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Surface tension of dimethyl ether + propane from 243 to 333 K
Fluid Phase Equilibria 298 (2010) 150–153
Contents lists available at ScienceDirect
Fluid Phase Equilibria journal homepage: www.elsevier.com/locate/fluid
Surface tension of dimethyl ether + propane from 243 to 333 K Shengshan Bi ∗ , Xin Li, Guanjia Zhao, Jiangtao Wu State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an Shaanxi 710049, People’s Republic of China
a r t i c l e
i n f o
Article history: Received 9 April 2010 Received in revised form 6 July 2010 Accepted 30 July 2010 Available online 7 August 2010 Keywords: Binary mixture refrigerant RE170 + R290 Surface tension
a b s t r a c t The surface tension of the binary refrigerant mixture dimethyl ether (RE170)(1) + propane (R290)(2) at three mass fraction of w1 = 0.3007, 0.4975 and 0.6949 was measured in the temperature range from 243 to 333 K with a differential capillary rise method. The uncertainties of the measurement of the temperature and the surface tension were estimated to be within ±10 mK and ±0.2 mN m−1 , respectively. A correlation for the surface tension of the binary refrigerant mixture RE170 + R290 was developed as a function of the composition. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Dimethyl ether (RE170) is an important clean alternative fuel, which has been used in the automobile and gas stove. Furthermore, RE170 and its mixture with hydrofluorocarbon (HFC) or hydrocarbon (HC) refrigerants have been shown to have excellent efficiency and environmental property and believed to be a promising alternative refrigerant. Recently, RE170 + R290 + R1270 mixture was used in residential air-conditioner, and the experimental results showed that RE170 + R290 + R1270 can be used as a drop-in substitute to R22 with a high coefficient of performance [1]. Surface tension as a basic thermophysical property influencing the heat transfer, flow and phase change characteristic of the working fluid, is useful for the condenser and evaporator design in a refrigerator. Unfortunately, there are no surface tension data of mixture refrigerants RE170 + R290 in the literature. In this work, the surface tension of RE170 + R290 was measured systematically at three mass fractions in the temperature range from 243 to 333 K using the differential capillary rise method under vapor–liquid equilibrium conditions. The experimental surface tension data was correlated as a function of the composition.
2. Experimental The surface tension was measured with a differential capillary rise method. The apparatus was described in detail in our previous work [2,3] and is briefly described here.
∗ Corresponding author. Tel.: +86 29 82666875; fax: +86 29 82668789. E-mail address: [email protected] (S. Bi). 0378-3812/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.fluid.2010.07.026
During the experiment, the capillary rise difference h0 was measured, and the surface tension can be calculated using the following expression as =
h0 + r1 /3 − r2 /3 (L − g )g = a2 (L − g )g 2(1/r1 − 1/r2 )
(1)
where is the surface tension, g is the local gravitational acceleration (in this work, g = 9.7965 m s−2 ), L and g are the densities of saturated liquid and vapor, respectively. h0 is the height difference of the meniscus bottom of the two capillaries. r1 and r2 are the bare radii of the two different capillaries used in the experiments. a2 is the capillary constant. The capillaries were placed in a small pressure cell with observation windows, and the pressure cell was placed in a thermostatic bath for which the temperature stability was within ±10 mK in 2 h. Silicon oil was chosen as a thermostat fluid. The temperature measurement system consisted of an Agilent 3458A and two 25 standard platinum resistance thermometers. One thermometer (No. 68033) is used in the temperature range 83.8058–273.16 K, and the other (No. 68115) is used in the temperature range 273.15–933.473 K. The thermometers were calibrated on the ITS90 scale at the National Institute of Metrology of China. The total uncertainty of temperature for surface tension was less than ±10 mK. The capillary rise difference was measured with a cathetometer with an uncertainty ±0.02 mm. In this work, all the measurements were carried out under equilibrium conditions between the liquid and its saturated vapor, and the uncertainty of surface tension was estimated to be within ±0.2 mN m−1 . RE170 and R290 were provided by Shandong Jiutai Chemical Co. Ltd. and Jinlaier Company. The mass purity was better than 99.95%. The samples were firstly purified by freeze–pump–thaw cycles. The mixture was prepared by the following process. First, a
S. Bi et al. / Fluid Phase Equilibria 298 (2010) 150–153
151
Table 1 Surface tension of R290 and RE170. T/K
l /kg m−3
g /kg m−3
/mN m−1
R290
278.18 283.18 288.19 293.18 298.10 303.18
521.7 514.7 507.5 500.0 492.4 484.4
11.98 13.79 15.83 18.09 20.59 23.47
9.5 8.9 8.3 7.7 7.1 6.4
RE170
278.16 283.21 288.17 293.15 298.10 303.13
692.6 684.9 677.3 669.5 661.6 653.3
6.90 8.09 9.41 10.90 12.55 14.43
14.7 13.9 13.1 12.6 11.8 11.0
1 /mN m−1
2 /mN m−1
9.6 8.9 8.3 7.6 7.0 6.4
9.5 8.9 8.2 7.6 7.0 6.4
3 /mN m−1
14.6 13.9 13.2 12.5 11.8 11.1
1, 2, 3 surface tension values from Refs. [5,6,2].
