Elsevier

Fluid Phase Equilibria

Volume 360, 25 December 2013, Pages 293-297
Fluid Phase Equilibria

Vapor–liquid equilibria for the 1,1,1,2-tetrafluoroethane (HFC-134a) + 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea) and 1,1,1-trifluoroethane (HFC-143a) + 2,3,3,3-tetrafluoroprop-1-ene (HFO-1234yf) systems

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Highlights

  • Vapor liquid equilibria data for HFC-134a + HFC-227ea were measured.

  • Vapor liquid equilibria data for HFC-143a + HFO-1234yf were measured.

  • PR-vdW model was employed to correlate the phase equilibrium data.

Abstract

Isothermal vapor–liquid equilibria (VLE) data for the binary 1,1,1,2-tetrafluoroethane (HFC-134a) + 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea) and 1,1,1-trifluoroethane (HFC-143a) + 2,3,3,3-tetrafluoropro-1-pene (HFO-1234yf) systems were measured at temperatures from 283.15 K to 323.15 K at 10 K intervals. The VLE experimental data for the HFC-134a + HFC-227ea system agree well with the literature data. The experimental data were correlated using PR EoS with vdW mixing rule, and binary interaction parameters in mixing rules were optimized to fit the experimental data of each binary mixture. The comparison between the experimental data and the correlated results shows a good agreement.

Introduction

Hydrofluorocarbons (HFCs) and hydrocarbons (HCs) are considered as promising alternatives for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), which are being phased out because of their ozone depletion effects. However, HFCs have high global warming potentials (GWP), and HCs are highly flammable and explosive. Recently, unsaturated fluorinated compounds were known as hydrofluoro-olefins (HFOs) have been proposed as next generation candidates, because of their low GWPs and extremely short atmospheric lifetimes [1], [2], [3]. HFO-1234yf, joint developed by Honeywell and DuPont, has a very low GWP of about 4 and a very short atmospheric lifetime of 0.03 yrs. Different thermophysical properties of HFO-1234yf have been experimentally measured [4], [5], [6], [7], [8], [9], [10], and various equations of state also have been developed [11], [12]. However, it's difficult to find a pure refrigerant with both excellent refrigeration performance and environmentally acceptable properties. Mixtures of the two or more compounds may have a good potential as alternative refrigerants. Recently, properties of several binary systems containing HFO-1234yf have been experimentally measured [13], [14], [15]. In the present work, isothermal vapor–liquid equilibria measurement were carried out for the HFC-134a + HFC-227ea and HFC-143a + HFO-1234yf binary systems from 283.15 K to 323.15 K, using a circulation-type VLE apparatus. The experimental data were correlated using PR EoS with the vdW mixing rules.

Section snippets

Chemicals

HFO-1234yf (2,3,3,3-tetrafluoroprop-1-ene) was provided by Honeywell with a declared purity of 99.9 wt%. HFC-134a (1,1,1,2-tetrafluoroethane), HFC-227ea (1,1,1,2,3,3,3-heptafluoropropane) and HFC-143a (1,1,1-trifluoroethane) were all supplied by Zhejiang Juhua (China) with purities of 99.9 wt%, 99.9 wt% and 99.8 wt%, respectively. The purities and suppliers of the pure components used in the measurements are summarized in Table 1. All samples were used without any further purification.

Apparatus

The VLE

VLE correlate

The PR equation of state [18] with van der Waals (vdW) mixing rules was used in this work to correlate VLE data for HFC-134a + HFC-227ea and HFC-143a + HFO-1234yf systems. The critical properties and the acentric factors for pure compounds needed in the VLE correlations were presented in Table 2 [19].

The vdW mixing rules are:a=i=12j=12xixjaijaij=(1kij)ai1/2aj1/2,i=1,2;j=1,2b=i=12xibiwhere kij is the binary interaction parameter, and kij = kji, kii = kjj = 0.

The binary interaction parameter kij can

Results and discussion

In order to check the reliability of the experimental apparatus, the vapor pressures of HFC-134a, HFC-227ea, HFC-143a and HFO-1234yf were measured at 10 K intervals from 283.15 K to 323.15 K. Table 3 shows the comparison of the measured vapor pressures of pure components with the values calculated by REFPROP 8.0 [19]. The average deviation is 0.27% compared with REFPROP 8.0.

The experimental VLE data for binary systems HFC-134a + HFC-227ea and HFC-143a + HFO-1234yf at temperatures from 283.15 to 323.15 

Conclusion

In this work, the experimental VLE data for HFC-134a + HFC-227ea and HFC-143a + HFO-1234yf at temperatures from 283.15 to 323.15 K were presented. PR EoS with vdW mixing rules was used to correlate these data. The binary interaction parameters kij were obtained by minimizing the objective function. The overall average absolute deviations of pressures and vapor phase compositions are 0.32% and 0.0013 for HFC-134a + HFC-227ea, 0.46% and 0.0009 for HFC-143a + HFO-1234yf. The calculated data show a good

Acknowledgment

This work is supported by the National Natural Science Foundation of China (Grant No.: 50976113).

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