Thermal Characterization of High Temperature Inorganic Phase Change Materials for Thermal Energy Storage Applications

As the importance of latent heat thermal energy storage increases for utility scale concentrating solar power (CSP) plants, there lies a need to characterize the thermal properties and melting behavior of phase change materials (PCMs) that are low in cost and high in energy density. In this paper, the results of an investigation of the melting temperature and latent heat of two binary high temperature salt eutectics are presented. Melting point and latent heat are analyzed for a chloride eutectic and carbonate eutectic using simultaneous Differential Scanning Calorimetry (DSC) and Thermogravimetric Analsysis (TGA). High purity materials were used and the handling procedure was carefully controlled to accommodate the hygroscopic nature of the chloride eutectic. The DSC analysis gives the values of thermal properties of the eutectics, which are compared with the calculated (expected/published) values. The thermal stability of the eutectics is also examined by repeated thermal cycling in a DSC and is reported in the paper along with a cost analysis of the salt materials.