Novel low melting point binary nitrates for thermal energy storage applications

•A novel binary low melting nitrates with low cost and good thermal stability was obtained.•Main thermophysical properties of the novel binary nitrates were measured.•The long-term stability test of 1200-h constant high temperature experiments were measured for the novel binary nitrates.

19 kinds of different ratio of binary mixed molten salt have been formulated, and the formulation of a low melting point binary molten salt has been exploited and its primary thermophysical properties were presented here. The eutectic temperature of the selected binary salt mixture was determined to be 116.9 ℃. Further the decomposition point, specific heat, density, viscosity, thermal conductivity and corrosion were determined respectively. Sensible thermal storage cost of the novel eutectic mixture was found to be lower than that of conventional solar salt and HITEC salt. The performance of the binary salt mixture taken at different stages during the test of 1200-h exposure to constant high temperature was discussed based on the results obtained from long-term thermal stability studies. The results show that thermodynamic properties of the molten salt show perfect repeatability before and after the experiments, and most variations rate of the thermal physical properties is within±10%, which can be considered as an implication that the candidate has good thermal stability. Therefore, this new kind of binary molten salt thermal storage materials is more competitive and promising to be used in solar power generation systems while providing a comprehensive data for its engineering application and theoretical research.