Experimental investigation and thermodynamic assessment of the RbCl CsCl ZnCl2 system and its subsystems

The RbClZnCl2 and CsClZnCl2 binary systems with different proportions are firstly prepared to determine the phase equilibrium relation using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) methods. The phase diagrams of RbClZnCl2, CsClZnCl2 and RbClCsCl are thus critically optimized by thermodynamic modeling based on the available experimental values. The associate solution model (ASM) is used to describe the liquid phases of RbClZnCl2 and CsClZnCl2 binary system, and the substitutional solution model (SSM) is applied for the RbClCsCl binary system. All Gibbs energies of intermediate compounds are treated with the Neumann-Kopp rule. In light of this, a set of self-consistent thermodynamic database is obtained and applied to predict the thermodynamic properties of the RbClCsClZnCl2 ternary system by merging the Gibbs energies in its subsystems via the Kohler-Toop interpolation method. These results could provide effective data supporting for the selection and optimization of multi-component molten salts for the concentrating solar power (CSP) plants.