Studies on low-temperature salt-hydrate for thermal storage applications

Abstract

A novel thermal-energy storage concept involving the use of salt-hydrates such as sodium thiosulphate pentahydrate, Na2S2O3·5H2O is under investigation. With fusion temperatures of many salts lying between 0 and 100°C, such substances may be considered as likely materials to be used in conjunction with solar energy flat-plate collector systems for domestic use. Phase change storage or latent heat storage is concluded to be a promising technique for storing solar energy. The solid-liquid transformation of salt-hydrates is actually a dehydration or hydration of salt, although this process resembles melting or freezing thermodynamically. Three types of behaviour can be identified: congruent, incrongruent, and semicongruent melting. None of the congruent melting salt-hydrates have been judged for use in thermal storage because of cost and safety considerations. © 1981.