Heat and Mass Transfer During Piloted Ignition of Wood

This paper presents the results of an experimental and theoretical study of the heat and mass transfer processes that occur during piloted ignition of wood. The main objective is to present an engineering solution to the piloted ignition problem for wood exposed in a bench-scale piloted ignition test. A detailed numerical model was used to analyse the data. A number of ignition criteria were examined, however, it was found that a piloted ignition criterion based on surface temperature is quite adequate for engineering analysis. Based on this finding, an approximate model was developed which unlike other similar models takes into account the variation of the ignition temperature with external heat flux. The approximate model was then used for correlation of experimental data and derivation of key ignition parameters, such as the critical irradiance, q"_cr, the ignition temperature, T_jg, and the critical mass flux, m"_cr.