几种典型熔盐冷却剂的热物性研究

Research on thermo-physical properties of several typical molten salt coolants

熔盐是一种优异的传热介质。热物性数据是熔盐传热应用过程中的关键基础数据。按照制定的样品制备规范、样品测试操作流程和数据处理分析方法,采用差示扫描量热仪(Differential Scanning Calorimetry,DSC)、自主研制的阿基米德法密度仪和旋转柱体式粘度仪、改进的激光闪光法导热仪对FLi Na K、Clo Kmag和HTS熔盐的熔点、比热容、密度、导热系数、粘度系数进行了实验测量和数据评估。首次系统地提供了FLi Na K和HTS熔盐在熔点以上80 K温区的粘度系数、Clo Kmag盐的关键热物性数据。为这些熔盐的热工水力设计分析提供了准确可靠的基础数据。

Background： As an ideal coolant, molten salt has been successfully used in molten salt reactor, and its thermo-physical properties have dramatic impact on heat transfer performances. However, the diversity in molten salt pretreatment and preparation induce discrepancies among the existing data which may cause puzzle in its applications. Purpose：The aim is to systematically investigate and evaluate thermo-physical properties of FLiNaK and HTS, especially viscosity in abnormal operation temperature range, and measure thermo-physical properties of CloKmag salt accurately.Methods： Molten salt coolants were prepared normatively, and their thermo-physical properties were systematically measured through testing instruments including the differential scanning calorimetry, self-developed Archimedes density device, improved thermal conductivity meter based on laser flash method, and self-developed rotating viscometer.Results： Through the measurement and analysis above, we have systematically obtained the thermo-physical properties of FLiNaK, CloKmag and HTS accurately, especially viscosity in abnormal operation temperature range.Conclusion： Heat capacity and thermal conductivity of molten salt are almost unaffected by temperature and can be regarded as constants. Viscosity at 80 K above melting point decreases with the increase of temperature and tends to that of room-temperature water in high temperature range. The thermo-physical properties of FLiNaK, CloKmag and HTS can provide accurate and reliable basic data for the application of molten salt.