known quality of RE170 with a lower saturation pressure was introduced into the cell by cooling the outside of the bulk with ice water. Second, R290 with a higher saturation pressure was introduced into a cylinder and connected to the cell put in a thermostat. When the temperature of the thermostat was down to 253 K, R290 was introduced to the cell by heating the cylinder with a hot-air generator for at least 20 min. The masses of refrigerants and cylinders were precisely measured by a balance (Shimadzu BW4200H) with a resolution of 0.01 g. Since the mass of refrigerant was about 100 g, the uncertainty of the composition of this mixture was estimated to be better than 0.01% in mass fraction. The RE170(1) + R290(2) mixtures were prepared with mass factions w1 of 0.3007, 0.4975 and 0.6949. 3. Results and discussion In this work three capillaries were selected and their bare radii were: r1 = (0.1556 ± 0.0002) mm, r2 = (0.3005 ± 0.0001) mm, r3 = (0.4528 ± 0.0008) mm. Their radii were determined by partially filling the capillaries with plugs of mercury. The plugs were weighed and their lengths were measured with a traveling microscope. The procedure was repeated at least six times for each capillary with different plugs of mercury. From Eq. (1) the surface tension could be obtained by measuring the height difference between two different capillaries, so two sets of surface tension results were obtained using the height difference between capillaries 1 and 2 and between capillaries 1 and 3. The surface tension of pure RE170 and R290 were measured along the saturation line from 278 to 303 K in order to test the reliability of the experimental apparatus. The densities of saturated liquid and vapor were obtained using NIST REFPROP 8.0 [4]. The experimental data are listed in Table 1 and compared with the experimental data from Refs. [2,5,6]. The results indicate that the maximum deviations for the surface tension of RE170 and R290 are 0.13 and 0.12 mN m−1 , respectively. The surface tension of the mixtures of RE170(1) + R290(2) at three mass fractions w1 of 0.3007, 0.4975 and 0.6949 were measured, and 114 experimental data were obtained and showed in Table 2 and Fig. 1. The densities of saturated liquid and vapor were also obtained from NIST REFPROP 8.0. The uncertainties in density are 0.2% in the liquid phase and vapor phase. The surface tension decreases as the temperature rises and becomes zero at the critical temperature, which means the surface tension against the reduced temperature (Tr = T/Tc ). The surface tension of pure refrigerant is usually correlated as a van der Waals type correlation:
= 0 1 −
T Tc
Fig. 1. Experimental data of mixture refrigerant RE170 + R290; (+) R290; (×) RE170; () 12 ,wRE170 = 0.3007; () 13 ,wRE170 = 0.3007; () 12 ,wRE170 = 0.4975; () 13 ,wRE170 = 0.4975; (♦) 12 ,wRE170 = 0.6949; (夽) 13 ,wRE170 = 0.6949.
where 0 and n are empirical parameters obtained from the experimental data. Tc is the critical temperature. The advantage of Eq. (2) is the better extrapolation compared to the other correlations [7]. The value of n normally falls between 1.2 and 1.3 for most fluids. For RE170, 0 and n are 62.401 mN m−1 and 1.223 [2], respectively. For R290, 0 and n are 55.28 mN m−1 and 1.258 [5], respectively.
n (2)
Fig. 2. Deviations of experimental surface tension data of RE170 + R290 from Eq. (3) C = 3.35, () wRE170 = 0.3007; () wRE170 = 0.4975; () wRE170 = 0.6949.
