Improvement of thermal cycle stability of paraffin/expanded graphite composite phase change materials and its application in thermal management

Paraffin/expanded graphite (PA/EG) composite phase change materials (PCMs) were prepared by melt blending. The effects of EG particle size and pressing direction on heat transfer performance and thermal cycle deformation were studied. The results show that by reducing the particle size of EG, the thermal conductivity is enhanced and the deformation degree of PA/EG during the thermal cycle is alleviated. When the non-pressurized surface is used as the heating surface, PA/EG thermal conductivity is enhanced and the effect of deformation is avoidable. After that, the thermal management performance of PA/EG before and after packaging was experimentally studied. The results show that the reduction of EG particle size is beneficial to thermal management, and the average temperature of the hot surface of PA/EG100(a) is 46.1 °C, which is 1.1 °C lower than that of PA/EG50(a). PA/EG100(b) with the non-pressurized surface as heating surface has better thermal cycle stability, and the change of ambient temperature and heat flux will not affect heat transfer performance. Even for the packaged PA/EG samples, PA/EG100(b) still exhibits better thermal management performance due to the little deformation on heating surface. The present work proves that the non-pressurized surface of PA/EG as heating surface is a better choice for practical applications.