Liquid Viscosity and Surface Tension of R1234yf and R1234ze Under

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Liquid Viscosity and Surface Tension of R1234yf and R1234ze Under Saturation Conditions by Surface Light Scattering Guanjia Zhao,† Shengshan Bi,† Andreas Paul Fröba,‡,§ and Jiangtao Wu*,† †

Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, 710049, China ‡ Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Straße 6, D-91052 Erlangen, Germany § Lehrstuhl für Technische Thermodynamik (LTT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Am Weichselgarten 8, D-91058 Erlangen, Germany ABSTRACT: In the present study, surface light scattering (SLS) was used for the simultaneous determination of liquid kinematic viscosity and surface tension of 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and of trans-1,3,3,3-tetrafluoroprop-1ene (R1234ze) under saturation conditions. A new SLS apparatus was built up and checked with 1,1,1,2-tetrafluoroethane (R134a), and a good agreement of our data from SLS with literature could be found. With the new apparatus, R1234yf and R1234ze were investigated in the temperature ranges between (293 and 365) K and between (295 and 373) K. For determination of the liquid kinematic viscosity the expanded uncertainties on a confidence level of more than 95 % (k = 2) are estimated to be ± 2 % for reduced temperatures Tr (= T/Tc) < 0.95, and ± 6 % for Tr close to 0.99. For the surface tension, the expanded uncertainties are less than ± 1.5 % (k = 2) in the whole temperature range.

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comparison of viscosity data for R1234yf1,4−6 and R1234ze4,5,7 shows discrepancies, which are clearly outside the combined uncertainties of the measurements. For the surface tension of R1234yf and R1234ze, only a few data at low temperatures based on the differential capillary rise method are available.7,8 In this work, the liquid kinematic viscosity and surface tension of R1234yf and R1234ze were studied between 293 K and the critical temperature under saturation conditions by surface light scattering (SLS) with a new experimental setup.

INTRODUCTION 1,1,1,2-Tetrafluoroethane (R134a) has been used as a refrigerant in mobile air conditioning (MAC) systems for more than 20 years. Since the beginning of 2011, the European Union (EU) has banned R134a in vehicles approved for sale due to its high global warming potential (GWP) of 1430 on a time horizon of 100 years. Furthermore, R134a will be phased out completely in MAC systems until 2017. In general, the MAC directive of the EU banned all refrigerants with a GWP larger than 150, which stimulated a search for alternatives. Recently, 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) developed by Honeywell and DuPont was proposed by the Society of Automotive Engineers (SAE) as a drop-in replacement for R134a.2 Beside zero ozone depletion potential (ODP), R1234yf has a very low GWP (100 year GWP = 4), and the thermophysical properties as well as the level of toxicity are similar to R134a.1 At present, only the mild flammability could hinder the application of R1234yf in MAC.1,3 trans-1,3,3,3Tetrafluoroprop-1-ene (R1234ze) is also an alternative with low GWP (100-year GWP = 6) and can be used as a component in refrigerant blends.3 For the design of condenser and evaporator in MAC systems, surface tension and viscosity are fundamental thermophysical properties, for example, for the characterization of the twophase heat transfer. The viscosity data available in the literature for R1234yf and R1234ze were measured by a high pressure vibrating-piston Cambridge viscometer,1 a vibrating wire viscometer,4 and a sealed gravitational capillary viscometer.5 A © 2014 American Chemical Society

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EXPERIMENTAL SECTION Materials. R134a was provided by Sinochem Modern Environmental Protection Chemicals (Xi’an) Co., Ltd., China with a mass fraction purity of 0.999. R1234ze and R1234yf were provided by Honeywell International with a nominal mass fraction purity of 0.999. Complete specification of chemical samples is listed in Table 1. Before use, all refrigerants were purified by freeze−pump−thaw cycles with liquid nitrogen and a vacuum pump to get rid of the noncondensable gas. Method. Surface light scattering (SLS) was used to measure simultaneously and noninvasively liquid kinematic viscosity and surface tension under saturation conditions. The SLS technique probes as the name indicates the dynamics of surface fluctuations on liquid surfaces or phase boundaries in a more

