Experimental Measurements and Thermodynamic Modeling of VLE for Strong-Zeotropic Ternary System of 2,3,3,3-Tetrafluoroprop-1-ene (R1234yf) + Ethane (R170) + Tetrafluoromethane (R14)

The isothermal experimental VLE data for the strong-zeotropic mixture of 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) + ethane (R170) + tetrafluoromethane (R14) were measured using a circulation type apparatus at temperatures ranging from 253.15 to 273.15 K. On the basis of the UNIFAC (Dortmund) method, the new group volume, the area parameters, and the six binary interaction parameters of C2H2F, CF4, CF3, and CH3 were obtained by fitting the experimental data. Two theoretical models, the NRTL-RK model and the PR-WS-MUNIFAC model were used to correlate the experimental data. The AARD of pressure and the AAD of vapor phase mass fraction are 0.28%, 0.0077, and 0.0277 using the NRTL-RK model, and 0.32%, 0.0098, and 0.0185 using the PR-WS-MUNIFAC model, respectively. The isobaric VLE properties for the mixture were predicted using PR-WS-MUNIFAC model at pressures ranging from 0.1 to 2 MPa, and the three-dimensional phase equilibrium diagrams were presented. It is concluded that the temperature glide phenomenon is the most obvious at the mass fraction ratio of 0.35/0.1/0.55, and the maximum temperature glide reaches 73.4 K at the pressure of 0.5 MPa.