Ž .Fluid Phase Equilibria 150–151 1998 297–302

Vapor–liquid equilibria for HFC-32 containing systems

Jaewon Lee a, Joncheon Lee b, Hwayong Kim a,)

a Department of Chemical Engineering, Seoul National UniÕersity, Seoul, South Koreab LG Chemical, Taejon, South Korea

Abstract

A circulation type apparatus was used to obtain vapor–liquid equilibrium data. Results are given at threeŽ . Ž .temperatures for the difluoromethane HFC-32 q1-chloro-1,1-difluoroethane HCFC-142b and for the difluo-

Ž .romethaneq2,2-dichloro-1,1,1-trifluoroethane HCFC-123 binary systems. Results are well represented withŽ .the Peng–Robinson equation of state P-R EOS . q 1998 Elsevier Science B.V. All rights reserved.

Keywords: Vapor–liquid equilibria; Equation of state; Refrigerants; HFC-32; HCFC-142b; HCFC-123

1. Introduction

HFC-32 is one of the most promising alternative refrigerants. It has zero ozone depletion potentialand low global warming potential. However, as it has high vapor pressure and flammability, it isexpected to mix with other materials when used as the refrigerant. Vapor–liquid equilibrium data forthese mixtures are essential to evaluate the efficiency and select the optimal composition for design

Ž . Ž .and operation. In this work, we have measured the equilibrium pressure P , temperature T , liquidŽ . Ž .phase composition x , and vapor phase composition y for the HFC-32qHCFC-123 and HFC-32

qHCFC-142b systems. We have reviewed the vapor–liquid equilibrium data for HFC-32 containingsystems. Most of them are for HFC-32qother HFCs systems, so we performed experiments forHFC-32qHCFCs systems. Although HCFCs are to be phased out by 2020, our results are expectedto help developing the database of vapor–liquid equilibria for halogenated compounds and thermody-namic model like UNIFAC.

) Corresponding author. Department of Chemical Engineering, Seoul National University, Seoul, 151-742 South Korea.Tel.: q82-2-880-7406; Fax: q82-2-888-7295; Eymail: hwayongk@plaza.snu.ac.kr

0378-3812r98r$ - see front matter q 1998 Elsevier Science B.V. All rights reserved.Ž .PII: S0378-3812 98 00329-X

( )J. Lee et al.rFluid Phase Equilibria 150–151 1998 297–302298

2. Measurement

2.1. Materials

HFC-32 and HCFC-142b are supplied by Ulsan Chemical with a minimum purity of 99.9 mass%,and HCFC-123 was supplied by DuPont with a purity of 99.95 mass%. Critical properties of thesematerials are given in Table 1.

2.2. Apparatus

In this work, we used the same apparatus that was used for the VLE measurement of thew xHFC-134aqHCFC-124 and HCFC-124qHCFC-142b systems 1 with some minor modifications in

the sampling part. The vapor and liquid phase samples were trapped between two 3-way valves. Theschematic diagram of the apparatus is given in Fig. 1. The vapor and liquid samples were analyzed

Ž .with a gas chromatograph. We used a flame ionization detector FID and Carbopack B column. Thesampling loop for vapor phase was heated slightly to prevent condensation of vapor samples. BecauseHCFC-123 is very heavy comparing with HFC-32, HCFC-123 is likely to condensate in the samplingloop without heating. The uncertainty of composition is estimated to be within "0.005 mole fractionfor both vapor and liquid phase. A Pt 100-V RTD thermometer was used to measure temperature and

Ž .pressure transducer Setra 280E was used to measure pressure. The thermometer was calibratedagainst ITS-90, and the uncertainty of temperature is estimated to be within "0.1 K. The pressuretransducer was calibrated with an air dead weight tester and the uncertainty of pressure is estimated tobe within "10y3 MPa.

3. Results

Experimental vapor–liquid equilibrium data were determined for two binary refrigerant mixtures:HFC-32qHCFC-142b and HFC-32qHCFC-123. The experimental data are listed in Tables 2 and 3.

