Effects of In Situ Porous Carbon Modification on Thermal Energy Storage of Paraffin/Expanded Vermiculite Form-Stable Composite Phase Change Materials

The utilization of form-stable phase change materials (PCMs) represents a reliable technology for achieving energy conversion. In this study, starch was impregnated into the layers of expanded vermiculite (EVM) and subsequently carbonized at high temperatures to produce in situ carbon layers modified materials (EVMC), which enhance heat storage efficiency. The EVMC, characterized by its carbon network, acted as encapsulated material, leading to the development of paraffin (P)/EVCM-based shape-stable composite PCM (EVMCP). The latent heat of the EVMCP was measured at 179 J/g, surpassing that of EVMP at 144.8 J/g. This finding suggested that in situ porous carbon significantly improves the heat storage ability. Furthermore, non-isothermal crystallization curves indicated that EVMC markedly accelerated the nucleation and simultaneously restricted the non-isothermal crystal growth.