Critical autoignition conditions for arbitrary reaction order

In this paper, the theoretical analysis of the critical autoignition conditions for exothermically reacting systems at any value of the reaction order was conducted. The calculated and approximate analytical dependencies for the relationship between the parameters at the ignition limit were obtained. On the basis of the obtained diagrams of critical parameters, the conditions of thermal explosion (TE) degeneration for reactions of arbitrary order were determined. It was established that the existing theory of TE gives the correct estimates of ignition temperatures for a given condition of exothermic reaction realization (heat transfer coefficient, specific surface area, initial concentration). However, the theory gives unsatisfactory predictions for the mentioned critical TE conditions at a given ambient temperature. Moreover, the classical theory cannot be applied in the intermediate case when the effect of reactant consumption is already significant but the reaction still proceeds with all the signs of a TE.