Received: February 12, 2014 Accepted: March 16, 2014 Published: April 2, 2014 1366

dx.doi.org/10.1021/je5001457 | J. Chem. Eng. Data 2014, 59, 1366−1371

Journal of Chemical & Engineering Data

Article

connection with the determination of viscosity and surface tension can be found in refs 10, 11, and 12. Apparatus. Figure 1 shows a scheme of the used SLS apparatus, which was built up in analogy to an apparatus described in refs 10 and 11. Here, a diode-pumped solid state laser (Spectra-Physics Excelsior, 300 mW) with a wavelength of λ0 = 532 nm was used as light source. The laser power was up to about 250 mW when working far away from the critical point and only a few milliwatts in the critical region. The incident angle Θi, which is the angle between the incident laser light and the direction of detection of the scattered light outside the sample cell, was adjusted with a high precision electric rotation table (DaHeng, GCD-011080) with an uncertainty of less than ± 0.05 %. The direction of detection of the scattered light is given by two pinholes (PH1 and PH2) having diameters of 2 mm and a distance from each other by 4 m. For the observation of light scattered by surface waves, the optical path has to be aligned in a way that the laser beam and the direction of detection intersect on the liquid surface or at the phase boundary in the measurement cell. For this, a translation stage (DaHeng, GCD-830305M) was used, on which the rotation table was mounted. For realizing heterodyne conditions, part of the incident laser light is split by a glass plate and superimposed with the scattered light behind the sample cell. The combination of polarization beam splitter and lambda half wave plate ensures that the E-vector is perpendicular to the scattering plane and enables the adjustment of the intensity of both the incident beam and the reference beam. By an additional neutral density filter the intensity of the latter may further be regulated. After passing through the two pinholes without any lens, part of the scattered light together with the coherent reference light reaches the detector system, mainly

Table 1. Specification of Chemical Samples chemical R134a

R1234yf R1234ze

source Sinochem Modern Environmental Protection Chemicals Co., Ltd., China Honeywell International Inc. Honeywell International Inc.

purity (mass fraction)

purification method

0.999

freeze−pump−thaw

0.999


0.999


general formulation. In the present case, for the refrigerants showing low viscosities, the amplitude of the surface fluctuations decreases with time in the form of a damped oscillation. In a first order approximation, the frequency and damping of surface fluctuations is determined by the surface tension and the liquid kinematic viscosity. In SLS, scattered light emerging from the interaction between the incident light and the fluctuating surface structure is analyzed. This can be done by a temporal analysis of the scattered light intensity using photon correlation spectroscopy (PCS). The kinematic viscosity of the liquid phase ν′ (= η′/ρ′) and the surface tension σ were determined under saturation conditions, within the scope of this work, by means of an exact numerical solution of the dispersion relation for surface waves.9 In addition to the information on the dynamics of surface fluctuations at a given wave vector q⃗ obtained from the SLS experiment, reference data for the density of both phases and the dynamic viscosity of the vapor phase under saturation conditions were utilized for this purpose. A more detailed description of the SLS method in

Figure 1. Surface light scattering apparatus. 1367



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tension from surface light scattering can be found in refs 10 and 11. For checking the SLS apparatus, the liquid kinematic viscosity and surface tension of R134a were investigated between (303 and 368) K under saturation conditions. Beside liquid kinematic viscosity and surface tension from SLS also reference data used for data evaluation are listed in Table 2.

consisting of two photo multiplier tubes (PMTs). The signals are amplified, discriminated, and fed into a digital correlator with a single-tau structure (ALV-LinCorr) for the computation of the pseudo cross-correlation function. The processing of the signals by a cross-correlation scheme avoids that after-pulses and dead-times of PMTs may distort the correlation function at short lag times, which is the case when using only one PMT. The main feature of the optical arrangement, however, is based on the analysis of scattered light at variable and relatively high wave vectors of capillary waves of an order of about 106 m−1, whereby instrumental broadening effects are negligible. The large wave vectors can be achieved more easily with the transmission geometry due to intensity considerations. Furthermore, light scattered on the liquid surface is detected perpendicularly to the surface plane. For this arrangement, the modulus of the wave vector q of the surface fluctuations observed can be deduced exactly as a function of the easily accessible angle of incidence, q = 2π /λ 0 sin(Θi)

Table 2. Liquid Density ρ′, Vapor Density ρ″, Dynamic Viscosity of the Vapor Phase η″, Kinematic Viscosity of the Liquid Phase ν′, and Surface Tension σ of R134a under Saturation Conditionsa T K 302.99 312.86 322.92 332.92 342.90 352.89 363.27 368.26

