Study on Solidification Process of Sodium Acetate Trihydrate from Supercooled State

Sodium acetate trihydrate is considered as the promising thermal energy storage material due to its high melting enthalpy at the melting temperature of 58°C. However, incongruent melting (phase separation) and remarkable supercooling are made difficult to use. In this study, solidification process of the sodium acetate trihydrate from supercooled state was both experimentally and numerically investigated. On the experiment, effects of supercooling and sodium acetate concentration on the crystal growth rate were measured by varying the supercooling temperature (-48K) and the sodium acetate concentration (40-55wt%) and obtained an empirical equation. Further, simplified crystal growth model, which is based on the experimentally obtained crystal growth rate, was also proposed and the heat release process, which is important for the thermal energy storage equipments, was investigated.