Numerical simulation of the glowing combustion of moist wood by means of a front-based model

摘要

A model is presented for the glowing combustion of thick moist wood samples exposed to fire-level heat fluxes. It includes the description of all the relevant heat and mass transfer phenomena and assumes that the thermally controlled drying, the finite-rate kinetics pyrolysis, and the mixed kinetic-diffusive controlled combustion take place at infinitely thin fronts. The solution, based on the integral method, shows that apart from short initial and final transients, an ablation regime is established given high external heat fluxes and/or high moisture contents, high wood density and thermal conductivity, and low char density. Drying, pyrolysis, and combustion take place simultaneously along a constant-thickness layer that propagates at a constant rate (the same for the three fronts) towards the cold sample side. Good quantitative agreement is obtained between model predictions and measurements.