Corrosion assessment of erythritol as a phase change material in latent heat thermal energy storage system

A thermal energy storage system combined with renewable energy sources or waste heat recovery will increase the dispatchability of the energy system. It also helps to reduce the gap between supply and demand. Among available techniques, latent heat thermal energy storage systems have been an attractive area of research. Selecting a phase change and construction material is vital in designing any storage system. In the present study, corrosion characterization was performed for erythritol used in the experimental prototype. The use of erythritol to develop a storage system requires understanding its corrosion behavior with storage container material and piping system to ensure the safety of construction and enhance the system's life. Corrosion rates were determined in stainless steel and mild steel sample by gravimetric tests, measuring the mass loss after 2000 h of immersion at 140 °C in two different test conditions. Simultaneously, surface morphology and corrosion products were analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray scanning (EDX). The experimental result confirms that stainless steel shows better corrosion resistance than mild steel for selected phase change material. SEM and EDX analysis shows no significant changes in the structure after 2000 h of immersion. Corrosion rates for open and closed crucible stainless steel sample have been observed at 0.003 mm y−1 and 0.004 mm y−1, respectively, whereas mild steel sample was more affected by PCM in both the open and closed crucible tests, giving 0.0221 mm y−1 and 0.0392 mm y−1. The study shows that further research is required in different operating conditions.