(1)

For the experiment, the angle of incidence Θi is set larger than 3° to avoid line-broadening effects and smaller than 4.5° to make sure that the intensity of the scattered light is not too low. The sample cell is made of stainless steel and equipped with quartz windows allowing optical access as indicated in Figure 1. The sample cell can be operated up to temperatures and pressures of about 420 K and 10 MPa. The inner diameter (70 mm) of the sample cell is relatively large to avoid a curved surface in the center. The volume of the sample cell is about 160 cm3 and can be sealed off from the surrounding with a valve. For the present measurements, the samples were filled into the evacuated sample cell, and the liquid volume was about 50 cm3. The temperature of the sample cell is regulated through resistance heating and measured by two calibrated 100 Ω platinum resistance probes with a total uncertainty of ± 0.03 K. The resistance probes were inserted into the main body of the sample cell and placed close to the liquid surface in the vessel. The temperature stability was better than ± 0.01 K during a single experimental run. For each temperature point, typically six measurements at different angles of incidence were performed, where the laser was irradiated from either side with respect to the axis of observation in order to check for a possible misalignment.

ρ′ kg·m

ρ″ −3

1188.1 1148.0 1103.4 1054.0 997.8 930.2 836.5 771.0

kg·m

η″ −3

37.4 49.7 65.9 86.9 114.8 153.9 217.7 268.6

μPa·s 11.90 12.36 12.90 13.57 14.45 15.73 18.06 20.18

ν′ 2 −1

mm ·s

0.1549 0.1409 0.1277 0.1167 0.1069 0.0979 0.0856 0.0790

σ mN·m

ν′ref −1

7.45 6.19 4.95 3.79 2.68 1.65 0.73 0.34

mm2·s−1 0.1544 0.1412 0.1289 0.1177 0.1072 0.0971 0.0863 0.0806

a

Directly measured values for frequency and damping at a defined wave vector of surface waves were combined with literature data for η″, ρ′, and ρ″ from ref 19 to derive ν′ and σ by an exact numerical solution of the dispersion relation. The uncertainties are ± 0.05 % for the densities and ± 5 % for the dynamic viscosity of the vapor phase.19 The reference data for the liquid kinematic viscosity ν′ref are calculated with an uncertainty of about ± 1.5 % according to a correlation of Huber et al.13 The combined expanded uncertainties Uc are Uc(T) = 0.03 K, Uc(ν′) = 0.02·ν′ for Tr < 0.95 and 0.06·ν′ for Tr close to 0.99, and Uc(σ) = 0.015·σ (level of confidence = 0.95).

Furthermore, the viscosity data from SLS are compared with a correlation of Huber et al.13 for which an uncertainty of 1.5 % can be found. The maximum deviation of the SLS data from the correlation of Huber et al.13 is less than 1 %, except for the data point at 368.26 K, where a deviation of −1.99 % can be found. The data for the surface tension of R134a as a function of temperature were correlated by a modified van der Waals type equation σ = σ0(1 − Tr)1.26 [1 + σ1(1 − Tr)0.5 + σ2(1 − Tr)]

■

(2)

where σ0, σ1, and σ2 are the fitting parameters determined to be 63.413 mN·m−1, −0.1546, and 0.0963, respectively. In eq 2 Tr (= T/TC) is the reduced temperature, where critical temperature Tc is 374.18 K for R134a.13 Figure 2 shows the deviations of the experimental surface tension data from those calculated by eq 2. For data comparison, reference data available in the literature are also included in Figure 2. Zhu et al.,14 Heide,15 and Higashi and Shibata16 measured the surface tension of R134a with the differential capillary rise method, for which an estimated uncertainty between (± 0.1 and ± 0.2) mN·m−1 can be found. Fröba11 measured the surface tension of R134a from (243 to 363) K also by SLS. The deviations of the data of Fröba11 from the data of this work are within ± 0.2 mN·m−1. As it can be seen from Figure 2, the deviations of all experimental data from eq 2 are within their uncertainties. Also included in Figure 2 are correlations of the surface tension data for R134a from the work of Zhu et al.,14 Fröba,11 Heide,15 Chae et al.,17 and Higashi et al.16 With the exception of the correlation given by Zhu et al.,14 which shows larger deviations

