Modeling study on the pyrolysis kinetics of wood composite in the thermally thin regime: The role of heating rates and thermal gradients

Abstract

Pyrolysis of wood composites is a complex process involving reactions with its primary condensed components: cellulose, hemicellulose, and lignin. Thermogravimetric Analysis, within the thermally thin regime, is extensively employed to deduce the kinetics of wood pyrolysis. However, the correlation between heating rates and the pyrolysis kinetics of each component remains unclear, raising concerns about the applicability of these rates in estimating kinetics under varying heating conditions. This paper focuses on examining the influence of heating rate and thermal gradients on the pyrolysis kinetics of wood composite components through a modeling study. The impact on kinetic parameters is analyzed using various chemical mechanisms. These parameters are determined using a model fitting method, which extracts a unique set of kinetics for each heating condition. The study reveals that the heating process interacts significantly with the overall pyrolysis process, and each thermal decomposition reaction of the condensed components is differently influenced by this process. The pyrolysis reaction rate and final mass fraction of the different components vary under distinct heating rates. Notably, higher heating rates tend to shift reactions to higher temperatures, and the interaction between thermal processes and pyrolysis reactions intensifies at increased global heating rates. This paper offers significant insights and considerations for simulating the thermal decomposition of wood on a larger scale.