Review on thermal conductivity improvement of phase change materials with enhanced additives for thermal energy storage

With the development of economy, more and more problems related to energy have been paid more and more attentions. Phase change materials (PCMs) can store energy, which can better solve the problems of energy distribution and supply in some aspects. Because PCMs may be endothermic or exothermic at constant phase change temperature, they are favored in various industries. However, PCMs have a problem of poor thermal conductivity, which affects the heat transfer efficiency of the PCMs. This work reviews the methods to enhance thermal conductivity of PCMs. Thermal conductivity of PCMs is mainly enhanced through adding carbon-based materials and metal-based materials, etc. The PCMs with carbon-based materials and metal-based materials have better thermal characteristics and potential prospects of development and application. In addition, determining thermal conductivity methods, including determining thermal conductivity of PCMs theoretically and experimentally are are presented. Finally, the applications of the PCMs in some fields, such as solar energy utilization, building conservation, waste heat recovery and textile regulating temperature, are summarized and analyzed.