Review of cold storage materials for air conditioning application

This paper reviews the recent development of available cold storage materials for air conditioning application. According to the type of storage media and the way a storage medium is used, water and ice, salt hydrates and eutectics, paraffin waxes and fatty acids, refrigerant hydrates, microencapsulated phase change materials/slurries and phase change emulsions are separately introduced as suitable energy storage or secondary loop media. Water storage and static ice storage, which are already well-established technologies, have little need for further study. Dynamic ice slurry application is discussed especially for its generation method, relating to the efficiency and reliability of converting water or aqueous solution to ice crystals or ice slurry. Thermal and physicochemical properties of different phase change materials have been summarized including latent heat, thermal conductivity, phase separation, supercooling, and corrosion. Moreover, corresponding solutions for issues of different materials are also discussed. Thermal and hydraulic characteristics of phase change slurries (mainly about clathrate slurries, microencapsulated phase change slurries, and phase change emulsions) are discussed and summarized. In addition, the principle of the sorption cold storage is described and different kinds of working pairs are introduced. Relevant perspectives for commercialization of storage materials are discussed.

► Various kinds of suitable and promising PCMs or PCM slurries are summarized and listed. ► Thermal properties of different PCMs for cold storage are compared in details. ► Phase change slurries are introduced from clathrate slurries, microencapsulated phase change slurries, phase change emulsions. ► Thermal and hydraulic characteristics of phase change slurries are introduced briefly. ► Storage capacities of different sorption working pairs are compared and analyzed.