On Radiative Transfer and Gray Body Parameter for Partially Transparent Media

We obtained a solution to radiative heat transfer equations, which describes a multi-layer gray semi-transparent medium in terms of an opaque body. It is shown that the thermal disturbance between the layers of a medium qualitatively changes its optical properties. We introduced a gray body parameter, which allowed us to describe multilayer gray semi-transparent media with low thermal conductivity. We propose a method for calculating heat transfer by thermal radiation in a gray semi-transparent medium and present the results of radiative heat transfer calculations for screen-vacuum and powder insulation materials as examples of such media.