Modeling pyrolysis-induced microstructural changes in biomass: A cellular automata approach

Abstract

Lignocellulosic biomass is a chemically and morphologically heterogeneous material. This heterogeneity is in part responsible for the vast number of thermal decomposition products seen in pyrolysis events. While modeling of biomass pyrolysis has been a subject of much research in past years at length-scales ranging from macro to molecular, the majority of these works have focused on a range of continuum-based approaches. Though effective at capturing global outcomes, these approaches are less tractable as frameworks for capturing microstructural effects and upscaling molecular information. This work demonstrates the use of kinetic-cellular automata (k-CA) as an alternative platform for the modeling and simulation of biomass pyrolysis. Asides from being effective at capturing transport and chemical processes in highly heterogeneous system, k-CA is capable of modeling microstructural changes that occur as a result of chemical and physical transformations. A number of benchmark trials demonstrated the convergence of the k-CA to global continuum outcomes. Application of the k-CA to actual two-dimensional (2-D) biomass microstructures show promise for this platform as an intermediate length-scale tool capable of predicting char morphologies that mimic experimental outcomes at length-scales between those of atomistic events and those governed by macroscopically averaged approaches.