditions  top  of  the  20  C)  fast  in  capsule  the  enough  melting.  of  to  The  forms  upper The  each  the  meaning  precipitate, efficiency of  Upon anhydrous lumps. for  This  thus  hydration  a  L-j  in  is  an  supplied  of  efficiency cycling,  if  in  loss  in  This  phenomenon  with  cycling  sufficient  anhydrous  the loss  amount rate in  of of  the  liquid  in  diffusion heat  of  to  voids  water  the  second  to  stage with  of  each  storage  bed  supplied  form  between the  for  the  conditions. the  large  sulfate  efficiency.  liquid  sulfate  not  sodium  not  the  fixed  to  is  for  responsible  is  at  remains  heat  tendency  the  storage  is  the  sulfate  sulfate  sodium the  at  composition  decreases  mixing  area  the  sodium  saturate  the  L-j  liquid  needed  adds  under  surface  the  a  to  before  has  of  the  the  time  and  anhydrous  additional  fixed  therefore  concentrat ion  amounts  under  needed  crystals  segregation  performed  sodium  the  28d,  sulfate  sulfate  sulfate  in  Figure  sodium  mixing  Lf,  an  after  at  of  precipitate  and  in  diffusion  be  form  cycle  (saturation  sulfate  reducing  results  the  segregation.  repeated  percent  would  the  second  melting,  remain  within  28c.  the  was  during  will  solution,  of  larger  storage  the  the  causing  to  sodium  Both  decrease,  sodium  (Lf),  will  Figure of  segment  contents  there  stage  mixing  because  no  first  weight  sodium  If  that  due  heat  15.2  amount  capsules, in  each  the  crystallization  3  liquid,  anhydrous  cycle,  Stage  saturate  (S-j).  loss  in  the  external  stage,  precipitate  cycle,  no  about  4th  unsaturated. (L-j)  with  If  the  of  mixing,  schematically  represents  process.  concentration  fixed  -  position  vigorous  For  indicated  28d  relative  Under  mixture.  that  Figure  the  142  the  available crystals  precipitate. If  the  amount  of  -  mixing  is  sufficient  crystals)  in  a  stages  1,  2 and  In  the  3  sodium  sulfate  a  chunks  was  0.11  in  of  found  heat to  heat  stage  be  only  the  when  efficiencies  tube  the  first  is  clearly  The  agitation  but  it  is  still  particulate  8.2  which  cycle  Figure in  cycle  keep  will  sulfate  repeat  the  the  On  the  the  betwen of  rotating  the  the  53.2%.  form  chunks  fluidization  in  improves  cycle  The  efficiency and of  the the  efficiency  of  bed  becomes  drum  As  fluidized  velocity  efficiencies  some  bed  61.9%  hand,  fluidized  was  particulate  heat  capsules.  water  the  capsules  in  the  anhydrous  other  fluidized  after  keep  the  the  capsules  the  to  some  Therefore  cycle.  with  fixed  to  superficial  in  presence  first  sufficient  cycle  after  difference  the  a  of  compared  accompanies  was  in  of  bed  precipitate  the  capsule  and  each  60% a t  fixed  are  sodium  the  29).  observed  efficiency  to  below  each  efficiency  bed  The due  agitation  (see  about  the  fixed  experiments.  53.2%  of  first  storage  having  the  were  storage  of  during  1  form,  (anhydrous  cycle.  reproduced  importance these  bed,  -  precipitate  thermal  suspension  During  the  each  was  the  particulate  precipitate  the  m/s.  cycles  in  efficiency  result,  bed  in  fluidized  saturated  some  keep  dispersed  liquid  storage  to  143  evident found  rotating 61.9%  and  precipitate. efficiency, with  a  precipitate.  Microencapsulation Effect As  salt  and  they  come  freezing  described anhydrous into  in  sodium  physical  continues,  Section  2.2,  sulfate  contact  adhesion  individual  crystals  adhere  to  one  another  (Herrick  et  a l .  1977,  causes  layers  of  the  two  of  Glauber's  tenaciously  1979).  As  substances  when  -  to  accumulate  sulfate  is  on  each  buried  beneath  "microencapsulation efficiency. 100  As  percent  attained, achieved. different  contribution  experiments explained  of  plotted  Section  6.1.  determining Glauber's  were  29.  small  The  evaporation  found (0.6  during  experimental  because,  profile  change  sodium  between  in  the  the  Sodium different  in  sulfate  thermal  the  sulfate  precipitate  the  and  No as  in  and  which in  analytical and  difference  curves  are  discussed is  histories  drawn  in  is  capacity  grade  be  Table  10  as  in  in  verified  by  (Mai 1 i n c k r o d t ) sodium  as  marked  probably through 6.1,  due  at  sulfate in  Figure  to  the the  smooth.  expected  under  to  explained was  not  be  the  A  sudden  interface  layers.  gradients give  is  section  probably  concentration solution  is  could  the  tabulated  weight,  be  These  experimental by  cannot  cycled  analyzer  method  that  sulfate  allows  figure  the  storage  which  storage  are  the  44.7%  capsules  the  heat  experimental  concentration  cycling  in  This  thermogravimetric  percent)  sampling..  concentration  a  44.1%  conditions  as  indicates  capacity  microencapsulation.  content  weight  points  loss  Theoretical  be  mixing  capsules.  legend  to  storage  sodium  heat  also  sodium  The  crystals.  study  find  29.  sulfate  heat  the  to  results  of  this  in  tested  The  accuracy  a loss  labelled  thermally  to  in  been  anhydrous  been  6.1.  Figure  sodium  contents  out  has  the  had  the  due  of  which  the  to  loss  carried  The  salt  within  the  Section in  were  is  7.2,  vigorous  capsules  all  This  result  Section  most  segregation  from  until  theoretical  conditions  were in  from  The  in  the  the  profiles  distinguished  are  under  mixing  concentration  of  -  decahydrate.  discussed  Samples  crystal  effect".  recovery  even  growing  144  in  valuable  the  capsules  information  with regarding  -  -  145  o 3  to in. Q  O to  u o QJ CO'  I  o  • •  3a  Fresh Cycled in the fluidized bed All cycles in the column Cycled in a fixed bed All cycles in the column plus 12 cycles in a fixed bed Theoretical Glauber's salt Experimental Glauber's salt  0.4  X /d s  0.6  0.8  1.0  p  F i g u r e 2 9 . Sodium S u l f a t e C o n c e n t r a t i o n as a F u n c t i o n o f A x i a l L o c a t i o n from Top t o Bottom in Sample C a p s u l e s w i t h D i f f e r e n t Thermal Cycling Histories. T o p and B o t t o m a r e D e f i n e d A c c o r d i n g t o the P o s i t i o n o f t h e P r e c i p i t a t e which i s a t t h e B o t t o m .  -  crystallization slight under  in  segregation vigorous  This  precipitate  while  which  triangles  in  saturation good  the  in  conditions.  above  the  found  to  the  29,  saturation be  smaller  measured  of  block  a layer  or  concentration  near  the  to  the  and  under  some  The  sulfate  of  to  the  = 0.65  p  Section  bottom  of  7.1)  of  the  to  precipitate.  The  concentration  measurements  capsules  the  same  and  capsule  wall  flow  diffuse  cycling  or  history  is  discussed The  the (see  in  Section  concentration  column, Section  including 7.1),  be  sodium  concentration was  to  the  also  the  presence  sulfate  suggests  that  space  under  the  for  some  the  consistent  except  sulfate  at  X  for  /d  =  the  two  0.65,  p  6.1. gradients  recovery  were  to  reasonably  s as  the  the  compared  leaving  were  by  found  concentration  sodium  concentration  is  sulfate  higher  lower  sample  shown  there  confirms  capsules  being  than  This  solution  thermal  the  bed,  the  fluidization  sodium  capsules  .  in  two  anhydrous  the  29,  crystallized  after  For  that  increasing  Xs/d  sealed  higher  Figure  sealing  concentration  capsule  sodium  was  and  fluidized  is  with  be  indicating  keep  in  crystallization  layer  to  bottom  attached  to  sulfate  a  enough  the at  of  which  filling  precipitate of  not  part  circles  temperature). in  C,  the  capsule  waiting  room  by  the  due  times  thus  (see  be  32.4  level.  concentration  fresh  sodium  at  was  at  shown  precipitate  liquid  suspension,  at  -  after  was  84  the  the  Agitation  in  a  may  hour  concentration  mixing  crystals  1  above  in  capsule  cycled  Figure  As  conditions  segregation  were  uniform  capsules. present  (approximately  capsules  almost  is  mixing  processes.  filled  the  146  found  in  cycles to  be  the  capsules  following  similar  to  the that  after  all  fixed of  bed  cycles cycles  fluidized  in  -  capsules  as  shown  slightly  lower  the  capsule.  the  original  recovery capsule the  column  Figure  the  the is  storage  capacity  after 29.  molecular  5 cycles  increase 12  in  fixed  This  the  bed  confirms  diffusion  of  and  with  the  the  being  cycles  sodium  Thus,  conditions  results  in  unsaturated  liquid  causing  amount  "all of  the  reported  capsules  cycles the  than  considering the  the  the the  "fresh"  expected was  in  on  the  recovered.  in  Chapters  heat  of  of  and  7,  the  suggests  efficiency  is  due  to  the  reported  capsules.  On  the  average,  89  to  layer  denser  as  as  90.9,  than  heat  10,  storage  of  the  bulk  storage  bottom  stars 8.1  is  in  that  not  under  fixed  bed  an  cycling  proceeds  efficiencies bed"  58.6.  and  and  55.3%  considerably  calculated  by  experimentally. efficiency  segregation,  8%  in  capacity.  determined  heat  fresh  the  and  fluidized  were  a  a  with  storage  the  Table  bulk  other  together  the  performed  and  cycling  respectively,  about  90%  liquid  in  in  99%  measured  factors  7.1  heat  6.1)  capacity  that  Sections  of  during  between  squares  storage  the  "cycled  about  the  layers  heat  segregation,  case,  by  of  fraction  showed  difference  was  bottom  Both  cycles  cycles)  becomes  the  the  repeated  Section  storage  capsule  This  5  (see  efficiencies, effect  in  "fresh",  column"  basis  which  decrease  labelled  theoretical  smaller  For  precipitate  a considerable As  for  of  all  the  saturated.  small  cycles.  sulfate  it  a  the  bed  in  keep  that  at  fixed  discussion  to  higher  recovered  shown  in  concentration  not  recovery  as  The  was  experienced  sufficient  increased  fact  concentration  the  29.  slightly  2.5%)  after  had  -  Figure  (about  cycles which  final  in  portion  consistent  a capsule (its  diamonds  upper  (fluidization) and  top  in This  considerable and  by  147  but  decrease  segregation efficiency  only  was 90.9%  in for was  "fresh"  -  expected 58.6%  from  was  factors  other  chunks  than  about  This  crystals  capsules  recovered  therefore case.  the  31%  the  expected  efficiency  consistent  actual  with  From be  the  less  the  loss  efficiency  crystal  under  water.  considerable  is  of  of  the  than  due  and  the  loss  heat  be  to  of  an  degree  is  of  from  in  formation  compared  clear  in  that  subcooling,  some  cycles to  an  only  of is  for  this  the  size  of  some  in  the  of  average  efficiency  bulk  is  the  bed  where in  theoretical  conditions),  depending  sodium  they  heat  are  storage  heat the  segregation  cooling  anhydrous  salt  decrease  considerable  but  efficiency  capacity  "all  microencapsulation,  resulting  the  increase  the  coded  bed",  contributions  storage  also  55.3%,  fluidized  30% d i f f e r e n c e  it  Glauber's  fluidized  of  the  capsules was  the  case.  results,  30% o f  to  The  previous  of  to  cycles  85%.  results  (about  under  clearly  8.3  the  few  efficiency  size,  layers  Since  capsules  believed  in  sum  theoretical  For  important  as  buried  is  above  factors in  the  precipitate. the  The  segregation  first  column",  well  of  -  "cycled  practice.  bulk  increase  after  of  in  coded  148  on  rate  such etc.  sulfate  capacity  The  being  inaccesible  storage  may  to  is  capacity  microencapsulation  in  the  effect  importance.  Subcooling  8.3.1  Effects of Subcooling Subcooling  different because  ways: of  Secondly,  the the  probably First,  more  decrease rate  of  affects  in  Glauber's  anhydrous  its  sodium  solubility  crystallization  salt  crystallization  sulfate  with  following  should  decreasing nucleation  in  two  precipitate  temperature. should  be  -  rapid  until  the  mixture  149  temperature  -  increases  to  the  crystallization  temperature. The sulfate  crystals  anhydrous causes (and  presence  salt,  the  sodium  phase  which  act  as  at  the  formation  of  extra  new  temperature.  nuclei)  This  mixtures  difficult  the  even  possibly  melting  in  to  sulfate.  It  the  rate.  Especially  cooling  rates,  small  slowly  (due  precipitate.  in  the  to  sulfate  crystals  storage  efficiency  are in  promoted. the  occurs. the  mixture If  the  negative  in  An the  small  remain  anhydrous on  is  bed  that  on  in  the  and  should  form  and  particulate  solution  would  of  anhydrous  storage  is  the  fast  amount  crystals  be present  sodium  disadvantageous  for  the  heat  and  microencapsulation  new  small  nucleation and  and  with  the  grow  It  anhydrous  to  until  in  congruently  conditions  a  C),  crystals  subcooling.  amount  if  (32.4  decrease  most  crystals  forming  sodium  the  these  with  of  on  mixing  smaller  crystals heat  sulfate  segregation  is  of  precipitated  sulfate  the  bulk  anhydrous  solubility  conditions  clearly  suspended  the  the  sulfate  effect  salt  newly  sizes)  in  the  decreases  from  insoluble  both  and  sodium  on  fixed  increase  negative  the  sodium  mixture  highest  precipitate  depends  the  The  influence  of  sodium  because  of  solubility  solid  under  of  transport  precipitate.  no  of  crystallization  different  form  their  Diffusion  insufficient  is  anhydrous  to  for  anhydrous its  probably  cooling  settle  as  form  determine  nuclei  material  temperature  behaviour  which  change  of  the  collect  efficiency  crystals  at  can  form  hydrate the  bottom,  be  considerable. With  sufficient  crystallization  during  subcooling  the  mixture  nucleation  without  can  absorb  exceeding  the  its  heat  of  crystallization  -  temperature. almost chain  salt  of  events, the  of  nuclei  a  shown  and  form  The  brief that  the  net time  the  some While  sequence  temperature  heat  nuclei. for  causes  instantaneously.  begins, rates  This  mass  is  interval  heat  cooling  period.  