Thermal conductivity of energy conversion and storage composite materials packing with short fiber fillers and artificial size cylinder fillers

Abstract

Enhancement of the thermal conductivity of energy conversion and storage composite materials has become more and more common in energy conversion and storage system by applying high thermally conductive fillers. In this paper, the effect of volume fraction, the thermal conductivity ratio between the fillers and matrix materials and the height to diameter ratio have been considered as three factors that influence the thermal conductivity of composite materials. It is found that the thermal conductivity of composite materials increases with the volume fraction, the thermal conductivity ratio and the height to diameter ratio. The thermal conductivity of composite materials increases in a linear form both with the volume fraction and the height to diameter ratio at a low volume fraction. This trend will both change to a nonlinear form when the volume fraction grows higher. A new generalized correlation is proposed by using the method of nonlinear regression based on the extensive results of numerical study. The new correlation can be used to predict the thermal conductivity of short fiber fillers and artificial size cylinder fillers at a large range of conductivity (1⩽κ⩽900) and volume fraction(0⩽ϕ⩽0.2).