Extinction in solid fuel combustion: Part II Detailed model

The output of this work is presented in two parts: part I uses simple kinetics and constant thermal transfer properties and the current part II uses detailed kinetics and varying thermal transfer properties in order to demonstrate that conclusions from the simplified model are still valid. Here we extend the study of part I to verify the applicability of the extinction criterion proposed in Part I using detailed numerical modeling for methane–air combustion in a counterflow diffusion flame configuration. For this purpose, heat flux curves are analyzed with two levels of complexity in chemistry namely, one-step, second-order Arrhenius kinetics and the detailed GRI 1.2 methane combustion mechanism, using a detailed transport model. The effects of radiation and chemical agents (not examined in Part I) added to the oxidant side are also examined. The proposed criterion is found to be applicable over a sufficiently wide range of conditions. Analysis of all the above data demonstrates the applicability of a generalized criterion along with its limitations. Finally, a methodology is proposed for determining the limits of solid fuel extinction from a limited number of experiments.

► An empirical and analytical criterion for extinction is numerically extended and validated.
► Gaseous effects are separated from solid pyrolysis.
► Part I uses simple kinetics and constant thermal transfer properties.
► Part II uses detailed kinetics, varying thermal transfer properties, flame radiation feedback.
► Mass flux for extinction includes effects of Damkohler number.