Expression for effective thermal conductivity of randomly packed granular material

Abstract This paper proposes an effective analytical expression for the accurate evaluation of the effective thermal conductivity (ETC) of randomly packed granular material with high solid-to-fluid conductivity ratio. The procedure is a novel combination of two key techniques: the parallel-column model and the pipe-network model. The ETC can be predicted using the proposed expression without microscopic analysis of the granular sample. Several practical issues associated with the accuracy and efficiency of the analytical expression are discussed, and test cases are provided to illustrate the applicability of the expression.