Oxidation of isolated porous carbon particles: Comprehensive numerical model

Abstract

A general mathematical formulation and a numerical solution approach are developed to model the oxidation of an isolated porous carbon particle in a quiescent atmosphere under quasi-steady conditions. A key element of the approach developed is the ability to decouple the internal surface area effects from the surface kinetic rates. The governing equations are integrated numerically from the centre of the particle to the edge of the gas-phase thermal mixing layer, with a novel transition layer introduced at the particle external surface. The numerical approach developed is then applied to a range of particle sizes and porosities in an enriched oxidizing environment. The existence of limiting combustion regime as a function of particle size, porosity, and ambient oxygen mole fraction is explored based on the model developed. Comparisons of the predicted particle mass burning rate and surface temperature with recent experiments, as well as the limiting or extinction conditions, are also presented.