基于最大气泡压力法的液态碱金属密度和表面张力测量

Experimental Investigation of Density and Surface Tension of Liquid Alkali Metals Based on the Maximum Bubble Pressure Method

液态碱金属是空间核反应堆的冷却剂材料之一,其热物性参数是冷却剂材料选取的重要依据。现有的液态碱金属的密度及表面张力实验研究数据较少,当今空间堆发展对其有更高要求。根据最大气泡压力法,研制了一套可同时测量液态碱金属密度和表面张力的实验装置,并以纯度为99.9%的锂为被测介质,对该装置的可靠性和可用性进行验证。结果表明,在200~650℃温度范围内,标准大气压下,实验结果与文献参考值相比,密度平均偏差为0.47%,表面张力平均偏差[12]为0.93%,具有较好的线性度。在此基础上,给出了液态锂密度和表面张力与温度的经验关系式。最后分析了管径、鼓泡速度对液态锂密度和表面张力测量结果的影响,并给出相应实验建议。本文工作可对高温液态碱金属的密度及表面张力开展高精度测量提供参考。

The liquid alkali metal is one of the coolant materials for space nuclear reactor,and its thermophysical parameters are an essential basis for the selection of coolant materials.The existing experimental data on the density and surface tension of liquid alkali metals are less,and the development of space reactors has higher requirements.According to the maximum bubble pressure method,an experimental device that can simultaneously measure the density and surface tension of liquid alkali metals is developed,and the reliability and availability of the device are verified with lithium with the purity of 99.9%as the measured medium.The results showed that the average deviation of the density was 0.47%,and the average variation of surface tension was 0.93%,with good linearity in the temperature range of 200℃~650℃and under standard atmospheric pressure compared with the literature reference values.The empirical relationship between liquid lithium’s density,surface tension,and temperature is given on this basis.Finally,the effects of the tube diameter and the bubbling speed on liquid lithium density and surface tension measurement results are analyzed,and corresponding experimental suggestions are given.The work in this paper can provide a reference for the high-precision measurement of the density and surface tension of liquid alkali metals at high temperatures.