Properties of solutions of a complex heat transfer model

A nonstationary complex heat transfer model including the heat equation and the nonstationary $P_1$ approximation of the radiative transfer equation is considered. The applicability of the steady-state equation for the radiative intensity to modelling of the complex heat transfer process is studied. It is shown that for large values of the parameter of speed of light the radiative intensity field comes close to the solution of the steady-state equation in a short time.