Corrosion testing of metals in contact with calcium chloride hexahydrate used for thermal energy storage

Abstract

Thermal energy storage (TES) using a phase change material (PCM) has been proposed as a supplemental cooling system to improve the performance of power plant air‐cooled condensers (ACCs). In this proposed system, frozen PCM would remove heat from plant's condensing steam during the day, which would melt the PCM. The PCM would be frozen at night as its stored heat is rejected to the cooler atmosphere. Calcium chloride hexahydrate (CaCl 2 · 6H 2 O) is an attractive material to serve as a PCM in this innovative system due to its appropriate melting temperature, low price, and relatively high latent heat of fusion. The corrosion of container materials is a major challenge in using CaCl 2 · 6H 2 O. Any material used needs to survive constant exposure to the salt for several years to ensure a long operational life for the system. In this study, the corrosion behavior of four metals in contact with CaCl 2 · 6H 2 O was experimentally investigated. Three different temperature conditions and two pH level conditions were considered under static metal exposure conditions.