Experimental Study of Shape-Stabilized Phase Change Materials Based on High-Density Polyethylene and Expanded Graphite

Low-temperature latent heat storage based on solid–liquid phase change materials (PCMs) is an effective energy saving technology. However, the problems of low thermal conductivity and liquid leakage exist, so effective encapsulation and enhanced heat transfer are the focus of current research. In this study, paraffin RT58 was selected as PCM and HDPE were selected as encapsulation materials. Three PCM/HDPE composites with different proportions were prepared by melt-blending method and their encapsulation effect was tested. According to the results, 80wt%paraffin/20wt%HDPE composite was used for the subsequent experiments. EG was used to construct a heat-conducting skeleton inside the composite. The effects of EG content on thermal properties, density, leakage rate, and heat storage/release rate of the composites were investigated. The results show that the melting temperature and solidification temperature of the composites decrease with the increase of EG content. Furthermore, the addition of EG greatly reduces the leakage of composite by at least 2/3. The heat storage and release rate of the composite is accelerated with the increase of EG. The content of EG should be optimized by comprehensively considering its effects on the heat storage/release rate, heat storage density, bulk density, and encapsulation effect of the composite.