Experimental investigation of saturated vapor pressure and critical parameter for R1234ze(Z) (cis-1,3,3,3-tetrafluoropropene) and R1336mzz (Z) (cis-1,1,1,4,4,4-hexafluoro-2-butene)

In this study, metal-bellows variable volumetry was used to measure the saturated vapor pressures and critical parameters of R1234ze(Z) and R1336mzz(Z). The critical temperature, critical pressure, and critical density values were evaluated, and new vapor pressure correlations were formulated based on the obtained data. The low uncertainties of the measured values indicate the reliability and reproducibility of the data. The combined expanded uncertainties of critical temperature, critical pressure, and critical density were less than 50 mK, 21 kPa, and 0.6 % (k = 2, 0.95 level of confidence), respectively. 17 vapor pressure data points of R1234ze(Z) and 20 vapor pressure data points of R1336mzz(Z) were obtained at temperatures ranging from 260 K to 441 K. The combined expanded uncertainties of the temperature and saturated vapor pressure measurements were less than 20 mK and 2.2 kPa (k = 2, 0.95 level of confidence), respectively. The results provide important thermophysical data for the use of R1234ze(Z) and R1336mzz(Z) in HTHP, and can aid in the design and optimization of HTHP systems.