Experimental measurements and correlations of the vapor phase pvTx behavior of binary mixtures of 1,1,1,2-tetrafluoroethane (R134a)+2,3,3,3-tetrafluoroprop-1-ene (R1234yf)

In the present study, the accurate determination of the vapor phase pvTx behavior of binary mixtures of 1,1,1,2-Tetrafluoroethane (R134a) + 2,3,3,3-Tetrafluoroprop-1-ene (R1234yf) by using a Burnett apparatus was demonstrated. Measurements have been performed over the temperature range from (303 to 388) K and at pressures up to 5023 kPa covering the mole fractions of x(R134a) = (0.000, 0.099, 0.328, 0.523, 0.726, 0.919, 1.000). The combined expanded uncertainties of temperature, pressure, mole fraction and vapor density with a level of confidence of 0.95 (k = 2) were estimated to be 24 mK, 1.6 kPa, 0.01 and within 0.2% over the entire temperature, pressure and mole fraction ranges, respectively. In order to facilitate practical industrial applications and explore the thermophysical behavior of the second and third virial coefficients, the experimental vapor density data of this work were used to develop the virial equation of state with the average absolute deviation of compressibility factor lower than 0.52% for each composition. Furthermore, the obtained gaseous pvTx properties of R134a/R1234yf mixtures were compared with the multi-parameter equation of state of REFPROP 10.0 (Lemmon et al., 2018) and the relative deviations were less than 1.2%.