Spectral radiative properties of open-cell foam insulation

A method to determine radiative properties of open-cell foam insulation is described. The spectral volumetric absorption and scattering coefficients a nd the spectral phase function are predicted from the dimensions and hemi s pherical reflectivity of particles that constitute the solid structure by a pplying to these particles a combination of geometric optics laws and diffr action theory. Three types of carbon foam of different porosities are studi ed. Particle dimensions and porosity can be obtained from microscopic analy sis, but solid hemispherical spectral reflectivity is very difficult to obt ain directly. It is determined by the Gauss method of linearization, applie d to bidirectional spectral transmittance data obtained from an experimenta l device using Fourier-transform infrared spectroscopy. Results obtained fr om this approach are consistent. Good agreement is observed between the exp erimental results of transmittance and reflectance and the theoretically pr edicted values computed from the identified values of particle hemispherica l reflectivity.