Ž . Ž . Ž . Ž . Ž .Fig. 1. Experimental apparatus. 1 equilibrium cell; 2 magnetic pump; 3 pressure gauge; 4 thermometer; 5 4-portŽ . Ž . Ž . Ž . Ž .valve; 6 gas sampling valve; 7 liquid sampling valve; 8 expansion vessel; 9 6-port valve; 10 sampling valve.

( )J. Lee et al.rFluid Phase Equilibria 150–151 1998 297–302 299

Table 1Critical properties and acentric factors of pure components

HFC-32 HCFC-123 HCFC-142ba a a

Ž .T K 351.26 410.26 456.8cŽ .P MPa 5.777 4.040 3.666c

v 0.277 0.235 0.283

a w xData from Sato et al. 5 .

We correlated the data with the Peng–Robinson equation of state and the van der Waals one-fluidw xmixing rule 2 . The objective function used for evaluating the interaction parameter k was12

Ž .2 w xÝ 1yP rP and the Marquardt algorithm was used 3 .cal exp< <The mean relative deviations between the measured and calculated pressure, D PrP , the mean

deviations of vapor composition of component 1, D y , and the values of k are listed in Table 4. The1 12

Table 2Ž . Ž .Experimental VLE data for the system HFC-32 1 qHCFC-142b 2

Ž .T K P rMPa P rMPa x y yexp cal 1, exp 1, exp 1, cal

295.45 0.310 0.307 0.000 0.000 0.0000.475 0.484 0.122 0.403 0.4150.775 0.780 0.339 0.698 0.6980.910 0.892 0.427 0.758 0.7611.143 1.143 0.633 0.854 0.8641.320 1.306 0.772 0.914 0.9171.422 1.414 0.863 0.948 0.9501.571 1.582 1.000 1.000 1.000

304.55 0.409 0.404 0.000 0.000 0.0000.610 0.613 0.116 0.363 0.3840.968 0.968 0.329 0.667 0.6721.143 1.149 0.437 0.750 0.7511.425 1.412 0.619 0.840 0.8471.677 1.663 0.774 0.907 0.9111.812 1.806 0.868 0.944 0.9471.998 2.016 1.000 1.000 1.000

314.95 0.549 0.543 0.000 0.000 0.0000.788 0.783 0.111 0.340 0.3451.238 1.240 0.330 0.631 0.6471.445 1.446 0.435 0.725 0.7291.845 1.838 0.630 0.828 0.8382.150 2.169 0.770 0.898 0.9002.323 2.330 0.870 0.938 0.9442.588 2.614 1.000 1.000 1.000

( )J. Lee et al.rFluid Phase Equilibria 150–151 1998 297–302300

Table 3Ž . Ž .Experimental VLE data for the system HFC-32 1 qHCFC-123 2

Ž . Ž . Ž .T K P bar P bar x y yexp cal 1, exp 1, exp 1, cal

294.95 0.0816 0.0812 0.000 0.000 0.0000.268 0.264 0.107 0.730 0.7070.573 0.571 0.298 0.895 0.8790.652 0.646 0.348 0.899 0.8980.824 0.841 0.483 0.927 0.9310.988 1.000 0.600 0.950 0.9501.096 1.110 0.683 0.962 0.9611.214 1.226 0.772 0.973 0.9711.554 1.561 1.000 1.000 1.000

304.55 0.116 0.115 0.000 0.000 0.0000.427 0.423 0.147 0.751 0.7430.591 0.586 0.228 0.828 0.8220.627 0.628 0.249 0.842 0.8360.844 0.845 0.362 0.891 0.8871.030 1.034 0.465 0.917 0.9151.225 1.256 0.591 0.942 0.9391.998 2.015 1.000 1.000 1.000

