Corrosion of metals and salt hydrates used for thermochemical energy storage

Solar energy can be efficiently used if thermal energy storage systems are accordingly designed to match availability and demand. Thermal energy storage by thermochemical materials (TCM) is very attractive since these materials present a high storage density. Therefore, compact systems can be designed to provide both heating and cooling in dwellings. One of the main drawbacks of the TCM is corrosion with metals in contact. Hence, the objective of this study is to present the obtained results of an immersion corrosion test following ASTM G1 simulating an open TCM reactor, under humidity and temperature defined conditions. Four common metals: copper, aluminum, stainless steel 316, and carbon steel, and five TCM: CaCl2, Na2S, CaO, MgSO4, and MgCl2, were studied. Aluminum and copper show severe corrosion when combined with Na2S, aluminum corrosion is more significant since the specimen was totally destroyed after 3 weeks. Stainless steel 316 is recommended to be used as a metal container material when storing all tested TCM.