The physical nature of thermal conduction in dry granular media

Abstract

This paper documents the results of a laboratory experimental study conducted to explore the relative contributions of phonon and electron heat conduction in an electrically conductive granular material under increasing confining stresses. The thermal conductivity of Ottawa sand under increasing confinement was also studied to offer a baseline for comparison. Simultaneous measurements of thermal conductivity, electrical conductivity and p-wave velocity were used to develop a parallel conduction model capable of predicting the thermal conductivity of dry granular media. The results suggest that the thermal conductivity of dry granular media is governed by the stiffness of the packing, regardless of whether it is electrically conductive or not. Furthermore, p-wave velocity measurements can be used to estimate the thermal conductivity of electrically conductive (granular lead) and non-conductive (Ottawa sand) granular media.