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Surface tension of pentafluoroethane + 1,1-difluoroethane from (243 to 328) K
Fluid Phase Equilibria 287 (2009) 23–25
Contents lists available at ScienceDirect
Fluid Phase Equilibria journal homepage: www.elsevier.com/locate/fluid
Surface tension of pentafluoroethane + 1,1-difluoroethane from (243 to 328) K Shengshan Bi, 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 30 May 2009 Received in revised form 2 September 2009 Accepted 7 September 2009 Available online 15 September 2009 Keywords: Binary mixture refrigerant HFC-152a + HFC-125 Surface tension
a b s t r a c t The surface tension of the binary refrigerant mixture pentafluoroethane (HFC-125) + 1,1-difluoroethane (HFC-152a) was measured in the temperature range from (243 to 328) K with a differential capillary rise method, for three compositions around the composition of the optimum refrigeration performance (HFC-125 + HFC152a, 15%/85%). 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 HFC-152a + HFC-125 was developed as a function of the composition. © 2009 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Under the burden of the ozone layer depletion and global warming, developing an environment friendly refrigerant has been a worldwide issue. Though the global warming potential (GWP) of some hydrofluorocarbon (HFC) refrigerants is relatively high, HFC refrigerants and their mixtures such as R-410A and R-407C have been accepted as one of the alternative refrigerants in many countries. Recently, a HFC-125 + HFC-152a mixture was used in a domestic refrigerator, and the experimental results showed that HFC-125 + HFC-152a can be used as a drop-in substitute to CFC-12, and the optimum composition is about 15%/85% in mass percent [1]. In addition, HFC-125 + HFC-152a + HFC-32 with a mass percent composition of 18%/48%/34%, can be an alternative for HCFC-22 and could be a potential refrigerant for domestic air-conditioners [2]. The surface tension is a basic thermophysical property which influences the heat transfer, flow and phase change of the working fluid, and is needed in the condenser and evaporator design of refrigerators. Heide [3] had measured the surface tension of HFC-125 + HFC-152a at three compositions, but there were only seven data points for each composition. In this work, the surface tension of HFC-125 + HFC-152a was measured systematically at three mass compositions around the optimum composition for the refrigeration performance in the temperature range from (243 to 328) K. The experimental surface tension data was correlated as a function of the composition.
In this work, the same experimental apparatus and procedure was used to measure the surface tensions as once used for the determination of the surface tension of some oxygenated fuels in our previous work [4–6]. During the experiment, the capillary rise difference h0 was measured, and the surface tension can be calculated using the following expression as:
∗ Corresponding author. Tel.: +86 29 82666875; fax: +86 29 82668789. E-mail address: [email protected] (J. Wu). 0378-3812/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.fluid.2009.09.005
=
(h0 + r1 /3 − r2 /3) (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 radii of the two different capillaries used in the experiments. In general, the capillary constant a2 is defined as: a2 =
h0 + r1 /3 − r2 /3 1/r1 − 1/r2
(2)
The bore radii of two capillaries used in this work are: r1 = (0.1712 ± 0.0001) mm, r2 = (0.2718 ± 0.0002) 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. 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
24
S. Bi et al. / Fluid Phase Equilibria 287 (2009) 23–25 Table 2 Surface tension data of HFC-125 + HFC-152a (9.70%/90.30% in mass percent).
