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Nabilou, Hamoun

University of British Columbia

Studying single-particle combustion is essential for understanding the fundamental behavior of solid particles, whether used as energy carriers or fuel additives. Compared to biomass and coal, relatively small amounts of volatile matter, ash, and moisture are available in hydrochar, which makes this a desirable fuel for energy applications. Additionally, while graphene oxide-based particles have proven efficacy as fuel additives, their combustion behavior as particles remains unknown. In the present study, the flame characteristics of single micron-sized carbon-rich hydrochar particles are studied for the first time and compared against those of coal and arbutus bark (the wood feedstock from which hydrochar is derived). Moreover, the combustion behavior of graphene oxide and iron-decorated graphene oxide are examined for the first time. Arbutus bark undergoes hydrothermal carbonization to produce hydrochar. Iron nanoparticles are added to octadecylamine-functionalized graphene oxide. A burner is used to combust the particles in the products of a premixed flat flame. Five oxygen mole fractions of the combustion products (12% to 38%) are examined at a fixed adiabatic flame temperature of 1850 K. Simultaneous shadowgraphy and luminosity imaging are conducted to study the combustion of the particles and measure the ignition delay and combustion time. Arbutus bark particles ignite heterogeneously at high oxygen mole fractions, while hydrochar and coal particles feature an overlapping two-stage combustion process. Graphene oxide burns similarly to hydrochar, while iron-decorated graphene oxide disintegrates violently upon ignition. At low oxygen mole fractions, the arbutus bark particles burn following a sequential two-stage process, while hydrochar and coal demonstrate overlapping combustion stages. Iron-decorated graphene oxide exhibits fragmentation behavior for all conditions. Hydrothermal carbonization of arbutus bark creates pores on the hydrochar particles which are hypothesized to cause fragmentation, rocketing, and fast particle ignition. This carbonization also increases hydrochar combustion time, but it still burns faster than coal. Generally, the results show that hydrothermal carbonization can upgrade biomass into a more energy-dense fuel with improved combustion characteristics, making this net-zero fuel suitable for thermal energy applications. Decorating graphene oxide with iron decreases the ignition delay and significantly increased the burning rate, which are desirable characteristics of a fuel additive.

Text

2024-09-19

Attribution-NonCommercial-ShareAlike 4.0 International

http://hdl.handle.net/2429/89266

Mechanical Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-sa/4.0/