Effect of radiant heat transfer on the minimum spark–ignition energy of gas suspensions

A mathematical model of spark ignition of a gas suspension is constructed on the basis of a two–temperature thermal diffusion model of gas–suspension combustion and the radiant heat transfer is modeled in a diffusion approximation. The dependences of the minimum ignition energy on the parameters which describe the disperse phase and the domain of the disperse–phase parameters in which the radiant heat transfer affects greatly the minimum spark–ignition energy is determined by solving the problem numerically. The analytical formula that was obtained for determination of the critical spark–ignition energy of the gas suspension and that takes into account the radiant heat transfer in the gas suspension gives values different from numerical results by not more than 30% in a broad range of determining parameters of the problem. The theoretically obtained values of the minimum spark–ignition energy of a gas suspension of coal dust agree satisfactorily with experimental data.