Effect of Release of Combustible Volatile Components from the Disperse Phase on Self-Ignition of a Gas–Particle Mixture

The paper presents a physicomathematical model for self-ignition of a gas-particle mixture whose disperse phase reacts heterogeneously with the gas-phase oxidizer and releases volatile components, which also react with the gas-phase oxidizer. The model takes into account the effect of Stefan flow of the volatiles and gaseous products of the heterogeneous reaction on the heat and mass transfer between the particles and the gas phase. Four regimes of self-ignition of the gas-particle mixture were established: ignition of individual particles (without interaction) ignition due to the heterogeneous reaction during self-ignition of a particle aggregate; self-ignition due to heat release from the gas-phase reaction of the volatiles released; self-ignition under the mutual effect of the gas-phase and heterogeneous reactions. The paper proposes a method for determining the parameter of the disperse phase in which different self-ignition regimes are observed. Analytical formulas for the self-ignition delay period of the gas-particle mixture are derived for each regime and compared with numerical results. The effect of Stefan flow on the self-ignition of the gas-particle mixture is analyzed. Key words: gas–particle mixture, volatiles, Stefan flow, self-ignition.