Thermodynamic Reevaluation and Experimental Validation of the CsNO3-KNO3-NaNO3 System and Its Subsystems

Phase equilibria and thermodynamic properties of the CsNO3-KNO3-NaNO3 system and its three subsystems were optimized thermodynamically and validated experimentally. The liquid and end solid solution phases of the KNO3-NaNO3 and CsNO3-KNO3 systems were modeled using the substitutional solution and compound energy formalism models, respectively. The CsNO3-KNO3-NaNO3 ternary system was described thermodynamically based on the self-consistent thermodynamic parameters of the three binary systems. A set of thermodynamic parameters was obtained to reproduce the available information on the thermodynamic properties and phase equilibria. Melting temperature, enthalpy, and specific heat capacity of a eutectic sample were determined using differential scanning calorimetry(DSC). The results show a good consistency with the calculated results, suggesting the reliability of the current thermodynamic database. This work is useful for the construction of multicomponent nitrates and to provide guidance for the development of new medium for thermal energy storage.