Methodical selection of thermal conductivity models for porous silica-based media with variation of gas type and pressure

If the effective thermal conductivity of a silica powder in any gas atmosphere is to be calculated analytically, one faced with whole series decisions. There are lot different models for pores, accommodation coefficient or itself literature. Furthermore, it has decided which input parameters should used. This paper gives an overview and recommendations as calculation methods best suited material classes precipitated silica, fumed gel glass spheres. All combinations described result total 2800 compared pressure-dependent measurements 15 powdery materials 7 gases using Matlab computations. The results show that model based on spherical unit cell, considers local Knudsen numbers, measuring points all powder-gas can determined average variance about 18.5%. class known beforehand, predicted accuracy 10% correspondingly methods.