High-temperature emission characteristics of open-cellular porous plates

Spectral or total normal emittances of an isothermal, plane-parallel, open-cellular porous plate placed on an opaque substrate were investigated theoretically. The equation of transfer governing the radiation field was solved using Barkstrom's finite difference method and our improved P, approximation. The necessary radiative properties of open-cellular porous materials such as the extinction coefficient, the albedo and the asymmetry factor of a scattering phase function were evaluated using Kamiuto's model. Emission characteristics of three kinds of open-cell foam including Alumino-Silicate, Cordierite and Ni-Cr foams were examined. Obtained theoretical results were compared with available experimental data. A comparison between numerical predictions based on Barkstrom's method and available spectral or total normal emittance data reported in literature shows satisfactory agreements within an experimental uncertainty. Moreover, it is found that our improved Pi approximation yields good results in predicting spectral or total normal emittances of isothermal, open-cellular porous plates.