Abstract: Phase change energy storage is a technology to realize energy storage through the absorption/release of latent heat during phase change processes. It can balance the mismatch of heat supply and demand in time, space and intensity. It has become the focus of attention in the field of energy storage due to its high energy storage density. However, its application is limited because of the low thermal conductivity of phase change materials. Aiming at the problem of slow heat transfer rate caused by low thermal conductivity of phase change materials in the melting/solidification process, this paper reviews the latest progress of phase change materials heat transfer enhancement research at home and abroad from three aspects:optimizing the structure of energy storage devices, improving the thermal conductivity of phase change materials with additives, and their combination. By comparing the advantages and disadvantages of various heat transfer enhancement methods, both experiments and simulations show that the combined heat transfer enhancement can solve the problems of low thermal conductivity and increase heat transfer area, thus improves the heat transfer performance of phase change materials; Porous metal materials as thermal conductive additives enable better thermal conductivity enhancement. The related technical problems to be solved in future for phase change energy storage technology to enhance heat transfer are also put forward.

Key words: heat conduction, porous media, composites, thermal energy storage, optimization, nanomaterials