152
S. Bi et al. / Fluid Phase Equilibria 298 (2010) 150–153
Table 2 Surface tension data of RE170(1) + R290(2). T/K
l /kg m−3
g /kg m−3
/mN m−1
a2 /mm2 (1, 2)
(1, 3)
(1, 2)
(1, 3)
3.33 3.96 4.70 5.64 6.62 7.70 9.00 10.44 12.06 13.87 15.90 18.16 20.74 23.56 26.78 30.31 34.35 38.82 43.94
5.051 4.844 4.696 4.509 4.315 4.167 3.979 3.792 3.599 3.418 3.211 3.024 2.792 2.637 2.456 2.276 2.114 1.914 1.733
5.046 4.847 4.695 4.500 4.320 4.173 3.979 3.794 3.604 3.419 3.230 3.054 2.827 2.637 2.471 2.276 2.120 1.902 1.717
15.2 14.5 13.9 13.1 12.4 11.8 11.1 10.5 9.8 9.1 8.4 7.8 7.0 6.5 5.9 5.3 4.8 4.2 3.7
15.2 14.5 13.9 13.1 12.4 11.8 11.1 10.5 9.8 9.1 8.5 7.9 7.1 6.5 5.9 5.3 4.8 4.2 3.7
653.7 647.5 641.2 634.1 627.8 620.8 613.8 606.7 599.4 592.0 584.4 576.6 568.5 560.2 551.4 542.5 533.1 523.5 513.2
2.92 3.50 4.18 5.03 5.89 6.94 8.12 9.45 10.95 12.62 14.50 16.59 18.95 21.56 24.55 27.81 31.54 35.65 40.35
5.031 4.870 4.696 4.522 4.386 4.218 4.018 3.850 3.689 3.521 3.321 3.153 2.973 2.792 2.572 2.424 2.237 2.050 1.856
5.027 4.875 4.704 4.529 4.391 4.216 4.031 3.860 3.690 3.519 3.320 3.163 2.974 2.803 2.599 2.438 2.239 2.073 1.864
16.0 15.4 14.7 13.9 13.4 12.7 11.9 11.3 10.6 10.0 9.3 8.7 8.0 7.4 6.6 6.1 5.5 4.9 4.3
16.0 15.4 14.7 14.0 13.4 12.7 12.0 11.3 10.6 10.0 9.3 8.7 8.0 7.4 6.7 6.1 5.5 5.0 4.3
688.3 681.7 675.3 668.4 661.8 654.8 647.7 640.4 633.0 625.5 617.8 610.0 601.7 593.5 584.7 575.9 566.6 557.0 547.0
2.53 3.07 3.68 4.42 5.22 6.16 7.23 8.45 9.82 11.36 13.10 15.00 17.20 19.58 22.32 25.33 28.71 32.47 36.72
5.135 5.019 4.818 4.664 4.476 4.309 4.115 3.979 3.786 3.689 3.502 3.295 3.166 3.005 2.798 2.631 2.437 2.276 2.088
5.126 4.984 4.809 4.657 4.482 4.320 4.126 3.974 3.784 3.671 3.495 3.296 3.168 3.007 2.803 2.637 2.461 2.281 2.110
17.3 16.7 15.9 15.2 14.4 13.7 12.9 12.3 11.6 11.1 10.4 9.6 9.1 8.4 7.7 7.1 6.4 5.8 5.2
17.2 16.6 15.8 15.2 14.4 13.7 12.9 12.3 11.6 11.0 10.4 9.6 9.1 8.5 7.7 7.1 6.5 5.9 5.3
w1 = 0.3007 243.56 248.27 253.08 258.42 263.33 268.05 273.14 278.13 283.13 288.12 293.11 298.08 303.15 308.11 313.17 318.13 323.17 328.12 333.12
618.9 613.0 606.9 600.0 593.5 587.1 580.1 573.1 566.0 558.6 551.1 543.3 535.2 526.9 518.2 509.3 499.8 490.0 479.5
w1 = 0.4975 243.40 248.19 253.09 258.38 263.11 268.16 273.16 278.15 283.16 288.15 293.13 298.09 303.12 308.08 313.17 318.13 323.17 328.13 333.14 w1 = 0.6949 243.46 248.43 253.23 258.34 263.16 268.16 273.15 278.16 283.16 288.15 293.17 298.10 303.17 308.11 313.18 318.16 323.17 328.14 333.13
The critical temperature of RE170 is 400.378 K from Ref. [2], and that of R290 is 369.818 K from Ref. [5]. The surface tension of the refrigerant mixture was developed as the following expressions: = w1 1 + w2 2 + Cw1 w2
Fitting the experimental data of this work with Eq. (3), the parameter C is found to be 3.35. Fig. 2 shows the deviation of the present data from Eq. (3) at different mass fractions. The average deviation and the maximum deviation of the experimental data to the calculated data are 0.04 and 0.22 mN m−1 , respectively.
