ABSTRACT
Heat transfer by combined radiation and conduction through thermal insulation is treated. A numerical solution based on a comprehensive theoretical study is presented. We paid particular attention to high temperature applications. We focused on the effect of variations of the material refractive index with temperature in order to obtain accurate results. We then studied the degradation of thermal properties with temperature. The strong non-gray behavior of glassfiber-like materials, along with the shift of the blackbody emission spectrum towards shorter wavelengths, leads to a modification of the spectral radiative flux profile. Moreover, the temperature profile, linear at room temperature, becomes strongly curved at higher temperature levels. Theoretical predictions of the total heat transfer through an industrial mineral wool product made of soda-lime type glass are presented. They are validated by experimental measurements at both room and elevated temperatures.