RESULTS AND DISCUSSION Data obtained from SLS for the dynamics of surface waves, that is, the frequency ωq (Δωq/ωq < 0.0005) and damping Γ (ΔΓ/ Γ < 0.005) at a defined wave vector q (Δq/q < 0.001), have been combined with reference data for the dynamic viscosity of the vapor phase η″ (Δη″/η″ < 0.05) and density data for both phases ρ′ (Δρ′/ρ′ < 0.0005) and ρ″ (Δρ″/ρ″ < 0.005) to get information about the liquid kinematic viscosity ν′ and surface tension σ. Taking into account the uncertainties of the individual quantities entering into the calculation, the expanded uncertainty (k = 2) of our liquid kinematic viscosity data is estimated to be less than ± 2 % for reduced temperatures Tr < 0.95. The expanded uncertainty (k = 2) is clearly larger at higher temperatures and increases up to about ± 6 % for Tr close to 0.99. For the surface tension data the expanded uncertainty is estimated to be less than ± 1.5 % for the whole temperature range. A more detailed discussion regarding the accuracy achievable for liquid kinematic viscosity and surface 1368



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Table 4. Liquid Density ρ′, Vapor Density ρ″, Dynamic Viscosity of the Vapor Phase η″, Kinematic Viscosity of the Liquid Phase ν′, and Surface Tension σ of R1234ze under Saturation Conditionsa ρ′

T K 295.23 303.19 313.21 323.19 333.00 343.05 353.00 363.12 373.14

Figure 2. Deviations of the experimental surface tension data of this work for R134a from eq 2 and comparison with literature: □, this work; △,···, Zhu et al., ref 14; ▽, −·−, Heide, ref 15; ○, - -, Fröba, ref 11; − −, Chae et al., ref 17; ◊, −··−, Higashi and Shibata, ref 16.

ρ′

ρ″

η″

ν′

σ

kg·m−3

kg·m−3

μPa·s

mm2·s−1

mN·m−1

293.15 303.09 313.20 323.19 333.14 343.11 353.08 358.05 363.05 365.05

1109.9 1073.5 1033.6 990.2 941.4 883.5 809.6 761.5 695.7 657.4

32.8 43.6 57.8 76.0 99.7 132.2 179.9 214.8 267.7 301.0

12.04 12.53 13.16 13.88 14.82 16.12 18.17 19.78 22.44 24.26

0.1442 0.1319 0.1223 0.1126 0.1016 0.0899 0.0820 0.0770 0.0700 0.0624

6.82 5.71 4.60 3.55 2.55 1.64 0.81 0.46 0.15 0.05

kg·m

kg·m

1172.5 1146.1 1111.1 1073.6 1033.3 986.7 924.0 866.8 776.9

24.1 30.6 40.8 53.6 69.8 91.3 119.7 160.4 225.2

μPa·s 12.11 12.46 12.93 13.46 14.06 14.82 15.80 17.28 19.89

ν′ 2 −1

mm ·s

0.1776 0.1607 0.1429 0.1319 0.1193 0.1132 0.1051 0.0924 0.0817

σ mN·m−1 8.88 7.91 6.66 5.48 4.36 3.30 2.26 1.35 0.54

Directly measured values for frequency and damping at a defined wave vector of surface waves were combined with literature data for η″, ρ′, and ρ″ from ref 19 to derive ν′ and σ by an exact numerical solution of the dispersion relation. The uncertainties are ± 0.5 % for the densities and ± 10 % for the dynamic viscosity of the vapor phase.19 The combined expanded uncertainties Uc are Uc(T) = 0.03 K, Uc(ν′) = 0.02·ν′ for Tr < 0.95 and 0.06·ν′ for Tr close to 0.99, and Uc(σ) = 0.015·σ (level of confidence = 0.95).

