Self-ignition of dust cloud in a hot gas

Abstract

A dust cloud autoignition in a hot gas is investigated based on the thermal explosion theory. A mathematical model that contains the energy equations for both particle and gas is used. The critical ignition conditions using the different forms of criticality in different planes of the solution have been presented analytically for both steady-state and transient conditions. The convection and radiation heat losses are used in this work. The critical conditions have been presented in mathematical expressions. A direct integration of the governing equations of the problem using the Runga–Kutta method of a high order for different planes is presented. The analysis showed that the critical ignition temperatures and ignition time values of the convection and radiation heat loss case are lower than those obtained for the case of convection heat loss only. The effect of ambient temperature, gas temperature, dimensionless characteristic parameters, and initial particle temperature on the critical ignition conditions is investigated. It was found that the ignition delay time, τ*, increases with decreasing gas temperature and increasing ambient temperature, θa.