Determination of thermal diffusivity of fibrous insulating materials at high temperatures by thermal wave analysis

This work investigates the potential of measuring thermal diffusivity of materials in the high temperature range up to 1580 °C by thermal wave analysis of cylindrical samples. In particular, aiming at the typical situation of fiber insulation materials, the method is evaluated for investigations on heterogeneous media with low thermal conductivity, low density and heat capacity, and significant internal radiative heat transport (participating media). Furthermore, a model for combined conductive and radiative heat transfer is introduced. The model is adapted to a commercial insulation material using experimental scattering and absorption spectra evaluated at 1000 °C. The predictions of this numerical model are in accordance with the thermal diffusivity data obtained from the thermal wave analyses.