Graphite foam as interpenetrating matrices for phase change paraffin wax: A candidate composite for low temperature thermal energy storage

Abstract

Paraffin wax-graphite foam (P-wax/G-foam) composite was fabricated by using low cost small scale process aiming to produce a stable phase change material with enhanced thermal transport. Its thermophysical properties such as thermal diffusivity, specific heat and thermal conductivity were examined as a function of temperature. The thermal conductivity of the P-wax/G-foam composite in both solid (2.6W/mK) and liquid (1.8W/mK) phases is by a factor of ≈ 11 (980%) higher than that of pristine paraffin wax in solid (0.24W/mK) and by a factor of ≈ 16 (1530%) in liquid (0.11W/mK) phases, respectively. This is due to both the G-foam morphology and graphitic content, allowing a rapid heat transfer to the P-wax. The thermal conductivity behaviour of the composite is also discussed in term of a theoretical model in which the G-foam is described by a 3D interpenetrating matrix for the P-wax. The model shows the self-consistency of all the measured data. The obtained results demonstrated that the stable P-wax/G-foam composite is a promising material for various thermal energy storage applications such as building and vehicle heating and cooling, solar thermal harvesting, and thermal management of electrochemical energy storage and electronic devices.