Review of salt hydrates materials in phase change heat storage and thermochemical heat storage: mechanism, optimization method and application

Abstract

The development of phase change heat storage and thermochemical heat storage technologies promotes the rational use of renewable energy. In particular, salt hydrates (SHS), which has dual-phase heat storage capability, i.e., phase change heat storage and thermochemical heat storage, has been widely investigated in various fields. However, SHS suffers from the problems of phase separation and supercooling in phase change heat storage and deliquescent caking in thermochemical heat storage, and has a common problem of corrosion, which hinders its commercialization and a wide practical application. In this paper, we first summarize and analyze the differences between the mechanisms of SHS phase change thermal storage and thermochemical thermal storage, and then conduct a comprehensive analysis of solving the phase separation and subcooling problems of SHS phase change materials by the thickener method, the shaped packaging method, and the nucleating agent method, and summarize the effects, advantages, and disadvantages of these methods. The preparation of composite SHS materials by loading SHS onto different types of porous carriers to overcome the common agglomeration and deliquescence problems of SHS in thermochemical applications is discussed, and the performance of porous carriers in enhancing the cycling stability is explored, and summarizes how to solve the problem of corrosion of metals by SHS. In addition, the performance of SHS in the field of phase change thermal storage such as battery thermal management, building temperature regulation, healthcare and solar energy harvesting, as well as in the field of thermochemistry such as building heating, is summarized, and finally, the future directions of SHS materials in thermal storage are outlined. The purpose of this paper is to provide theoretical basis and practical guidance for the application of SHS in a wider range of fields, and to promote the continuous progress and development of SHS thermal storage technology.