UBC Theses and Dissertations
End effects in packed beds Clark, Craig
Results are reported of steady-state heat transfer studies on various beds of 0.7-inch diameter porous spheres packed in simple cubic configuration, in which the simultaneous transfer of mass and heat occurs between the surface of these spheres and an air stream. The thermal wall effect, which is caused by the participation of the packing container walls in the heat transfer process, was investigated for seven different beds of spheres. The serious effect associated with brass walls was rendered almost insignificant by the use of perspex packing containers. The thermal end effects associated with air flow through a two-layer perspex-walled assemblage were practically eliminated by the addition of three inert layers at the bed entrance and two at the exit. Part of the apparent reduction in the heat transfer factor with the addition of inert layers to the shallow bed was attributed to a decrease in driving force caused by the development of perfect void-cell mixing within the bed. The residual difference in jH between the unguarded and guarded forms of the shallow bed was attributed to a decrease in the coefficient of heat transfer brought about by the removal of the sudden contraction and expansion of the air from the active portion of the bed.
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