A Three dimensional computational fluid dynamics model for pyrolysis of thermally thick biomass particles

Abstract

The solid biomass especially the wood has been used as a source of energy for centuries in the world. However, the present world has started giving it a more value not because it is known for a longer time. But as a renewable energy source it lessens the fossil fuel depletion and be a part of climate change mitigation. Conversion of biomass to energy is done through several methods such as bio-chemical conversion and thermo-chemical conversion. In the present work, the drying and pyrolysis process of a thermally thick single wood particle has been investigated. A novel approach has been introduced considering the two-phase gas and solid inside the particle are not in thermal equilibrium. Mathematical relationship was built to determine distinct temperatures at the boundaries of solid and gas. An unsteady threedimensional (3D) model is developed and simulated in Computational Fluid Dynamics (CFD)

framework.

The Euler-Euler approach for modeling of single biomass particle has been succeeded with the help of C++ CFD toolbox in OpenFOAM. The 3D model can simulate the thermochemical conversion process of different particle types, particularly for different shapes to examine the spatial variations during the process. The model was validated by comparing the simulation results with data obtained by experiments conducted using a single particle reactor. Further, the model was applied in torrefaction of single wood particle then expanded to thermochemical conversion in packed bed.