Table 1 Surface tension of HFC-152a and HC-600a. Refrigerant
T (K)
L (kg m−3 )
g (kg m−3 )
(mN m−1 )
r (mN m−1 )
T (K)
L (kg m−3 )
g (kg m−3 )
a2 (mm2 )
(mN m−1 )
HFC-152a
298.183 303.228 308.195 313.135
899.366 886.399 873.236 859.708
18.489 21.405 24.633 28.270
9.75 9.06 8.51 7.73
9.73 9.06 8.40 7.76
HC-600a
313.170 318.131 323.163 328.128
531.160 524.400 517.353 510.189
13.673 15.521 17.601 19.875
8.28 7.70 7.18 6.67
8.41 7.86 7.31 6.78
243.165 248.126 253.550 258.109 263.065 268.122 273.182 278.182 283.130 288.165 293.171 298.095 303.165 308.095 313.157 318.115 323.160 328.110
1064.503 1053.355 1040.965 1030.376 1018.666 1006.481 994.026 981.432 968.659 955.306 941.634 927.745 912.928 897.937 881.841 865.236 847.267 828.199
3.784 4.642 5.751 6.836 8.195 9.797 11.64 13.73 16.10 18.84 21.94 25.42 29.50 34.03 39.37 45.41 52.62 61.10
3.261 3.145 3.011 2.905 2.808 2.716 2.595 2.494 2.392 2.304 2.166 2.082 1.972 1.865 1.750 1.620 1.482 1.385
17.0 16.2 15.3 14.6 13.9 13.3 12.5 11.8 11.2 10.6 9.8 9.2 8.5 7.9 7.2 6.5 5.8 5.2
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 ITS-90 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 . Refrigerants HFC-125 and HFC-152a were provided by Zibo Huaan Company. The mass purity was better than 99.95%. In this work, the refrigerants were firstly purified by freeze-pump-thaw cycles. The mixture was prepared by the following process. First, a known quality of HFC-125 and HFC-152a were introduced into two separate cylinders. Then, the two cylinders were connected by a two-way valve, and the refrigerants HFC-125 and HFC-152a were mixed adequately by cooling one of the cylinders with liquid nitrogen and heating the other one 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 HFC-125 + HFC-152a mixtures were prepared with mass factions of 9.70%/90.30%, 20.19%/79.81% and 29.96%/70.04%. 3. Result and discussion The surface tension of pure HFC-152a and HC-600a was measured along the saturation line from (298 to 313) K in order to test the reliability of the experimental apparatus. The purity of the HC-600a, which was supplied by the Dupont Company, was better than 99.8%. The densities of saturated liquid and vapor were obtained using NIST REFPROP 8.0 [7]. The experimental data are listed in Table 1 and compared with the calculated data from NIST REFPROP 8.0. The results indicate that the maximum deviations for the surface tension of HFC-152a and HC-600a are 0.11 mN m−1 and 0.16 mN m−1 , respectively. In this work, the surface tension of the mixtures of HFC125 + HFC-152a at compositions of 9.70%/90.30%, 20.19%/79.81% and 29.96%/70.04% were measured, and 54 experimental data points were obtained which are given in Tables 2–4 and shown in Fig. 1. The densities of saturated liquid and vapor were also obtained from the NIST REFPROP 8.0. The surface tension of pure refrigerant is usually correlated as a van der Waals type correlation:
= 0 1 −
T Tc
n (3)
where 0 and n are the empirical parameters obtained from the experimental data. Tc is the critical temperature. In this work, the
Table 3 Surface tension data of HFC-125 + HFC-152a (20.19%/79.81% in mass percent). T (K)
L (kg m−3 )
g (kg m−3 )
a2 (mm2 )
(mN m−1 )
243.080 248.095 253.125 258.157 263.185 268.170 273.189 278.420 283.153 288.160 293.145 298.083 303.133 308.095 313.105 318.109 323.138 328.102
1109.032 1096.790 1084.296 1071.559 1058.571 1045.407 1031.833 1017.303 1003.779 989.031 973.837 958.210 941.538 924.353 906.023 886.488 865.224 841.908
5.028 6.154 7.475 9.014 10.795 12.831 15.185 18.006 20.923 24.437 28.434 32.958 38.260 44.259 51.277 59.499 69.382 81.459
3.053 2.951 2.854 2.757 2.628 2.545 2.443 2.318 2.198 2.096 2.018 1.930 1.814 1.708 1.602 1.496 1.371 1.274
16.5 15.8 15.1 14.4 13.5 12.9 12.2 11.4 10.6 9.9 9.4 8.8 8.0 7.4 6.7 6.1 5.4 4.8
parameters 0 and n are from Ref. [8]. For HFC-125, 0 and n are 52.60 mN m−1 and 1.240, respectively. For HFC-152a, 0 and n are 59.06 mN m−1 and 1.221, respectively. The critical temperature of HFC-125 is 339.17 from Ref. [9], and that of HFC-152a is 386.41 from Ref. [10].
