Modelling thermal behaviour of a single solid particle pyrolysing in a hot gas flow

Wardach-Święcicka, Izabela; Kardaś, Dariusz

doi:10.1016/j.energy.2021.119802

Cited by 10 publications

(1 citation statement)

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“…While Di Blasi concludes that anisotropic permeability effects are minimal for particles in this regime, these results with high L / D show the contrary. Wardach-Świȩcicka and Kardaś noticed in their simulations of wood that the advection of gases leaving wood particles during pyrolysis greatly reduces the particle heating rate compared with ignoring the critical phase change phenomenon. However, this work did not incorporate anisotropic pore structure via a permeability tensor.…”

Section: Resultsmentioning

confidence: 99%

Impacts of Anisotropic Porosity on Heat Transfer and Off-Gassing during Biomass Pyrolysis

et al. 2021

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The pore structure of biogenic materials imbues the ability to deliver water and nutrients through a plant from root to leaf. This anisotropic pore granularity can also play a significant role in processes such as biomass pyrolysis that are used to convert these materials into useful products like heat, fuel, and chemicals. Evolutions in modeling of biomass pyrolysis as well as imaging of pore structures allow for further insights into the concerted physics of phase change-induced off-gassing, heat transfer, and chemical reactions. In this work, we report a biomass single particle model which incorporates these physics to explore the impact of implementing anisotropic permeability and diffusivity on the conversion time and yields predicted for pyrolysis of oak and pine particles. Simulation results showed that anisotropic permeability impacts predicted conversion time more than 2 times when the Biot number is above 0.1 and pyrolysis numbers (Py 1 , Py 2 ) are less than 20. Pore structure significantly impacts predicted pyrolytic conversion time (>8 times) when the Biot number is above 1 and the pyrolysis number is below 1, i.e., the "conduction controlled" regime. Therefore, these nondimensional numbers reflect that when internal heat conduction limits pyrolysis performance, internal pyrolysis off-gassing further retards effective heat transfer rates as a closely coupled phenomenon. Overall, this study highlights physically meaningful opportunities to improve particle-scale pyrolysis modeling and experimental validation relevant to a variety of feedstock identities and preparations, guiding the future design of pyrolyzers for efficient biomass conversion.

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Section: Resultsmentioning

confidence: 99%