Numerical Predictions of Conditions for Ignition of a Combustible Gas by a Hot, Inert Particle

Abstract

Numerical predictions are made of the radial and temporal variation of species concentration and temperature in a combustible gas around a hot, inert, spherical particle. The governing equations are integrated in dimensionless form, and ten dimensionless parameters are found to govern the solution. Five gas species were modeled: fuel, oxidizer, water, carbon dioxide, and nitrogen. Predictions are made of the critical particle diameters and temperatures above which a propane/air mixture is ignited by a particle which has the density and specific heat of aluminum. From the results of the model and from experimental results cited in the literature, it is argued that an aluminum particle formed by abrasion must be larger than 800 μm in diameter to ignite a stoichiometric propane/air mixture.