Preparation and thermophysical property analysis of a new kind of mixed molten salts with wide temperature ranges for energy storage
摘要
Molten salt is considered as a promising heat storage and heat transfer medium for solar power generation, renewable energy consumption and flexible peak shaving of coal power due to its advantages of low cost, low vapor pressure, heat capacity and wide temperature range. In this paper, in order to acquire molten salts with low melting points, high decomposition temperatures and good thermophysical properties, different proportions of KNO3, NaNO3, Ca(NO3)2·4H2O, K2CO3 and MgO are used as materials to obtain new mixed molten salts. Through the orderly experiment, two groups of new molten salt with best comprehensive properties are selected out finally. It is found that the decomposition temperature of the new molten salts can reach higher than 662 °C, and their melting point can be reduced to below 89 °C. In addition, specific heat capacity, viscosity and thermal stability are also measured and analyzed. The average specific heat capacity of the new molten salts is as high as 2.42 J g−1 K−1 and the average thermal conductivity can reach 0.67 W m−1 K−1. In the 4-day thermal stability test, the parameters fluctuate slightly and relatively stable. Compared with the commercial solar salt (60 mass% NaNO3-40 mass% KNO3) and HITEC salt (7 mass% NaNO3-53 mass% KNO3-40 mass% NaNO2), the comprehensive performance of the new mixed molten salts is significantly improved and has broad prospects in the application of heat transfer and energy storage.