Metal alloys as phase change materials for thermal energy storage between 300 °C and 400 °C

The thermal energy storage (TES) system represents a promising alternative energy source for industrial steam generation systems and a tool to decrease fossil fuel consumption. Numerous research studies focused on the use of organic and inorganic phase change materials (PCMs) as energy storage mediums for TES systems. The primary limitations of these PCMs are their low thermal conductivity, which restricts their charging and discharging capabilities. This study focuses on the viability of using metal or metal alloy PCMs as energy storage mediums for TES systems. Metal or metal alloy PCMs offer the advantage of high thermal conductivity, which mitigates the issues commonly associated with organic or inorganic PCMs; however, the primary challenge is the limited data available in the existing literature concerning these materials. From a comprehensive list of metal alloy PCMs, three PCMs, PbAg2.4, Pb, and ZnAl6, were selected based on the relevant temperature range for steam generation. The ZnAl6 metal alloy PCM was estimated to exhibit minimal density variation with respect to temperature, specifically 0.001302 kg/m 3 ·°C. Additionally, the ZnAl6 metal alloy PCM was subjected to 1000 thermal cycles alongside conventional construction and heat-resistant stainless containers. It was determined that the heat-resistant stainless steel container serves as a more effective encapsulation medium for the ZnAl6 metal alloy PCM, exhibiting an exceptionally low corrosion rate of 0.15 μm per day. Furthermore, the eutectic composition of ZnAl6 was found to remain stable even after 4128 h of thermal cycling.