Experimental data for the saturated liquid viscosity are often correlated by a modified Andrade-type equation. However, such an equation fails to represent the experimental viscosity data approaching the critical point. In this work, a polynomial equation and an additional term 3

ν′ =

∑ νiT i + ν4(1 − Tr)n i=0

(3)

was chosen to represent the viscosity over the complete investigated temperature range. In eq 3, νi (i = 0, 1, 2, 3, 4) and n are the fitting parameters, which are listed in Table 5 for R1234yf and R1234ze. Figures 3 and 4 show the deviations of the experimental viscosity data for R1234yf and R1234ze and literature data are also included for comparisons. Husle et al.1 measured the viscosity of R1234yf between (287 and 307) K by a high-pressure vibrating-piston Cambridge viscometer with an uncertainty of ± 5 %. It is easy to find in Figure 3 that the data from Husle et al. have a maximum deviation of 2.8 % from our data in 307 K, but it is still within the stated uncertainty. Raabe and Maginn6 applied a force field method to predict the viscosity of R1234yf between (298 and 303) K, and the simulation results agree well with our data. Cousins and Laesecke5 used a sealed gravitational capillary viscometer to measure the viscosity of R1234yf and R1234ze between (290 and 340) K and (294 and 340) K, respectively. The declared uncertainties for the two compounds were decreasing with temperature from ± 5.2 % in 246 K to ± 2.6 % in 340 K. In Figure 4, the maximum deviation of their viscosity data for R1234ze from our data is 4.97 % in 320 K, which is still within range of the uncertainty stated (± 3.2 % was stated at the temperature point). However, clear deviations of their R1234yf viscosity data from our data can be found in Figure 3, which are increasing with the temperature from about 5.9 % in 310 K and up to 11 % in 340 K. Meng et al.4 measured R1234yf and R1234ze by a vibrating wire viscometer in our group with the same sample between (293 and 363) K and (303 and 373) K, respectively. In Figure 3, the experimental viscosity data for R1234yf of this work show a good agreement with their data

Table 3. Liquid Density ρ′, Vapor Density ρ″, Dynamic Viscosity of the Vapor Phase η″, Kinematic Viscosity of the Liquid Phase ν′, and Surface Tension σ of R1234yf under Saturation Conditionsa T

η″ −3

a

at low temperatures, all correlations agree well within ± 0.2 mN·m−1. The liquid density of R1234yf and R1234ze at saturated conditions is calculated from NIST REFPROP19 with a stated uncertainty of ± 0.5 % above 320 K and ± 0.1 % between (240 and 320) K. In the whole experimental range, the deviations of liquid density for both compounds calculated from NIST REFPROP and the EOS developed by Akasaka20 are less than ± 0.2 %. Such a small difference in liquid density can be neglected for the determination of surface tension and viscosity in present work. The density and dynamic viscosity of the vapor phase were also calculated from NIST REFPROP, and the uncertainties were stated to be ± 0.5 % and ± 10 %, respectively. The results of viscosity and surface tension for the two compounds were listed in Tables 3 and 4.

K

ρ″ −3

a

Directly measured values for frequency and damping at a defined wave vector of surface waves were combined with literature data for η″, ρ′, and ρ″ from ref 19 to derive ν′ and σ by an exact numerical solution of the dispersion relation. The uncertainties are ± 0.5 % for the densities and ± 10 % for the dynamic viscosity of the vapor phase.19 The combined expanded uncertainties Uc are Uc(T) = 0.03 K, Uc(ν′) = 0.02·ν′ for Tr < 0.95 and 0.06·ν′ for Tr close to 0.99, and Uc(σ) = 0.015·σ (level of confidence = 0.95). 1369



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Table 5. Parameters of Equation 3 for R1234yf and R1234ze ν0 sample R1234yf R1234ze

2 −1

mm ·s

−5.930 −22.770

ν1·102 2 −1

mm ·s ·K

ν2·105 −1

3.342 −1.420

2 −1

mm ·s ·K

−2

−8.626 31.235

ν3·107

ν4

mm2·s−1·K−3

mm2·s−1

n

1.077 −3.114

4.145 35.059

0.906 1.006

R1234ze between (301 and 368) K by a capillary viscometer with a stated uncertainty of ± 2.5 %. However, their viscosity data for R1234ze are about 8 % larger than our data above 313 K. The experimental surface tension data for the two compounds were also listed in Tables 2 and 3. The surface tension data of R1234yf and R1234ze can be correlated by eq 2, and the fitted parameters of σ0, σ1, and σ2 for two compounds were listed in Table 6. Figure 5 shows the experimental surface Table 6. Parameters in eq 2 for R1234yf and R1234ze

a

Tc

σ0

sample

K

mN·m−1

σ1

σ2

R1234yf R1234ze

367.85a 382.52b

23.700 57.905

6.196 −0.054

−8.185 0.064

From Hulse et al.1 bFrom Higashi et al.18

Figure 3. Kinematic viscosity of liquid R1234yf under saturation conditions from SLS in comparison with literature data: □, −, this work; △, Raabe and Maginn, ref 6; ▽, Hulse et al., ref 1; ○, Meng et al., ref 4; ◊, Cousins and Laesecke, ref 5.

