Measurements of Critical Properties for Binary Mixture of HFO-1234ze(E) + HFC-134a and Ternary Mixture of HFO-1234ze(E) + HFC-134a + HFC-32

The critical properties of the binary mixture of trans-1,3,3,3-Tetrafluoropropene (HFO-1234ze(E)) + 1,1,1,2-tetrafluoroethane (HFC-134a) and ternary mixture of HFO-1234ze(E) + HFC-134a + difluoromethane (HFC-32) were measured by an apparatus with variable volume. The critical properties of refrigerants can be determined by visually observing the critical opalescence phenomenon and reappearance of the meniscus. The combined expanded measurement uncertainties of the critical temperature, critical pressure and mole fraction were estimated to be less than 57 mK, 23 kPa, and 0.015 (k = 2, 0.95 level of confidence), respectively. The saturated vapor pressures and critical properties of pure HFO-1234ze(E) and HFC-134a were measured to verify the reliability of the apparatus. Redlich–Kister equations were used to correlate the critical properties of HFO-1234ze(E) + HFC-134a and the results were in good agreement with the experimental data. Cibulka’s equations were used to correlate the critical properties of HFO-1234ze(E) + HFC-134a + HFC-32 and the critical surfaces were plotted using Cibulka’s equations.