Table 4 Surface tension data of HFC-125 + HFC-152a (29.96%/70.04% in mass percent). T (K)
L (kg m−3 )
g (kg m−3 )
a2 (mm2 )
(mN m−1 )
243.215 248.120 253.133 258.163 263.170 268.177 273.180 278.170 283.170 288.179 293.176 298.106 303.175 308.118 313.186 318.164 323.173 328.160
1149.981 1137.117 1123.725 1110.008 1096.050 1081.753 1067.091 1052.046 1036.494 1020.370 1003.660 986.473 967.942 948.868 928.049 906.010 881.691 854.302
6.234 7.575 9.172 11.034 13.177 15.645 18.477 21.713 25.423 29.674 34.529 40.014 46.501 53.819 62.573 72.749 85.127 100.641
2.785 2.711 2.614 2.535 2.448 2.327 2.226 2.106 2.046 1.962 1.828 1.727 1.639 1.523 1.445 1.352 1.269 1.163
15.6 15.0 14.3 13.7 13.0 12.2 11.4 10.6 10.1 9.5 8.7 8.0 7.4 6.7 6.1 5.5 5.0 4.3
S. Bi et al. / Fluid Phase Equilibria 287 (2009) 23–25
25
Fitting the experimental data of this work and the data of Heide [3] with Eq. (4), the parameter C is found to be 0.40 which is a little different from the value 0.23 as obtained by Heide [3]. Fig. 2 shows the deviation of the present data from the Eq. (4) at different mass fractions. The average deviation and the maximum deviation of the experimental data to the calculated data are 0.02 mN m−1 and 0.23 mN m−1 , respectively. 4. Conclusion The surface tension of the refrigerant mixture HFC-125 + HFC152a was measured over a temperature range from (243 to 328) K using the differential 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 HFC-152a + HFC-125 was developed. The result can be used to evaluate the heat transfer, flow and phase change of this mixture refrigerant. Fig. 1. Experimental data of mixture refrigerant HFC-125 + HFC-152a; (+) HFC-152a; (×) HFC-125; (♦) wHFC-125 = 0.0970; () wHFC-125 = 0.2019; (夽) wHFC-125 = 0.2996.
Acknowledgments This study was supported by the National Natural Science Foundation of China (Grant No. 50806060) and the Foundation for the Author of National Excellent Doctoral Disseration (Grant No. 200540). 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 saturated vapor density the surface tension
Fig. 2. Deviations of experimental surface tension data of HFC-125 + HFC-152a from Eq. (4). C = 0.40, () wHFC-125 = 0.800, Heid (Ref. [3]); (䊉) wHFC-125 = 0.554, Heid (Ref. [3]); () wHFC-125 = 0.265, Heid (Ref. [3]); (♦) wHFC-125 = 0.0970; () wHFC-125 = 0.2019; (夽) wHFC-125 = 0.2996.
The surface tension of the refrigerant mixture was developed as the following expressions: = w1 1 + w2 2 + Cw1 w2
(4)
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.
References [1] [2] [3] [4] [5] [6] [7]
M.G. He, T.C. Li, Z.G. Liu, Appl. Therm. Eng. 25 (2005) 1169–1181. J.T. Wu, Y.J. Chu, J. Hu, Z.G. Liu, Int. J. Refrig. 32 (2009) 1049–1057. R. Heide, Int. J. Refrig. 20 (1997) 496–503. J.T. Wu, F.K. Wang, Z.G. Liu, C. Ren, J. Chem. Eng. Data 48 (2003) 1571–1573. F.K. Wang, J.T. Wu, Z.G. Liu, Fluid Phase Equilib. 220 (2004) 123–126. X.P. Wang, J. Pan, J.T. Wu, Z.G. Liu, J. Chem. Eng. Data 51 (2006) 1394–1397. E.W. Lemmon, M.L. Huber, M.O. McLinden, NIST Standard Reference Database 23, version 8.0, 2007. [8] M. Okada, Y. Higashi, Int. J. Thermophys. 16 (1999) 791–800. [9] Y. Higashi, Int. J. Refrig. 17 (1994) 524–531. [10] Y. Higashi, M. Ashizawa, Y. Kabata, JSME Int. J. 30 (1987) 1106–1112.