(3)
where 1 and 2 are the surface tension of the pure components, and w1 and w2 are the mass fractions. C is an empirical parameter obtained from the experimental data.
4. Conclusion The surface tension of the refrigerant mixture RE170 + R290 was measured over a temperature range from 243 to 333 K using the dif-
S. Bi et al. / Fluid Phase Equilibria 298 (2010) 150–153
ferential capillary rise method. The uncertainty of surface tension measurements is estimated to be within ±0.2 mN m−1 . On the basis of the present results, a correlation of the surface tension for the binary refrigerant mixture RE170 + R290 was developed. The result can be used to evaluate the heat transfer, flow and phase change of this mixture refrigerant. List of symbols a2 capillary constant g local gravitational acceleration h capillary rise height n fitting parameter, exponent r radius of capillary T temperature w mass fraction Greek letters L saturated liquid density
g
153
saturated vapor density the surface tension
Acknowledgments This study was supported by the National Natural Science Foundation of China (Grant No. 50806060) and the Specialized Research Fund for the Doctoral Program of Higher Education (200806981012). References [1] [2] [3] [4]
J.K. Park, D. Jung, Energy Build. 39 (2007) 675–680. J.T. Wu, F.K. Wang, Z.G. Liu, C. Ren, J. Chem. Eng. Data 48 (2003) 1571–1573. S.S. Bi, G.J. Zhao, J.T. Wu, Fluid Phase Equilib. 287 (2009) 25–27. E.W. Lemmon, M.L. Huber, M.O. McLinden, NIST Standard Reference Database 23, Version 8.0, 2007. [5] K. Tanaka, Y. Higashi, Int. J. Refrig. 30 (2007) 1368–1373. [6] H. Lin, Y.Y. Duan, J. Chem. Eng. Data 48 (2003) 1360–1363. [7] R. Heide, Int. J. Refrig. 20 (1997) 496–503.
Contents lists available at ScienceDirect
Fluid Phase Equilibria journal homepage: www.elsevier.com/locate/fluid
Surface tension of dimethyl ether + propane from 243 to 333 K Shengshan Bi ∗ , Xin Li, Guanjia Zhao, Jiangtao Wu State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an Shaanxi 710049, People’s Republic of China
a r t i c l e
i n f o
Article history: Received 9 April 2010 Received in revised form 6 July 2010 Accepted 30 July 2010 Available online 7 August 2010 Keywords: Binary mixture refrigerant RE170 + R290 Surface tension
a b s t r a c t The surface tension of the binary refrigerant mixture dimethyl ether (RE170)(1) + propane (R290)(2) at three mass fraction of w1 = 0.3007, 0.4975 and 0.6949 was measured in the temperature range from 243 to 333 K with a differential capillary rise method. The uncertainties of the measurement of the temperature and the surface tension were estimated to be within ±10 mK and ±0.2 mN m−1 , respectively. A correlation for the surface tension of the binary refrigerant mixture RE170 + R290 was developed as a function of the composition. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Dimethyl ether (RE170) is an important clean alternative fuel, which has been used in the automobile and gas stove. Furthermore, RE170 and its mixture with hydrofluorocarbon (HFC) or hydrocarbon (HC) refrigerants have been shown to have excellent efficiency and environmental property and believed to be a promising alternative refrigerant. Recently, RE170 + R290 + R1270 mixture was used in residential air-conditioner, and the experimental results showed that RE170 + R290 + R1270 can be used as a drop-in substitute to R22 with a high coefficient of performance [1]. Surface tension as a basic thermophysical property influencing the heat transfer, flow and phase change characteristic of the working fluid, is useful for the condenser and evaporator design in a refrigerator. Unfortunately, there are no surface tension data of mixture refrigerants RE170 + R290 in the literature. In this work, the surface tension of RE170 + R290 was measured systematically at three mass fractions in the temperature range from 243 to 333 K using the differential capillary rise method under vapor–liquid equilibrium conditions. The experimental surface tension data was correlated as a function of the composition.
