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 kij of the Peng-Robinson (PR) equation and the Lee-Kesler-Plöcker (LKP) equation were determined with the experimental data on the basis of the present measurements. The binary interaction constant kij 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 kijare 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 kij 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 presented.