Contents lists available at ScienceDirect
Fluid Phase Equilibria journal homepage: www.elsevier.com/locate/fluid
Surface tension of pentafluoroethane + 1,1-difluoroethane from (243 to 328) K Shengshan Bi, 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 30 May 2009 Received in revised form 2 September 2009 Accepted 7 September 2009 Available online 15 September 2009 Keywords: Binary mixture refrigerant HFC-152a + HFC-125 Surface tension
a b s t r a c t The surface tension of the binary refrigerant mixture pentafluoroethane (HFC-125) + 1,1-difluoroethane (HFC-152a) was measured in the temperature range from (243 to 328) K with a differential capillary rise method, for three compositions around the composition of the optimum refrigeration performance (HFC-125 + HFC152a, 15%/85%). 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 HFC-152a + HFC-125 was developed as a function of the composition. © 2009 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Under the burden of the ozone layer depletion and global warming, developing an environment friendly refrigerant has been a worldwide issue. Though the global warming potential (GWP) of some hydrofluorocarbon (HFC) refrigerants is relatively high, HFC refrigerants and their mixtures such as R-410A and R-407C have been accepted as one of the alternative refrigerants in many countries. Recently, a HFC-125 + HFC-152a mixture was used in a domestic refrigerator, and the experimental results showed that HFC-125 + HFC-152a can be used as a drop-in substitute to CFC-12, and the optimum composition is about 15%/85% in mass percent [1]. In addition, HFC-125 + HFC-152a + HFC-32 with a mass percent composition of 18%/48%/34%, can be an alternative for HCFC-22 and could be a potential refrigerant for domestic air-conditioners [2]. The surface tension is a basic thermophysical property which influences the heat transfer, flow and phase change of the working fluid, and is needed in the condenser and evaporator design of refrigerators. Heide [3] had measured the surface tension of HFC-125 + HFC-152a at three compositions, but there were only seven data points for each composition. In this work, the surface tension of HFC-125 + HFC-152a was measured systematically at three mass compositions around the optimum composition for the refrigeration performance in the temperature range from (243 to 328) K. The experimental surface tension data was correlated as a function of the composition.
In this work, the same experimental apparatus and procedure was used to measure the surface tensions as once used for the determination of the surface tension of some oxygenated fuels in our previous work [4–6]. During the experiment, the capillary rise difference h0 was measured, and the surface tension can be calculated using the following expression as:
∗ Corresponding author. Tel.: +86 29 82666875; fax: +86 29 82668789. E-mail address: [email protected] (J. Wu). 0378-3812/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.fluid.2009.09.005
=
(h0 + r1 /3 − r2 /3) (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 radii of the two different capillaries used in the experiments. In general, the capillary constant a2 is defined as: a2 =
h0 + r1 /3 − r2 /3 1/r1 − 1/r2
(2)
The bore radii of two capillaries used in this work are: r1 = (0.1712 ± 0.0001) mm, r2 = (0.2718 ± 0.0002) 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. 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
24
S. Bi et al. / Fluid Phase Equilibria 287 (2009) 23–25 Table 2 Surface tension data of HFC-125 + HFC-152a (9.70%/90.30% in mass percent).
