为研发出与太阳能热发电技术相匹配的新型传/蓄热熔盐材料,选取KNO3、NaNO2和KNO2作为研究对象,基于亚正规溶液模型对KNO3-NaNO2-KNO2三元系相图展开热力学理论计算,同时采用相图软件FactSage 8.2对该体系相图进行模拟,结合试验确定体系共晶点,并对优选熔盐的储热能力进行研究。结果表明,采用亚正规溶液模型计算的三元熔盐的共晶点数据具有较高的准确性。优选出的混合熔盐的组成为42.0% KNO3-48.5% NaNO2-9.5% KNO2（百分数为物质的量分数）,实测熔点为139.8 ℃,熔化终止点为146.3 ℃,熔化热为71.1 J/g,分解温度为652.0 ℃,平均液态比热容约为1.48 J/（g∙K）。
Abstract
To develop a new type of heat transfer/storage molten salt material that matches solar thermal power generation technology, KNO3, NaNO2, and KNO2 are selected as research objects. Based on the subregular solution model, thermodynamic theoretical calculation is carried out on the phase diagram of the KNO3-NaNO2-KNO2 ternary system, and the phase diagram of the system is simulated using the phase diagram software FactSage 8.2. The eutectic point of the KNO3-NaNO2-KNO2 system is determined through experimental results, and the heat storage capacity of the preferred molten salt is investigated. The results indicate that the eutectic point data of the ternary molten salt calculated using the subregular solution model has high accuracy. The preferred mixed molten salt has the composition of 42.0% KNO3-48.5% NaNO2-9.5% KNO2 （percentages are mole fractions）, with the melting point of 139.8 ℃, the melting end point of 146.3 ℃, the heat of fusion of 71.1 J/g, the decomposition temperature of 652.0 ℃, and the average liquid specific heat capacity of about 1.48 J/（g∙K）.
关键词
太阳能热发电 /
熔盐 /
储能 /
相图 /
共晶 /
热特性
Key words
solar thermal power /
molten salt /
energy storage /
phase diagrams /
eutectics /
thermodynamic properties
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基金
国家重点研发计划（2022YFB4202402）; 国家自然科学基金（52076006）
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