It  storage  efficiency  to  occur  it  to  determine  is  transfer  result  is  or  is  after  to  in  capsule  in  the the  borax  depend  crystals  as  the  where  the  to  nucleation  sources rapid  7.1,  it  that  the  of  cooling was  a decrease  expect of  the  Glauber's  only  Section  degree  precise  moment,  very  with  quickly, the  whether  having  decreases  reasonable  decrease  and  In  very  that  are  s i m i l a r to  efficiency  on  at  capsule,  nucleation.  therefore  should  difficult  likely  probably  storage  -  crystallization  gradient  immediately  150  in  the  heat  subcooling  increases. The  above  d i s c u s s i o n shows  influence  on  the  could  be  measured  not  encapsulated some  and  phase  experiments  different are  8.3.2  heat  efficiency.  in  study  this  material  performed  circumstances.  discussed  subcooling  storage  change  were  that  The  to  The  because was  not  find  a  negative  magnitude  external  degree  were  of  the  effect  nucleation  possible.  the  experiments  has  On  of  the  of  other  subcooling  explained  in  the hand, under  Section  6.3  below.  I n f l u e n c e o f B o r a x C o n c e n t r a t i o n and D e g r e e o f A g i t a t i o n Nucleation  functions  of  borax  were  tabulated  salt  without  16.6  C,  while  and  in  any its  crystallization  concentration Table  borax  14. as  and  Under  the  degree  vigorous  nucleating  crystallization  temperatures  agent  of  mixing was  temperature  were  mixing.  The  conditions,  found was  determined  to  32.4  subcool C as  as  results Glauber's to  reported  in  -  many  references  1980).  In  the  (1952),  the  increasing in  the  (Hodgins 3 to  30.4  nucleation  further  was  This  K lower  0.6  Glauber's  temperatures weight.  with  Under  optimal  for  The  mixed  mixing.  initiates  in  fixed the  bed  heat  reduced  the  C at and  C for  was  low  The  1974,  suggested  3% w e i g h t  there  degree  Li  of  was  no  change  increase  in  borax  degree  of  by  by  Telkes  almost  subcooling  no  change  with  crystallization  3% w e i g h t  almost  Telkes  borax,  borax  concentration.  c r y s t a l l i z a t i o n temperature  mixing was  container disturbing  showing  about  salt  the  conditions. storage of  that  (1980)  Glauber's  degree  the  temperatures  Telkes  information  31.8  temperature  crystallization  of  a  of  without  respectively,  be  as  and  in  the  of  pure  crystallization  concentration  weight  borax  is  subcooling without  up  to  5%  by  probably sacrificing  the  temperature.  influence  salt  the  c i r c u m s t a n c e s , 4%  achieving  crystallization Glauber's  in  29  concentration.  further  these  crystallization  to  or  Grace  range,  borax,  there  a  borax  4% w e i g h t  than  but  1955,  was  borax  found  salt,  weight  temperature  increases in  is  Hoffman  -  temperature  C at  temperature  gently  5% b y  nucleation to  and  151  capacity  the  nucleation  checked where the  were  both  by  the  using liquid  bottom  found  to  that  conditions  would  appear  under  various  subcooling  resulting  she that  by  part  weight  on  borax  (lignant)  30.4  28.3 are  C  and  dependent  5 weight 27.2 used, part  C. but of  they  the  on  the  agitation.  borax  was  no  were  is  and  degree  probably  improvement  conditions  in  C  percent There  the  was  be  mixing from  4%  and  Nucleation  3 to  c r y s t a l l i z a t i o n at  temperature  precipitate.  temperatures  reported  mixing It  on  due  to  in the  -  8.3.3  the  sodium  second  sulfate  temperatures  was  compositions. fluidized while in  the  K.  Each  sodium  bed  when  capsule  using been  the  contained  nucleation capsules  agitated rate  4  percent  close  to  most  place  for  initial  nucleation  in  Section  8.3.4  realistic and  as  shown  crystallization  sulfate had  l i t t l e  or  no  range  maximum  of  change this in  value is  not  value  the  in  is  believed  causing  to  Figure  C at  more  than  the  range  was be  a decrease  on  studied.  27.4  nucleation  concentration  in  influence  concentration  wall  temperatures  concentration  in  to the  the  to  The as  was from  weight the  A  44.1  recognizable  to  solubility  amount  of  of  borax  borax which  the to  of  is  the  remains  sodium  in  the  but  a the  increased (about  beyond 1.5  K)  sulfate  weight. the  the  nucleation  reached  sulfate,  in  be  concentration  sodium  by  its  proved  decrease  the  39.5%  in  about  of  thought  temperature  sodium  when  only  temperature  concentration  found  was  (This  rate  the  regardless  sulfate  nucleation  bath  cooling  experimental  The  by  bath  the  the  because  functions  sodium  to  high,  was  occur.  plotted The  this  in  C water  measured  crystallization  studied.  decreased  borax,  because  times  compared  water  the  K when  temperature  due  30.  a 25  was  were  below).  are  44.1%  0.7  and  Temperatures  capsule  fast  of  different  many  temperature  capsule  weight  concentration.  in  influence  crystallization  five  cycled  temperature  precipitate likely  was  the  and  of  gently  nucleation the  experiments  thermally  capsule  between  the  the  cooling  the  near  on  were  Although  difference  sulfate  subcooling  by  had  They  comparable  temperature  the  capsules  system.  fluidized  of  investigated  cooled.  were  part  concentration  The  bed  they  rates  2  -  I n f l u e n c e o f Sodium S u l f a t e C o n c e n t r a t i o n In  the  152  This  extra in  decrease water,  crystal  form.  ^  ® Nucleation temp. Crystalization temp  —1  1  40  igure  1"—  !  —  1  !  45 50 55 WEIGHT PERCENT SODIUM SULFATE 30.  Average Different  Nucleation  and  Compositions.  Crystallization  Temperatures  for  Capsules  —  with  -  8.3.4  experiments  thermocouples  aim  in  was  the to  the  in  bottom  of  change  slightly  lower.  fixed  gentle are  center there  The  from was  a  For  a  Figures  Figures  smaller reach  higher  then  the  almost  sulfate  sulfate  in  concentration  in  the  center water in  lag at  the  gently is at  in  at 32.4  solution  and  most  Section the  in  fixed and  33.4%  of  even  capsules  in  capsules Almost  the  in  C),  but  a decrease  with  the  formation  in of  the  to  the  whereas equal  Figures  sodium  weight  the  therfixed  transported  center  by  capsule  addition,  capsule. the  is  Comparison  longer  mixed  would  temperature  In  is  capsules,  above  a  agitated  was  the  in  8.3.3.  capsule.  of  temperature  give  gently  part  nucleation  the  As  contains  importance  temperture  mixed  The  borax  which  profiles 33  temperature  lower the  form,  in  the  of  where  the  determine  capsule,  and  bottom  or  in  32  fixed  the  6.3).  the  wall  immediately  time  that  sodium  the  nucleation  and  of  in  in  to  and  starts  indicates  gradients  temperatures  the  33  crystallization  bottom  at  and  as  capsule  Section  and  temperature  agitated  32  (see  suspension  capsule  the  circumstances.  mixed  while  considerable  concentration  the  of  two  different  precipitate  condition,  to  indicate  nucleation  the  crystallization 33  under  shows  gently  wall  location  a uniform  near  inserting  center  capsule  vigorously  in  by  the  capsule 33,  Temperature  the  the  at  31  with  period  one  where  material  significantly  capsule.  capsule  capsules  31  and  Figure  mixing.  cooling  32  performed  nucleation  the  somewhere  bed  for  Figure  in  present.  start  profiles  31,  the  near  initial  gradients  probably  of  the  were  capsule,  precipitate  are  phase  under  each  Figures  crystals the  in  find  temperature shown  -  Temperature V a r i a t i o n s Inside Capsules During C o o l i n g Further  other  154  32  sulfate  (solubility sodium  Glauber's  salt  Figure  31.  T e m p e r a t u r e P r o f i l e s i n a F i x e d C a p s u l e w i t h C o m p o s i t i o n D i n T a b l e 11 while C o o l e d i n a 25 C Water B a t h . The C a p s u l e was n o t S u b j e c t t o any M o t i o n During the C o o l i n g .  or I  3 Figure  32.  r  T  6  r—  9 TIME  12  ™T~"  15  18  (minutes)  T e m p e r a t u r e P r o f i l e s i n an A g i t a t e d w h i l e C o o l e d i n a 25 C W a t e r B a t h . Section 6 . 3 During the C o o l i n g .  Capsule with Composition T h e C a p s u l e was M i x e d a s  D in Table 11 Explained in  \  1  -i  0  3  6  Figure  33.  r — " — T  9  1  12 TIME (minutes)  T e m p e r a t u r e P r o f i l e s i n an A g i t a t e d w h i l e C o o l e d i n a 25 C W a t e r B a t h . Section 6 . 3 During the C o o l i n g .  r  1  15  18  Capsule with Composition B in Table 11 The C a p s u l e was M i x e d as E x p l a i n e d in  -  crystals  forces  decline. this  At  decline  a  the  the  to  The the  ordinary  at  the  a  sphere  of  time In  the  each  after  of  sulfate due  the  time  the  run  at  to  case  temperature  temperature  crossing  end  later  -  temperature  sodium  center.  estimate  considerable  center. toward  at  overall  crystallization  difficult of  crystallization  higher  starts  concentration 31),  the  158  at  which  of  occurs  and  is  higher  the  center  is  center  the  the  complete.  It  begins bottom  temperature  capsule  33),  sulfate  capsule low.  to  (Figure  sodium  fixed  between  the  because  crystallization  center  crystallization  difference  bottom  the  concentration  the  the  at  behaves  (Figure is  also  because and  the  traces like  an  -  9.  9.1  essential  part  determining emphasized  heat  comes  for  for  required  thermal unit  volume  material system  of  and  of  of  It or  considerable  influence  heat  unit  storage  industry  would  for  heat In  in  unit  between  transfer be  the  fluid  used  in  industry  a temperature  buffer.  the  cost  because  the  number  be  very  per of  different  7.2.1),  also  unit  the  for  of  thermal than  for  of  of  of per  change  applicability  cycles  etc.  affects  rates  phase  would  in  the  number  transfer  energy  problem  location  climate  the  of  resulting  the  storing  This  the  capacities  style  encapsulated  broadens  specific  standard  example,  heat  a  develop  devising  living  high  to  analysis  systems  an  be  economic  houses,  and  should  not  for  is  in  It  was  different  For  unit  case,  in  storage  use  factor  unit  Section  ranges,  storage  on  likely  heat  for  study  As  storage  unit.  detailed  (see  heat  main  storage  influence.  our  the  this  c h a r a c t e r i s t i c s and  can as  of  process.  designed  each y e a r .  heat  storage  the  temperature,  the  storage  heat  units  use  a considerable  the  time  of  specially  studied.  periods  range  for  is  heat  makes  storage  varying  size  cycles  available  system  cost  purpose  This  heat  wide  any  a complex  construction have  proposed  because  main  size.  testing  systems  house,  the  system  needs,  occupants the  that  given  the  the  study  a commercially a  from  this  of  a p p l i c a b i l i t y of  storage  different  the  of  again  or  methods  Even  FUTURE OF ENCAPSULATED HEAT STORAGE  analysis  the  promote  purpose the  -  E c o n o m i c A n a l y s i s and C o m p a r i s o n Economic  and  159  heat  for  of  the short  have  recovered per  year  household  use.  from in  the  -  A design  useful  variables  Components capacity Since be  of  are  the  results  heat  As  depth  at  in  for  Appendix  Dc  or  to  and  hold  for  are  cost  for  for  for  every  only  for  to  cost  and  possible some  terms  storage  this  case  are  section. too  cases.  some  of  application.  heat in  sample  with  in  the  variables  purposes  diameter (Lmf)  the  of  initial  (Dc),  and  column  long  to  These  commercially  from  system  cost  are  length  (L),  bed  superficial  expressions  obtained  the  accurate  the  the  L  are  local  cost  + 0.5  and  was  (The  chosen  tubes.  heavy  data the  for  the as  and  water  given  velocity  below,  companies,  m is bottom  in  while  are  price  listed  in  material  could  was  based  top  on  of  and  plates  and  construction  are  size  usually would  PVC cheaper be  steel.  bring  not  tube  inlet  lifetime  with  may  the  or  variable  expected  tanks  molding  The  costs  problems  tank  and  because  delivered  are  for  screen.  PVC  polyethylene custom  cylindrical  0.5  Although  weight  column  a  screen,  and  available  density  for  m  distributor  steel  high  includes  distributor,  system  with  expression  column  length  corrosion  Custom-molded but  according  design  components  column  commercially  comparable  longer,  15,  component,  compartments),  material tubes  of  formulated  10.  diameter  flanges  be  units.  Bases  Material  outlet  terms  fluidization  (U).  each  of  to  operating  comparison  Table  terms  minimum  column  data  in  needs  cost,  reported  for  -  changed  results  storage  shown  expressed  in  are  used  be  system  analysis  be  analysis  could  formulated  results  can  available  which  initial  cost  listed,  the  economic  160  be  some  savings,  obtained.  0.35  m,  0.61  The m  and  -  Table  15.  161  -  I n i t i a l S y s t e m C o s t Components f o r a L i q u i d F l u i d i z e d Bed Heat S t o r a g e U n i t U s i n g E n c a p s u l a t e d G l a u b e r s Salt as Phase Change M a t e r i a l ( R e f e r e n c e s t o t h e p r i c e s a r e given in Appendix 10)  Cost Component  Price  (1984  $Cdn.)  for the  Sample (1984  Material  for the  (365  + 270  Piping  (200  + 70 L )  Pump  800  Control  column  for the  Capsules Phase Labour  column  and e n c a p s u l a t i o n  change (at  + 0 . 5 ) ) D lcA  1,606  D**4  513  + 2 1 5 PP  1,371  350  equipment  Insulation Frame  (L  125  L  50  D  7  $ 2 0 p e r man  350  1440  material hour)  0  '  3  500  Conti ngency  20%  Case* $Cdn.)  0 C  L  156  Lmf  L  390  C  D2C  mf  D0 c  D  4,176 204  c  559  , 5  of total  component  1,865  cost Total  Where  Dc  :  Diameter  of  L  :  Length  Lmf  :  Bed depth  PP  :  Power  t h e column  of t h e column  of  a t minimum  11,190  (m)  from  the distributor  fluidization  the recirculation  pump  to the screen  (m)  (m)  (kW)  (given  by E q .  (9.1))  Note: When p a r t i c l e s o c c u p y t h e e n t i r e v o l u m e b e t w e e n t h e d i s t r i b u t o r and t h e s c r e e n , t h e f o l l o w i n g e x p r e s s i o n c a n be w r i t t e n w i t h t h e p r e s e n t p a r t i c l e and f l u i d p r o p e r t i e s by u s i n g R i c h a r d s o n and Z a k i equation ( R i c h a r d s o n and Zaki 1954) f o r v o i d a g e : L  *For  sample  case,  Dc  (1  -  1.44  = 1.25 m,  L  = 2 . 5 m and U = 0.115 m / s .  f  = L  U°-  4 2  )/0.565  -  1.22  m column  case. be  diameters.  Distributor,  made  (hole  of  12.7  size  <  water  the  piping  0.35  cost  from  the  m diameter pump a n d  102  mm a n d  76  the  the  column  keeping  the  column  cross  five  elbows  Cost pump  power.  function 7.5  kW  (»  the  or  are the  the  10  the  of  pipes  and  and  fittings  for  in  the  bottom.  It  the  and  bottom  each  assumed  plastic  to  mesh  does  storage  the  recirculation  top  not  compartment  are  pipe  cross  section  taken  as  pipe  length  measurement fittings  (see  pump  in  the five  is  estimated  elbows  constant  150  mm H 2 0 .  Pump e f f i c i e n c y  required  pump  the  size  was  range was  and  this  increased area  twice in  of  as  a  by  ratio  the  column  the  line;  function  linearly 0.75  («  by  the  calculated  bed,  across  sudden  the  is  70%.  taken  1  as  kilowatts:  HP)  the  as  a to  distributor,  contraction is  of  fitted  kW  distributor  in  as  line.  10)  the  is  in  a and  taken  system  included  the  fluidized  across  is  in  requirement  in  the  device  Appendix  kilowatts  is  For  compartment  to  area  include  unit.  diameter  drop  the  the  pipe  pressure  gives  heat  between  The  expression  a coarse  the  power  to  to  expansion. at  is  diameters,  only  losses  due  screen  mm i n  are  experimental  data  The  head  flanges  the  recirculation  power  HP).  the  8.3  for  section  flow  Pump c o s t  of  evaluation in  of  as  recirculation  valve  pipe  pump a n d  larger  No  and  was  The  diameters  mm r e s p e c t i v e l y  length.  thickness  plates  collectors  pipe  For  90°  the  solar  column,  Total  wall  plate.  compartment  study.  constant.  -  diameter).  top  between  column  bottom  PVC  includes  between  the  and  mm t h i c k  particle  Piping of  top  The  162  assumed The  and to  be  following  -  PP  =  Since  1.12  U D2  pumps  are  bigger  motor  included  by  the  will  and  the  no  optimization  cost  expression  insulation  area  surface  area. A  column 32  frame  0.25  mm x  of  32  of  the  frame  a  thicker  As  noted  in  Glauber's this  the  and  time.  recirculation  of  In  base  steel  the  to  tube  capsules 4,  there the  tube  frame  no  present  on  75  is  widely cost  the  total  as  for  with  larger  are  cost;  therefore out.  The the  cost  is  the based  and  cuts.  to  on  a  The  diameter  total column  support  diameter  cross  The  fiberglass  to  Its  at  cost allow  diameters. are  difficult  studies  accepted  estimation  located  column.  65% o f  column  is  on-off  system.  assumed  allow  an  carried  mm t h i c k  m column  cost  are  the  been  taken  is  a 0.35  there  and  in  has  closest  1.2.  and  connections.  to  the  pump  by  recirculation  linearly for  in  encapsulation  although is  for  using  power  unit  tubes  pipe  (9.1)  Thermocouples  system  length  vary  and  based the  1.47)  additional  thickness  steel  for  column  assumed  Chapter  salt,  square  the  steel of  column  +  thermocouples  pump.  insulation  f  sizes,  component  is  6 times  Costs  a major  L  pump  storage  insulation  made  is  heat  1.9  This  three  for  mm s q u a r e  of  includes  the  the  +  theoretical  the  not  U2  discrete  for  m from  length  for  of  is  covering  surface  in  recirculation  outlet  Insulation  592  -  necessary.  the  equipment for  -jj- + c only  be  multiplying  unit  inlet  U2  available  size  Control control  (14.31  163  method  for for  to  estimate.  encapsulating encapsulation  calculations,  it  has  been  at  V assumed fill  -  that  the  the  capsules  manufacturing, the  same  for  our  with  and,  when for  small  order  (8000  was  not  taken  capacity  and  phase  percent  of  inside  volume  Labour  for  estimated  shop.  A  to  be  the  As  of  the  quantities,  (phase empty  heat  transfer  data  available  are  would  capsule could  charge  material  extra)  The  of  capsules. because  capsules  they  change  variable  of  in  of  each  and  20  for  all  cost  without  this  and to  of  Sample  cost  material  encapsulation adjustments influence  on  the  the  for  of  size  experimental only  for  as the  heat the  25  mm  which was  factor and to  the  any  show  These  an  increase  of  the  the  this  95%  allowance components are  are  machine  the  method  is  needed  is  allowed  provided  variation.  because cost.  and  figures  with  is  basis.  reduction  cheaper  0.35  department's  calculations  system  96  occupying  diameter  our  from  expressions  total  of  installation)  in  possible  a new  of  additional  cost  to  borax  production.  derived  total  a mixture  (excluding  shows  some  of  column.  columns  mass  analysis  due in  in  cost  percent  professionals  the  contingency  the  system  hours  case  is  weight  the  estimations,  20%  construction  4  capsule  man  the  cost  and  diameter  and  considerable  salt  column  contingency.  lead  material  expression  for  would  large  during  a design  cost  contingencies.  capsules  in  capsules)  discussions with  for  the  polypropylene  material  capsules  manufacturing  15  labour  square-root  in  hollow  as  Glauber's  m respectively on  change  filled  change  weight  based  the  -  capsules.  The  0.61  of  ordered  price  diameter  the  phase  unit  capsules storage  manufacturer  164  in for  they  Any the  with change  cost  of  encapsulation have  a  -  Since prices  for  likely  if  all  single the  consumption  by  derived  the  the  pump  cycle,  Since  these  Table  in  16.  from  is  the  used  local  needed  cost  estimations  for  are  considerable  purchased  margins  16,  operating  of  the  required by  of  cycles  thermal is  are  the  costs  pump a n d  multiplied  variables  in  in  larger  retail savings  are  quantities  manufacturing  and  from  retail  included.  recirculation  result  -  companies,  are  profit  Table  power  number  electricity,  been  the  power  the  units  not  shown  for  prices  Therefore  have  As  the  materials  manufacturers. companies  of  165  the  given  recirculation per  year  and  electricity  location  The  by  equation  Eq.(9.1).  period the  electricity  on  of  maintenance.  pump w a s  yearly  dependent  consist  per  local  and  the  thermal  price  consumption  When  for  cost.  purpose  of  the  E s t i m a t e d O p e r a t i n g C o s t f o r a L i q u i d F l u i d i z e d Bed Heat S t o r a g e U n i t U s i n g t h e E n c a p s u l a t e d Phase Change M a t e r i a l Annual Cost (Canadian D o l l a r s , 1984 p r i c e s )  Component  Electricity  for  recirculation  Maintenance  (at  $20  per  pump  1.2  man-hour)  20  PP  x  At N c  Pg  4  Where Nc  :  Number  Pe  :  Cost  At  :  of  of  Duration thermal  thermal  cycles  electricity which cycle  per  year  ($/kW-h)  recirculation (h/cycle)  pump o p e r a t e s  during  each  -  heat  storage  electricity  unit, cost  calculations. using  pumps  have  may  the  proposed  system  total  Heat capsules  the  closest  of  for  rest  construction  and  insulation  capacity  of  the  recirculation  the  system  during  The capsule  is  expression in  Table  pump  in  values  the  later  above,  pumps  come  in  discrete  bigger  motor  size  is  necessary.  e f f i c i e n c i e s than  the  system  is  the  main  also  As  generated  by  but  4  by  heat  the  shown in  sample  sizes  and  Also  allow  some  for  1.2.  these  The  problems.  material sensible  transfer  components  for  man-hours/year  change  including  the  To  unexpected  phase  included  70%.  multiplied  and  materials,  system.  is  heat  formulated for  17  capsule  the  capsules  the  heat  the  is  single  heat using  heat  based  of  Table  the  heat  in  heat  heat  storage  pump e n t e r s  the  of  (water),  total  17,  the  heats  fluid  the  in  the  the  same  capacity  capacity  To  allow  capacity  of  temperature  of  of  theoretical  parentheses)  of  procedure  on m u l t i p l i c a t i o n  (second  (ric).  storage  storage  parentheses),  storage of  assigned  inspection  the  are  theoretical  (first  terms  parameters  storage  input  by  capacity  storage  of  unit  cycle.  column  in  etc.  because  each  of  proposed  the  are  c a p a c i t i e s of  the  material,  unknown  electricity  and  capsule  -  be m a i n t e n a n c e - f r e e ,  allowed  storage  as  They  lower  cost  should  was  left  mentioned  somewhat  factors,  maintenance  are  expression.  As  therefore  they  166  and  number  the  heat  for  the  of  which  the  contents  in  of  system  of  in of  The  capsules the a  efficiency  of  applications,  capsules is  the  capacity  storage  each  5.1.3.  capsules  different the  of  Section  contents  storage  calculations  to  as  the  heat  contents  the  heated  is  formulated  during  each  -  Table  17.  Heat  Storage  Unit  Using  Capacity  the  of  the  capsules  of  -  a  Liquid  Encapsulated  Component  Contents  167  Heat  Storage  20  and  C  (73364  (1)  Fluidized  Phase  Change  Capacity  of  Heat  input  Annual  the  system  by  heat  the  (2)  pump  (3)  storage  1.45  L |  1296  PP  ((1)  +  Heat  Storage  kJ)  between  Thp  -JD2)(1.4  f  V Rest  (in  Temperature  L  Bed  Material  +  2.873  x  10  \ D2  4178  (The  -  20)  At (2)  +  (3))  N.  where:  cycle  T^e  :  Hot  ric  :  Heat s t o r a g e ( f r a c t i o n of  and  also  in  change  material,  7.1).  The  heat  storage  cold  end  terms which  end  1.45  s e n s i b l e heat times  of  the  depends  the  heat on  temperature  heat  the  storage  process  e f f i c i e n c y of  operating  taken  as  described of  storage  the  in  20 C  because  for  this  Section  rest  capacity  the  conditions  available only  capacity  s e n s i b l e heat  storage  was  are  experiments storage  during  (C)  e f f i c i e n c y of the phase change m a t e r i a l the t h e o r e t i c a l heat s t o r a g e c a p a c i t y )  e f f i c i e n c y data  Calibration the  temperature  of of  5.1.2  the water  (see  Section  experimental temperature. showed  system in  phase  an  is  that  about  empty  -  column  (volume  storage  between  capacity  the  168  -  distributor  expression  for  the  and  rest  the  of  top  the  screen).  system  is  The  heat  based  on  this  finding. Heat  input  electricity assumed  to  by  the  consumed be  70%,  by  the  recirculation the  pump.  remaining  pump  Since 30%  is  the  should  calculated  efficiency be  released  as  30%  of  the  of  the  pump  was  in  the  form  of  heat. The  computer  expressions sample  in  assigned chosen  the  the  the  velocity  in of  that  Section  The  heating 7.1.  at  is  1  Although  of  the  analysis,  there  hour it  Column  is  the  the  column  of  The  to  heat  these  fixed  basis  taken  is at  were  diameter as  storage  height  3 m.  The  0.115  efficiency  a marked  decrease  in  efficiency  believed  that  was  about  experiments  only.30  m/s.  selecting  in  the  is  outlet  increase  during  m  The  experimentally, for  period  was  2.5  unit  slight  pump o p e r a t i n g  Some  perform  and  the  several  column  inlet  was  with  was  determined  capacity. a  the  using  consideration  length  total  velocity,  cooling) is  for  addition  m each,  only  order  under  the  this  In  one  With  written  calculations.  the  part  in  was  comparisons  units.  suitable  water  11  economic  make  room  recirculation and  to  except  storage  there  whereas  perform  storage  0.25  of  17  to  Appendix  variable.  houses. length  in  first  the  efficiency  velocity,  hour  of  theoretical  was  velocities.  heat  the  velocity  storage of  In  given  performed  independent  limited  superficial  (1  to  variables  height  compartments  this  all  values.  as  because  60%  15  available  calculations,  heat  Tables  c a l c u l a t i o n s were  commercially  often  program  minutes  was  the  above at 2  lower  hours  discussed of  in  -  fluidization the in  same the  sample  is  economic  operating heated  temperature are  also  usually  cost the  work  per  in of  18  Energy  seen  be  basis  of  cheaper based of  on  the  real  cost  heat  is  based  system cheaper  on  would than  in  per the  On an  Inc.  heat  observed  be the  40%  bed  of  about  in  than  the  the  price  are  not  Heat  the  units.  as  the  end They  units  the  from  which  a  Products  in  Inc.  by  are  on  the  considerably  units the  is  the  Module  system is  for of  given  are  often  efficiencies  well  known  that  theoretical  fluidized  Otherwise, cost  34  function  Storage  bed  a  system  Figure  units  it  below  predicted From  in  Although  for  cold  initial  commercial  well  60%.  the  Bank  available,  price of  OEM  fluidized  for  usually the  unit  by  Calmac  data  The  Thermal  capacities.  efficiency than  Battery  storage  units,  available The  with  the  available  given  storage  used  K.  18. is  was  experiments.  storage  Table  capacity  Heat  20  heat  figure.  and  previous  commercially  commercially  hand,  commercial  the  heat  storage  cheaper  with  given  comparison  other  temperature  available  while  The  This  range  c a p a c i t i e s are  the  which  same  megajoule,  in  to  temperature  with  provide  pump o p e r a t i o n  The C.  and  to  consistent  cheaper  others.  used  the  the  slightly  storage  capacities.  for  sufficient  be  storage  fluidized  Storage  theoretical  units  heat  Costs  only  than  of  are  be  c a l c u l a t i o n s to  comparison  (1982)  would  recirculation  consistent  commercially  located  Thermal  of  40  temperature  liquid  are  as  -  period  analysis  are  for  megajoule  volume.  to  C  a  hours  taken  Michaels  proposed  Table  20  suitable  by  column  cooling  experience.  