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Fluid Phase Equilibria 316 (2012) 66– 73

Contents lists available at SciVerse ScienceDirect

Fluid Phase Equilibria

j o ur nal homep age: www.elsev ier .com/ locate / f lu id

mplementation of PC-SAFT and SAFT + Cubic for modeling thermodynamicroperties of haloalkanes. I. 11 halomethanes

lya Polishuk ∗, Maxim Katz, Yulia Levi, Helena Lubarskyepartment of Chemical Engineering & Biotechnology, Ariel University Center of Samaria, 40700 Ariel, Israel

r t i c l e i n f o

rticle history:eceived 13 October 2011eceived in revised form8 November 2011ccepted 1 December 2011vailable online 9 December 2011

a b s t r a c t

In the current study the widely implemented theoretically based model PC-SAFT and the recently pro-posed SAFT + Cubic have been applied for correlating and predicting various thermodynamic propertiesof 11 halomethanes. It has been found that thanks to the correct estimation of the experimental criticaltemperatures and pressures, SAFT + Cubic exhibits a superior robustness and reliability in modeling bothpure compounds under consideration and their mixtures. In addition, SAFT + Cubic has a clear advantagein predicting sound velocities and isochoric heat capacities. However PC-SAFT is more accurate in mod-

eywords:quation of statetatistical association fluid theoryefrigerantsensity

eling certain kinds of data, such as the isobaric heat capacities of saturated liquids and vapor pressuresaway from the critical points.

© 2011 Elsevier B.V. All rights reserved.

ound velocity

. Introduction

Haloalkanes present a very important family of compoundsidely used as refrigerants, solvents, propellants, and fumigants. In

ddition, haloalkanes are particularly interesting from the thermo-ynamic viewpoint since their densities might substantially exceedhe typical values characteristic for most organic compounds. Theractical importance of haloalkanes has initiated numerous exper-

mental studies. The significant amount of experimental data onhese compounds has allowed derivation of accurate empirical

odels for interpolating their thermodynamic properties (see forxample [1–11]).

The theoretically based Equation of State (EoS) models such asifferent variations of Statistical Association Fluid Theory (SAFT)ight be less precise than the above empirical equations in their

rescribed P–V–T ranges of applicability. However the theoreticallyased models have certain doubtful advantages. In particular, theyre not supposed to be restricted by the applicability ranges, requireess adjustable parameters and might be more easily applied forredicting data in mixtures.

Thus far different theoretically based models have been imple-

ented for modeling data of pure and mixed haloalkanes (see

or example [12–21]). The current series of studies aims a com-rehensive description of their various thermodynamic properties

∗ Corresponding author. Tel.: +972 3 9066346; fax: +972 3 9066323.E-mail addresses: polishuk@ariel.ac.il, polishyk@bgumail.bgu.ac.il (I. Polishuk).

378-3812/$ – see front matter © 2011 Elsevier B.V. All rights reserved.oi:10.1016/j.fluid.2011.12.003

using of two equations of state, namely PC-SAFT and SAFT + Cubic.The present work considers 11 halomethanes: carbon tetrachlo-ride (R10), trichlorofluoromethane (R11), dichlorodifluoromethane(R12), chlorotrifluoromethane (R13), carbon tetrafluoride (R14),chlorodifluoromethane (R22), trifluoromethane (R23), difluo-romethane (R32), methyl chloride (R40), methyl fluoride (R41)and bromotrifluoromethane (R13B1). Previously [22], SAFT + Cubichas been implemented for modeling data of chloroform (R20) anddichloromethane (R30). Therefore these compounds have not beenconsidered in the current study. In further studies we intend to con-sider the thermodynamic properties of haloethanes, halopropanesand mixtures of haloalkanes.

2. Theory

Being based on analytical solution of the Percus–Yevick molec-ular approximation, PC-SAFT [23] is currently one of the mostsuccessful and widely used theoretically based approaches [24]. Wehave found that in the case of haloalkanes the previously detectednumerical pitfalls characteristic for PC-SAFT [25–27] take place farbelow the measured and the estimated solidification lines of both

pure compounds and mixtures, and, therefore, are not expected toaffect the performance of the model.

