Review on phase change materials for cold thermal energy storage applications

Phase change materials (PCMs) based thermal energy storage (TES) has proved to have great potential in various energy-related applications. The high energy storage density enables TES to eliminate the imbalance between energy supply and demand. With the fast-rising demand for cold energy, cold thermal energy storage is becoming very appealing. In this paper, a review of TES for cold energy storage consisting of various liquid-solid low-temperature PCMs has been carried out. The classification of the PCMs is briefly introduced. Recent approaches to optimizing the properties of PCMs, particularly to remedy the poor thermal conductivity, leakage of liquid PCMs and the high degree of super-cooling, which limits the cold applications of TES, have also been reviewed. Methods for increasing the thermal performance including using composite PCMs and solid mesh are compared. Both modelling and experimental research on cold energy storage devices have been examined. The current cold energy storage applications including air conditioning, free cooling, etc. have been summarised. Compared with previous reviews, this work emphasises the cold energy storage applications instead of the materials aspects. The main challenges and approaches to cold thermal energy storage from the perspective of the engineering applications have been identified. Recommendations for future low charging rates and device design methodology are proposed.