An innovative modified calcium chloride hexahydrate–based composite phase change material for thermal energy storage and indoor temperature regulation

Hydrated salt phase change materials (PCMs) can play an important role in the temperature regulation of buildings by storing and releasing latent heat. However, hydrated salt PCMs are affected by phase separation, supercooling, and leakage, which greatly limit their application. In this study, an innovative modified calcium chloride hexahydrate (CaCl 2 ·6H 2 O) PCM was prepared with potassium chloride (KCl) as the temperature regulator and strontium hydroxide octahydrate (Sr(OH) 2 ·8H 2 O) as the nucleating agent. Subsequently, 15 wt% expanded graphite (EG) was immersed into 85 wt% modified PCM to prepare form-stable composite PCM, which is suitable for space thermal regulation with a phase transition temperature of 26.25 °C, phase change enthalpy of 153.03 J/g and a thermal conductivity of 4.3893 W/(mK). After 500 heating–cooling cycles, the phase change temperature changed little, and enthalpy lost only 5.95%. The test chamber prepared with a composite PCM and polyvinyl chloride (PVC) board was studied to evaluate its temperature regulation performance. In the heating and cooling process, the indoor temperature is maintained at 24.5–27.5 °C for 180 to 652 min. Therefore, the prepared composite PCM can have a good application in the temperature management of buildings. Graphical abstract