Vapor-liquid equilibrium measurements for binary mixtures of carbon dioxide (CO2) + 2,3,3,3-Tetrafluoroprop-1-ene (R-1234yf) and carbon dioxide (CO2) + 3,3,3-Trifluoropropene (R-1243zf)

The verification experiments of vapor-liquid equilibrium (VLE) for the CO2 + R-1234yf mixture were carried out along three isotherms from (283.15 to 313.15) K by a recirculation-analytical apparatus. The experimental data were in good agreement with the literature, which proved the reliability of the measurement apparatus and method for the binary system containing CO2. The VLE experiments for the CO2 + R-1243zf mixture were carried out along six isotherms from (273.15 to 313.15) K. The standard measurement uncertainty of temperature, pressure and mole fraction were 5 mK, 2.2 kPa and 0.0035, respectively. The Stryjek-Vera version of the Peng-Robinson (PRSV) equation of state combined with the Wong-Sandler (WS) mixing rule and the non-random two-liquid (NRTL) activity coefficient model (PRSV + WS + NRTL) was used to correlate the VLE data. For the CO2 + R-1234yf mixture, the average relative deviation of pressure (ARD(p)) and the average absolute deviation of compositions (AAD(y)) was 0.41% and 0.0028, respectively. For the CO2 + R-1243zf mixture, the ARD(p) and AAD(y) were 0.29% and 0.0021 for the data of this work; the literature data of CO2 + R-1243zf mixture show a systematic positive deviation from the data of this work and the established PRSV + WS + NRTL model.