Prediction method of both azeotropic and critical points of the binary refrigerant mixtures

Abstract

The prediction of the azeotropic point and the determination of the critical point inbinary mixtures is very important in refrigerating industry. In this task, a simple method ispresented in order to predict and determine both azeotropic and critical points. Our methodemploys experimental data and a thermodynamic model. 1,1,1,2‐tetrafluoroethane (R134a) in themixture presents the possibility of inventing the azeotropic and critical properties. The mixturesstudied in this work are: Cyclopropane (RC270), Propylene (R1270), Hexafluoroethane (R116) andCarbon dioxide (R744) based on 1,1,1,2‐tetrafluoroethane (R134a). The model consists of thePeng–Robinson equation of state (EoS), the Mathias–Copeman alph a function and the Wong‐Sandler mixing rules involving the NRTL model. The results proved that there is a good agreementbetween the predicted values and the experimental data. The presented methods are able topredict the azeotropic and determine critical positions.