Table 1 Surface tension of HFC-152a and HC-600a. Refrigerant
T (K)
L (kg m−3 )
g (kg m−3 )
(mN m−1 )
r (mN m−1 )
T (K)
L (kg m−3 )
g (kg m−3 )
a2 (mm2 )
(mN m−1 )
HFC-152a
298.183 303.228 308.195 313.135
899.366 886.399 873.236 859.708
18.489 21.405 24.633 28.270
9.75 9.06 8.51 7.73
9.73 9.06 8.40 7.76
HC-600a
313.170 318.131 323.163 328.128
531.160 524.400 517.353 510.189
13.673 15.521 17.601 19.875
8.28 7.70 7.18 6.67
8.41 7.86 7.31 6.78
243.165 248.126 253.550 258.109 263.065 268.122 273.182 278.182 283.130 288.165 293.171 298.095 303.165 308.095 313.157 318.115 323.160 328.110
1064.503 1053.355 1040.965 1030.376 1018.666 1006.481 994.026 981.432 968.659 955.306 941.634 927.745 912.928 897.937 881.841 865.236 847.267 828.199
3.784 4.642 5.751 6.836 8.195 9.797 11.64 13.73 16.10 18.84 21.94 25.42 29.50 34.03 39.37 45.41 52.62 61.10
3.261 3.145 3.011 2.905 2.808 2.716 2.595 2.494 2.392 2.304 2.166 2.082 1.972 1.865 1.750 1.620 1.482 1.385
17.0 16.2 15.3 14.6 13.9 13.3 12.5 11.8 11.2 10.6 9.8 9.2 8.5 7.9 7.2 6.5 5.8 5.2
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 ITS-90 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 . Refrigerants HFC-125 and HFC-152a were provided by Zibo Huaan Company. The mass purity was better than 99.95%. In this work, the refrigerants were firstly purified by freeze-pump-thaw cycles. The mixture was prepared by the following process. First, a known quality of HFC-125 and HFC-152a were introduced into two separate cylinders. Then, the two cylinders were connected by a two-way valve, and the refrigerants HFC-125 and HFC-152a were mixed adequately by cooling one of the cylinders with liquid nitrogen and heating the other one 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 HFC-125 + HFC-152a mixtures were prepared with mass factions of 9.70%/90.30%, 20.19%/79.81% and 29.96%/70.04%. 3. Result and discussion The surface tension of pure HFC-152a and HC-600a was measured along the saturation line from (298 to 313) K in order to test the reliability of the experimental apparatus. The purity of the HC-600a, which was supplied by the Dupont Company, was better than 99.8%. The densities of saturated liquid and vapor were obtained using NIST REFPROP 8.0 [7]. The experimental data are listed in Table 1 and compared with the calculated data from NIST REFPROP 8.0. The results indicate that the maximum deviations for the surface tension of HFC-152a and HC-600a are 0.11 mN m−1 and 0.16 mN m−1 , respectively. In this work, the surface tension of the mixtures of HFC125 + HFC-152a at compositions of 9.70%/90.30%, 20.19%/79.81% and 29.96%/70.04% were measured, and 54 experimental data points were obtained which are given in Tables 2–4 and shown in Fig. 1. The densities of saturated liquid and vapor were also obtained from the NIST REFPROP 8.0. The surface tension of pure refrigerant is usually correlated as a van der Waals type correlation:
= 0 1 −
T Tc
n (3)
where 0 and n are the empirical parameters obtained from the experimental data. Tc is the critical temperature. In this work, the
Table 3 Surface tension data of HFC-125 + HFC-152a (20.19%/79.81% in mass percent). T (K)
L (kg m−3 )
g (kg m−3 )
a2 (mm2 )
(mN m−1 )
243.080 248.095 253.125 258.157 263.185 268.170 273.189 278.420 283.153 288.160 293.145 298.083 303.133 308.095 313.105 318.109 323.138 328.102
1109.032 1096.790 1084.296 1071.559 1058.571 1045.407 1031.833 1017.303 1003.779 989.031 973.837 958.210 941.538 924.353 906.023 886.488 865.224 841.908
5.028 6.154 7.475 9.014 10.795 12.831 15.185 18.006 20.923 24.437 28.434 32.958 38.260 44.259 51.277 59.499 69.382 81.459
3.053 2.951 2.854 2.757 2.628 2.545 2.443 2.318 2.198 2.096 2.018 1.930 1.814 1.708 1.602 1.496 1.371 1.274
16.5 15.8 15.1 14.4 13.5 12.9 12.2 11.4 10.6 9.9 9.4 8.8 8.0 7.4 6.7 6.1 5.4 4.8
parameters 0 and n are from Ref. [8]. For HFC-125, 0 and n are 52.60 mN m−1 and 1.240, respectively. For HFC-152a, 0 and n are 59.06 mN m−1 and 1.221, respectively. The critical temperature of HFC-125 is 339.17 from Ref. [9], and that of HFC-152a is 386.41 from Ref. [10].
