Corrosion of metals and salt hydrates used for thermochemical energy storage

Abstract

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.

The research leading to these results has received funding from the European Commission Seventh Framework Programme (FP/2007-2013) under grant agreement no ENER/FP7/295983 (MERITS). Aran Solé would like to thank the Departament d'Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya for her research fellowship. Laia Miró would like to thank the Spanish Government for her training researcher personal fellowship (BES-2012-051861). The work is partially funded by the Spanish Government (ENE2011-28269-C03-02 and ENE2011-22722). The authors would like to thank the Catalan Government for the quality accreditation given to the research group GREA (2014 SGR 123).