A Perturbation Theory approach to Equation of State and Excess energy of Size-Asymmetric Square-Well Fluid Mixtures

Accurate prediction of the equation of state and excess energy is essential for the thermodynamic modeling of fluid mixtures, particularly those exhibiting size asymmetry. In this study, a new mixing rule proposed by Binay and Solana is applied within a perturbation-theory framework and its performance is evaluated against the conventional Dieters’, Ely and Jonha mixing rules. The results show that the proposed mixing rule yields consistently improved predictions of both the equation of state and excess energy across a broad range of mixture compositions and thermodynamic conditions. These finding demonstrate the robustness and predictive superiority of the Binay-Solana mixing rule for complex mixture system.