Table 4 Surface tension data of HFC-125 + HFC-152a (29.96%/70.04% in mass percent). T (K)
L (kg m−3 )
g (kg m−3 )
a2 (mm2 )
(mN m−1 )
243.215 248.120 253.133 258.163 263.170 268.177 273.180 278.170 283.170 288.179 293.176 298.106 303.175 308.118 313.186 318.164 323.173 328.160
1149.981 1137.117 1123.725 1110.008 1096.050 1081.753 1067.091 1052.046 1036.494 1020.370 1003.660 986.473 967.942 948.868 928.049 906.010 881.691 854.302
6.234 7.575 9.172 11.034 13.177 15.645 18.477 21.713 25.423 29.674 34.529 40.014 46.501 53.819 62.573 72.749 85.127 100.641
2.785 2.711 2.614 2.535 2.448 2.327 2.226 2.106 2.046 1.962 1.828 1.727 1.639 1.523 1.445 1.352 1.269 1.163
15.6 15.0 14.3 13.7 13.0 12.2 11.4 10.6 10.1 9.5 8.7 8.0 7.4 6.7 6.1 5.5 5.0 4.3
S. Bi et al. / Fluid Phase Equilibria 287 (2009) 23–25
25
Fitting the experimental data of this work and the data of Heide [3] with Eq. (4), the parameter C is found to be 0.40 which is a little different from the value 0.23 as obtained by Heide [3]. Fig. 2 shows the deviation of the present data from the Eq. (4) at different mass fractions. The average deviation and the maximum deviation of the experimental data to the calculated data are 0.02 mN m−1 and 0.23 mN m−1 , respectively. 4. Conclusion The surface tension of the refrigerant mixture HFC-125 + HFC152a was measured over a temperature range from (243 to 328) K using the differential 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 HFC-152a + HFC-125 was developed. The result can be used to evaluate the heat transfer, flow and phase change of this mixture refrigerant. Fig. 1. Experimental data of mixture refrigerant HFC-125 + HFC-152a; (+) HFC-152a; (×) HFC-125; (♦) wHFC-125 = 0.0970; () wHFC-125 = 0.2019; (夽) wHFC-125 = 0.2996.
Acknowledgments This study was supported by the National Natural Science Foundation of China (Grant No. 50806060) and the Foundation for the Author of National Excellent Doctoral Disseration (Grant No. 200540). 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 saturated vapor density the surface tension
Fig. 2. Deviations of experimental surface tension data of HFC-125 + HFC-152a from Eq. (4). C = 0.40, () wHFC-125 = 0.800, Heid (Ref. [3]); (䊉) wHFC-125 = 0.554, Heid (Ref. [3]); () wHFC-125 = 0.265, Heid (Ref. [3]); (♦) wHFC-125 = 0.0970; () wHFC-125 = 0.2019; (夽) wHFC-125 = 0.2996.
The surface tension of the refrigerant mixture was developed as the following expressions: = w1 1 + w2 2 + Cw1 w2
(4)
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.
References [1] [2] [3] [4] [5] [6] [7]
M.G. He, T.C. Li, Z.G. Liu, Appl. Therm. Eng. 25 (2005) 1169–1181. J.T. Wu, Y.J. Chu, J. Hu, Z.G. Liu, Int. J. Refrig. 32 (2009) 1049–1057. R. Heide, Int. J. Refrig. 20 (1997) 496–503. J.T. Wu, F.K. Wang, Z.G. Liu, C. Ren, J. Chem. Eng. Data 48 (2003) 1571–1573. F.K. Wang, J.T. Wu, Z.G. Liu, Fluid Phase Equilib. 220 (2004) 123–126. X.P. Wang, J. Pan, J.T. Wu, Z.G. Liu, J. Chem. Eng. Data 51 (2006) 1394–1397. E.W. Lemmon, M.L. Huber, M.O. McLinden, NIST Standard Reference Database 23, version 8.0, 2007. [8] M. Okada, Y. Higashi, Int. J. Thermophys. 16 (1999) 791–800. [9] Y. Higashi, Int. J. Refrig. 17 (1994) 524–531. [10] Y. Higashi, M. Ashizawa, Y. Kabata, JSME Int. J. 30 (1987) 1106–1112.