was  of  Prices review  the  efficiencies, 2  previous unit  during  169  the  and  performance  bed  system  fluidized  then  it  point  would of  bed be  view,  Table  18.  S p e c i f i c a t i o n s and  Prices  of  Some  Commercially  Available  Heat  Storage  Units  Corrected Name  Calmac  Heat  Thermal Thermal  OEM Heat  Bank  Energy Storage Storage Module  Products  Inc.  Inc.  Temp. (K)  1984  Price (U.S.$/MJ)*  Price  (m3)  Operating Range  1.357  19  7.98  (1980)  12.5  1.115  21  13.27  (1980)  20.8  7.23  20  (1980)  11.1  V o l time  7.09  (Cdn.$/MJ)**  Battery  * P r i c e s a r e c a l c u l a t e d by M i c h a e l s ( 1 9 8 2 ) by d i v i d i n g t h e p r o v i d e d t o t a l s y s t e m c o s t by t h e c a p a c i t y of the system in m e g a j o u l e s . The y e a r i n p a r e n t h e s e s shows t h e y e a r t h e p r i c e i s * * U . S . d o l l a r s i n previous y e a r s are c o r r e c t e d to o b t a i n Canadian d o l l a r E n g i n e e r i n g magazine M & S equipment c o s t index (2nd q u a r t e r 1984) and d o l l a r exchange rate i s used i n the c o n v e r s i o n .  value in 1984. 1 U.S. dollar =  heat storage applicable.  Chemical 1.32 Canadian  COLUMN Figure  34.  Initial-Cost Storage Taken  as t h e  Superficial Diameter  of  a Liquid  Capacity  as  a  Fluidized  Function  Experimentally Velocity  = 2 5 mm;  VOLUME of  Bed the  = 0.115  m/s;  Volume.  Capacity.  Heat  Range:  3  Storage  Column  Recovered  Temperature  Heat  (m )  Storage  20 t o  40  Unit  per  Heat  Column  Length  Efficiency C.  Megajoule  Storage  = 2.5  = 60%;  of  Heat  Capacity m;  Capsule  is  -  the to  liquid the  commercially For  initial annual  the  heat in  the  is  difficult  summation to  the  experimental  not  show  any  of  set-up of  and  is  assumed  interest  rate  that and  for  advantages  in in  Section this  heat as  section,  storage  recovery  taken  as  compared  9.2. the  unit  functions  Heat  be  to  fixed  over the  cents/kW-h,  an  in  both  are be  provided  system  depreciated  energy cost  lifetime  used  this  of  and  column  was  average  25  10%  capital  based  for  a  calculation average  and  on  daily  rates  cost  is  in  with of  the  British  the  capsules,  years.  annual under  of  plastics  annual  operating Columbia  column, did  an  a  the  different with  analysis  rates  so  that  circumstances the  system)  payments. costs  system  fixed  economic  interest  for  in  light,  choosing  the  the  it  Since  ultraviolet than  unit  Although  including  calculated  equal  costs. of  durable  price  storage  and  investment,  15%  the  capsules  two  Rather  (purchase  years  to  capital  interest  cost  study,  and  from  operating  the  within  25 y e a r s .  for  and  subject  the  recovered  of  strong  not  borrowing  The  in  the  different  initial  electricity 5.25  are  of  capital  are  they  for  made.  the  bed  plotted  might  deterioration  PVC  lifetime  be  previously  are  which  many  discussed  respectively.  cost  fixed  estimate  where  can  year,  has  fluidized  unit  36  unit  as  specified  and  per  environment  projections  35  units  the  storage  sign  polypropylene  calculations  storage  a liquid  from  -  unit.  annual  is  case  for  Figures  storage The  cost  cycles  heat  available  recovery  thermal  heat  bed  sample  system  diameter 150  fluidized  172  is  house  assumption is The  borrowed cost  taken  as  use  (see  of  0.0 Figure  35.  0.5  1.0 1.5 COLUMN DIAMETER (m)  2.0  I n i t i a l C o s t o f a L i q u i d F l u i d i z e d Bed H e a t S t o r a g e U n i t a s a Column D i a m e t e r . C o l u m n L e n g t h = 2 . 5 m; S u p e r f i c i a l V e l o c i t y C a p s u l e D i a m e t e r = 2 5 mm. C o s t s a r e i n 1984 $ C d n .  Function of the = 0.115 m/s;  I  0.0 ure  36.  1—  1  r—  !  1  r-  0.5  1.0 1.5 2.0 R e c o v e rCOLUMN y f r o m a L i q u i dDIAMETER F l u i d i z e d B e d H(m) eat S t o r a g e U n i t  Annual Heat as a F u n c t i o n o f Column D i a m e t e r . C o l u m n L e n g t h = 2 . 5 m; Superficial V e l o c i t y = 0.115 m / s ; H e a t S t o r a g e E f f i c i e n c y = 6 0 % ; C a p s u l e D i a m e t e r = 2 5 mm; T e m p e r a t u r e R a n g e : 20 t o 40 C ; Number o f T h e r m a l C y c l e s p e r Y e a r = E q u i v a l e n t t o 150 C y c l e s .  -  Appendix costs  10).  are  given  operating factor.  Annual  cost  on  represent  the  the  efficiency operating  independent  of  the  initial the  and  that  costs  of  energy  plotted  as  function  a  storage  considerable  15%  costs Figure  and  for  total  37.  The  the  presented and  and  contingency  for  no  a 20%  rate.  contingency  These  two  cases  predictions. costs  are  should  and at  are  rate  in  rate  interest  cost  effort  even  on  the  recovered  different  is  of  interest  column  clearly  very  small  clearly  improving expense  is  increased  up  to  with  further  As  shown does  recovered  not  from has  increases column,  the  in  the  a  thus  about  39,  have much storage  positive bed  cost  increases  Figure  be  the  of  compared  to  concentrated heat  on  storage  somewhat  decreasing  in  and  to  per 1  in  the  higher  on  fluidized  contingency  Figure  38.  interest  unit  energy  meter.  The  rate. the  decrease  heat  allowances  The  when  bed  cost  of  There  is  are  a  column  is  relatively  .diameter.  superficial  unit.  An  on  velocity the  increase  the  leading the  a liquid  rates  influence  effect  expansion  from  diameter  sensitive the  velocity  a  costs  in  m/s  and  operating  decrease  diameter  cost  interest  maximum  capsules,  for  of  cost  system  unit  0.14  a 10%  diameter  interest  total  Research  storage  gradual  and  and  capital  costs.  The  energy  cost  shows  costs.  of  fixed  column  minimum  capital  costs,  of  system  37  -  function  capital  the  Figure  reducing  a  allowance  allowance  fixed  is  Fixed  contingency  as  operating  175  to  heat  in  per the  storage  fewer  theoretical  cost  in  range  unit  of  0.075  to  energy  superficial  efficiency  capsules  heat  the  in  storage  a  but  fixed  capacity  length of  the  o. I  5 2O  CO  total cost (a) no contingency, 10°/. int (b) 20/£ » ,15Z »  CO  o  ^ fixed capital cost fa] no contingency, 107 int. (b)207o » ,15X » operating cost  o.  ( a }  05  0.0 Figure  *5  COLUMN DIAMETER (m) 37,  0  2.0  A n n u a l O p e r a t i n g , F i x e d C a p i t a l and T o t a l C o s t s f o r a L i q u i d F l u i d i z e d Bed Heat S t o r a g e U n i t as a F u n c t i o n o f t h e Column D i a m e t e r . Column Length =2.5 m; S u p e r f i c i a l V e l o c i t y = 0 . 1 1 5 m / s ; C a p s u l e D i a m e t e r = 2 5 mm; Fluidization P e r i o d per Thermal C y c l e = 2 H o u r s .  I  1  0.0 ure  38.  0.5  •  I  T  1.0 1.5 COLUMN DIAMETER (m)  1  2.0  T o t a l C o s t o f E n e r g y R e c o v e r e d f r o m a L i q u i d F l u i d i z e d Bed H e a t S t o r a g e U n i t Under D i f f e r e n t C i r c u m s t a n c e s as a F u n c t i o n o f the Column D i a m e t e r . Column L e n g t h = 2 . 5 m; S u p e r f i c i a l V e l o c i t y = 0 . 1 1 5 m/s; Heat S t o r a g e E f f i c i e n c y = 60%; C a p s u l e Diameter 25 mm; F l u i d i z a t i o n P e r i o d p e r T h e r m a l C y c l e = 2 h o u r s ; N u m b e r o f T h e r m a l C y c l e s p e r Y e a r = E q u i v a l e n t t o 150 C y c l e s ; T e m p e r a t u r e R a n g e : 20 t o 40 C .  2 0 % contingency, 15% int.*-  o-  a) 2 hrs. per cycle fluidazation. b) 30 min. per  »  »  no contingency, 10% int. a) 2 hrs per cycle fluidazation b) 30 min per »  »  —r  "T"  70  gure  39.  100 115 130 85 SUPERFICIAL VELOCITY ( m m / s )  Total as  Cost  of  a Function  Length Year  =  2.5  Energy of m;  Recovered  Superficial Capsule  = Equivalent  to  150  from  a  Velocity.  Diameter Cycles;  = 25  Liquid  Fluidized  Column mm;  Diameter  Number  Temperature  of  Range:  Bed  145 Heat  = 1.25  Thermal 20  to  40  Storage m;  Cycles C.  Column per  Unit  -  system. in  the  At heat  increase loss  in  energy to  37,  the  shows  a  0.1  shows  superficial  slight  with  minutes/cycle in  most  is  2  water  not  rates  Figure  savings  39,  the  of  influence  heat  system.  As heat for  discussed  storage a  under  few  bed  and  and  This  The  are a  capsules. and  the  to  fluidized  7.1,  fixed  bed  On  the  cost  suggests  be  for  bed  that  the  in  in  other  at  high  the  fluidization  cost  energy  capsules cycling  the  in  when  thus  the  as  the  they be  transfer heat  system  recover  In  are  shown  recovered  can  capsules  conditions,  of  recovered.  heat  hand,  30  even  fluidization  the  a  also  of  decrease  which  are  periods  small  cost.  with  energy  higher  Figure  total  case  up  storage  shown  of  unit  the  the  efficiency  this  unit  increased  recovered  change  the  per  cost  initial  per  of  an  for  cost  from  negligible,  s a c r i f i c i n g the a  with  is  as  storage  may  fourfold  shorter  velocity  fraction  costs  the  the  However,  heat  nearly  risking  Section due  same  increase  compensate  recovered  small  affecting  from  to  the  material  Therefore  fluidization  even  rates on  in  capacity  cycles.  fixed  the  justify  the  interest  considerable storage  to  fluidization  efficiency  in  enough  m/s.  a  m/s,  change  energy  0.1  only  savings  significant  is  0.1  superficial  period.  velocities;  insufficient  during  storage  The  phase  unit  above  7.1,  than  capacity.  per  hours/cycle  39.  the  when  comprise  Section  applications,  probably  cost  fluidization  Figure  superficial period  in  storage  -  smaller  velocity  increase  costs  noted  of  decrease  The  a slight  operational  shown  heat  m/s.  obtained  velocities  efficiency  theoretical  As is  storage  in  about  unit  superficial  179  from  the  in have the  lost  are  refluidized  cycled  alternately  decreasing  the  -  average  fluidization  recovered  from  fluidization the  the  previous  bed  unit  in  costs  plotted  Figure  as  40.  in  the  This  fluidized  heat bed  a  per  is  cost  storage  energy of  the  average  increases  consistent the  cycles  unit  function  Energy  i n s i g n i f i c a n c e of  decrease  economic  facility  fluidized velocity savings  bed at  are  reduced  if  heat  energy  storage  unit  expected  is  consitute  about  45%  column  the  high  used. of  present  recovered  1.23  with  operating  efficiency  as  the  cost due  increases the  additional from  at  and  density  total  analysis.  a  was  to  the  cost  of  a  1.25  cents  new,  per  the  capital  cost  Therefore  for  liquid  Further  methods  of  could  also  costs  or  of  to  water  Cdn./MJ.  material  cost  due  m diameter  cheaper  polyethylene  and  cost  superficial  1.98  Construction  Capsules  the  the  development  salt.  custom-molded be  the  that  operating  between  with  Glauber's  could  shows  unit  m/s  materials  in  analysis  per  0.115  encapsulating  other  be  cheaper  encapsulation a 1.25  savings  in  m  diameter  these  items  would  significant. A  7.2,  are  The  decreased.  the  between  cycle.  unit  is  -  energy.  storage  or  per  cycle  when  The  cycles  The  be  per  period  paragraph  demonstrated. fixed  storage  period  fluidization  period  180  tube  detailed was  economic  outside  the  the  heat  storage  capsules  were  rotated.  savings  in  the  size  expense  of  decreased  analysis  scope  of  efficiency  of  While the  heat  of  this of  transfer  study.  the  rotating  system  rotating  the  As  capsules drums  required, rates  may this  because  capsules  discussed was  would of  in  higher  bring  in  a  drum  Section  when  the  considerable be  lower  at  the  external  heat  c  o  o  20% contingency, 15^ int  >LU  z  no contingency, 10% int.  CO  O u  04  Figure  i  10 15 20 5AVERAGE FLUIDIZATION FE 40,  Total as  a  0.096  Cost  of  Function m/s;  Energy of  Other  Recovered  Average  from  a  Fluidization  Parameters  are  as  in  Liquid Period. Figure  30 (min/cycle)  Fluidized  Bed  Superficial 39.  Heat  Storage  Velocity  =  Uni  -  transfer  coefficients  would  more  be  significant  more  conductive  from  rotating  detailed  be  more  9.2  in  if  material)  capsules  economic  sacrifice  compared  heat  -  fluidized  a more  conductive  used.  needed  analysis  may  transfer  rates  systems.  show  a more  that  is  capsule  Experimental  for  in  The  some  possible  wall  heat  sensible  difference (thinner  transfer  rotating  rates  comparison.  applications drum  or  A  where  systems  some may  economical.  A d v a n t a g e s and D i s a d v a n t a g e s Compared t o O t h e r Systems Advantages  phase  change  mentioned  important  in  are any  discussions,  will  such  summarized heat  the  voidage  and  increased  interstices  under to  are  minimum 60% a t  filled  phase  most  high with  of  unit  reduced  extent  by  small  using  the  difference  of  agitated  to  systems  capsules have  advantages  the  factors  repeating  avoided  of  been  and which  are  previous  and  generalized  references. change  materials  phase  For  the  heat  give  higher  material  capsules  used  was  velocities. compensates  systems,  in  this  43.5%  of  Although for  heat  part  of  the  per  Voidage  could  decreased  diameters.  capsules  and  unit  However,  water,  total  the  capacity be  but  study  the  storage  capsule  between  change  conditions  which  somewhat.  a distribution  density  be  superficial water  capacity,  section  avoid  will  fluidization  storage is  To  other  spaces.  volumetric storage  unit.  using  proposed  this  without  of  void  other  reference  information  capsules  storage  In  with  storage  be w r i t t e n  contain  to  chapters.  e f f i c i e n c i e s than  systems  energy  relative  numerical  Agitated storage  thermal  previous  in  statements  of  materials  disadvantages  the  to  were  are  182  lost  volume to  due  capsules  some to of  -  varying  size  void  space  even  when  could  is  that  warm  efficiency  of  The  segregate  water a  fluid  capacity  with  not  a  an  low  in  energy  transfer is  during  transfer  is  solar  heat  transfer  heat  transfer  and  consideration  of  heat  rates  While the  their  crystallization  convection  is  occurs.  