Dynamic measurement of thermophysical properties of molten salt and error correction method

doi:10.3969/j.issn.0438-1157.2012.08.002

Abstract

Abstract: As there are little data and measurement methods for the thermophysical properties of high temperature phase-change heat storage materials with molten salt at present, a dynamic measuring apparatus with Stefan model and Lamvik M model was designed to determine the thermophysical properties of high-temperature molten salt at the melting point based on the relationship between the speed of the moving phase-transition interface location and the thermophysical properties of the liquid-solid phase during the melting and solidification processes. An error correction method was put forward to correct test result by simulating the dynamic testing processes, and was numerically implemented by using User Defined Functions(UDFs). Some samples of sodium nitrate, potassium nitrate and zinc bromide with known thermophysical properties were measured and the results were corrected. Compared the experimental results and corrective results of thermal conductivity and thermal diffusivity of sodium nitrate and potassium nitrate with the values recommended in literature reference，both errors are less than 5%.The results of three molten salts show a significantly smaller error between the calculation and the test result after the correction than before the correction, and both the thermal conductivity confirming that the error correction method allows a significant reduction in the error arising from non-one-dimensional heat conduction and unstable temperature boundary conditions. Combining dynamic measurement with an error correction could reduce the requirements for testing devices. Meanwhile, this research could offer the basic data and theoretical foundation for further investigation of thermophysical properties of other high temperature molten salts. And the reliability of the method is experimentally confirmed.

Key words: molten salt, thermophysical properties, dynamic measurement, numerical simulation, error correction

摘要： 针对目前高温熔盐相变蓄热材料热物性参数测定方法的不足，在借鉴Stefan模型和Lamvik模型的基础上，利用相变材料相变时相界面移动速率与液固相热物性参数之间的关系，设计了一套高温熔盐熔点附近热物性的动态测定装置，并提出了一种基于数值模拟的测定误差修正方法。利用该装置对已知热物性的熔盐硝酸钠、硝酸钾及溴化锌进行了动态实验测定，并利用数值模拟对测定结果进行了修正。修正后的结果和参考值之间的误差比修正前要显著减小，硝酸钠和硝酸钾的热导率、热扩散率误差均小于5%。表明该修正方法可以有效地降低测定过程中由于非一维导热、边界条件不稳定所造成的测定误差，将动态测定与该修正方法结合起来能提高测试精度，为其他熔盐热物性的深入研究提供了基础数据和理论依据。

关键词: 熔盐, 热物性, 动态测定, 数值模拟, 误差修正

CLC Number:

O551.1

ZHAN Shuiqing1，ZHOU Jiemin1，WU Ye2，LI Yuan1，LIANG Yannan1，YANG Ying1. Dynamic measurement of thermophysical properties of molten salt and error correction method[J]. CIESC Journal, 2012, 63(8): 2341-2347.

詹水清1，周孑民1，吴烨2，李远1，梁艳南1，杨莺1. 高温熔盐热物性的动态测定与误差修正方法[J]. 化工学报, 2012, 63(8): 2341-2347.

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