RADIATION HEAT-TRANSFER IN FOAM INSULATION

The contribution of radiation heat transfer to the overall conductivity of foam insulations has been examined. The absorption and scattering coefficients as well as the phase function were measured for foam and glassfiber insulation. A simple absorption coefficient can be derived from transmissivity measurements over a range of sample thickness. When this absorption coefficient is used in the diffusion equation to predict the radiative flux for foams, the error in the calculated radiant flux is of the order of ten percent for foams. For fibrous insulation, transmissivity measurements with an integrating sphere are necessary.