barrier  to  of  Low  applying  materials.  high  heat  transfer  transfer  area  adjusted  by  only  an  also  open  per  changing  new  fluctuations electricity  areas in  energy  rates,  and  of  even  to  the  It  is  difficult  for  storage  been  to  by  to  of  the  continues overall  an  overlooked  in  heat  the  due  employing  constant  storage  storage  studies  storage  the  units.  beginning  of  natural  has  a  a  sharp  major phase  the  advantage the  heat  can  be  characteristic  is  The  rate  systems,  could  temperature directly  but  include  benefitting  energy  most  increases  enormously. This  heat  unattainable  salt-hydrate  encapsulation  supply,  heat  constitute  capsules  Examples  and  crystallization  probably  heat  high  in  to  diameter.  solar  result  transfer of  material  A  available  agitated  volume  or  change  at  end  units  application.  storage  water  satisfactory  rates  other  demand  be  heat  the  capsule  collecting  and  parameter.  have  because  maintaining  transport  advantages  when  storage  compared  advantage  increases the  phase  would  may  storage  the  the  rate  transfer  rates  unit  advantage  buffer),  heat Heat  to  toward  heat  this  commercially  process,  effective,  decline  change  appears  transfer  and  An  capsules  important  This  in  between  between  potential. also  fluidization.  use,  extremely  point  -  system.  rate  heat  183  from (as  on  may  levelling  differential  a  the  it  not  temperature capsules  for  unit. determine  encapsulated  phase  whether  change  or  not  materials  there  are  compared  cost to  other  of  -  systems. from  the  their  heat  added  barrier  fewer  safety  system.  easier,  volume.  alternate for  of  is  storage  leaks  encapsulation  exchange  contents  entire for  Although  systems.  bulk  phase  Also  the  precautions at  finding  materials,  there  is  no  field  may It  heat  well has  storage  refluidized. thickened  been  has  a  of  the  This  to  is  needed. a cheap  an  cycles  due  costs  due  to  advantage  replaced to  of  over  systems  (usually  the  the  is  and  be  capsules bed  can  mixing  problem  taken  against  have  been phase  a  change  in  this  systems. recover  most  they bed  in  phase  change  unrecoverable  with  loss  its  of  of  and  container)  heat  the  are  fixed  together  an  number  conventional the  is  surroundings,  c y c l i n g when  which  the  a  Developments  different  and  encapsulation the  there  than  usually  should Since  savings  capsules  encapsulating  of  fixed  are  costly  corrosion  Although way  there of  less  material  fluidized  change m a t e r i a l be  and  accepted method.  that lost  mixing  systems.  change  relative  shown  efficiency  phase  material number  alter  cost,  precautions  material  widely  the  tanks,  safety  are  aimed  to  efficient  phase  studies  adds  steel  change  between  -  Mechanical  more  For  184  after  storage  capacity. Nucleation change  materials.  materials employ  without  external for  storage  materials  important  This any  Glauber's  first  to  be  disadvantage  be  suitable  salt  which  sight  initiated  could  nucleating  problem  At  has  have  higher for  a disadvantage  nucleating  devices and  internally  some  for  operating  capsules  for  agent.  encapsulated phase  Bulk  well-known  nucleating costs  agitated  This  phase  may  is  not  change  a heat  agents.  may in  phase  change  systems  such m a t e r i a l s .  other  suitable  for  be a  thought  fluidized  to  be  bed.  an  -  However, costs  the  are  economic  negligible  fluidization providing  This  materials  are  is  capsules  of  in  using  higher  heat  usually  conductivity  heat  fluidized other  pentahydrate  (MacCracken  1981)  nucleating would  be  to  agent  another  fluidized  system.  sufficient  to  prevent  also  help  The  phase  temperature change  Even  (<  in  space In  materials  heat  high  C)  heat  storage  applications  have  our  definite  in  a  by  the phase  whose  the  (see  lower  system.  to Table  thermal  Sodium  crystallization If  and  change  capsules  a  suitable  thiosulfate  sodium  hand,  brings  the  during  fluidized  considered  pentahydrate  agitated  system  in  would  thiosulfate  fluidization  energy not  results  is  The  transport  out  of  indicate  advantages  in  Application  applications.  are  of  paraffins  formation.  of  it  in  example,  sodium  other  encapsulated  proposed  operating  simultaneously  because  mixing  that  a probably  dihydrate  and  the that  not  this of  study  for  encapsulated  restricted  advantages and  are  heat  may  to  exchange  low  phase low  also  be  systems.  question. encapsulated  potential  in  phase  integrated  be  and  sel f - n u c l e a t i o n .  storage.  temperature  of  encapsulated  materials  agitated  summary,  be  formation  initiate  change  50  materials  temperature useful  to  gentle  the  agitation  materials  the  shows  of  materials  For  change  Agitation the  On  systems  dihydrate  to  costs.  future  identified,  candidate  bed  would  be  9.1  uniform  change  using  prevent  could  and  rates.  needs  Section  advantage  the  phase  overcome  thiosulfate  in  the  bed  phase  -  capital  for  transfer  be  to  transfer  worry-free  can  given  has  important  agitated  possibility  1)  the  compared  effective  capsules.  provide  of  analysis  185  change solar  -  energy storage  recovery/storage systems.  for  as  -  well  Future  studies  and  should  investigate  phase  change  materials  encapsulation devices  systems  186  should  as  in  seek  suitable  which  have  other cheaper  thermal methods  energy for  nucleating  agents  or  nucleation  problems.  -  10.  187  -  C O N C L U S I O N S AND R E C O M M E N D A T I O N S FOR F U T U R E STUDIES  10.1 Conclusions Glauber's agitated  by w a t e r  fluidized The  heat  average volume the  transfer  capsules  fluid  with  salt  change  percent  superficial  water  was found  velocity  in the heating capsules  rate  showed  efficiency  o f t h e c a p s u l e s between,  system,  gentle  cycles.  with  of  Heat  percent  i n t h e f l u i d i z e d bed capacity.  The  by i n c r e a s i n g t h e period.  effect.  7  in their  cycles  20 and 40 C was o n l y  decreased  of the  efficiency  (96 weight  storage  o r 67% o f t h e c o r r e s p o n d i n g  and t h e p e r f o r m a n c e  agitation  three  mixture)  After  (where t h e  rates,  storage  a considerable decrease  bed c o n d i t i o n s .  l e d t o an  t h e c a p s u l e s and  transfer  material  o r no  system.  o r a heating run  t o be i m p r o v e d  had l i t t l e  under  capacity  heat  heat  storage  and by i n c r e a s i n g t h e c o o l i n g  efficiency  theoretical  fixed  between  the f i r s t  borax  liquid  o f 6 0 kW/m3  i n t h e heat  after  spheres and  by e n c a p s u l a t i o n ,  rate  uniform  60% o f t h e t h e o r e t i c a l  o f t h e system  The  loss  energy  cooling  to high  cycling  o f t h e phase  performance  Changes  a typical  further  thermal  thermal  or recovery  provided  hollow  ( 0 . 3 4m diameter)  enormously  In a d d i t i o n  and 4 w e i g h t  was about  size  of the capsules)  during  prevented  efficiency  Glauber's system  volume  of the capsules  which  capsules  increased  delivery  20 a n d 4 0 C .  fluidization  storage  transfer  transfer  plant  i n 2 5 mm d i a m e t e r  t o be a p r o m i s i n g  area,  i s the inside  heat  encapsulated  in a pilot  b e d , proved  heat  between  the  salt,  t h e heat 38.4%  agitated  further  heat  cycling.  storage storage  of the  (fluidized) 97.5%of  -  the  original  when  these  showed  capsules  were  operating  costs  Therefore  pumping  the  costs. bed  systems,  system. higher  despite  total  rotation  rotating  regular  to  the  79.2% the  theoretical  sulfate the  from  or  cost  are  recovered  within  fluidized  bed  almost  three  costs  are  cost  of  heat  negligible  of  only the  commercially  the  small  around  cycles  available  storage  compared  a minor  system  encapsulation  a  the  was  which  fixed  for  found  heat  system  to  factor  to  the be  storage  contributes  change  heat  weight  of  phase  concentration tube  was  45%  of  thermal  anhydrous  sodium  the  change found  of  of  but heat  material, to  be  the  that  in  heat  theoretical  heat  even  the  excess the led  under  optimal  for  in  were or of  the  per  percent  the  from  recovery  capacity  weight  tube  sulfate  a decrease  storage 47  rotating  sodium  vigorous  recovered  percentage to  full  improved  efficiencies  and  improved  basis  of  to  performed  unit  sodium  rotating  drum  and  cases.  Thermogravimetric different  drum  leads  possible,  storage  capacity,  indicated  axis  not  Addition  material  storage On  was  heat  experiments,  systems,  recovery  rotating  respectively.  phase  full  capsules  the  tube  horizontal  maximum  in  rotating scale  However,  capacity.  rotating  and  in  The  capsules  theoretical  volume  high  capsule  a  conditions.  water  liquid  initial for  of  capacity  and  the  than  capsules  storage  83.2%  The  same  efficiencies.  the  of  drum  storage  mixing  was  cost.  The the  the  -  refluidized.  that  slightly  with  capacity  analysis  fluidized  the  storage  Economic  capital  only  heat  188  cycling sulfate  analysis  of  histories is  not  the  the  samples  showed only  from  the  that  the  bulk  reason  for  the  capsules  with  segregation loss  of  heat  of  -  storage  capacity  material. layer  in  Glauber's  salt  degrees  of  periods  lead  storage  efficiency.  subcooling, to  Glauber's  salt  that  both  with  temperatures  10.2  found  in to  sizes  microencapsulation,  for  crystallization nucleation  and  that  and  the  C  and  by  low  beneath  borax  of  The  gently  the  heat  in  subcooling experiments  crystallization and  cooling  reducing  weight  a  Higher  shorter  degree  Nucleation  capsules,  31.8  a  sulfate  thereby  4%  change  important.  temperatures.  agitation.  regular  27.4  as  phase  also  temperatures  crystallization  agitated  in  a  water  bath,  respectively.  Recommendations  (1)  Although  studied  phase  on  aspects  many  example,  change of  work  is  diffusion  solution,  rate  the  of  sizes  of  the  for  Glauber's thermal  needed of  crystals  microencapsulation, the  the  degree  is  energy salt on  with  initial  one  of  storage  and  in  cycling  nucleation are  following:  most  are  water or  in  the  scientific  in  areas  Glauber's  salt  unsaturated  and  magnitude and  data  available.  the  cycling.  process  all  extensively  not  formation,  thermal  affecting  subcooling  of  water  nuclei  repeated  the  the  materials,  diffusion  sulfate  growth  include  thermal  the  variables  of  studies  salt  sodium  crystal  microencapsulation,  determining  future  Glauber's  crystals,  of  crystal  as  sodium  least  achieving  Recommendations  For  at  optimal  the  be  is  increased  increased  salt  anhydrous  showed  the  -  Glauber's  experiments  sacrificing  increase  were  is  of  crystals  enhanced  Subcooling  showed  using  Microencapsulation  of  without  systems  189  changes The  mechanism  of variables  which  must  in  be  -  carefully agitated  studied  The  with  high  of  using  and  encapsulation thermal  cost  systems  performance even  further  the  the  encapsulation encapsulated  economic  encapsulation should  energy  be  The  effect  changes  in  the  heat  has  effect  on  heat  storage  efficiency  under  phase  costs, to  the  of  change the  new  make  major  material.  proposed  methods the  component  for  system  in  heat  Since  system  is  the  promising  cheaper  a highly  competitive  unit. of  capsule  transfer  the  is  outlook  sought  storage  (3)  any  improve  -  conditions.  (2) storage  to  190  heat  size  rate  should  and  storage  to  be  studied  evaluate  efficiency  of  to  whether the  determine capsule  phase  the  size  change  material. (4) and  Hollow  volume  utilization  availability should  be  the  cost  the  would  system  improve  the  considerably.  metal  capsules  or  is  reliable  nucleating  borax  a  of  subcooling  agent  or  device  ways  of  heat  transfer  rate  Therefore manufacturing  them  is  would  not  negligible.  increase  the  heat  agent  for  Therefore storage  Glauber's a  better  efficiency  of  salt.  (6)  In  the be  of  degree  Glauber's  should  low  Although  nucleating  between  of  capsules  sought.  (5) salt,  metal  view  phase  carried  of  the  change out  high  heat  material  also  with  transfer  and  the  other  rates  heat  in  the  transfer  encapsulated  phase  fluidized  medium,  bed  tests  change  materi a l s . (7) change  Since  materials,  internal  nucleation  nucleating  agents  is or  essential devices  for  should  encapsulated be  sought  for  phase  -  phase  change  material  remembered  that  conditions  may  some work  which  are  191  not  nucleating  self-nucleating.  agents  successfully  -  which  under  the  do  not  It work  agitation  of  should under the  be fixed  bed  fluidized  bed. (8) as  a  draft  Some m o d i f i c a t i o n s  in  tube  and  collisions  may  efficiency  of  capsules  the  the  such  Using  minimum  fluidization  different found  or  new  liquid  volume shapes  a  target and  However,  circumstances  and  density.  of  capsules which  the  bed  and  bed  Therefore should rotate  also more  fluidized  at  the  top  thus  the  heat  strength be  shapes  other  the  liquid  should  capsule  fluidized velocity  manufactured  ordinary  agitation  non-spherical  in  same  the  the  capsules.  problem  the  center  improve  under  (9)  at  an  voidage  cost be  of  not  cause  increases to  encapsulation  vigorously.  if  of  the  carefully.  