313.95 0.159 0.158 0.000 0.000 0.0000.427 0.410 0.0992 0.639 0.6240.632 0.657 0.199 0.783 0.7740.887 0.884 0.290 0.869 0.8370.997 1.006 0.345 0.878 0.8631.290 1.310 0.478 0.909 0.9051.552 1.570 0.591 0.938 0.9291.729 1.749 0.677 0.953 0.9441.945 1.999 0.769 0.966 0.9582.527 2.551 1.000 1.000 1.000

value of k does not vary significantly with temperature over the range of this work so it is not12

necessary to set k to be temperature-dependent. Maximum deviation of pressure does not exceed12

2%. Pressure–composition diagrams and a comparison of the calculated and experimental values for

Table 4Results of VLE correlation by the Peng–Robinson equation of state

Ž . < <System T K n k D PrP =100 D y =10012 1

HFC-32qHCFC-142b 295.45 8 0.0357 0.976 0.500304.55 8 0.0383 0.565 0.683314.95 8 0.0346 0.566 0.717

HFC-32qHCFC-123 294.95 9 0.0463 0.886 0.671304.55 8 0.0476 0.530 0.483313.95 10 0.0485 1.72 1.26

( )J. Lee et al.rFluid Phase Equilibria 150–151 1998 297–302 301

Ž . Ž . Ž . Ž . Ž .Fig. 2. a Pressure–composition diagram for HFC-32 1 q HCFC-142b 2 : ` liquid phase v vapor phase at 295.45Ž . Ž . Ž . Ž . Ž .K; ^ liquid phase ' vapor phase at 304.55 K; I liquid phase B vapor phase at 314.95 K; - - - Peng–Robinson

Ž .equation of state. b Deviation of experimental pressures from calculated pressures with Peng–Robinson equation of state:Ž . Ž . Ž . Ž . Ž . Ž .` liquid phase v vapor phase at 295.45 K; ^ liquid phase ' vapor phase at 304.55 K; I liquid phase B vapor

Ž .phase at 314.95 K; Peng–Robinson equation of state.

the two systems are presented in Figs. 2 and 3. Neither system forms an azeotropic mixture over therange of this work and they show nearly ideal behaviors. In 1944, Ewell et al. divided materials into

w xfive classes and summarized the phase behavior for each binary pair 4 . According to his study,halocarbon–halocarbon mixtures form quasi-ideal systems for there is no special interaction in thesemixtures. Pressure changes almost linearly to liquid composition in Figs. 2 and 3. From this, it can be

Ž . Ž . Ž . Ž . Ž .Fig. 3. a Pressure–composition diagram for HFC-32 1 q HCFC-123 2 : ` liquid phase v vapor phase at 294.95 K;Ž . Ž . Ž . Ž . Ž .^ liquid phase ' vapor phase at 304.55 K; I liquid phase B vapor phase at 313.95 K; - - - Peng–Robinson

Ž .equation of state. b Deviation of experimental pressures from calculated pressures with Peng–Robinson equation of state:Ž . Ž . Ž . Ž . Ž . Ž .` liquid phase v vapor phase at 294.95 K; ^ liquid phase ' vapor phase at 304.55 K; I liquid phase B vapor

Ž .phase at 313.95 K; Peng–Robinson equation of state.

( )J. Lee et al.rFluid Phase Equilibria 150–151 1998 297–302302

concluded that systems of HFC-32qHCFC-142b and HFC-32qHCFC-123 form nearly idealmixtures as expected.

4. Conclusion

We measured vapor–liquid equilibria for the binary systems of HFC-32qHCFC-142b andHFC-32qHCFC-123. These mixtures showed nearly ideal behavior and could be correlated wellwith the Peng–Robinson equation of state and one adjustable parameter.

5. List of symbols

k Binary interaction parameter12

n Number of data pointsP Pressure< < Ž < <.D PrP Mean relative deviation of pressure, Ý 1yP rP rncal exp

T Temperaturex Mole fraction of liquid phasey Mole fraction of vapor phaseD y Mean absolute deviation of vapor composition of component 11

Greek lettersv Acentric factor

Subscriptsc Criticalcal Calculatedexp Experimental

References

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Tables, Vol. 1, Tokyo, 1994.