2. Experimental The surface tension was measured with a differential capillary rise method. The apparatus was described in detail in our previous work [2,3] and is briefly described here.
∗ Corresponding author. Tel.: +86 29 82666875; fax: +86 29 82668789. E-mail address: [email protected] (S. Bi). 0378-3812/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.fluid.2010.07.026
During the experiment, the capillary rise difference h0 was measured, and the surface tension can be calculated using the following expression as =
h0 + r1 /3 − r2 /3 (L − g )g = a2 (L − g )g 2(1/r1 − 1/r2 )
(1)
where is the surface tension, g is the local gravitational acceleration (in this work, g = 9.7965 m s−2 ), L and g are the densities of saturated liquid and vapor, respectively. h0 is the height difference of the meniscus bottom of the two capillaries. r1 and r2 are the bare radii of the two different capillaries used in the experiments. a2 is the capillary constant. The capillaries were placed in a small pressure cell with observation windows, and the pressure cell was placed in a thermostatic bath for which the temperature stability was within ±10 mK in 2 h. Silicon oil was chosen as a thermostat fluid. The temperature measurement system consisted of an Agilent 3458A and two 25 standard platinum resistance thermometers. One thermometer (No. 68033) is used in the temperature range 83.8058–273.16 K, and the other (No. 68115) is used in the temperature range 273.15–933.473 K. The thermometers were calibrated on the ITS90 scale at the National Institute of Metrology of China. The total uncertainty of temperature for surface tension was less than ±10 mK. The capillary rise difference was measured with a cathetometer with an uncertainty ±0.02 mm. In this work, all the measurements were carried out under equilibrium conditions between the liquid and its saturated vapor, and the uncertainty of surface tension was estimated to be within ±0.2 mN m−1 . RE170 and R290 were provided by Shandong Jiutai Chemical Co. Ltd. and Jinlaier Company. The mass purity was better than 99.95%. The samples were firstly purified by freeze–pump–thaw cycles. The mixture was prepared by the following process. First, a
S. Bi et al. / Fluid Phase Equilibria 298 (2010) 150–153
151
Table 1 Surface tension of R290 and RE170. T/K
l /kg m−3
g /kg m−3
/mN m−1
R290
278.18 283.18 288.19 293.18 298.10 303.18
521.7 514.7 507.5 500.0 492.4 484.4
11.98 13.79 15.83 18.09 20.59 23.47
9.5 8.9 8.3 7.7 7.1 6.4
RE170
278.16 283.21 288.17 293.15 298.10 303.13
692.6 684.9 677.3 669.5 661.6 653.3
6.90 8.09 9.41 10.90 12.55 14.43
14.7 13.9 13.1 12.6 11.8 11.0
1 /mN m−1
2 /mN m−1
9.6 8.9 8.3 7.6 7.0 6.4
9.5 8.9 8.2 7.6 7.0 6.4
3 /mN m−1
14.6 13.9 13.2 12.5 11.8 11.1
1, 2, 3 surface tension values from Refs. [5,6,2].
known quality of RE170 with a lower saturation pressure was introduced into the cell by cooling the outside of the bulk with ice water. Second, R290 with a higher saturation pressure was introduced into a cylinder and connected to the cell put in a thermostat. When the temperature of the thermostat was down to 253 K, R290 was introduced to the cell by heating the cylinder with a hot-air generator for at least 20 min. The masses of refrigerants and cylinders were precisely measured by a balance (Shimadzu BW4200H) with a resolution of 0.01 g. Since the mass of refrigerant was about 100 g, the uncertainty of the composition of this mixture was estimated to be better than 0.01% in mass fraction. The RE170(1) + R290(2) mixtures were prepared with mass factions w1 of 0.3007, 0.4975 and 0.6949. 