compared  sought  capsule  lifetime  studied  small  provide  such  storage  and  should  than  to  bed,  shapes  any in  the  spheres in can  be  of  -  192  -  NOMENCLATURE  A  A c  Total s u r f a c e area of the heat s t o r a g e system i n s i d e b a l a n c e b o u n d a r y e x p o s e d t o s u r r o u n d i n g a i r (m )  the  Heat t r a n s f e r fluid (m2)  transfer  area  between  the  capsules  and  the  heat  heat  C^  Effective heat c a p a c i t y of a l l m a t e r i a l i n s i d e the heat boundary except the contents of the c a p s u l e s (kJ/K)  balance  C^'  Modified  form  of  (kJ/K)  Cp  Specific  heat  capacity  Cni-i  S p e c i f i c heat c a p a c i t y of component the l i q u i d phase ( k J / k g - K )  "k"  inside  the  capsules  in  S p e c i f i c heat c a p a c i t y of the s o l i d phase ( k J / k g - K )  component  "k"  inside  the  capsules  in  CpW  Specific  heat  capacity  of  water  C  S p e c i f i c heat (kJ/kg-K)  capacity  of  capsule wall  p K I  C-i.p K 5  n w m p w m  d  Q r  Diameter  of  the  when  capsules  distributor  Capsule  Dc  Column  hQ  External  heat  H-  Enthalpy  of  column  inlet  HQ  Enthalpy  of  column  outlet  ^GS  Thermal  conductivity  kw  Thermal  conductivity  k  Thermal c o n d u c t i v i t y of (polyproplene) (W/m-K)  L  Length  diameter  of  the  are  not  in  the  column  (kJ/kg-K)  dp  w m  diameter  C^  (kJ/kg-K)  orifices  material  (polypropylene)  (m)  (mm) (m)  transfer  column  coefficient water  (W/m2-K)  (kJ/kg)  water  (kJ/kg)  of  Glauber's  salt  of  water  (W/m-K)  capsule wall  from  (W/m-K)  distributor  material  to  screen  (m)  -  Lm1r  m  GS  Bed  depth  at  Weight of capsules  minimum  Glauber's (kg)  m.j  Total  m^  Weight  mQ  Total  n  Number  of  capsules  Nc  Number  of  thermal  N o  r  weight  of  of  weight  water  of  heat  input  by  Pe  Cost  of  electricity  PP  Power  q  Rate  per  change  inside  the  system  during  the  the  capsules  the  system  the  unit  during  area  recirculation  pump  the  Modified  QQL  Heat a c c u m u l a t i o n capsules (kJ)  due  to  the  £<j  Heat a c c u m u l a t i o n capsules (kJ)  due  to  sensible  by  capsules  Heat  input  Heat  losses  to  the  Q0  Heat  output  by  water  Qp  Heat  input  by  run  (kg)  distributor  pump  (kJ/h)  (kW)  (W)  Q^'  Qn-  (kg)  (kg)  Heat a c c u m u l a t i o n due to s e n s i b l e heat o f m a t e r i a l s i n c l u d i n g e v e r y t h i n g other than the contents of the  n  run  ($/kW-h)  transfer  when  the  year  per  recirculation  heat  phase  column  (orifices)  of  of  the  cycles  Rate  the  inside  leaving  in  P  of  "k"  (m)  undergoing  entering  water  Number o f h o l e s (orifice/m2)  -  fluidization  salt  component  193  water  are  entering  not  latent  the  surroundings  leaving  recirculation  Theoretical heat s t o r a g e in the column (kJ)  in  the  heat  heats  column  column  of  of  (kJ)  the  the  contents  contents  of  of  the  the  (kJ)  (kJ)  column  pump d u e  capacity  the  in the system capsules (kJ)  of  to  the  (kJ)  friction  contents  (kJ)  of  the  capsules  -  194  -  R.j  Internal  heat  transfer  resistance  (K/W)  RQ  External  heat  transfer  resistance  (K/W)  Rwm  Resistance  t  Elapsed  T  Temperature  of  Tb  Temperature  inside  7^  Time  T^  Temperature  inside  the  column  at  the  end  T^-  Temperature  i n s i d e the  column  at  the  beginning  TCf  Temperature  of  the  c a p s u l e s at  the  end  Tc^  Temperature  of  the  capsules at  the  beginning  Tm  Congruent  Tg  Surrounding  Tg  Time-averaged  U  Superficial  to  heat  time  transfer  across the  capsules  (C)  the  the  column  air  surrounding  water  transfer boundary  UQ  Capsule  to  U  Water  fluid  velocity  V  Volume  at  any  relative  occupied  the  a  of  of  the  the  sodium  run  (C)  of  the  run  (C)  of  the  sulfate  run  run in  (C)  (C)  water  (C)  system i n s i d e (kJ/m2-K-h)  the  (C)  temperature  (C)  (m/s)  velocity  heat  transfer  between  capsule  the air  (m/s)  orifices'in  velocity  by  of  (C) (C)  c o e f f i c i e n t between and t h e s u r r o u n d i n g  overall  in  time  temperature  air  velocity  fluidization  Average  inside  temperature  Minimum  Up  column  s o l u b i l i t y temperature  Umf  Q r  wall.(K/W)  (h)  averaged  Overall heat heat b a l a n c e  capsule  (m  )  coefficient  distributor  a capsule  and  (kW/m2-K)  (m/s)  water  (m/s)  -  X$  V e r t i c a l d i s t a n c e measured o f t h e c a p s u l e (mm)  X$s  Weight  fraction  of  sodium  X ^  Volume  fraction  of  the  AP^  Pressure  drop  At  Duration  which  cycle  across  195  -  downwards  sulfate  capsules  the  in  a  the  top  center  mixture  occupied  distributor  recirculation  from  by  (mm  wall  material  H20)  pump o p e r a t e s  during  each  thermal  (h/cycle)  AT  Temperature fluid (K)  difference  the  heat  nc  P e r c e n t of t h e o r e t i c a l heat of f u s i o n p l u s s e n s i b l e the contents of the capsules during c o o l i n g c y c l e  heat  nn  Percent of t h e o r e t i c a l g a i n e d by t h e c o n t e n t s  Agg  Latent  PQ<J  Density  of  Glauber's  Pm  Density  of  sodium  Pp  Overall  density  Pw  Density  of  water  Pwm  Density  of  wall  y  Viscosity  heat  of  of  phase  between  latent of the  change  salt  the  for  Glauber's  (kg/m  capsules  (kg/m  water  mixture  (kg/m  (kg/m  (kg/m-s)  salt  )  )  (kg/m  transfer  lost  plus sensible heating cycle (kJ/kg)  )  )  material  and  heat of m e l t i n g capsules during  sulfate-water  of  capsules  )  by  heat  -  196  -  REFERENCES  ASHRAE  94-77,  "Methods  of  Testing  Thermal  Storage  Devices  Based  on  Thermal P e r f o r m a n c e , " The A m e r i c a n S o c i e t y of H e a t i n g , Refrigeration a n d A i r C o n d i t i o n i n g E n g i n e e r s I n c . 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M a t e r i a l s , " I n t e r n a t i o n a l e s Sonnenforum, 2, 3 6 3 - 3 7 2 (1978).  Weast, R . C , 1976.  CRC H a n d b o o k  of  Chemistry  and P h y s i c s ,  CRC P r e s s ,  Ohio,  -  Wilkinson Co. L t d . , October, 1984.  Vancouver,  200  Retail  -  price  information  by  telephone,  Wood, R . J . , Gladwell, S.D., O ' C a l l a g h a n , P . W . and P r o b e r t , S . D . , "Low T e m p e r a t u r e Thermal Energy S t o r a g e U s i n g Packed Beds of Encapsulated P h a s e Change M a t e r i a l s , " P r o c e e d i n g s of I n t e r n a t i o n a l C o n f e r e n c e on Energy S t o r a g e , V o l . 1, pp. 145-158, B r i g h t o n , U.K., A p r i l 29 May 1 , 1981. Zahavi, E., "Heat Transfer, Vol.  Transfer in Liquid Fluidized 44, pp. 835-857, 1971.  Beds,"  Int.  J.  Heat  Mass  -  201  -  APPENDICES  -  202  -  APPENDIX 1  Contents  1.  Numerical  Values  or  Appendices  in  the  2.  Design  3.  Minimum  of  the  for  Some  Parameters  Used  Distributor  Fluidization  Velocity  Evaluation  in  the  Text  -  1.  Numerical  Values  for  203  -  Some P a r a m e t e r s  Used  in  the  Text  or  in  the  Appendices Cpw  pwm  C  d  1  ,  9  2  5  k J  /  9 "  k  (at  K  = 2 5 mm = 0 . 0 2 5  p  W/m-K  (at  k ^  = 0.138  W/m-K  (Perry  r2  =  =  =  c  ° '  1  7.7  x  lO"6  = 0.7975  P  =  P  p  wm  Design The under  =  of  d  9 0 0  the  minimum  f  Q r  x  of =  10~3  and  30 C)  and  Chilton  Sherwood  (Weast  and  1973)  1981)  1976)  Chilton  1973)  m  (  k g / n i 3  kg/m-s  (Telkes  kg/m3  (at  p e r r  (at  C)  (Weast  1976)  1975)  30 C)  y  30  a n d  (Weast  Chilton  1976)  1973)  Distributor was  designed  fluidization  water  in  to  mm = 0 . 0 0 9 5  to  produce  conditions  the  5 8 . 8 mm = 0 . 0 5 8 8 calculations)  = 9.5  (Perry  m3  kg/m3  distributor  distribution U  1460  = 995.6  W  )  1976)  6  yw  G S  (Chadwick  mm = 0 . 0 1 1 5  7  c  (Weast  m  = 0.614  11.5  30 C)  3 0  kw  wm  W/m-K  (at  = 0.51  V  H2O  =  kJ/kg-K  kQS  X  2.  = 4.1785  to  a  pressure drop  provide  of  125  uniform  bed. m (from  m  minimum  fluidization  velocity  mm  -  Dc  p  liq  =  APd  9  =  9  5  ,  6  KG C  '  drag  Rec  x  U  Number  of  p  liq  y  l i q  U  coefficient  104  (Kuni  or  ci  - 3  o  r  w  a  t  e  r  a  kg/m-s  t  (for  mf  of  C  )  (  water  W e a s t  at  1 9 7 6  30 C)  _ 0.34 x 995.6 x 0.0588 — — — — — — — — — — — — — 0.7975 x l O " 3  (Cj1)  is  almost  and L e v e n s p i e l  )  (Weast  1976)  v  P  l  .  1 iq  '  =  o.6 *  constant  _ 9 K — c. %0 X 1U  and e q u a l  to  0.6  1969).  v  (2  X  \  £  995.6  or  = j  (0.0095)2  = 880.62  holes  in  x 0.942  orifice/m  x  *  1 2 5  )  1 / 2  -  0.942 m/s  holes  N  Q r  2  the d i s t r i b u t o r  = ) d 2 N 4 c or = j  Number  3 0  = Ji d 2 U N J or or or  o  0.0588  N  x 10  f  1 2 5 mm H 2 0  m f  Orifice  ^  k g / m 3  _ Dc £ —  D q  u  -  = 0.34 m  = 0.7975  > 1  204  in the d i s t r i b u t o r  =  79  (0.34)  2  x 880.62  = 79  holes  for  -  3.  205  -  Minimum F l u i d i z a t i o n V e l o c i t y E v a l u a t i o n The  procedure  Pp  p  =  l i q  1340  =  9  9  5  ,  is  kg/m3  6  = 25  x  from  (from  (  k g / m 3  = 0.7975 dp  taken  mm = 0 . 0 2 5  (1982).  statistical  w a t e r  lO"3  Grace  a t  3 0  kg/m-s  c  )  analysis)  (  (water  W e a  at  st  1976)  30 C)  (Weast  1976)  m  "3V, 3 Ar  p  =  l1 1iC q 1  995.6  x  (|pp ' P  "  %  (1340  l i q  p  -  }  9  d p  995.6)  x  9.81  (0.7975  x  lO"  x 3  )  (0.025)3  2  Then  J  U  U  mf  mf  m f  -  0.202  / '  P  P ; J  =  0 . 2 0 2 ,^M"X 9 5 . 6V 9 or-  = 0.0588  m/s  P  l  i  ^ g d p '  liq  9.81  = 58.8  x  mm/s  0.025  m/s  =  8 > 2 6  x  1 C j  7  > i  x  1  0  ?  -  206  APPENDIX  -  2  SIMULATION OF HEAT TRANSFER BETWEEN THE CAPSULES AND THE HEAT TRANSFER MEDIUM  (WATER)  -  1.  -  E v a l u a t i o n o f E x t e r n a l Heat T r a n s f e r C o e f f i c i e n t ( h ) 0  It  is difficult  calculation fluidized narrow large is  207  of  find  (Zahavi of  1971).  Most  parameters.  In  ( 2 5 mm) a n d t h e d e n s i t y  small  well-established  p a r t i c l e - t o - f l u i d heat  beds  ranges  to  (344 kg/m ) .  transfer  expressions coefficient  of the expressions  this  study  difference  The c o r r e l a t i o n  proposed  in  liquid  are valid  the p a r t i c l e  beteen  f o r the  for  diameter  the p a r t i c l e s by S u n k o o r i  i s  and  and  fluid  Kaparthi  (I960),  NU  predicted  about  expression sphere  10  times  suggested  and f l u i d  survey  made  of  flowing  t h e heat  by Z a h a v i  past  particles  smaller  than  liquid  over  a single  by McAdams  external  coefficient,  measured  i n most  case,  the effect  between  indicates  h  liquid of  the capsules  transfer  (1954)  0  1 / 2  P r  that  1  transfer  than  the  between  a  particle.  transfer  coefficient  study  A 2 . 2 , was used  fluidized  bed s t u d i e s  resistance  literature  to or  somewhat  in the corresponding In t h i s  gives  in the  bed i s c l o s e  it  and water  (A2.2)  3  reported  the heat  coefficient  Equation  /  , because  external  coefficient  f o r heat  in a fluidized  transfer  (1954),  (A2.1)  2 , 1  coefficients  spherical  proposed  heat  = 2 + 0.6 R e  and l i q u i d  the heat  R e  i t ,  transfer  (1971)  between  higher  b y McAdams  NU  A  = 0.00391  values  (Zahavi  small.  to  the  values  1971).  heat  of  expression  evaluate  close  in overall  is relatively  to  the  flow  In any  transfer  Therefore  rate some  -  error  in  "h0"  will  expanded  form  of  Nu  The  physical  not  Equation  =Jjp> =  were  Appendix  1.  Ur  velocity  between  in  the  in  above  velocity  velocity  which  (U)  maximum  Substitution and  external  the  of  this  at  30  C,  expression water.  0.11  2 (  results.  The  JW\L}1/3  the  is It  average These  the will  (  temperature  values  average be  are  is  close  efficiency  under  fluidized  A  2  in  given  resistance  r  to  T  =  = TJ37  together  with  Eq.(A2.3)  heat  transfer  =  1  1  9  the  to  gives is  physical h0  = 2059  in  the  bed  at  a  superficial  conditions  was  properties W/m2-K.  of  The  therefore  = 0.247  K/W  TT(0.025)2«2059  Q  E v a l u a t i o n o f R e s i s t a n c e t o Heat T r a n s f e r A c r o s s t h e Capsule Wall The be  inside  r e s i s t a n c e to  evaluated a  sphere  using  heat  the  (McAdams  transfer  expression  1954).  across for  heat  the  3  capsule  transfer  wall,  Rwm,  resistance  )  the  ™/s  3  — I  = h  2  = ° '  >  relative  calculated  which  into  TT d  can  final  m/s  value  capsules  R  2.  the  Then,  U  water  on  calculations.  and  of  effect  (-P-LV/  0.6  the  -  i s :  water  a capsule  superficial  obtained.  +  of  used  much  A2.2  2.0  properties  experiments,  at  have  208  -  r  R  209  r  p -  -  l  (A2.4)  wm  where k  r  wm  P  Thermal  conductivity  Outside  radius  Inside  Substituting  3.  these  Evaluation of There  transfer capsule the  (solid,  internal  cool  in  down  what  the  to  point  the  magnitude  of  capsules  method  gas),  bed  C,  melting of  convectional  to  liquid  C,  pure  100% the  the  there  of  K/W.  to  first  the  heat  form  at  transfer the  end  due  phases  to  is  in  the  stagnant  is  the  is  easy of  capsule.  because  each  This in  the  of  of  the  capsules  capsules,  not  case  unlikely.  in  agitation  the  not  heat  fraction  When  in  grow  it  problem of  internal  a certain  begin and  transfer a  the  complexity.  should  in  (Rj)  three  contents  capsules),  conduction  heat  are  occupying  the  (W/m-K)  m  = 4.02  crystallization  phase  mateial  m  evaluating  each  adds  will  (heating  to  Rwm  crystallization  crystals  0.0125  = 0.0115  for  32.4  fluidized  earlier,  some  obtain  Mixing  the  complexity  capsule  =  wall  Heat T r a n s f e r R e s i s t a n c e  Above and  capsule  capsule  area.  relative  explained  be  obvious  liquid  32.4  case  will  no  of  we  Internal  wall  the  extra  values  coefficient.  capsules  at  is  radius  of  of  clear. to  In  predict  agitated As brings  practice  crystallization  but  an there  process  -  although  it  Due  should to  the  not above  transfer  coefficient  reliable  model.  decided heat the  not  to  transfer  go  made  100%  volume  of  five  are  Above  mixed  so  the  case),  that  we  the of  the  the  capsules  are  assumed  to  surface, solid  large,  form  while  layer  above  When  32.4  C.  this  and  remain  the  crystallization order the  to  this  an  heat  obtain  the  a  it  idea  transfer. 25%,  was  internal  approximate  crystallization, The  heat  study,  of  of  Estimates 50%,  75%  and  simplifying  temperature,  32.4  that  the  contents  of  in  the  capsule  wall  Since  assumption  on  the  to  is  is  entire  is  and  This  means  the  due  to  are equal that  contents the  of  capsule  reasonable. a  uniform  agitated  crystal capsule  proceeds.  