Abstract
This paper describes one approach to predicting radiative heat flux in fibrous insulations. The spectral extinction coefficients and scattering albedo in the wavelength range 1.5 < λ < 27 micro-meter at 293K and 723K for three kinds of commercial fibrous insulations composed of Al2O3 and SiO2 were determined from results of optical transmission and reflection measurements and the four-flux radiative transfer calculation. Extinction coefficients of radiative heat transfer in the temperature range 350-800K were predicted from the spectral optical properties in the case where the radiative heat flux can be calculated according to Fourier's law. The radiation extinction coefficients were obtained from effective thermal conductivities in vacuum in the temperature range 373-773 K as measured by the guarded hot plate method, where the conduction form of thermal conductivity was predicted by the heat transfer model earlier proposed by the authors. The radiation extinction coefficients obtained by heat transfer experiments were compared with the predicted ones, and quantitative agreement was obtained.
