In this study, we predict the locus of azeotropes for binary mixtures by using the relative volatility is presented. A simple method is used in binary mixtures: At first we applied the method which is based on experimental data and then we evaluated by thermodynamic model. The model composed:
• Peng-Robinson equation of state
• Mathias-Copeman alpha function
• Wong-Sandler mixing rules
• NRTL model
1,1-difluoroethane (R152a) + n-butane (R600) , carbon dioxide (R744) + 1,1-difluoroethane (R152a) and 1,1,1,2-Tétrafluoroéthane (R134a) + 1,1-difluoroethane (R152a) are the binary mixtures used in this work. The results confirm that there is a good agreement between the predicted values and the experimental data and the relative error does not exceed 1% for the molar fraction and 0.5% for the pressure. In conclusion, this method is considered able to predict the azeotropic location.
Equation of State, Mixing Rules, Excess Free Energy, Azeotrope, Relative Volatility.
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