3. Results and discussion In this work three capillaries were selected and their bare radii were: r1 = (0.1556 ± 0.0002) mm, r2 = (0.3005 ± 0.0001) mm, r3 = (0.4528 ± 0.0008) mm. Their radii were determined by partially filling the capillaries with plugs of mercury. The plugs were weighed and their lengths were measured with a traveling microscope. The procedure was repeated at least six times for each capillary with different plugs of mercury. From Eq. (1) the surface tension could be obtained by measuring the height difference between two different capillaries, so two sets of surface tension results were obtained using the height difference between capillaries 1 and 2 and between capillaries 1 and 3. The surface tension of pure RE170 and R290 were measured along the saturation line from 278 to 303 K in order to test the reliability of the experimental apparatus. The densities of saturated liquid and vapor were obtained using NIST REFPROP 8.0 [4]. The experimental data are listed in Table 1 and compared with the experimental data from Refs. [2,5,6]. The results indicate that the maximum deviations for the surface tension of RE170 and R290 are 0.13 and 0.12 mN m−1 , respectively. The surface tension of the mixtures of RE170(1) + R290(2) at three mass fractions w1 of 0.3007, 0.4975 and 0.6949 were measured, and 114 experimental data were obtained and showed in Table 2 and Fig. 1. The densities of saturated liquid and vapor were also obtained from NIST REFPROP 8.0. The uncertainties in density are 0.2% in the liquid phase and vapor phase. The surface tension decreases as the temperature rises and becomes zero at the critical temperature, which means the surface tension against the reduced temperature (Tr = T/Tc ). The surface tension of pure refrigerant is usually correlated as a van der Waals type correlation:
= 0 1 −
T Tc
Fig. 1. Experimental data of mixture refrigerant RE170 + R290; (+) R290; (×) RE170; () 12 ,wRE170 = 0.3007; () 13 ,wRE170 = 0.3007; () 12 ,wRE170 = 0.4975; () 13 ,wRE170 = 0.4975; (♦) 12 ,wRE170 = 0.6949; (夽) 13 ,wRE170 = 0.6949.
where 0 and n are empirical parameters obtained from the experimental data. Tc is the critical temperature. The advantage of Eq. (2) is the better extrapolation compared to the other correlations [7]. The value of n normally falls between 1.2 and 1.3 for most fluids. For RE170, 0 and n are 62.401 mN m−1 and 1.223 [2], respectively. For R290, 0 and n are 55.28 mN m−1 and 1.258 [5], respectively.
n (2)
Fig. 2. Deviations of experimental surface tension data of RE170 + R290 from Eq. (3) C = 3.35, () wRE170 = 0.3007; () wRE170 = 0.4975; () wRE170 = 0.6949.
152
S. Bi et al. / Fluid Phase Equilibria 298 (2010) 150–153
Table 2 Surface tension data of RE170(1) + R290(2). T/K
l /kg m−3
g /kg m−3
/mN m−1
a2 /mm2 (1, 2)
(1, 3)
(1, 2)
(1, 3)
3.33 3.96 4.70 5.64 6.62 7.70 9.00 10.44 12.06 13.87 15.90 18.16 20.74 23.56 26.78 30.31 34.35 38.82 43.94
5.051 4.844 4.696 4.509 4.315 4.167 3.979 3.792 3.599 3.418 3.211 3.024 2.792 2.637 2.456 2.276 2.114 1.914 1.733
5.046 4.847 4.695 4.500 4.320 4.173 3.979 3.794 3.604 3.419 3.230 3.054 2.827 2.637 2.471 2.276 2.120 1.902 1.717
15.2 14.5 13.9 13.1 12.4 11.8 11.1 10.5 9.8 9.1 8.4 7.8 7.0 6.5 5.9 5.3 4.8 4.2 3.7
15.2 14.5 13.9 13.1 12.4 11.8 11.1 10.5 9.8 9.1 8.5 7.9 7.1 6.5 5.9 5.3 4.8 4.2 3.7
653.7 647.5 641.2 634.1 627.8 620.8 613.8 606.7 599.4 592.0 584.4 576.6 568.5 560.2 551.4 542.5 533.1 523.5 513.2
2.92 3.50 4.18 5.03 5.89 6.94 8.12 9.45 10.95 12.62 14.50 16.59 18.95 21.56 24.55 27.81 31.54 35.65 40.35
5.031 4.870 4.696 4.522 4.386 4.218 4.018 3.850 3.689 3.521 3.321 3.153 2.973 2.792 2.572 2.424 2.237 2.050 1.856
