Thermal properties of KCl-MgCl2 eutectic salt for high-temperature heat transfer and thermal storage system

摘要

Molten chloride salt is recognized as a promising heat transfer and storage medium in concentrating solar power (CSP) in recent years, but there is a serious lack for thermal property data of molten chloride salts under hightemperature condition. In this work, temperature and component dependence of local structure and physical properties for binary KCl-MgCl2 mixture were computed by molecular dynamics simulations (MD) method based on Born-Mayer-Huggins (BMH) potential. As the temperature rises, the distances between ions change and the structures turn into loose state, thus the density, thermal conductivity and the shear viscosity decrease, which also agree well with the experimental results. The calculation errors of thermal properties are mainly within 8%. The results show that density and thermal conductivity have negative linear correlation with temperature. Specific heat capacity is invariant with temperature at a constant pressure. When K+ increases in the salt, thermal conductivity is significantly improved, and shear viscosity and specific heat capacity decrease. The formulas of temperature-thermal properties-component correlations are obtained, which provide the fundamental property database for the precise design of high-temperature thermal storage system.

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