Thermal performance analysis of latent heat thermal energy storage with cascaded phase change materials capsules under varying inlet temperature

The cascaded phase change materials (PCMs) design is an efficient solution for improving the thermal perfor-mances of latent heat thermal energy storage system (LHTESS). This work investigated the effects of varying inlet temperatures of heat transfer fluid (HTF) on thermal performances. The thermal performance parameters of LHTESS with cascaded PCM capsules, such as exergy storage, heat storage capacity, temperature rise and liquid fraction of PCMs, were calculated and compared using a numerical method. The results show that the thermal performance parameters of the unsteady inlet temperature of HTF are superior to that of the corresponding steady inlet temperature of HTF at their peak. However, the varying inlet temperature of HTF is non-optimal from an energy-efficiency perspective. The aim is to provide information for further research and develop-ment for designing LHTESS in solar thermal systems.