A Novel Equilibrium Equation for Binary Mixtures

In the thermodynamic of non-ideal solutions, there are two valuable approaches for linking the saturated vapor and liquid phases in an equilibrium system, i.e. the γ-φ and φ-φ approaches. Nevertheless, these methods are complex and need huge calculation procedures. Therefore, developing novel equations, with a simple format, is necessary for decreasing the size of the calculation procedure or increasing the accuracy of the predicted values for the required thermodynamic parameters. This study aims to develop a simple and accurate (with less than ۵% mean absolute error for several cases of validation) relation among the thermodynamic parameters of two phases of a pure or binary mixture vapor-liquid equilibrium system. The format of this equation is very simple, which improves its applicability for solving various thermodynamic problems in vapor-liquid equilibrium systems. For this purpose, the compressibility factors of each phase that are suitable combinations of the PVT parameters of the system, are chosen for relating the thermodynamic parameters of these phases. Therefore, obtaining a relation between the compressibility factors of the saturated liquid and vapor phases relates the PVT parameters of these phases to each other. Although the idea of this theory-based equation has been raised from the investigation of equilibrium PVT values of pure substances, this equation has also been validated using the experimental PVTxy data of several binary mixtures. Comparing the predictions of the obtained equilibrium equation with the experimental data of pure and binary mixtures approves the accuracy of the predictions of the obtained equation.