Preparation and thermal properties of Na2CO3·10H2O-Na2HPO4·12H2O eutectic hydrate salt as a novel phase change material for energy storage

This study focuses on the design, preparation, microstructure and thermal properties of a novel Na2CO3·10H2O-Na2HPO4·12H2O eutectic hydrate salt (EHS) phase change material, which has been characterized by SEM, XRD and DSC techniques. The EHS with appropriate phase transformation temperature and no phase separation was expected based on the binary eutectic phenomenon and a solubility theory. The SEM results indicate that Na2CO3·10H2O and Na2HPO4·12H2O in the EHS interact with each other, causing alteration on crystal growth. However, the XRD results suggest that two hydrated salts are only simple physical mixing. Moreover, the DSC results show that the 40 wt% Na2CO3·10H2O-60 wt% Na2HPO4·12H2O eutectic hydrate salt is suitable PCM for comfort applications in buildings in terms of phase change temperature of 27.3 °C, supercooling degree of 3.6 °C and latent heat of 220.2 J/g.