Figure 5. Surface tension of R1234yf under saturation conditions from SLS in comparison with literature data: □, −, this work; ○, - -, Tanaka and Higashi, ref 7.

tension data for R1234yf in comparison with literature data. Tanaka and Higashi7 measured the surface tension data of R1234yf with the differential capillary rise method between (300 and 334) K. Their surface tension data are about (0.1 to 0.3) mN·m−1 smaller than our data. Figure 6 shows the experimental surface tension data for R1234ze and literature data for comparison. Grebenkov et al.8 measured the surface tension for R1234ze with the capillary rise method between (253 and 313) K, and their data are about 0.22 mN·m−1 in 293 K and 0.50 mN·m−1 in 313 K smaller than our data. Figure 6 also includes the correlation from NIST REFPROP19 for comparison. The correlation from NIST REFPROP shows positive deviations compared with our correlation but decreasing with the temperature increasing from a maximum deviation of about 0.35 mN·m−1 at 295 K.

Figure 4. Kinematic viscosity of liquid R1234ze under saturation conditions from SLS in comparison with literature data: □, −, this work; △, Cousins and Laesecke, ref 5; ▽, Grebenkov et al., ref 8; ○, Ment et al., ref 4.

below the temperature of 340 K, but large deviations up to 10 % were found above the temperature of 353 K (Tr = 0.96). The large deviations could be caused by larger uncertainties for viscosity measurement by both techniques when approaching the critical point. In Figure 4, the viscosity data of R1234ze from both apparatus agree well, and the maximum deviation is less than ± 3 %. Grebenkov et al.8 measured the viscosity of 1370



