Molten chloride salts for next generation CSP plants: Selection of promising chloride salts & study on corrosion of alloys in molten chloride salts

Abstract

Molten chloride salts are promising high-temperature thermal energy storage (TES) and heat transfer fluid (HTF) materials in concentrated solar power (CSP) plants due to their high stability limits (>800°C) but low prices, compared to the commercial nitrate salt mixtures. However, severe corrosion of structural materials in contact with chloride salts is one of the most critical challenges to limit their applications at elevated temperatures. First, this work presents the properties (melting point, vapor pressure, heat capacity, hygroscopy) and large-scale prices of single chlorides and chloride mixtures for selecting the suitable molten chloride salt mixtures in next generation CSP. Then, based on our previous and current work, it discusses hot corrosion behaviors and mechanisms of metallic alloys in molten chloride salts, as well as corresponding corrosion mitigation strategies to develop the technology towards commercial applications of molten chlorides in next generation CSP.