Abstract NaCl–CaCl2–MgCl2 ternary molten salt is a potential material for thermal transfer and storage applications at high temperatures. In the present work, its microstructures and thermophysical properties over a wide operating temperature range were investigated by using ab-initio molecular dynamics simulations. An approach-to-equilibrium molecular dynamics method was used to calculate the thermal conductivity of molten salts. The local coordination structures and mechanisms of their temperature dependence were investigated. It can be found that the dominant bonding interactions are between cation-chlorine ion pairs, which can be considered as bridges connecting the local structures in liquids. The interaction between ions decreases with the increase of temperature as distances of ion clusters get larger. The thermophysical properties were evaluated in detail from 703 to 1173 K, showing a good accordance with the experimental data. A detailed relationship between operating temperature, microstructure, and thermophysical properties has been studied. The results suggest that the changes in thermodynamic properties with increasing temperature are caused by the variations of microstructures, in terms of the distances and bonding characteristics of ions.

中文翻译：

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用于聚光太阳能的 NaCl-CaCl2-MgCl2 微观结构和热物理性质的从头算分子动力学计算

摘要 NaCl-CaCl2-MgCl2 三元熔盐是一种潜在的高温热传递和储存材料。在目前的工作中，通过使用 ab-initio 分子动力学模拟研究了其在很宽的工作温度范围内的微观结构和热物理性能。一种接近平衡的分子动力学方法被用来计算熔盐的热导率。研究了它们的温度依赖性的局部配位结构和机制。可以发现，主要的键合相互作用是在阳离子-氯离子对之间，可以认为是连接液体中局部结构的桥梁。随着离子簇的距离变大，离子之间的相互作用随着温度的升高而降低。从 703 到 1173 K 对热物理性能进行了详细评估，表明与实验数据具有良好的一致性。已经研究了工作温度、微观结构和热物理性能之间的详细关系。结果表明，热力学性质随温度升高的变化是由微观结构的变化引起的，就离子的距离和键合特性而言。