Randomly mixed model for predicting the effective thermal conductivity of moist porous media

A randomly mixed model is developed for the prediction of the effective thermal conductivity of a multi-phase system. The proposed model is based on the assumption that the smallest part of the phases is a cube, and all the cubes are randomly dispersed in the space. The effective thermal conductivity therefore can be found numerically from thermal conductivities and volume fractions of the components, using the principle of heat conduction in anisotropic media. The prediction does not depend upon empirical parameters and the algorithm is easy to perform in a personal computer. The validation of the proposed model is tested by several types of moist porous media with various porosities and degrees of saturation. Compared with the experimental data of the soils and building materials, the proposed model can give a fine prediction of the moist porous media for porosity less than 0.6. Finally, the deviations between the predicted and experimental results for high porosity are also analysed