Thermal conductivity enhancement of erythritol as PCM by using graphite and nickel particles

We developed new phase change composites (PCC) using erythritol as a phase change material (PCM) and graphite and nickel particles as highly thermal conductive fillers. Their effective thermal conductivities became two orders of magnitude larger than that of the original PCM. The PCC was prepared by using a conventional dispersion technique and its effective thermal conductivity was measured by the laser flash method at room temperature. We interpreted the results based on percolation theory, for which the effects of the graphite structure and the volumetric ratio on the effective thermal conductivity were examined. The results showed that the effective thermal conductivity increased gradually with increasing filler content and aspect ratio of filler. Of significance, they increased remarkably when we used 20 vol% spherical graphite. Moreover, among the three samples that we prepared, the greatest thermal conductivity, 4.72 W(m K)(-1), was recorded for the PCC with 15 vol% expanded graphite content. This was 6.4 times higher than the thermal conductivity of pure erythritol. (C) 2012 Elsevier Ltd. All rights reserved.