Effect of the phase transition on the ignition process

A direct relation in the form of a first-order differential equation is obtained between the phase-transformation depth (phase-boundary position) and the Frank-Kamenetskii parameter characterizing the intensity of chemical heat release. As a particular case, this equation yields a solution of the problem obtained previously for cylindrical and plane-parallel reactors. The presence of a stable intermediate position of the interphase boundary is generalized to symmetric regions of an arbitrary (even fractional) dimension, which appears to have some physical meaning.