The vapor–liquid equilibrium for the binary system (HFO-1234yf + HFO-1234ze­(E)) has been investigated using a liquid-recirculation apparatus from 284 to 334 K. The Peng–Robinson equation of state with the Mathias–Copeman alpha function (PR-MC), combined with Wong–Sandler (WS) mixing rule and simplified Wong–Sandler (WS_S) mixing rule, respectively, was chosen to correlate all of the experimental data. The results correlated by PR-MC + WS + NRTL and PR-MC + WS_S + NRTL models showed a good agreement with the experimental data; the average absolute relative deviation of pressure (AARDp) was within 0.5%, and the average absolute deviation of the mole fraction of HFO-1234yf in the vapor phase (AADy 1) was less than 0.002. This system exhibited no azeotropic behavior within the investigated temperature range. In addition, the relative volatilities of the system at each temperature were obtained.

The vapor−liquid equilibrium (VLE) for the binary systems 1,1,2,3,3,3-hexafluoro-1-propene (R1216) + 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and 1,1,2,3,3,3-hexafluoro-1-propene (R1216) + trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) have been investigated from 283.43 to 323.32 K and 283.28 to 323.16 K, respectively. The experimental apparatus was a recirculation system with a liquid phase pump to accelerate the VLE process. The Peng−Robinson equation of state combined with Mathias−Copeman alpha function, modified Huron−Vidal mixing rule, and nonrandom two-liquid activity coefficient model was employed to correlate the VLE data. The correlated results showed good agreement with the experimental results for the two mixtures. The average absolute relative deviation of pressure (AARDp) and average absolute deviation of vapor composition (AADy) were 0.32% and 0.003 for R1216 + R1234yf, and 0.21% and 0.004 for R1216 + R1234ze(E), respectively. The experimental and correlated results showed that there was a positive azeotrope for the system R1216 + R1234yf over all tested temperatures.

The vapor–liquid equilibria for the binary systems difluoromethane (R32) + trans-1,1,1,4,4,4-hexafluoro-2-butene (R1336mzz­(E)) and fluoroethane (R161) + trans-1,1,1,4,4,4-hexafluoro-2-butene (R1336mzz­(E)) have been investigated using a liquid recirculation apparatus from 283.17 to 333.06 K and 283.12 to 333.00 K, respectively. The experimental data were correlated by the PR + WS + NRTL model. The correlated results showed good agreement with the experimental results for the two binary mixtures. The average absolute relative deviation of pressure (AARDp) and average absolute deviation of vapor composition (AADy) were 0.88% and 0.003 for R32 + R1336mzz­(E) and 0.86% and 0.005 for R161 + R1336mzz­(E), respectively. These systems exhibited no azeotropic behavior within the investigated temperature range. Also, the relative volatilities α12 for the two mixtures were further obtained and correlated by the PR +WS +NRTL model. The results showed that the correlated results had good agreement with the experimental results, and the deviations were less than 4.3 and 7.2% for R32 + R1336mzz­(E) and R161 + R1336mzz­(E), respectively.

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The absorption refrigeration system (ARS) was important for energy saving, which can be driven by low-grade energy. In this work, the mixtures of trans-1,3,3,3-tetrafluoropropene (R1234ze­(E)) + N-methyl-2-pyrrolidone (NMP) and R1234ze­(E) + triethylene glycol dimethyl ether (DMETrEG) were considered as the promising new working fluids for ARS. The vapor–liquid equilibrium (VLE) data of R1234ze­(E) + DMETrEG and R1234ze­(E) + NMP binary mixtures were measured using a liquid-recirculation apparatus from 293.15 to 353.15 K. The VLE data were correlated by the five-parameter non-random two-liquid activity coefficient model, and the correlated results showed a good agreement with the experimental VLE data. The average absolute relative deviation and maximum absolute relative deviation of the pressure were 1.70 and 5.11% for R1234ze­(E) + NMP and 1.30 and 3.22% for R1234ze­(E) + DMETrEG, respectively. The two binary mixtures exhibited positive deviations from Raoult’s law.