The density of molten salt is crucial for the performance of phase change energy storage systems. Accurately predict the density based on temperature and composition is challenging. A new density model based on modified quasi-chemical approaches was developed. By introducing a temperature-dependent molar volume expression for the pure component, and incorporating the contribution of each pair formation in the bond fraction, the volume and temperature dependent molar volume parameters of the second-nearest-neighbor cation-cation pairs was accounted in the model. This enables to reproduce and predict the molar volume and the density of the multicomponent liquid phase. The modified quasi-chemical density model is combined with Redlich–Kister model to form a hybrid model. These models were applied in NaCl-KCl-CaCl2-MgCl2 molten salt systems to verify their reliability. The fitting error of new modified quasi-chemical model ranges from 0.2% to 1.79%, while the hybrid model only ranges from 0.09% to 0.27%, demonstrated the reliability.

中文翻译：

---

新的改进的准化学密度模型及其在氯离子熔盐系统中的应用


熔盐的密度对于相变储能系统的性能至关重要。根据温度和成分准确预测密度具有挑战性。开发了一种基于改进的准化学方法的新密度模型。通过为纯组分引入温度依赖性的摩尔体积表达式，并将每个对形成的贡献纳入键分数，在模型中考虑了第二近邻阳离子-阳离子对的体积和温度依赖性摩尔体积参数。这能够重现和预测多组分液相的摩尔体积和密度。将改进的准化学密度模型与 Redlich-Kister 模型相结合，形成混合模型。这些模型应用于 NaCl-KCl-CaCl2-MgCl2 熔盐体系，以验证其可靠性。新改进的准化学模型的拟合误差在 0.2% 到 1.79% 之间，而混合模型仅在 0.09% 到 0.27% 之间，证明了可靠性。