Quaternary Chloride Eutectic Mixture for Thermal Energy Storage at High Temperature

Abstract

For thermal energy storage application at higher temperature, a new quaternary eutectic salt mixture consisting of sodium chloride calcium chloride potassium chloride and magnesium chloride was designed according to the phase diagram. DSC technology was used to confirm the actual eutectic point of this quaternary salt mixture and the result turned to be 385oC. Then, thermo-physical properties of this quaternary salt mixture were measured. Heat of fusion was up to 151.1J/g. Heat capacity of the eutectic salt mixture was calculated from DSC curves as function of temperature in the reference of sapphire standard material. The calculated heat capacity was consistent with theoretical value in the solid state and increased with increasing temperature in liquid state. After thermal circling of 10 circles at 280-500oC, negligible change were seen in the melting point and freezing point of this quaternary salt mixture which showed excellent thermal circling stability. Meanwhile, mass loss curves under isothermal conditions were determined and the result showed that the thermal stability of this novel quaternary eutectic salt mixture was excellent under 650oC, which means this new quaternary eutectic salt mixture was a good thermal energy storage and transfer media.