A new model for heat transfer through the contact network of randomly packed granular material

A new model termed as the parallel-column model for heat transfer through the contact network of the granular materials with random packing structure is presented. In the framework of the proposed model, the expression for effective thermal conductivity (ETC) of granular materials is derived. The numerical tests are performed on the granular samples with different structural sizes and particle size distributions. Initial arrangements of particles in the granular samples are generated using the inwards packing methods. The validity of the proposed model is verified by the good agreement between theoretical prediction given by the proposed expression and numerical results over a wide range of structural sizes and particle size distributions. It is demonstrated that the parallel-column model is a simplified and physically acceptable model, and the proposed expression is competent to accurately predict the effective thermal conductivity of granular materials while with no need of particle scale analysis of granular materials.