Prediction of pressure dependent effective thermal conductivity of two phase materials in high temperature applications-An analytical method using hexagon and octagon models

The prediction of Effective Thermal Conductivity (ETC) of two phase porous materials is becoming more important to evaluate its suitability in various engineering applications. This article has aimed to develop the geometry dependent resistance models using Hexagon and Octagon by considering the effects of contact resistance, conductivity ratio, concentration, natural convection due to buoyancy effects, pressure dependent Knudsen effects and radiation effects due to elevated temperature. The general analytical expressions have been derived based on unit cell parallel isotherm approach for hexagon and Octagon geometries. The expressions are validated for its correctness using standard models and compared with wide range of experimental data for various geometrical configurations and at different temperatures. The results have declared the suitability of the present models in predicting the ETC of various two phase materials at any kind of ambient conditions.