5.027 4.875 4.704 4.529 4.391 4.216 4.031 3.860 3.690 3.519 3.320 3.163 2.974 2.803 2.599 2.438 2.239 2.073 1.864
16.0 15.4 14.7 13.9 13.4 12.7 11.9 11.3 10.6 10.0 9.3 8.7 8.0 7.4 6.6 6.1 5.5 4.9 4.3
16.0 15.4 14.7 14.0 13.4 12.7 12.0 11.3 10.6 10.0 9.3 8.7 8.0 7.4 6.7 6.1 5.5 5.0 4.3
688.3 681.7 675.3 668.4 661.8 654.8 647.7 640.4 633.0 625.5 617.8 610.0 601.7 593.5 584.7 575.9 566.6 557.0 547.0
2.53 3.07 3.68 4.42 5.22 6.16 7.23 8.45 9.82 11.36 13.10 15.00 17.20 19.58 22.32 25.33 28.71 32.47 36.72
5.135 5.019 4.818 4.664 4.476 4.309 4.115 3.979 3.786 3.689 3.502 3.295 3.166 3.005 2.798 2.631 2.437 2.276 2.088
5.126 4.984 4.809 4.657 4.482 4.320 4.126 3.974 3.784 3.671 3.495 3.296 3.168 3.007 2.803 2.637 2.461 2.281 2.110
17.3 16.7 15.9 15.2 14.4 13.7 12.9 12.3 11.6 11.1 10.4 9.6 9.1 8.4 7.7 7.1 6.4 5.8 5.2
17.2 16.6 15.8 15.2 14.4 13.7 12.9 12.3 11.6 11.0 10.4 9.6 9.1 8.5 7.7 7.1 6.5 5.9 5.3
w1 = 0.3007 243.56 248.27 253.08 258.42 263.33 268.05 273.14 278.13 283.13 288.12 293.11 298.08 303.15 308.11 313.17 318.13 323.17 328.12 333.12
618.9 613.0 606.9 600.0 593.5 587.1 580.1 573.1 566.0 558.6 551.1 543.3 535.2 526.9 518.2 509.3 499.8 490.0 479.5
w1 = 0.4975 243.40 248.19 253.09 258.38 263.11 268.16 273.16 278.15 283.16 288.15 293.13 298.09 303.12 308.08 313.17 318.13 323.17 328.13 333.14 w1 = 0.6949 243.46 248.43 253.23 258.34 263.16 268.16 273.15 278.16 283.16 288.15 293.17 298.10 303.17 308.11 313.18 318.16 323.17 328.14 333.13
The critical temperature of RE170 is 400.378 K from Ref. [2], and that of R290 is 369.818 K from Ref. [5]. The surface tension of the refrigerant mixture was developed as the following expressions: = w1 1 + w2 2 + Cw1 w2
Fitting the experimental data of this work with Eq. (3), the parameter C is found to be 3.35. Fig. 2 shows the deviation of the present data from Eq. (3) at different mass fractions. The average deviation and the maximum deviation of the experimental data to the calculated data are 0.04 and 0.22 mN m−1 , respectively.
(3)
where 1 and 2 are the surface tension of the pure components, and w1 and w2 are the mass fractions. C is an empirical parameter obtained from the experimental data.
4. Conclusion The surface tension of the refrigerant mixture RE170 + R290 was measured over a temperature range from 243 to 333 K using the dif-
S. Bi et al. / Fluid Phase Equilibria 298 (2010) 150–153
ferential capillary rise method. The uncertainty of surface tension measurements is estimated to be within ±0.2 mN m−1 . On the basis of the present results, a correlation of the surface tension for the binary refrigerant mixture RE170 + R290 was developed. The result can be used to evaluate the heat transfer, flow and phase change of this mixture refrigerant. List of symbols a2 capillary constant g local gravitational acceleration h capillary rise height n fitting parameter, exponent r radius of capillary T temperature w mass fraction Greek letters L saturated liquid density
g
153
saturated vapor density the surface tension
Acknowledgments This study was supported by the National Natural Science Foundation of China (Grant No. 50806060) and the Specialized Research Fund for the Doctoral Program of Higher Education (200806981012). References [1] [2] [3] [4]
J.K. Park, D. Jung, Energy Build. 39 (2007) 675–680. J.T. Wu, F.K. Wang, Z.G. Liu, C. Ren, J. Chem. Eng. Data 48 (2003) 1571–1573. S.S. Bi, G.J. Zhao, J.T. Wu, Fluid Phase Equilib. 287 (2009) 25–27. E.W. Lemmon, M.L. Huber, M.O. McLinden, NIST Standard Reference Database 23, Version 8.0, 2007. [5] K. Tanaka, Y. Higashi, Int. J. Refrig. 30 (2007) 1368–1373. [6] H. Lin, Y.Y. Duan, J. Chem. Eng. Data 48 (2003) 1360–1363. [7] R. Heide, Int. J. Refrig. 20 (1997) 496–503.