Detailed description of PC-SAFT EoS is provided in the originalRef. [23]. Similarly to other versions of SAFT, PC-SAFT is expressed

I. Polishuk et al. / Fluid Phase Equilibria 316 (2012) 66– 73 67

Table 1Pure compound adjustable parameters of PC-SAFT EoS.

Compound m ε/k (K) � (Å)

R10 2.51900 280.700 3.71079R11a 2.34570 244.680 3.66220R12a 2.27650 202.810 3.53570R13a 2.22230 160.780 3.35210R14b 2.24740 120.360 3.10600R22a 2.54660 185.470 3.10920R23a 2.95990 140.910 2.74040R32c 2.76400 173.158 2.75400R40 1.93600 241.090 3.20701R41 2.01300 184.230 2.91358R13B1 2.53900 169.870 3.31702

a

if

A

wtrl�εkεpItpmuftbStawi

a

A

w

P

t

P

TPriihSfc

Table 2Pure compound parameters of SAFT + Cubic EoS.

Compound Adjustable parameters Parameters obtained solvingthe critical point conditions

m c (L/mol) a (bar-mol2/L2) � (Å) ε/k (K)

R10 2.08000 0.153170 16.9703 4.05354 403.788R11 2.02000 0.149295 12.5046 3.93335 346.541R12 1.95000 0.137109 8.69634 3.81586 283.631R13 1.80000 0.123107 5.46185 3.67817 221.021R14 1.56000 0.133124 3.12233 3.58630 168.350R22 1.86000 0.114640 6.76849 3.51420 269.776R23 1.69000 0.110412 4.69908 3.34585 217.277R32 1.50000 0.104441 5.40866 3.31525 244.658

R22. Nevertheless, it should be recognized that the overall accuracyof SAFT + Cubic is superior due to the correct estimation of the crit-ical points. As seen, PC-SAFT overestimates the critical constantsof halomethanes with different degrees of extend. In particular,

90 250 410 5700

20

40

60

80

P(bar)

R14 R23

R41 R32

R22

R40

R11 R10.0001

.001

.01

.1

1

10

100

R10

R11

R14 R4

1

R22

R40

From Ref. [19].b From Ref. [20].c From Ref. [21].

n terms of the following contributions to the residual Helmholtzree energy:

res = Ahs + Achain + Adisp + Aassoc (1)

here the superscripts hs, chain, disp and assoc correspond tohe hard sphere, chain, dispersion and association contributions,espectively. These contributions, in turn, are functions of the fol-owing adjustable parameters: m – effective number of segments,

– Lennard–Jones temperature-independent segment diameter,/k – segment energy parameter divided by Boltzmann’s constant,AB – volume of interaction between the association sites andAB/k – interaction of association energy. Thus, for the associatingolar compounds the model requires five adjustable parameters.

n the case of the non-associating compounds the association con-ribution is deleted and the model stays with three adjustablearameters. Swaminathan and Visco [13] have discussed imple-entation of the association contribution for modeling haloalkanes

sing SAFT of Variable Range (SAFT-VR). They have concluded thator compounds having a nonzero dipole moment, irrespective ofheir molecular structure, the two sites association scheme shoulde assumed. At the same time, the references implementing PC-AFT for modeling haloalkanes [18–21] have preferred reducinghe number of the adjustable parameter by neglecting the possiblessociation. This approach has been adopted by the current study asell (the PC-SAFT pure compound adjustable parameters are listed

n the Table 1).The mean idea of the recently proposed SAFT + Cubic EoS is

ttaching SAFT by the attractive term of cubic EOS as follows:

res = Ares,SAFT − a

v + c(2)

here a and c are empirical correction parameters. Since

= RT

V−

(∂Ares

∂V

)T

(3)

he pressure is obtained as:

= PSAFT − a

(V + c)2(4)

he theoretical basis of SAFT + Cubic is weaker in comparison withC-SAFT. Unlike PC-SAFT, SAFT + Cubic relies on generalizing theegularities exhibited by experimental data rather than approx-mating the results of molecular simulations. At the same timet should be pointed out that the empirical part of SAFT + Cubic

as a relatively modest numerical contribution [28]. In addition,AFT + Cubic is free of the well-known disadvantages characteristicor several SAFT approaches, such as the inability to correlate theritical and subcritical pure compound data simultaneously and

