Isothermal vapor–liquid equilibria for the pentafluoroethane + propane and pentafluoroethane + 1,1,1,2,3,3,3-heptafluoropropane systems

https://doi.org/10.1016/j.fluid.2009.09.008Get rights and content

Abstract

A new circulation-type vapor–liquid equilibrium (VLE) apparatus was developed, and two binary systems of pentafluoroethane (R125) + propane (R290) and pentafluoroethane (R125) + 1,1,1,2,3,3,3-heptafluoropropane (R227ea) were measured. The estimated uncertainties of the measured data are ±0.005 K for temperatures, ±600 Pa for pressures, and ±0.001 for mole fractions for both the liquid and vapor phases. The VLE data for the R125 + R290 system were used to validate the experimental setup by comparing with the literature ones. The experimental VLE data for the two measured systems were correlated using the Peng–Robinson equation of state with the classical mixing rules. The two systems were further described using predictive model.

Introduction

Chlorofluorocarbons (CFCs) have been widely used as refrigerants, blowing agents, propellants, and cleaning agents due to their attractive properties. However, production and usage of CFCs are prohibited under the international Montreal Protocol agreement and its amendments because of global environmental concerns [1], [2], [3]. Hydrofluorocarbons (HFCs) and related mixtures have been considered as promising alternatives due to their zero ozone depletion potentials and low global warming potentials. Vapor–liquid equilibrium (VLE) data for such compounds are required as fundamental data for evaluating the performance of refrigeration cycles and determining optimal compositions [4], [5].

In this work, isothermal vapor–liquid equilibrium data were measured for the pentafluoroethane (R125) + propane (R290) and pentafluoroethane (R125) + 1,1,1,2,3,3,3-heptafluoropropane (R227ea) binary systems using a circulation-type VLE apparatus. The combined standard uncertainties of the measured data are ±0.005 K for temperatures, ±600 Pa for pressures, and ±0.001 for mole fractions for both the liquid and vapor phases. The R125 + R290 system has been experimentally studied by 4 groups [6], [7], [8], [9] with data available for reliable comparisons. Thus, VLE data for the R125 + R290 system at three temperatures were directly compared with the literature values to validate the experimental setup. There is no known VLE data available for the R125 + R227ea system.

The experimental vapor–liquid equilibrium data for the measured systems were correlated using the Peng–Robinson equation of state [10] with the classical mixing rules. Both the R125 + R290 and R125 + R227ea systems can be well represented by the model. The predictive ability of the model developed by Hou et al. [5] was tested using the two binary systems. The azeotropes at each temperature were also evaluated for the R125 + R290 system.

Section snippets

Apparatus

Vapor–liquid equilibrium data were measured with a circulation-type apparatus, with the mixtures of both the vapor and liquid phases continuously circulated using a magnetic pump. A schematic diagram of the apparatus is shown in Fig. 1. The experimental system was composed of several parts, including a liquid thermostatic bath to provide the constant temperature environment for the whole experimental system, an equilibrium cell containing the studied mixtures, a home-made magnetic pump and

Vapor pressures for the pure compounds

The vapor pressures for the pure compounds serve as the first validation of the experimental system reliability and the experimental data accuracy. Table 1 lists the experimental vapor pressure data for R125, R290 and R227ea and data calculated using REFPROP version 8.0 [11] at five temperatures. The relative deviations between the measured and calculated values are within ±0.5% for all the compounds at all temperatures, with an average absolute deviation of 0.134% for R125, 0.195% for R290 and

Conclusions

Vapor–liquid equilibrium for the R125 + R290 and R125 + R227ea systems were measured using a circulation-type apparatus. Both systems were well represented by the PR EoS with the classical mixing rules. The VLE data for the R125 + R290 system were compared with literature ones to validate the reliability of the experimental system. The R125 + R290 system showed positive homogeneous azeotropes at all 5 temperatures, with the pressures and compositions of the azeotropes reported here. The VLE data for

Acknowledgement

This work was supported by the National Natural Science Foundation of China (50636020).

References (12)

  • A. Valtz et al.

    Fluid Phase Equilib.

    (2004)
  • J.H. Kim et al.

    Fluid Phase Equilib.

    (2003)
  • S. Bobbo et al.

    Fluid Phase Equilib.

    (2002)
  • P.L. Jackson et al.

    Fluid Phase Equilib.

    (1995)
  • The Montreal Protocol on Substances that Deplete the Ozone Layer. Ozone Secretariat, United Nations Environment...
  • J.A. Creazzo et al.

    Zero-ODP blowing agents for polyurethane foams

There are more references available in the full text version of this article.

Cited by (25)

  • Isothermal vapour-liquid equilibrium data for environmentally friendly binary system {R1234ze(E) + R245fa}

    2022, Journal of Chemical Thermodynamics
    Citation Excerpt :

    The frequent occurrence of natural disasters and rising sea levels over the past few decades have forced a greater focus on greenhouse gas emissions reduction [1–3], which results in the enactment of No. 517/2014 regulation and the Kigali Amendment to the Montreal Protocol. No. 517/2014 regulation stipulates that refrigerants whose Global Warming Potential (GWP) is more than 150 should never be put into use in domestic refrigeration equipment, such as the air conditioners [4–5], and the Montreal Protocol prohibits the use of HFC refrigerants [6–8], implying that it has become necessary and urgent to find a new generation of refrigerants that meet the requirements. [9] Scholars' study has found that it is nearly hard to find a pure refrigerant that fits all of the conditions of having good thermal physics performance, being environmentally friendly, and being safe and inexpensive at the same time.

  • Vapor-liquid equilibrium measurements for binary mixtures of carbon dioxide (CO<inf>2</inf>) + 2,3,3,3-Tetrafluoroprop-1-ene (R-1234yf) and carbon dioxide (CO<inf>2</inf>) + 3,3,3-Trifluoropropene (R-1243zf)

    2022, Fluid Phase Equilibria
    Citation Excerpt :

    Fig. 1 shows the recirculation-analytical VLE experimental system. The design idea and detailed introduction have been given in the previous work [20–23]. Here is only a brief introduction.

  • Vapor-liquid equilibrium measurements for the binary mixtures of pentafluoroethane (R125) with 2,3,3,3-Tetrafluoroprop-1-ene (R1234yf) and 3,3,3-Trifluoropropene (R1243zf)

    2022, International Journal of Refrigeration
    Citation Excerpt :

    The recirculation-analytical method is an efficient and accurate measurement method of VLE. Our group has devoted to the VLE measurement of mixed refrigerants for HFCs/HFCs, HFCs/HCs (Hou and Duan, 2010), and HFOs/HFCs (Li et al., 2021) by using the recirculation-analytical method. In this work, 16 vapor pressure data points of R1243zf were measured from 263 K to 313 K, and the VLE data of R125 + R1234yf and R125 + R1243zf binary systems were carried out along six isotherms by a recirculation-analytical type VLE apparatus.

View all citing articles on Scopus
View full text