Heat Transfer Performance Enhancement of Paraffin/Expanded Perlite Phase Change Composites with Graphene Nano-platelets

The efficiency of latent heat thermal energy storage systems is often limited by the low thermal conductivity of phase change materials (PCMs), which limits the heat transfer rate and energy storage efficiency. Therefore, this study investigates the performance enhancement of form-stable PCMs with the addition of exfoliated graphene nano-platelets (xGnP) as a heat transfer promoter. Experimental research was carried out on fabrication, characterization and testing the properties of paraffin/EP/xGnP composite PCMs. It was shown that the xGnP particles formed an interconnecting network inside the open pores of EP, which remarkably improved the thermal properties and thermal energy storage/retrieval properties of composite PCMs. For instance, in comparison with paraffin/EP composites, addition of 1% of xGnP increased the thermal conductivity by up to 49%. Thermal energy storage/release test also revealed that the paraffin/EP/xGnP composites reduced the heat storage/ release duration by up to 33%, compared to paraffin/EP composite PCM. The enhancement of thermal properties and thermal energy storage rate of paraffin/EP/xGnP composites is a promising way to achieve high energy storage efficiency in numerous latent heat thermal energy storage applications such as solar energy storage and energy conversation in buildings.