R40 1.40000 0.121820 5.56144 3.60316 296.178R41 1.25000 0.117502 4.53533 3.38329 219.009R13B1 1.95000 0.124226 7.01135 3.71260 250.229

generating artificial unrealistic phase equilibria. Another advan-tage of SAFT + Cubic is the smaller number of the pure compoundadjustable parameters (two for the compounds treated as non-associative). More details concerning this model can be found inRef. [28]. It should only be pointed out that similarly to othersmall molecules, the critical volume displacement factor for 9halomethanes considered in the present study has been set to 1.065.The latter factor has been set to unity for R40 and R41. The pertinentparameter matrix of SAFT + Cubic is given in Table 2.

All the calculations (including the fitting of parameters) havebeen performed in the Mathematica 7® software. Implementationof both models under consideration usually requires similar com-putation times. The pertinent routines can be obtained from thecorresponding author by request.

3. Results

Fig. 1 depicts the vapor pressures, data that together with densi-ties have been used for the parameter fitting of both models. Havingmore adjustable parameters, PC-SAFT exhibits a higher flexibil-ity that SAFT + Cubic. This fact might explain the somewhat betterresults of PC-SAFT away from the critical points. In particular, itcan be seen that SAFT + Cubic slightly overestimates the vapor pres-sures of R32 and underestimates them in the cases of R10, R11 and

T(K)

Fig. 1. Vapor pressures. © – Pseudo-experimental (evaluated from the compound-specific empirical EoS) data [8–11]. Predictions: SAFT + Cubic – solid lines, PC-SAFT– dashed lines.

68 I. Polishuk et al. / Fluid Phase Equilibria 316 (2012) 66– 73

P(bar)260 52 78-25000

-20000

-15000

-10000

-5000

0

H(J/g) R13

R22R23

R40

R41

P(bar)260 52 78-100

-50

0

S(J/g)

R13R22 R40R41

R40,R41

F[

tntrItsa

act

ommderRettofsp

vSAtop

(g/L)0 800 1600 240080

200

320

440

T(K)

R14

R41

R13B1

R12

R40

R13

R40

R12

R13B1

R13

R14

(g/L)0 600 1200 180090

190

290

390

490

590

T(K)

R23R32

R22

R11

R10

R32

R23

R22

Fig. 3. Densities of saturated phases. © (liquid), � (vapor) – Pseudo-experimentaldata [8–11]. Predictions: SAFT + Cubic – solid lines, PC-SAFT – dashed lines.

W(m/s)0 600 1200 180 0

80

190

300

410

T(K)

R41

R12R13

W(m/s)0 500 1000 1500

90

190

290

390

490

T(K)

R11

R22

ig. 2. Enthalpies and entropies of condensation. © – Pseudo-experimental data11]. Predictions: SAFT + Cubic – solid lines, PC-SAFT – dashed lines.

his overestimation is relatively small in the case of R14 and sig-ificant in the case of R41. Unfortunately, our attempts to movehe PC-SAFT’s critical points closer to the experimental ones haveesulted in serious deterioration of accuracy in modeling densities.n other words, due to the inability of PC-SAFT to fit the critical andhe sub-critical data simultaneously, the experimental critical con-tants have to be sacrificed in order to obtain a reasonable over-allccuracy of modeling.

Fig. 2 provides representative examples of predicting enthalpiesnd entropies of condensation. As seen, an overestimation of theritical points affects the capability of PC-SAFT to predict accuratelyhese practically very important data.

Fig. 3 depicts the phase envelop densities. As already pointedut, these data have been used for the parameter fitting of bothodels. Therefore their over-all satisfactorily accurate perfor-ance is not surprising. Nevertheless, some deviations from the

ata should be noticed. In particular, SAFT + Cubic tends to under-stimate the near-critical liquid densities and PC-SAFT exhibits theelatively poor accuracy in the case of R32. It has been found that40 and R41 are the compounds uneasy for modeling with bothquations under consideration, and there was a price to pay forheir reasonably accurate fitting. In the case of PC-SAFT it washe substantial overestimation of the critical data and in the casef SAFT + Cubic – cancellation of the critical volume displacementactor used for the rest of the compounds. The latter might be con-idered as analogous to implementation of an additional adjustablearameter.

