Preparation and characterization of CaCl₂·6H₂O based binary inorganic eutectic system for low temperature thermal energy storage

As a cost-effective phase change thermal storage material, calcium chloride hexahydrate exhibits high heat capacity and holds tremendous promise in building energy savings. However, as a kind of hydrated salt, it also suffers from the issues of phase stratification and high degree of supercooling. Thus, present work has studied the inorganic mixtures of hydrated chloride salts and prepared a novel kind of binary eutectic phase change thermal storage material via replacing calcium chloride hexahydrate by various mass ration of magnesium chloride hexahydrate. The initial research results showed that both the components liquefied simultaneously during melting and the phase stratification of eutectic system could be effectively alleviated. Nucleating agent led to a good restrain to the supercooling of inorganic eutectic and the subcooling degree could be found as small as 1 °C.Meanwhile, the small amount of additive would little affect the melting point and enthalpy of fusion of energy storage material. The thermal cycling tests showed that our as-prepared eutectic salts exhibited good thermal reliability with fixed phase transition temperature and almost no diminution of enthalpy, which indicated that this novel binary eutectic material possessed excellent and stable performance suitable for heat storage in building energy savings.