Evaluation of Thermal-Physical Properties of Novel Multicomponent Molten Nitrate Salts for Heat Transfer and Storage

Abstract

In this work, a novel eutectic nitrate molten salt mixture of the NaNO3-KNO3-Ca(NO3)2 (16:48:36 wt%) ternary system with the significant advantage of low melting temperature was successfully designed and prepared using the static fusion method. Then, its thermal-physical properties, such as the melting point, fusion enthalpy, thermal stability, specific heat capacity, thermal diffusivity, thermal conductivity, density, and viscosity, were respectively measured by a modified or self-developed experimental device. Meanwhile, for better understanding and evaluating the heat transfer and storage performances of the material, the thermal-physical properties of this studied molten salt were further compared with those of other currently potential nitrate/nitrite systems in concentrating solar power (CSP) applications. The results proved that the newly developed NaNO3-KNO3-Ca(NO3)2 system has excellent thermal-physical properties and flow characteristics. Moreover, the cost analysis also showed the new salt has good economic performance with potential market competitiveness, its price is determined to be only 42.48 ¥/kg. All of these advantages make it a promising candidate material for heat transfer fluid (HTF) and thermal energy storage (TES) in CSP applications. This work is useful and significant for developing new molten salt materials and choosing appropriate media of HTF and TES in CSP plants or other probable thermal power generation facilities.