Vapor liquid equilibrium measurements for difluoromethane (R32) + 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and fluoroethane (R161) + 2,3,3,3-tetrafluoroprop-1-ene (R1234yf)
Graphical abstract
Introduction
According to the Montreal and Kyoto protocols, chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) were scheduled to phase out because of their depletion of the ozone layer and contribution to global warming [1]. Moreover, the EU Regulation No. 517/2014 is going to phase out most of the refrigerants (R134a, R404A and R410A) commonly used in refrigeration and air conditioning systems due to their higher GWP [2]. Alternatives that can meet the requirements of both thermodynamic properties and environmental performance are eager to be developed. In the mobile air conditioners (MAC) sector, R1234yf (ODP = 0, 100 years GWP < 1 [3]), with similar thermodynamic properties to R134a, has become the most promising compound for the replacement of the widely used R134a [4]. However, R1234yf is still not an ideal solution in all regards. Compared with R134a, the volumetric efficiency of R1234yf was decreased around 3%–5%, its average cooling capacity is 9% lower, and its COP dropped about 3%–11% in series drop-in experiments [5]. Therefore, R1234yf is often discussed as a component of refrigerant blends. R32 is a refrigerant with superior thermodynamic properties, large latent heat and relatively low GWP (100 years GWP = 677 [3]), which is a commonly used component in mixtures containing R1234yf [2], [6]. R161 is also an environmental friendly refrigerant with extremely low GWP (100 years GWP = 4 [3]). To evaluate comprehensively the performance of refrigerant blends in technical applications, measurements of their thermophysical properties are essential. In this work, we present new vapor liquid equilibrium data for R32 + R1234yf and R161 + R1234yf in the temperature range of (283.15–323.15) K, measured by a quasi-static analytical apparatus. The new apparatus here was improved from a previous recirculation analytical apparatus [7] and validated by the VLE measurements of R32 + R1234ze(E). At the same time, the accuracy of temperature and pressure measurement was validated by measuring the saturated vapor pressures of R161 and R1234yf in the same temperature range. The PRSV + WS + NRTL model was used to correlate the VLE data. Finally, both the vapor pressure and vapor liquid equilibrium data were compared comprehensively with literature data.
Section snippets
Chemicals
R32 and R161 were supplied by Zhejiang Lantian Environmental Protection Fluoro Material Co., Ltd. with a stated mass purity higher than 0.998 and 0.997, respectively. R1234ze(E) and R1234yf were obtained from Honeywell International Inc. with a declared mass purity higher than 0.995. Freeze-pump-thaw cycles were used to degas the non-condensable components of the refrigerants before the experiments. Subsequently, the sample purity was analyzed at least three times by gas chromatography and the
Saturated vapor pressure
Saturated vapor pressures of R161 and R1234yf were measured over the temperature range of (283.15–323.15) K and the data are listed in Table 2.
Vapor liquid equilibrium
New VLE data of R32 + R1234ze(E) were carried out at three compositions from (283.15–323.15) K to examine the performance of the modified apparatus. Later, the VLE data for R32 + R1234yf and R161 + R1234yf were measured along five isotherms, T = (283.15, 293.15, 303.15, 313.15 and 323.15) K, at nine compositions. The experimental results for
Discussion
Fig. 2, Fig. 3 present the relative deviations of the experimental vapor pressure data of literature and this work from the calculated results of the Helmholtz equations of state [10], [11] for R161 and R1234yf, respectively.
For R161, the data of Chen et al. [15] and this work both show good agreement within 0.3% with the calculated data of the Helmholtz EOS [10]. The data of Vidaurrl [16] are also in good agreement with deviations within 1%, except the point at 306.592 K. The deviations of Cui
Conclusion
In this work, saturated vapor pressure data of R161 and R1234yf were measured in the temperature range of (283.15–323.15) K. Good agreement between the vapor pressure of this work and literature can be observed, confirming the quality of the temperature and pressure measurements. Vapor liquid equilibrium data of R32 + R1234ze(E) show good consistency with the literature data, which indicates the satisfactory performance of the improved apparatus. Then, the VLE data of R32 + R1234yf and
Funding
This work was supported by the National Natural Science Foundation of China (No. 51476130), the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20130201110046) and the Fundamental Research Funds for the Central Universities.
Notes
The authors declare no competing financial interest.
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