A biomass pyrolysis sub-model for CFD applications

Abstract

The complex reactions of biomass pyrolysis and the evolution of different volatile species can be well represented by a Distributed Activation Energy Model (DAEM). The incorporation of this model in a comprehensive Computational Fluid Dynamic model is computationally expensive because of the requirement for multiple integrations for each computation cell at every time step. In this work, the integrals have been mathematically expressed in closed forms so that DAEM can be incorporated more efficiently in a CFD code. A computer program was developed to solve for the yield and rate of evolution of individual pyrolysis products with given kinetic parameters under any given heating conditions. The model requires kinetic parameters as inputs which may be obtained from TG–FTIR or TG–MS analysis of the sample. The results are presented for a number of pyrolysis products from cellulose, charcoal and a tobacco sample and compared with the experimental data. The agreement between the model prediction and the data is generally good; further improvement may be achieved by a small adjustment of the activation energy and/or the standard deviation.