INFERENCE OF EFFECTIVE THERMAL-DIFFUSIVITY OF POROUS MATERIALS

The effective thermal diffusivities of porous materials are calculated with correlative equations for effective thermal properties. To check these calculated results, the effective thermal diffusivities were me asured using the Flash-Method by a finite element method under the sam e operating conditions for the porous materials. The calculated result s agree closely with the data from the Flash-Method by numerical analy sis. From the results of temperature distribution calculated numerical ly, the factors which influence the effective thermal diffusivity in t he porous materials are mainly void fraction and the thermal conductiv ity ratio of two phases. It is pointed out that the standard for appli cation of the Flash-Method to effective thermal diffusivities of porou s materials is not only a ratio of size between a sample and vacant sp ace, but also affected with the thermal conductivity ratio of two phas es and the void fraction.