Fig. 4 provides representative examples of predicting the soundelocities in the saturated phases. The doubtless advantage ofAFT + Cubic over PC-SAFT in modeling this property is evident.

lthough both models are capable of its accurate description in

he vapor phase, only SAFT + Cubic yields acceptable predictionsf sound velocities in the saturated liquids. More details on thesehenomena are given below.

Fig. 4. Sound velocities of saturated phases. © (liquid), � (vapor) – Pseudo-experimental data [11]. Predictions: SAFT + Cubic – solid lines, PC-SAFT – dashedlines.

I. Polishuk et al. / Fluid Phase Equilibria 316 (2012) 66– 73 69

CV(J/g-K).34 .48 .62 .7 6140

260

380

500

T(K)

R11

CV(J/g-K).27 .43 .59 .7 5100

200

300

400

T(K)

R12

C (J/g-K).2 .4 .6 .880

140

200

260

320

T(K)

R13

C (J/g-K).3 .5 .7 .9100

200

300

400

T(K)

R22

F

F

V

ig. 5. Isochoric heat capacities of saturated phases. © (liquid), � (vapor) – Pseudo-expe

CP(J/g-K)1140

260

380

500

T(K)

R11

T

CP(J/g-K)180

140

200

260

320

T(K)

R13

T

ig. 6. Isobaric heat capacities of saturated phases. © (liquid), � (vapor) – Pseudo-experi

V

rimental data [11]. Predictions: SAFT + Cubic – solid lines, PC-SAFT – dashed lines.

CP(J/g-K)1100

200

300

400

(K)

R12

CP(J/g-K)1100

200

300

400

(K)

R22

mental data [11]. Predictions: SAFT + Cubic – solid lines, PC-SAFT – dashed lines.

70 I. Polishuk et al. / Fluid Phase Equilibria 316 (2012) 66– 73

(g/L)1300 1420 1540 16600

200

400

600

P(bar)

Fig. 7. High pressure densities of carbon tetrachloride (R10). Experimental data[29]: � – 329.83 K, – 367.38 K, – 408.77 K. Predictions: SAFT + Cubic – solidl

crccbopFrcibww

tdtoco

stt

FdS

(g/L)0 700 1400 21000

300

600

900

1200P (bar)

Fig. 9. High pressure densities of carbon tetrafluoride (R14). Pseudo-experimentaldata [31]: � – 120 K, – 220 K, – 320 K, – 420 K. Predictions: SAFT + Cubic –solid lines, PC-SAFT – dashed lines.

(g/L)6000 1200 18000

1800

3600

5400

P (bar)

Fig. 18 depicts the ratios between SAFT + Cubic and PC-SAFTin predicting the constituent parts of Eq. (5). As seen, the

ines, PC-SAFT – dashed lines.

The next properties to be considered, namely the isochoric heatapacities of the saturated phases (see Fig. 5) are difficult for accu-ate prediction due to the inability of both analytical models underonsideration to describe the critical exponents. Nevertheless, itan be seen that SAFT + Cubic correctly estimates the patterns ofehavior of this property in saturated liquids, which is not a casef PC-SAFT. At the same time, PC-SAFT is surprisingly precise inredicting the isobaric heat capacities of the saturated liquids (seeig. 6), exhibiting yet doubtless superiority over SAFT + Cubic. Theseesults might partially be explained by its overestimation of theritical data, a disadvantage that in this particular case is turningnto advantage. Both models under consideration yield compara-le accuracy in predicting heat capacities of the saturated vapors,hich is satisfactorily good at low temperatures but deteriorateshile approaching the critical points.

In the following discussion let us proceed to consideration ofhe single-phase properties at high pressures. Figs. 7–12 depict theensities. As seen, in most of the cases SAFT + Cubic is more accuratehen PC-SAFT in modeling this property. Its advantage is most obvi-us in the cases of R12 (Fig. 8) and R41 (Fig. 12). However in certainases, such as the high pressure and high temperature density dataf R22, PC-SAFT exhibits better accuracy than SAFT + Cubic.

