Review of the Heat Transfer Enhancement for Phase Change Heat Storage Devices

The imbalance of energy supply and demand and a series of environmental problems are associated with traditional energy. In order to alleviate the above concerns, renewable energy is getting more and more attention, although it has intermittent and regional characteristics, heat storage technology is the key to solve these. In this review, by comparing with sensible heat storage and chemical heat storage, it is found that phase change heat storage is importance in renewable energy utilization, because of its simple system, low price, high heat storage density, and stable heat storage temperature. Then, the application of phase change heat storage technology in different fields is discussed, including building energy saving, thermal management of electronic equipment, solar energy system and energy storage system. By investigating the literatures, it is found that the phase change heat storage technology is not only related to the phase change material, but also associates with the phase change heat storage device. Therefore, how to enhance the performance of the device is divided into two aspects in this paper: On the one hand, phase change material should be researched. It is well known that single phase change material has problems such as supercooling, low thermal conductivity, phase separation, etc. In order to solve these shortcomings, a eutectic composite phase change material has appeared by mixing two or more phase change materials. Phase separation can be inhibited by porous skeleton materials. Or package the phase change materials in different shapes and sizes; Mixing of graphite or nanoparticles helps to enhance the low thermal conductivity of phase change materials. On the other hand, the heat storage performance is improved through optimizing the phase change heat storage device. The tubular, plate and special shape phase change heat storage devices are summarized. U-shaped tube, Z-shaped tube, W-shaped tube, spiral tube and other different structures of heat exchange pipes can be adopted. Cascade phase change heat storage is also used; Varies structure and number of fins on the heat transfer fluid side or the phase change material side employed, too. In addition, the application of bionic configuration principle in phase change heat storage device also been summarized.