Conduction  resistance  to  layer  capsule  uniform  when  resistance  (no  the  capsule. ignored  C  are  still  heat  layer inside  wall  through  this  transfer,  assumed  is  to  be  but  well  the mixed  temperature.  preserve  capsule,  the  the  starts,  the  solid  of  transfer  additional  and  inside  inside  an  air  bubble  capsules.  crystallization  provides  In  to  the  inside heat  and  (3)  of  obtain  no  assume  to  liquid at  can  internal  evaluation  was  crystallization  the  the  resistance  temperature  resistance  quite  in  we  the  experiments  objective  in  crystallization  internal  (2)  Instead  of  follows:  temperature  is  an  details  which  modelling  detailed  not  internal  cases  the  wall  some  was  great  the  as  crystallization  the  into  crystallization  (1)  to  this  -  theoretically.  complexities,  coefficient.  for  assumptions  well  there  requires  Since  contribution  were  be  210  the  occupying  geometrical 5% o f  the  symmetry, inside  the  volume  of  air capsule,  -  is  assumed  of  the  to  form  a 8 . 5 mm d i a m e t e r  internal  the  heat  above  to  an  Glauber's  annular  inside  surface  time.  The  different  heat  of  salt  the  annular  the  shell  of  the  of  where  km i s t h e  which  i s taken (kQs)»  fraction  of  values  layer  center  at  in  the  end  must  For  the  be e x p r e s s e d cases,  rj  a case  comes  to  at  inner  x  and  the  the  center  surface  due t o 2  in  the with  at  be c a l c u l a t e d  r  only  conduction  3 2 . 4 C on  toward  resistance r  where  from  form  on t h e  radii  r  2  thermal In  in  the  this  1  for  -  0.0737  phase  using  conduction  i s given  change  conductivity problem  is constant.  Appendix  =  of  by  By  r^  of  material  solid  varies  inserting  r£ and k m ,  we  Glauber's  with the  obtain  r. rx  (K/W)  (A2.6)  meters.  no c r y s t a l l i z a t i o n ,  crystallization,  to  the  (A2.5)  0.0115  r\  calculating  can e a s i l y  The  and o u t e r  the  while  given  capsule starts  salt.  borax.  R,-  volume  the  =  to  the  of  and p r o p a g a t e s  conductivity  as equal  ignoring  the  crystal  inner  thermal  crystallized  numerical  where  at  simplified  which  wall  crystallized  shell  is  problem  crystallization  R.  salt  a i r sphere  the  inside  capsule  percentages of  resistance  transfer  thickness  volume an  assumptions,  transfer  resistance  in  -  crystallization. With  the  211  was c a l c u l a t e d  2 5 % , 5 0 % , 75% as 0 . 0 1 1 5 ,  and 100%  0.0105,  by  0.0093,  -  0.0076  and  resistances  0.0043 (R-j)  m respectively.  212  -  The  corresponding  internal  are:  For  no  crystallization  For  25%  by  volume  For  50%  by  volume  For  75%  by  For  100%'by  R-j  =  crystallization,  R-j  =  1.29  K/W  crystallization,  R-j  =  3.21  K/W  volume c r y s t a l l i z a t i o n ,  R-j  =  6.96  K/W  volume  R-j  = 22.7  crystallization,  ,  0  K/W  -  213  -  APPENDIX 3  1.  Computer  Program  Temperature by  2.  Raw  Eq.  Data  (1.2)  Data  from  in  Which and  Integrates  Performs  Section  Fluidized  the  the Heat  6.1.2.  Bed  Studies.  Time  Versus  Balance  Given  -  214  -  c c C C C C C  THIS I S THE PROGRAM WHICH INTEGRATES THE TIME VERSUS TEMPERATURE DATA AND PERFORMS THE HEAT BALANCE GIVEN BY -EQUATION 12 IN SECTION 6.1.2 OF THE T E X T . CORRECTION O P T H E EVALUATED HEAT STORAGE CAPACITY FOR THE 20 C TO ' 1 0 C TEMPERATURE INTERVAL IS ALSO PERFORMED IN THIS  C C  PROGRAM.  C  DIMENSION  T I M E U O O ) , TEMP(400), AR(3)  C  C  INPUT O F THE EXPERIMENTAL  PARAMETERS  C  10 20  READ ( 5 , 2 0 ) IR, 1 0 , IHC, TPLOW, N, ROOMT, DPRES FORMAT ( 1 3 , I I , I I , F 6 . 1 , 1 3 , F 4 . 1 , F 4 . 1 ) READ  3 0  (5,30)  FORMAT-  (TIME(I),TEMP( I ),I= 1 , N )  ( 2 F 9. 3 )  CPC  = 1 4 0 . 7  CPU  = 1 6 3 . 1  C  C  INTEGRATION OF THE TIME VERSUS TEMPERATURE  CURVE  C IA  =  1  = N AREA = Q I N T 4 P(TIME,TEMP, N, IA, I B) A R ( I O ) = AREA IF ( I O .EQ. 2 ) GO TO 4 0 IB  GO  TO  10  C  C C  AVERAGE  BED TEMPERATURE CALCULATIONS  40 TOP = 0 D O 50 I = 1 , N KI = I + 1 IF (KI .GT. N) KI = N 50 TOP = TOP + T E M P ( l ) * ( T I M E ( K I ) TN = N ABEDT = TOP / (TIME(N) - T I M E ( l ) )  TIME(l)J  C,  C C  EVALUATIONS OF THE TERMS  IN THE HEAT BALANCE EQUATION  DELT = ABEDT - ROOMT DTI ME = T I M E ( N ) - T I M E ( l ) FLOWRA = TFLOW / DTIME SUPVE = 0.137524 * (62547.5*DPRES + 29724) ** 0.5 + FLOWRA 11854 DTEMP = TEMP(N) - T E M P O ) DELA = A R ( 1 ) - A R ( 2 ) ATEMPD = DELA / DTIME HEATS = ATEMPD * TFLOW * ( 8 . 0 2 / 8 . ) * 4.186 HEINPU = 8734.4 * DTIME / 60. HELOSS = 23.65 * 1.1 * DELT * DTIME / 60. SPHEGA = 860.2 * DTEMP DHPCM = HEATS + HEINPU - HELOSS - SPHEGA C C C  END TEMPERATURE IF GC  CORRECTIONS  FOR THE HEAT STORAGE CAPACITY  (TEMP(1) .LT. T E M P ( N ) ) GO TO 60 = 20.0 - TEMP(N)  -  215  -  GH = TEMP(1) - 40.0 GO TO 70 60 GC = TEMP(1) - 2 0 . 0 GH = 4 0.0 - TEMP(N) 70 CEC = GC * CPC HEC = GH * CPU CORREC = DHPCM + CEC + HEC C C C  PRI.NTING OF RESULTS WRITE (6,80) IR, TEMP( 1) , T E M P ( N ) , DTI ME, SUPVE, DHPCM, CORREC 80 FORMAT (3X, 13, 2 ( 3 X , F 4 . l ) , 2 ( 3 X , F 5 . l ) , 2 ( 3 X , F 7 . 1 ) ) WRITE (6,90) IR, HEATS, HEINPU, HELOSS, SPHEGA, DHPCM 90 FORMAT (3X, 13, 4X, F8 . 1 , 5X, F7 . 1 , 4X, F 6 . 1 , 4X, F8.1 , 7X, F 7 . 1 ) STOP END  Table  RUN NO:  A l . Experimental  INITIAL TEMP.  Results  216  -  f o r the F l u i d i z e d  Bed Runs  ( C)  PINAL TEMP. ( O  RUN PERIOD (MIN.)  SUPERFICIAL VELOCITY (mm/s)  2 1  19.. 3  39. 8  67. 0  96. 1  9492. 9  94  25  18,,6  39 .7  6 70.  96. 1  9325. 5  9173.9  40  40,,0  1 9.4  71 .0  96. 2  -8719. 1  -8632. 1  44  40.. 2  19., 4  76. 0  96. 2  -8690. 4  -8566.6  48  40,, 1  19. 4  71 .0  96. 4.  -8891 . 2  -8501.5  52  39., 7  19. 2  68. 0  8 1 23 .  -8783. 2  -87  56  40., 3  19. 2  66. 0  111. 0  -8855. 5  -8699.7  62  39,. 8  19. 4  60. 0  79. 1  -7639. 9  -7585.0  7 1  18., 8  39. 9  70. 0  96. 0  9725. 6  9571.8  75  19., 3  40. 0  66. 0  96. 1  9083. 2  8992.1  79  19., 3  39. 9  64 .0  96. 1  8840. 3  8748.8  83  19., 2  39. 9  65. 0  96. 1  8791 . 5  8701 .0  87  19., 3  40. 1  65. 0  96. 1  8713. 2  8592.6  91  19., 4  40.. 1  64. 0  96. 1  8830. 4  8725.7  95  19., 3  40., 2  63. 0  96., 1  " 8751.5  8629.7  ' -8638.3  -8563.2  HEAT STORED BY CAPSULE CONTENTS (kJ)  CORRECTED HEAT STORAGE (kJ)  14.7  1 3. 0  100  .40, .0  19.. 5  64 .0  95.,3  1 04  40 .0  19., 5  61 .0  95., 3  -8639. 1  -8564.9  1 08  40.. 0  19., 4  65. 0  95,, 3  -8588. 8  -8497.6  11 2  40..0  19.,6  64 .0  95,, 3  -8572. 4  -8516.3  116  39 .9  19.,6  60. 0  95,, 3  -8572. 2  -8533.9  120  40 .0  19 . 4  64. 0  95,. 3  -8496. 0  -8400.3  1 24  39 .9  1 9. 4  68 , ,0  73 .9  -7174.,5  -7097.3  1 28  40 .0  1 9. 4  67 , ,0  81 .6  -6850.,7  -6759.2  1 32  40 . 1  1 9. 4  76,.0  88 .6  -7685..-2 -  -7586.3  1 36  40 . 1  1 9. 4  74,.0  95 .2  -7821 .,2  -7709.5  1 40  39 .9  19 .3  74,.0  101 .3  -8181 ,.7  -8106.4  144  39 . 9  19 . 4  76. ,0  107,.0  -8518. 7  -8451.8  -  217"-  Table  A 1. Cont i nue  RUN NO:  INITIAL TEMP. ( O  FINAL TEMP. ( C)  RUN PERIOD (MIN.)  SUPERFICIAL VELOCITY (mm/s)  1 48  39 . 9  1 9. 3  75. 0  112,, 5  -8633. 8  -8552.,  1 52  40.0  1 9. 4  7 1 0.  117,,7  -8735. 8  -8657.,9  1 5b  40.1  1 9. 5  62. 0  1 22,7,  -8710. 7  -8629.,0  1 60  39. 9  1 9. 3  63. 0  1 27,5.  -9120. 9  -9046,, 6  1 64  40.0  1 9. 5  62. 0  1 32, .1  -8656. 5  -8585,, 4  1 68  39.9  I 9. 5  6  1 36, ,5  -8503. 7  -8452,. 5  172  40.1  19 . 6  56. 0  1 36. ,6  -7259. 2  -7184,, 9  1 76  40.2  19 .6  57. 0  140,,9  -7403. 4  -7312,. 6  180  40.2  19 . 5  52. 0  145,, 2  -7627. 2  -7528,.8  184  40.  19 . 6  51 .0  ,2 1 49,  -7672. 3  -7592,.8  188  40.1  19 . 6  50. 0  153,, 2  -7253. 5  -7 172,. 5  1 92  40 .  19 .6  50. 0  158,,9  -7280. 8  -7199 . 0  1 1  1 0.  HEAT STORED BY CAPSULE CONTENTS (kJ)  CORRECTED HEAT STORAGE (kJ)  1  -  Table  RUN NO:  A2. Heat  HEAT IN BY INLET WATER (kJ) •  Balance  218  Results  -  f o r the F l u i d i d z e d  HEAT IN BY PUMP (kJ)  HEAT LOSS (kJ)  SPECIFIC HEAT GAIN (kJ)  Bed Runs  HEAT STORED BY CAPSULE CONTENTS (kJ)  2 1  1 7702. 5  9755.0  331.2  17633.5  9492.9  25  18036 . 3  9754 . 4  375.7  18089.5  9325.5  40  -36643,. 7  10337.6  74.7  -17661.8  -8719:1  44  -37569,. 5  1 1064 . 9  43.0  -17857.2  -8690.4  48  -36536,.8  10337.3  65.5  -17673.7  -8591.2  52  -36238 . 1  9899.4  46.3  -17601 .7  -8783.2  56  -3 6398 . 3  9609. 1  103.6  -18037.2  -8855.5  62  -33788 .0  8735.6  85.5  -17498.0  -7639.9  71  18001 .6  10190.3  385.3  18080. 9  9725.6  75  17545 . 1  9608 . 1  37 5.7  17694.3  9083.2  79  1 7568.7  9317.1  343.5  17702.0  8840.3  83  17394 . 3  9462.4  364 . 1  17701.2  8791.5  87  17410 . 5  9462 . 4  3 11.1  17848.6  8713.2  91  17554 . 5  9317.0  283.3  17757.8  8830.4  95  17698 .0  9171.4  266.8  17851.2.  8751.5  1 00  -35483 . 6  9316.5  62.7  -17591.5  -8638.3  1 04  -35035 . 3  8880.3  68.7  - 17584.6  -8639.1  1 08  -35668 .2  9462.3  66.0  -17683.2  -8588.8  11 2  -35290 . 5  9317.0  78 . 1  -17479.2  -8572.4  11 6  -34632 .9  8734.7  61.4  -1 7387 . 5  -8572.2  1 20  -35439 . 2  9317.4  84.8  -17710.6  -8496.0  1 24  -34629 . 4  9899.3  61.6  -17617.2  -7174.5  1 28  -34224 . 3  9753.6  70.9  -17690.9  -6850.7  1 32  -36412 .0  1 1 063.9  57 . 1  -17720.0  -7685.2  1 36  -36311 .2  10772.9  75.8  -17792.9  -7821.2  -  Table  A2. C o n t i n u e  RUN NO:  HEAT IN BY INLET WATER (kJ)  219  -  HEAT IN BY PUMP (kJ)  HEAT LOSS (kJ) 94 . 1  1 40  -36473. 2  1 0772 . 7  1 44  -37000. 5  )1063.9  1 48  -37061. 6  1 52  SPECIFIC HEAT GAIN (kJ)  HEAT STORED BY CAPSULE CONTENTS (kJ)  -17612.9  -8181 . 7  139.2  -17557.2  -8518 . 7  10918.3  142.0  -17651.5  -8633 .8  -36563. 0  10336.0  12 1.7  -17612.9  -8735 .8  1 56  -35264. 8  9025.8  96. 6  -17624.9  -8710 . 7  1 60  -35801. 8  91?1.4  95.7  -17605.2  -9120 .9  1 64  -35137. 8  9025.8  112.0  -17567.5  -8656 . 5  1 68  -34752. 3  8880.3  98.0  -17466.3  -8503 . 7  172  -32917. 2  8152.5  73 . 2  -17578.6  -7259 . 2  176  -33286. 2  8298.0  75. 1  -17660.0  -7403 . 4  1 80  -32800. 2  7570 . 1  104.3  -1 7707.2  -7627 . 2  184  -32618. 6  7424.7  84.5  -17606.0  -7672 .3  188  -3208 1 . 9  7279.1  61.0  -17610.3 .  -7253 .5  1 92  -32101 . 8  7279 . 1  76. 1  -17618.0  -7280 .8  -  220  -  APPENDIX 4  Computer  Program  Transfer  from  as  a  Rate  Function  of  Heat  the of  which  calculates  Capules  to  Time.  Transfer  Data.  the  the Heat  Rate  of  Transfer  Heat Fluid  c c  -  C C C C C  T H I S I S THE COMPUTER PROGRAM WHICH C A L C U L A T E S THE RATE OF HEAT TRANSFER FROM THE C A P S U L E S TO THE HEAT TRANSFER F L U I D AS A FUNCTION OF T I M E  DIMENSION 1 DIMENSION 1 C C C  DATA  -  ' _ . T T M E ( 3 , 9 9 9 ) , TCR( 3 9 9 9 ) , TEM-P ( 3 , 999 ) , A R ( 3 ) , N l ( 3 ) , TEMPP(3,999), TIMEP(3,999) BTEMP(999), BTIME(999), CTEMP(999), CTIME(999), DHPCM(999) (  INPUT  . WRITE ( 6 , 10) 10 FORMAT (//8X, " RUN NO:79', /8X, RUN PERIOD= 64. MINUTES', /8X, 1 ' S U P E R F I C I A L V E L O C I T Y = 96.1 (mm/s)', ///8X, 'TIME', 5X, 2 'HEAT TRANSFER', /7X, ' ( M i n . ) ' , 8X, 'RATE', /21X, '(kW)', 3 ) 20 READ ( 5 , 3 0 ) IR, 10, I.HC, TFLOW, N, ROOMT, DPRES 30 FORMAT ( 1 3 , I I , I I , F 6 . 1 , 13, F 4 . 1 , F 4 . 1 ) NI(IO) = N READ ( 5 , 4 0 ) (TIME(IO,I),TEMP(IO,I),1=1,N) 40 FORMAT ( 2 F 9 . 3 ) I F ( I O .EQ. 2) GO TO 50 GO TO 2 0 I N T E G R A T I O N OF THE T I M E VERSUS TEMPERATURE DATA 1  C C C  221  50  60 70  AL =-- 1 . AL2 = 1 L = 1 L2 == 1 I = 0 M = 0 IO == I I = I + I F (I ,GT. N I ( 1 ) ) GO TO 130 BTEMP(I) = TEMP(IO,I) BTIME(1) = TIME(IO,I) I F ( T I M E ( 1 0 , 1 ) . L T . A L ) GO TO 70 K = I - 1 TIMD = T I M E ( I 0 , I ) - T I M E ( l O , K ) TED = T E M P ( I O , l ) - T E M P ( I O . K ) RATI = T E D / TIMD DEL = T I M E ( I O , I ) - AL TDE = DEL * RATI BTIME(I) = BTEMP(I ) = IF (L . L T . IA = 1  IB  TDE  =  Q I N T 4 P ( B T I M E , B T E M P , 1 ,1 A , I B )  AR(IO) = AREA L = L + 1  1 AL 90  AL T E M P ( I 0,1) 1) G O T O 8 0  = I  AREA 80  1  =  1 - 1 =  AL  +  IO = 2 M = M + 1 IF (M . G T .  1  NI(2))  GO TO  130  /  -  222  CTIME(M) = T I M E ( I O , M ) CTEMP(M) = T E M P ( l O , M ) IF ( T I M E ( I O , M ) . L T . A L 2 ) GO  MN = M - 1  TO  -  90  TI MD = T I M E ( I O , M ) - T I M E ( l O , M N ) TED = T E M P ( l O , M ) - TEMP(IO,MN) RATI = T E D / TIMD DEL = T I M E ( I 0 , M ) - AL2 , TDE = DEL * RATI C T I M E ( M ) = AL2 CTEMP(M) = T E M P ( I O , M ) - TDE IF ( L 2 . L T . I) GO TO 120 .. IA = I IB = M AREA = Q I N T 4 P ( C T I M E , C T E M P , M , I A , I B ) A R ( I O ) = AREA C C C  AVERAGE  100 C C C  BED TEMPERATURE  TOP = 0 DO 10 0 J = 1 , M KM = J + 1 I F (KM .GT. M) KM = M TOP = TOP + T E M P ( I O , j ) * TN = L2 EVALUATIONS  OF THE TERMS  CALCULATIONS  (TIME(IO,KM) -  IN THE HEAT  TIME(lO,J))  BALANCE  ABEDT = TOP / ( T I M E ( l O , M ) - T I M E ( I O , l ) ) D E L T = ABEDT - ROOMT DTIME = C T I M E ( M ) - C T I M E ( l ) JL = NI(2) DTI = T I M E ( 2 , J L ) - T I M E ( 2 , 1 ) FLOWRA = TFLOW / DTI DTEMP = CTEMP(M) - C T E M P ( 1 ) DELA = A R( 1 ) - A R ( 2 ) ATEMPD = DELA / DTIME HEATS = ATEMPD * FLOWRA * DTIME * 4.186 HEINPU = 8734.4 * DTIME / 6 0 . HELOSS = 2 3 . 6 5 * 1.1 * D E L T * DTIME / 6 0 . SPHEGA = 860.2 * DTEMP D H P C M ( L 2 ) = HEATS + H E I N P U - HELOSS - SPHEGA J K L = L2 - 2 I F ( L 2 . L E . 2) GO TO 120 SHK = ( D H P C M ( J K L ) - D H P C M ( L 2 ) ) / ( 2 . * 6 0 . ) C C  P R I N T I N G OF  RESULTS  C 110 120  130 140  WRITE ( 6 , 1 1 0 ) DTIME, SHK FORMAT ( 8 X , F4 . 0, 8X, F 6 . 4 ) L2 = L2 + 1 AL2 = AL2 + 1 M = M - 1 GO TO 60 GO TO 20 STOP END  EQUATION  -  Table  223  -  A3. H e a t t r a n s f e r r a t e s between t h e c a p s u l e s and t h e h e a t t r a n s f e r f l u i d f o r one m i n u t e t i m e i n t e r v a l s d u r i n d a sample c o o l i n g r u n  RUN NO:50 RUN PERIOD= 66. MINUTES SUPERFICIAL VELOCITY- 123.8 (mm/s)  TIME (Min.)  3 . 4 . 5. 6. 7 . 8 . 9. 10. 11 . 12. 13. 14. 15. 16. 17. 18.  19. 20. 21 . 22. 23. 24. 25. 26. 27 . 28 . 29. 30. 31 . 32. 33. ' 34. 35. 36. 37 . 38 . 39. 40. 41 . 42 . 43. 44. 45. 46. 47. 48.  HEAT TRANSFER RATE (kW) 1.4184 1.6464 1.9402 1.8763 2.2891 2.2295 1.5873 1.5743 1.4357 1.5981 1.8511 1.7988 1.7415 1.4371 1.6147 1.2256 1.2324 3.7847 6.3061 6.6463 6.2213 5.8688 5.3322 4.8097 4 .7500 4.4193 4.2100 4.0882 3.7314 3.5531 3.1732 2.8123 2.5865 2.3821 2.3511 2.1346 2.0939 2.0758 1.9825 1.9889 1.7649 1.5896 1.6286 1.4909 1.1777 1.1756  -  49. 