Heat Transfer Characteristics of High Porosity Fibrous Insulation Materials (Analysis of Radiative Heat Transfer Using the Zonal-GEF Method)

Abstract

†The zonal method, together with the concept of generic exchange factor (GEF), is shown in to an efficient and accurate approach to analyze radiative heat transfer in high porosity insulation materials which have a large scattering coefficient. Numerical predictions generated by the method correlate well with experimental data generated for LI900, a material used in the insulation tile for the space shuttle. Comparisons are presented for measurement in emitted surface intensity, effective thermal conductivity and thermal response under radiant heating. The heat transfer characteristics for the material are also determined. For LI900 which is effectively a pure scattering material at the short wavelength region (λ < 5 µm), radiation from high temperature sources can be transmitted through the material even when the optical thickness is large. Radiative heat transfer in this class of material is non-localized in the optically thick limit. A non-localized radiation model such as the zonal-GEF method is needed to determine the thermal behavior of the material for design purpose.