Vapor-liquid equilibria of the binary system HFC134a/HCFC133a

Eighteen values of the bubble-point and dew-point temperature, pressure, and molar volume for the binary HFC134a/HCFC133a system were measured with a constant-volume method. The saturated points were observed with a transparent sample cell inside a thermostatic bath. The experimental results for the variable compositions cover the temperature range of 300-360 K, corresponding to the pressure range of 0.2909-2.6393 MPa. The experimental uncertainties of temperature and pressure are estimated to be no greater than ±10 mK and ±3.4 kPa; the maximum and minimum uncertainties of molar volume are 3.63% and 0.043%, respectively. The binary interaction constants k_ij of the Peng-Robinson (PR) equation and the Lee-Kesler-Plocker (LKP) equation were determined with the experimental data on the basis of the present measurements. The binary interaction constant k_ij of the PR equation is 0.013, and the maximum saturated pressure calculation deviation is 0.71%. When bubble-point and dew-point properties were estimated using the LKP equation, the interaction constants k_ij are 0.9933 and 0.9942, respectively, and the maximum saturated pressure calculation deviations are 0.61% and 0.89%, respectively. Using the PR and LKP equations with the corresponding estimated k_ij values, the deviations of calculating the saturated temperature are ±0.2 K and ±1 K, respectively. The calculation results of vapor-liquid equilibrium properties based on the PR equation of state are also prepared.