In this study, an excess Gibbs free energy model combined with a short-range term, stated by the nonelectrolyte UNIQUAC-NRF model, and a long-range contribution expressed by the Pitzer–Debye–Hückel equation is developed to describe the solid–liquid-phase behavior equilibrium of a wide range of strong aqueous electrolyte solutions. The parameters of the model are first obtained by correlating the experimental data of the activity coefficients of more than 130 binary aqueous electrolyte systems at 298.15 K and 1 bar. The model results are compared with electrolyte-NRTL, electrolyte-UNIQUAC-NRF, and nonelectrolyte- Wilson-NRF, revealing that this model is appropriate for electrolyte solutions. In the next step, by applying the adjusted parameters, the mean activity, osmotic coefficient, vapor pressure, ternary phase diagram, and salt solubility for some strong binary and ternary aqueous salt types are predicted at electrolyte concentrations up to saturation and temperatures up to 373.15 K. In the third step, for the first time, the nonelectrolyte UNIQUAC-NRF is applied to predict the salt solubility and ternary phase diagrams for the aqueous ternary systems: K2SO4 + Na2SO4 + H2O and NaCl + Na2SO4 + H2O at different temperatures. Finally, the combination of the nonelectrolyte UNIQUAC-NRF with solvation contribution and explicit MSA equation as long range part have been investigated. The results show the Nonelectrolyte UNIQUAC-NRF model can adequately predict the presence of crystallization zones, univariant curves, and invariant points by applying only two binary adjustable energy parameters. Finally, some electrolytes’ heat capacity and excess enthalpy are calculated at different temperatures and molality.

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