Molecular simulations of the thermal and transport properties of alkali chloride salts for high-temperature thermal energy storage
Molecular simulations of the thermal and transport properties of alkali chloride salts for high-temperature thermal energy storage
复制标题
用于高温热能储存的碱金属氯化物盐的热和传输特性的分子模拟
DOI：
10.1016/j.ijheatmasstransfer.2016.07.042
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发表时间：
2016
影响因子：
5.2
通讯作者：
Wang WL
中科院分区：
文献类型：
--
作者：
Pan Ge-ChuanQi;Ding Jing;Wang Weilong;Lu Jianfeng;Li Jiang;Wei Xiaolan;Ding J;Wang WL
为了开发太阳能发电系统中的潜在盐，必须确定整个工作温度范围内的热容量、导热系数、密度和粘度等几个特性，由于高温极端条件，这些特性很难通过实验测量获得。希望寻找一种替代方法来准确预测这些特性，以用于高温能量存储系统中的熔盐设计和相对传热增强。在这项研究中，通过分子模拟计算了包括锂、钠和钾阳离子在内的氯化物盐的热和传输特性。模拟中采用Tosi、Fumi等获得的参数Born-Mayer-Huggins对势[1,2]作为离子间的相互作用。通过模拟计算得出的液相密度被低估了实验值的 9.0%，而热容被高估了 5.0%。提出了 RNEMD 方法来计算粘度和热导率。与传统的EMD和NEMD模拟方法相比，RNEMD在更短的时间内得到了更准确的结果。通过 RNEMD 计算的热导率显示，LiCl 的模拟与实验之间的偏差为 30.0%，NaCl 为 8.1%，KCl 为 6.0%；而通过相同方法计算的粘度显示，LiCl 的模拟与实验之间的偏差为 5.8%，NaCl 为 5.2%，KCl 为 5.7%。随后讨论了微观结构和宏观性能之间的关系。本研究采用的BMHTF力场已被证明可以合理地计算熔融碱金属氯化盐的热导率、热容、粘度和密度等性质，可在未来的工作中用于预测其他熔盐及其混合物的性质。
To develop a potential salt in a solar power generation system, several properties must be determined including heat capacity, thermal conductivity, density and viscosity over the entire operating temperature range, which is really difficult to be obtained from experimental measurement due to high-temperature extreme conditions. It is desired to look for an alternative way to predict these properties accurately for molten salts design and relative heat transfer enhancement in high-temperature energy storage systems. In this study, thermal and transport properties for chloride salts including lithium, sodium, and potassium cations were computed by molecular simulations. The Born–Mayer–Huggins pair potential [1,2] with parameters obtained by Tosi, Fumi, etc. was taken as the interaction between ions in the simulation. Densities for the liquid phases calculated from simulations were underestimated by 9.0% of the experimental values, while heat capacities were overestimated by 5.0%. A RNEMD method was proposed to calculate viscosities and thermal conductivities. Compared with conventional EMD and NEMD simulation method, RNEMD got more accurate results in a shorter time. Thermal conductivity calculated from RNEMD show a 30.0% deviation between simulation and experiment for LiCl, 8.1% for NaCl and 6.0% for KCl, respectively, while viscosity calculated from the same method show a 5.8% deviation between simulation and experiment for LiCl, 5.2% for NaCl and 5.7% for KCl. The relationship between microstructure and macroscopic properties was discussed subsequently. The BMHTF force field adopted in this study had been proved to be reasonable to compute the properties of molten alkali chloride salts including thermal conductivities, heat capacities, viscosities, and densities, which could be used in future work to predict the properties of other molten salts and their mixtures.