Melt path formation in a high temperature molten salt horizontal shell and tube storage system for CSP plants

Latent heat thermal energy storage systems working at higher temperatures around 800 °C are considered as a promising alternative in conjunction with the sCO2 Brayton cycle for the next generation of concentrating solar power plants. At higher temperatures, a detailed thermo-mechanical analysis of the system is crucial, particularly during a melting/charging process with a high temperature difference (50-100 K) between the solid phase change material (PCM) and heat transfer fluid. Here, the melt path formation of a high temperature PCM in a horizontal shell and tube system is investigated. Three different levels of modelling were conducted. The results of the study showed that the melted PCM around the tubes connect and form a path after about 50 seconds, which provides a way for the high temperature PCM to flow through. This imposes a temperature gradient along the tubes preventing a localised hot spot and high thermal stresses. Refereed/Peer-reviewed