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(2) Navarro-Esbrí, J.; Mendoza-Miranda, J.; Mota-Babiloni, A.; Barragán-Cervera, A.; Belman-Flores, J. Experimental analysis of R1234yf as a drop-in replacement for R134a in a vapor compression system. Int. J. Refrig. 2012, 36, 870−880. (3) Minor, B.; Spatz, M. HFO-1234yf low GWP refrigerant update. International Refrigeration and Air Conditioning Conference, Purdue University, West Lafayette, IN, July 14−17, 2008; p 937. (4) Meng, X.; Qiu, G.; Wu, J.; Abdulagatov, I. M. Viscosity Measurements for 2, 3, 3, 3-Tetrafluoroprop-1-ene (R1234yf) and trans-1,3,3,3-Tetrafluoropropene (R1234ze). J. Chem. Thermodyn. 2013, 63, 24−30. (5) Cousins, D. S.; Laesecke, A. Sealed gravitational capillary viscometry of dimethyl ether and two next-generation alternative refrigerants. J. Res. Natl. Inst. Stand. Technol. 2012, 117, 231−256. (6) Raabe, G.; Maginn, E. J. A Force Field for 3,3,3-Fluoro-1propenes, Including HFO-1234yf. J. Phys. Chem. B 2010, 114, 10133− 10142. (7) Tanaka, K.; Higashi, Y. Thermodynamic properties of HFO1234yf (2, 3, 3, 3-tetrafluoropropene). Int. J. Refrig. 2010, 33, 474− 479. (8) Grebenkov, A. J.; Hulse, R.; Pham, H.; Singh, R. Physical Properties and Equation of State for Trans-1,3,3,3-tetrafluoropropene. In 3rd IIR Conference on Thermophysical Properties and Transfer Processes of Refrigerants, Boulder, CO, June 23−26, 2009; p 191. (9) Lucassen-Reynders, E. H.; Lucassen, J. Properties of capillary waves. Adv. Colloid Interface Sci. 1970, 2, 347−395. (10) Fröba, A. P.; Leipertz, A. Accurate Determination of Liquid Viscosity and Surface Tension Using Surface Light Scattering (SLS): Toluene Under Saturation Conditions Between 260 and 380 K. Int. J. Thermophys. 2003, 24, 895−921. (11) Fröba, A. P. Simultane Bestimmung von Viskosität und Oberflächenspannung transparenter Fluide mittels Oberflächenlichtstreuung. Ph.D. Thesis, Friedrich-Alexander-Universität ErlangenNürnberg, 2002. (12) Langevin, D. Light scattering by liquid surfaces and complementary techniques; Dekker: New York, 1992. (13) Huber, M. L.; Laesecke, A.; Perkins, R. A. Model for the viscosity and thermal conductivity of refrigerants, including a new correlation for the viscosity of R134a. Ind. Eng. Chem. Res. 2003, 42, 3163−3178. (14) Zhu, M. S.; Han, L. Z.; Lu, C.-X. Surface tension of HFC-134a. Fluid Phase Equilib. 1993, 86, 363−367. (15) Heide, R. The surface tension of HFC refrigerants and mixtures. Int. J. Refrig. 1997, 20, 496−503. (16) Higashi, Y.; Shibata, T. Surface Tension for 1,1,1-Trifluoroethane (R-143a), 1,1,1,2-Tetrafluoroethane (R-134a), 1,1-Dichloro2,2,3,3,3-pentafluoropropane (R-225ca), and 1,3-Dichloro-1,2,2,3,3pentafluoroproane (R-225cb). J. Chem. Eng. Data 1997, 42, 438−440. (17) Chae, H. B.; Schmidt, J. W.; Moldover, M. R. Alternative refrigerants R123a, R134, R141b, R142b, and R152a: critical temperature, refractive index, surface tension, and estimates of liquid, vapor, and critical densities. J. Phys. Chem. 1990, 94, 8840−8845. (18) Higashi, Y.; Tanaka, K.; Ichikawa, T. Critical parameters and saturated densities in the critical region for trans-1, 3, 3, 3tetrafluoropropene (HFO-1234ze). J. Chem. Eng. Data 2009, 55, 1594−1597. (19) Lemmon, E. W.; Huber, M. L.; McLinden, M. O. NIST Standard Reference Database 23. Reference Fluid Thermodynamic and Transport Properties (REFPROP), Version 9.0; National Institute of Standards and Technology: Gaithersburg, MD, 2010. (20) Akasaka, R. New Fundamental Equations of State with a Common Functional Form for 2, 3, 3, 3-Tetrafluoropropene (R1234yf) and trans-1, 3, 3, 3-Tetrafluoropropene (R-1234ze). Int. J. Thermophys. 2011, 32, 1125−1147.

Figure 6. Surface tension of R1234ze under saturation conditions from SLS in comparison with literature data: □, −, this work; ○, Grebenkov et al., ref 8; - -, Lemmon et al., ref 19.

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CONCLUSION In this work, surface tension and liquid kinematic viscosity of R1234yf and R1234ze were determined with a new SLS apparatus in the temperature range from (293 to 365) K and from (293 to 373) K. Based on the experimental data, simple correlations were developed for the description of the liquid kinematic viscosity and surface tension as a function of temperature. For R1234yf and R1234ze, the average absolute deviations of the experimental surface tension data from the correlations are 0.025 mN·m−1 and 0.011 mN·m−1. For the liquid kinematic viscosity of R1234yf and R1234ze, corresponding values of 1.10 % and 0.62 % can be found.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Fax: +86-29-82663737. Funding

The authors acknowledge the financial support of the Specialized Research Fund for the Doctoral Program of Higher Education of China (no. 20100201120014 and no. 20100201110017) and the National Natural Science Foundation of China (grant no. 51276142) and the Fundamental Research Funds for the Central Universities. This work was also supported by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) by funding the Erlangen Graduate School in Advanced Optical Technologies (SAOT) within the German Excellence Initiative. Notes

The authors declare no competing financial interest.

■ ■

ACKNOWLEDGMENTS We thank Ryan Hulse of Honeywell International for providing samples of R1234yf and R1234ze. REFERENCES

(1) Hulse, R.; Singh, R.; Pham, H. Physical Properties of HFO1234yf. 3rd IIR Conference on Thermophysical Properties and Transfer Processes of Refrigerants, Boulder, CO, June 23−26, 2009; p 178. 1371


Liquid Viscosity and Surface Tension of R1234yf and R1234ze Under

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