混合硝酸盐热物性对比分析

Comparative analysis of thermophysical properties of mixed nitrates

熔融盐作为传蓄热介质已经广泛应用于太阳能光热发电中,硝酸盐以其熔点低、成本和腐蚀性小等优点成功应用于商业电站。采用差示扫描量热法、热重法、DIN法、激光闪射法、阿基米德原理和旋转法对Solar salt(60%NaNO3+40%KNO3)、Hitec(7%NaNO3+53%KNO3+40%NaNO2)、Hitec XL[7%NaNO3+45%KNO3+48%Ca(NO3)2]以及本课题组自主研制的四元混合硝酸盐[16.67%Ca(NO3)2 4H2O+44.17%KNO3+5.83%NaNO3+33.33%NaNO2]的熔点、分解温度、比热容、热导率、密度及黏度进行测量和对比研究,分析4种混合硝酸盐热物性优缺点,为工程应用提供基础性数据。结果显示,在四种混合硝酸盐中,四元盐熔点最低、分解温度最高、平均比热容和热导率均高于其他三种混合硝酸盐,Hitec XL密度最大,Solar salt黏度最低。

Molten salt as heat transfer and storage medium has been widely used in solar power generation.Nitrate has been successfully applied in commercial power plants due to its low melting point,low cost and low corrosiveness.In this paper,different characterization techniques including differential scanning calorimetry,thermogravimetric method,DIN method,laser flash method,Archimedes principle and rotation method will be used to measure and compare the melting point,decomposition temperature,specific heat,thermal conductivity,density and viscosity of solar salt(60%NaNO3+40%KNO3),Hitec(7%NaNO3+53%KNO3+40%NaNO2),Hitec XL[7%NaNO3+45%KNO3+48%Ca(NO3)2]and quaternary mixed nitrates(16.67%Ca(NO3)2 4H2O+44.17%KNO3+5.83%NaNO3+33.33%NaNO2)independently developed by our group.The advantages and disadvantages of thermal properties of four kinds of mixed nitrates were analyzed,which provided basic data for engineering application.The results show that among the four kinds of mixed nitrates,the quaternary salt has the lowest melting point,the highest decomposition temperature,the highest average specific heat and thermal conductivity,while the Hitec XL has the highest density and Solar salt has the the lowest viscosity.