50. 51. 52. 53. 54. 55 . 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66.  224  -  1.0576 1.2149 1.2843 1.0711 0.9174 1.1787 1 . 2547 0.9123 0.8671 0.5710 0.6868 0.7801 0.7993 0.6668 0.6846 0.8086 0.6525 0.7424  T a b l e A4. Heat t r a n s f e r r a t e s between t h e c a p s u l e s and t h e h e a t t r a n s f e r f l u i d f o r one m i n u t e t i m e i n t e r v a l s d u r i n g a sample h e a t i n g run  RUN NO:79 RUN PERIOD= 64. MINUTES SUPERFICIAL VELOCITY= '96.1  TIME (Min.)  3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22.  HEAT  TRANSFER RATE (kW)  2.3363 2.7167 3.1379 2.8487 2.7714 2.8795 2.9453 3.0742 3.0700 3.4124 3.3508 2.8947 3.0048 3.1288 3.0493 2.9468 3.0785 3.0245 3.0369 3.1222  (mm/s)  23. 24. 25. 26. 27 . 28. 29. 30. 31 . 32. 33. 34 . 35. 36. 37.  3.8. 39. 40. 41 . 42. 43. . 44 . 45. 46. 47 . 48. 49. 50. 51 . 52 . 53 . 54 . 55. 56. 57 . 58. 59. 60 . 61 . 62 . 63 . 64 .  2.8840 2.9263 3.2633 3.2703 3.0128 3 .0342' 3.2453 3.2527 3.3193 3.347 1 3.1979 3.1140 3.1046 3.1366 3.2337 3.1962 3.0267 2.9964 2.9852 2.9012 2.7300 2.5209 2.3366 2.0267 1.6828 1 .2909 0.9033 0.8072 0.8502 0.7296 0.5381 0.6200 0.5500 0.3987 0.2211 0 .2353 0.3140 0.1961 0.4366 0.5689 0.4905 0.4490  -  226  -  APPENDIX 5  RAW D A T A :  F I X E D BED STUDIES  TableAS. RUN NO:  Experimental  R e s u l t s f o r t h e F i x e d Bed Runs  INITIAL TEMP. ( c)  FINAL TEMP. ( c)  RUN PERIOD (MIN.)  SUPERFICIAL VELOCITY (mm/s)  1 94  40. 1  19.5  72. 0  59.4  -7767.0  -7683.2  1 98  40. 2  19.6  67 .0  59. 4  -6641.5  -6545.5  202  40.2  19.5  63.0  59.4  -5932.2  -5832.0  206  40.4  19.5  62.0  59. 5  -5678.6  -5541.4  210  40. 1  19.7  61 .0  59.5  -5621.7  -5555.9  212  40.3  19.5  63.0  59.4  -5687.8  -5572.1  214  40. 2  19.7  61.0  59.4  -5475.5  -5386.6  216  40. 1  19.6  62.0  59.4  -5494.5  -54 12.5  HEAT STORED BY CAPSULE CONTENTS (kJ)  CORRECTED HEAT STORAGE (kJ)  T a b l e A6. Heat B a l a n c e R e s u l t s  RUN NO:  HEAT IN BY INLET WATER (kJ)  f o r t h e F i x e d Bed Runs  HEAT IN BY PUMP (kJ)  HEAT LOSS (kJ)  SPECIFIC HEAT GAIN (kJ)  HEAT STORED BY CAPSULE CONTENTS (kJ)  1 94  -35756.0  10482.0  1 30.8  -17637.7  -7767.0  1 98  -33953.2  9754.1  133.4  -17690.9  -6641.5  202  -32697.6  9171.8  122.2  -17715.7  -5932.2  206  -32499.4  9026.1  119.9  -17914.6  -5678.6  210  -31913.1  8880.7  "111.3  -17522.0  - -5621.7  21 2  -32538.5  9171.8  119.2  -17798.0  -5687.8  214  -31881.6  8880.7  118.4  -17643.8  -5475.5  216  -32026.5  9026.0  111.1  -17617.2  -5494.5  -  229  -  APPENDIX 6  RAW D A T A :  REFLUIDIZATION  STUDIES  T a b l e A7. E x p e r i m e n t a l  RUN NO:  R e s u l t s f o r the Recovery  of E f f i c i e n c y  Runs  INITIAL TEMP. ( C)  FINAL TEMP. ( C)  RUN PERIOD (MIN.)  21 8  40. .0  1.9. 5  55.0  122.8  -7110.2  -7042.2  220  39.8  19.5.  63.0  122.7  -7800.3  -7756.0  222  39.9  19.6  61.0  122.7  -8108.8  -8057.5  224  39.9  19.4  62.0  1 22.7  -8032.9  -7967 . 9  226  40.0  19.6  60.0  118.8  -8035.4  -7986.7  SUPERFICIAL VELOCITY (mm/s)  HEAT STORED BY CAPSULE CONTENTS (kJ)  CORRECTED HEAT STORAGE (kJ)  T a b l e A8. Heat B a l a n c e R e s u l t s f o r t h e R e c o v e r y o f E f f i c i e n c y RUN NO:  HEAT IN BY INLET WATER (kJ)  HEAT IN BY PUMP (kJ)  HEAT LOSS (kJ)  SPECIFIC HEAT GAIN (kJ)  Runs  HEAT STORED BY CAPSULE CONTENTS (kJ)  218  -32594.0  8007 . 1  78.7  -17555.4  -7110.2  220  -34353.0  917 1.6  56.0  - 17437. 2  -7800.3  222  -34336.3  8880. 6  111.7  -17458.6  -8108.8  224  -34567.6  9026. 1  37 .4  -17546.0  -8032 . 9  226  -34 184.6  8735.0  24 . 7  -17438.9  -8035.4  -  232  APPENDIX  -  7  COMPUTER PROGRAM TO ANALYZE ROTATING DRUM AND TUBE EXPERIMENTAL  DATA  ROTATING  -  233  -  C C  c c c c  THIS IS A COMPUTER PROGRAM WRITTEN TO ANALYZE THE DRUM AND THE ROTATING TUBE EXPERIMENTAL DATA  DIMENSION C C C  DATA  TIME(900),  ROTATING  TEMP(900), AR(3)  INPUT  10 READ (5,20) IR, IO, N, MOTION, SPEED, WCAP, NCOMP, ELTIME 20 FORMAT (13, I I , 13, 11, F4.1, F5.2, 11, F4.1) IF (IO .GE. 3) GO TO 160 READ (5,30) ( T I M E ( I ) , T E M P ( I ) , I = 1 , N ) 3 0 FORMAT (2F9.3) C C C  INTEGRATION  OF THE TEMPERATURE DATA  IA = 1 IB = N AREA = QINT4P(TIME,TEMP,N,IA,IB) AR(IO) = AREA IF (IO .EQ. 2) GO TO 40 GO TO 10 40 DIFAR = AR(2) - AR(1) UA = 0.2376 HEATLO = UA * DI FAR T I N I T = (TEMPI 1) + TEMP(2) + T E M P ( 3 ) ) / 3. JN = N - 2 JL = N - 1 TFINAL = (TEMP(JN) + TEMP(JL) + TEMP(N)) / 3. SYSHC = 443.0 DHC =. SYSHC * (TINIT - TFINAL) HGBC = DHC - HEATLO HGBCC = HGBC - 1.428 * 8. * 0.46 * (TFINAL - 20.0) WPCM = WCAP - 1.428 * 8.0 FRW =0.0 FRSS = 0.0 IF (NCOMP .EQ. 1) GO TO 50 IF (NCOMP .EQ. 2) GO TO 60 IF (NCOMP .EQ. 3) GO TO 7 0 IF (NCOMP .EQ. 4) GO TO 80 IF (NCOMP .EQ. 5) GO TO 90 STOP 50. FRSS = 0.25 SONWEF = 217.77 GO TO 100 60 FRSS = 0 . 1 5 SONWEF = 2 4 5.65 GO TO 100 70 FRSS = 0 . 0 5 SONWEF = 273.52 GO TO 100 80 FRW =0.10 SONWEF = 2 53.75 GO TO 100 90 SONWEF = 287.46 100 TC = 20.0 TH = TFINAL WEIGHT = WPCM  -  234 -  PERSS = ((FRSS*100.) + (1 - 0.04 - FRSS - FRW)*44.1) / 0.96 PERH20 = 100. - PERSS DENM = 0.99716 + 9.8552E-3 * PERSS - 2.7614E-5 * PERSS ** 2 + 9. 1864E-7 * PERSS ** 3 DENPCM = 1.E5 / (96./DENM + 4./1.7269) C C C  HEAT STORAGE CAPACITY CALCULATIONS SOL = 15.2 IF (PERSS ..GE. SOL) GO TO 1 1 0 PEGS = (PERSS/44.1) * 100. PCRY = 0.0 PWA = 100: - PEGS PANSS = 0.0 HABWA = 0.99908 * (TH - TC) * PWA HABGS = 0.79 * (TH - TC) * PEGS i THS =.HABWA + HABGS GO TO 140 110 IF (PERSS .GE. 33.38) GO TO 120 PANSS = 0. EFFSS = (PERSS - SOL) / 2. + SOL PCRY = 100. * ( 1 . - (44.1 - PERSS)/(44.1 - S O L ) ) TEFF = -5.4292'+ 2.4945 * EFFSS - 6.528E-2 * EFFSS ** 2 + 7.2547E14 * EFFSS ** 3 PEGS = (PERSS/44.1) * 100. PWA = 1 0 0 . - PEGS HABWA = 0.99908 * (TH - TC) * PWA HABGS = (PEGS - PCRY) * 0.79 * (TH - TC) + PCRY * 0.79 * (TH 1TEFF).+ PCRY * 0.42 * (TEFF - TC) HPHCH = PCRY * 60. THS = HABWA + HABGS + HPHCH GO TO 140 120 I F (PERSS .GE. 44.1) GO TO 130 PANSS = 0. PCRY = 100. * ( 1 . - (44.1 - PERSS)/(44.1 - S O L ) ) PEGS =.(PERSS/44.1) * 100. PWA = 100. - PEGS HABWA = 0.99908 * (TH - TC) * PWA HABGS = (PEGS - PCRY) * 0.79 * (TH - TC) + PCRY * 0.79 * (TH - 32. 14) + PCRY * 0.42 * (32.4 - TC) HPHCH = PCRY * 60. THS = HABWA + HABGS,.+ HPHCH GO TO 140 130 PEGS .= 100. .* (100.. - PERSS) / 55.9 PCRY = 100. PANSS = 1 0 0 . - PEGS PWA = 0 . HABGS = PEGS * 0.79 * (TH - 32.4) + PEGS * 0.42 * (32.4 - TC) HPHCH = PEGS * 60. HABSS .= PANSS * 0 . 23 1 * (TH - TC) THS = HABGS + HABSS + HPHCH 140 SONWE = (THS*0.96 + 4.*0.385*(TH - T C ) ) * 4.186 / 100. CORREC = SONWEF - SONWE HGB = ((HGBCC*4.186/WEIGHT) + CORREC) THECA = SONWEF PERST = (HGB*100.) / THECA PERGS = (HGB*100.) / 298.093 HSCVOL = DENPCM * HGB / 1000.  C C  PRINTING THE RESULTS  -  235  -  WRITE (6,150) PERSS, SPEED, DENPCM, HGB, HSCVOL, PERST 150 FORMAT (4X, F 4 . 1 , 4X, F 4 . 1 , 4X, F5.0, 5X, F7.2, 7X, F 7 . 1 F 5 . 2 , /) 160 STOP END  -  236  -  APPENDIX 8  I N I T I A L NUCLEATION AND C R Y S T A L L I Z A T I O N TEMPERATURES I N CAPSULES WITH DIFFERENT COMPOSITIONS  -  Table  (%  A9.  237  -  I n i t i a l n u c l e a t i o n and c r y s t a l l i z a t i o n t e m p e r a t u r e s in c a p s u l e s w i t h d i f f e r e n t c o m p o s i t i o n s w h i l e c o o l e d i n 25 water bath. The c a p s u l e s were m i x e d as e x p l a i n e d i n Section 6.3. The c o m p o s i t i o n s g i v e n as w e i g h t percent sodium s u l f a t e , r e f e r to T a b l e 11, column 5.  Composition  Nucleation  sodium  Temperature  Temperature  (C)  (C)  25.9  31.3  39.5  44.1  sulfate)  25.9  31.2  25.8  31.3  27.4 27.6  31.7 31.8 31.8  27.2 .47.0  52.8  58.7  C r y s t a l 1i  26.5 26.9 26.6  31.7 31.7 31.6  26.8 26.8  31.6 31.6  26.6  31.3  26.9 27.0 26.8  31.6 31.4 31.7  C  zation  -  238  APPENDIX  -  9  COMPUTER PROGRAM TO CALCULATE THEORETICAL STORAGE CAPACITY OF SODIUM SULFATE-MATER  HEAT  MIXTURES  -  c c c c c c c  239 -  PROGRAM TO CALCULATE THEORETICAL HEAT STORAGE CAPACITY OF SODIUM SULFATE - WATER MIXTURES AT DIFFERENT CONCENTRATIONS WITH OR WITHOUT FOUR WEIGHT PERCENT BORAX IN THE MIXTURE  SPECIFICATION OF THE I N I T I A L AND FINAL CONDITIONS  PERSS = 0 . 0 AINC = 0.1 SOL = 15.25 TH = 40. TC = 20. 10 I F (PERSS ,.GT. 100.) GO TO 70 PERH20 = 100. - PERSS C DENSITY CALCULATIONS DENM = 1000. * (0.99716 + 9.8552E-3*PERSS - 2.7614E-5*PERSS**2. + 19.864E-7*PERSS**3.) DENPCM = 100. / (96./DENM + 4 . / 1 7 2 6 . 9 ) C HEAT STORAGE CAPACITY CALCULATIONS C IF (PERSS .GE. SOL) GO TO 2 0 PEGS = (PERSS/44.1) * 100. PCRY = 0.0 PWA = 100. - PEGS PANSS = 0 . 0 HABWA = 0.99908 * (TH - TC) * PWA HABGS = 0.79 * (TH - TC) * PEGS THS = HABWA + HABGS GO TO 50 20 I F (PERSS .GE. 33.4) GO TO 30 PANSS = 0. EFFSS = (PERSS - SOL) / 2. + SOL TEFF = -5.5492 + 2 . 4 9 4 5 * E F F S S - 6.528E-2 * EFFSS ** 2. + 7. 12547E-4 * EFFSS ** 3. PCRY = 100. * ( 1 . - (44.1 - PERSS)/(44.1 - S O L ) ) PEGS = (PERSS/44'. 1 ) * 100. PWA = 100. - PEGS HABWA = 0.99908 * (TH - TC) * PWA HABGS = (PEGS - PCRY) * 0.79 * (TH - TC) + PCRY * 0.79 * (TH 1TEFF) + PCRY * 0.42 * (TEFF - TC) HPHCH = PCRY * 60. THS = HABWA + HABGS + HPHCH GO TO 50 30 I F (PERSS .GE. 44.1) GO TO 40 PANSS = 0 . PCRY = 100. * ( 1 . - (44.1 - PERSS)/(44.1 - S O L ) ) PCRYIN = 100. * (PERSS - 33.4) / (44.1 - 33.4) PCRYFI = PCRY - PCRYIN EFFSS = (33.4 - S O L ) / 2. + SOL TEFF = -5.5492 + 2.4945 * EFFSS - 6.528E-2 * EFFSS ** 2. + 7. 12547E-4 * EFFSS ** 3. PEGS = (PERSS/44.1) * 100.. PWA = 100. - PEGS HABWA = 0 . 9 9 9 0 8 * (TH - TC) * PWA HABGS = (PEGS - PCRY) * 0.79 * (TH_- TC) + PCRYIN * ( 0 . 7 9 * ( T H 132.4) + 0.42*(32.4 - T C ) ) + PCRYFI * ( 0 . 7 9 * ( T H - T E F F ) + 0.42*( 2TEFF - T O ) HPHCH = PCRY * 60. THS. = HABWA + HABGS + HPHCH GO TO 50  -  240  -  40  PEGS = 100. * (100. - PERSS) / 55.9 PCRY = 100. PANSS = 100. - PEGS PWA = 0 . HABGS = PEGS * 0.79 * (TH - 32.4) + PEGS * 0.42 * (32.4 - TC) HPHCH = PEGS * 60. HABSS = PANSS * 0.231 * (TH - TC) THS = HABGS + HABSS + HPHCH 50 SONWE = THS * 0.96 + 4. * 0.385 * (TH - TC)  C C THEORETICAL HEAT STORAGE CAPACITY OF PHAHSE CHANGE MATERIAL AS C kJ/kg . C HSCWE = SONWE * 4.186 / 100. C C THEORETICAL HEAT STORAGE CAPACITY OF PHASE CHANGE MATERIAL AS C kJ/CUBIC METER. C HSCVOL = DENPCM * HSCWE C C PRINTING OF RESULTS C WRITE (6,60) PERSS, HSCWE, HSCVOL 60 FORMAT ( F 6 . 2 , 3X, F8.2, 3X, F9.2) PERSS = PERSS + AINC GO TO 10 70 STOP END  -  241  -  APPENDIX  10  MATERIAL AND U T I L I T Y COST DATA  -  242  -  RAW MATERIAL COSTS Price (1984 C a n a d i a n  Item 76  mm-Sch.  102  40  mm S e n .  PVC  40  PVC  pipe pipe  $)  Source  $7.2/m  Scepter  1984  $10.2/m  Scepter  1984  0.35  m OD  PVC  pipe  $48/m  Scepter  1984  0.61  m OD  PVC  pipe  $145/m  Scepter  1984  1.22  m OD  PVC  pipe  $350*/m  Scepter  1984  12.7  mm t h i c k  76  nm S c h .  102  40  mm S c h .  to  15  plate  $84/m2  Cadillac  PVC  90°  $8.7  Scepter  1984  $5.9  Scepter  1984  $1,030  Pumps  & Power  1984  $1,103  Pumps  & Power  1984  40  Centrifugal (10  PVC  PVC  elbow  90°  elbow  1984  Pumps  m water  head)  1  HP  (0.7457  2  HP  (1.5  3  HP  (2.24  kW)  $1,361  Pumps  & Power  1984  5  HP  (3.73  kW)  $1,515  Pumps  & Power  1984  7.5  HP  kW)  kW)  (5.6  kW)  $1,831  Pumps  & Power  1984  (7.46  kW)  $2,253  Pumps  & Power  1984  $12/m2  Fleck  Bros.  $2.9/m  Wilkinson  $25/1000  Euro-Matic  10  HP  38  mm t h i c k  (humidity 32  nm x  25  mm OD  fiberglass  barrier  32  on  mn s q u a r e  hollow  insulation  one steel  1984  side) tube  polypropylene  1984 1982  spheres Phase  change  •Predicted  by  material the  company;  See it  was  not  Table  1  in  the  text  available  in  the  stock  U T I L I T Y COSTS Electricity  6.19  cents/kW-hr  ( f o r t h e f i r s t 550 kW-hr) 4.31 cents/kW-hr (for the rest)  B.C.  Hydro  1984  -  243  APPENDIX  -  11  COMPUTER PROGRAM TO PERFORM ECONOMIC ANALYSIS  CALCULATIONS  FOR THE F L U I D I Z E D BED HEAT STORAGE SYSTEM  -  C C C  c c c c c c  244  -  THIS PROGRAM PERFORMS THE ECONOMIC ANALYSIS CALCULATIONS FOR THE FLUIDIZED BED HEAT STORAGE SYSTEM STUDIED IN THIS PROJECT. SEE SECTION 9.1 >  INPUT OF CONDITIONS  DATA RELATING THE SIZE AND OF THE SYSTEM: SI UNITS  OPERATION  DIMENSION VOLUME(100) COSTMJ(100) GCOSMJ(100) DIMENSION ZPRICE(100) GPRICE(100) THSC(100) DIMENSION T O T A L ( 1 0 0 ) , GTOTAL(100), TOPERA(100) GEMORT(100) DIMENSION YEMORT(100) D( 100) GYCOST(100) DIMENSION TYCOST(100) REAL PP DO 10 I = 1 , 22 D ( I ) = 0.15 + 0. i ZL = 2. 5 UO = 0. 1 1 5 ZNC = 0.6 ZLMF • •= ( Z L * ( 1 1 .44*UO**0.42)) / 0.565 ZNOFC = 150. TEMP •• = 40. DELTI = 2. ZINTE = 0.1  c c c  I N I T I A L COST OF THE SYSTEM PP = 1.12 * UO * D ( I ) ** 2 * (14.31*U0**2*ZL/D(I) + 592*UO**2 1.9*ZLMF + 1.47) COLMAT = ( 3 6 5 . + (ZL + 0.5)*270.) * D ( I ) ** 1.4 PIPE = ( 2 0 0 . + ZL*70.) * D ( I ) ** 1.4 PUMP = 800. + 215. * PP * 1.2 CONTRO = 3 5 0 . FRAME = 50. * D ( I ) * ZL ZINSUL = 125. * ZL * D( I ) CAPSUL = 1.44E3 * D ( l ) ** 2 * ZLMF PCM = 70.3 * D ( I ) ** 2 * ZLMF ZLABOU = 500. * D ( I ) ** 0.5 T O T A L ( I ) = COLMAT + PIPE + PUMP + CONTRO + FRAME + ZINSUL + CAPSUL + PCM + ZLABOU G T O T A L ( I ) = TOTAL(I ) * 1.2  c c c  OPERATION  COST  ENERGY = 1.2 * PP * DELTI * ZNOFC * 0.0525 ZMAINT = 20. * 4. TOPERA(I) = ENERGY + ZMAINT  c c c  ENERGY STORAGE CAPACITY HSCAP = ( 5 7 6 2 0 . * Z L M F * D ( I ) * * 2 ) * (1.4 + 0.02873*TEMP) * ZNC HSSYS = 1.139 * ZL * D ( l ) ** 2 * 4178. * (TEMP - 20.) HEINPU = 1.2 * PP * 0.3 * DELTI * 3600. T H S C ( I ) = (HSCAP + HSSYS + HEINPU) * ZNOFC * 1.E-3  c c c  PROFITABLITY ANALYSIS AND  PRINT OF THE RESULTS  YEMORT(I) = ( T O T A L ( I ) * ZINTE/(1 - (1 + Z I N T E ) * * ( - 2 5 ) ) ) GEMORT(I) = ( G T O T A L ( I ) * Z I N T E / ( 1 - (1 + Z I N T E ) * * ( - 2 5 ) ) )  +  -  245  -  G P R I C E ( I ) = (GEMORT(I) + T O P E R A ( I ) ) / . ( T H S C ( I ) * 0 . 0 1 ) Z P R I C E ( I ) = (YEMORT(I) + T O P E R A ( I ) ) / ( T H S C ( I ) * 0 . 0 1 ) VOLUME(I) = ZL * 3.1416 * ( D ( I ) / 2 . ) ** 2. COSTMJ(I) = T O T A L ( I ) / ((HSCAP + HSSYS)* 1 .E-3) G C O S M J ( I ) = G T O T A L ( I ) / ((HSCAP + HSSYS)* 1 . E-3) T Y C O S T ( I ) = T O P E R A ( I ) + YEMORT(I) GYCOST(I) = TOPERA(I) + GEMORT(I) 10' CONTINUE WRITE (6,20) (D(L) ,ZPRICE(L) ,L=1 ,22) WRITE (6,20) ( D ( L ) , G P R I C E ( L ) , L = 1 , 2 2 ) 20 FORMAT (3X, 2F16.5) STOP END  

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