In this work, the vapor + liquid phase equilibrium for the ternary system isobutane + 1,1-difluoroethane + 1,1,2,2-tetrafluoroethane was measured using an apparatus based on the recirculation method at temperatures range from 253.150 to 273.150 K. The uncertainties of the temperature, pressure and composition were less than ±5 mK, ±0.0005 MPa and ±0.005, respectively. PR-VDW and PR-MHV2-NRTL models were employed to describe the VLE properties of system concerned. Both models can give satisfied results, and PR-MHV2-NRTL model exhibited better performance than PR-VDW model on the VLE description. A saddle point azeotropic behavior was found, and the azeotropic compositions were calculated by both methods. With the regressed binary interaction parameters from ternary VLE data, the binary VLE were predicted, and the results agree well with the experimental data. 

Fluid Phase Equilibria, 2015 

The phase diagram of the R600a (1) + R152a (2) + R134 (3) ternary system at 273.150 K. The VLE data were calculated by PR-VDW model.