Figs. 13–17 present the sound velocities at high pressure. Aseen, yet the advantage of SAFT + Cubic over PC-SAFT is unques-ionable. In most of the cases PC-SAFT underestimates the data and

hese deviations increase with pressure. In order to analyze these

(g/L)1180 1380 1580 17800

600

1200

1800

P (bar)

ig. 8. High pressure densities of dichlorodifluoromethane (R12). Experimentalata [30]: � – 253.15 K, – 273.15 K, – 293.15 K, – 313.15 K. Predictions:AFT + Cubic – solid lines, PC-SAFT – dashed lines.

Fig. 10. High pressure densities of chlorodifluoromethane (R22). Experimental data[32]: � – 298.2 K, – 373.2 K, – 473.2 K, – 573.2 K. Predictions: SAFT + Cubic –solid lines, PC-SAFT – dashed lines.

results let us consider the typical example of R10. Sound velocity isgiven as:

W =√

− CP

CV

v2

Mw

(∂P

∂v

)T

(5)

differences between the models in predicting√

Cp/CV and vare relatively small and nearly cancelling each other. Thus the

(g/L)0 420 840 12600

1100

2200

3300

4400

P(bar)

Fig. 11. High pressure densities of methyl chloride (R40). Experimental data [33]:� – 298 K, – 373 K, – 473 K, – 573 K. Predictions: SAFT + Cubic – solid lines,PC-SAFT – dashed lines.

I. Polishuk et al. / Fluid Phase Equilibria 316 (2012) 66– 73 71

(g/L)0 400 800 12000

800

1600

2400

3200

P(bar)

Fig. 12. High pressure densities of methyl fluoride (R41). Experimental data [34]:� – 298.15 K, – 373.15 K, – 448.15 K, – 573.15 K. Predictions: SAFT + Cubic –solid lines, PC-SAFT – dashed lines.

W (m/s)400 700 1000 13000

500

1000

1500

P (bar)

Fdl

dtmC((ueme

FmS

W (m/s)400 600 800 10000

200

400

600

P (bar)

Fig. 15. High pressure sound velocities in chlorodifluoromethane (R22). Experimen-tal data [36]: � – 283.15 K, – 303.15 K, – 323.15 K. Predictions: SAFT + Cubic –solid lines, PC-SAFT – dashed lines.

W (m/s)0 450 900 13500

200

400

600

800

P(bar)

ig. 13. High pressure sound velocities in carbon tetrachloride (R10). Experimentalata [29]: � – 283.86 K, – 350.55 K, – 454.97 K. Predictions: SAFT + Cubic – solid

ines, PC-SAFT – dashed lines.

ifference in estimating√

−(∂P/∂v)T has the major impact onhe final result. As seen (Fig. 7), PC-SAFT slightly underesti-

ates the slopes of isotherms in the density–pressure projection.onsequently, this model underestimates (∂P/∂�)T, overestimates∂P/∂v)T and, lastly, underestimates −(∂P/∂v)T and

√−(∂P/∂v)T

see Fig. 18). These results explain the characteristic for PC-SAFT

nder-prediction of sound velocities (see Fig. 13). In other words,ven relatively minor deviations in the density–pressure projectionight substantially affect the accuracy in predicting auxiliary prop-

rties. At the same time it should be emphasized that the attempts

W (m/s)400 700 1000 13000

800

1600

2400

P (bar)

ig. 14. High pressure sound velocities in trichlorofluoromethane (R11). Experi-ental data [35]: � – 353.25 K, – 373.12 K, – 393.23 K, – 413.19 K. Predictions:

AFT + Cubic – solid lines, PC-SAFT – dashed lines.

Fig. 16. High pressure sound velocities in difluoromethane (R32). Experimental data[37]: � – 248.2 K, – 278.12 K, – 313.19 K, – 343.29 K. Predictions: SAFT + Cubic– solid lines, PC-SAFT – dashed lines.

to improve the accuracy of PC-SAFT in modeling sound velocitiesby rescaling its parameters result in substantial deterioration inestimation of all other properties.

Figs. 19 and 20 depict the isothermal compressibilities of R14and the isentropic compressibilities of R22. Yielding the compara-ble predictions for the high pressure densities of R14, both models

estimate the isothermal compressibilities of this compound withthe similar degree of accuracy as well. However since SAFT + Cubicis a better estimator of sound velocities, it is also advantageous inpredicting isentropic compressibilities.

W (m/s)200 360 520 6800

200

400

600

P(bar)

Fig. 17. High pressure sound velocities in bromotrifluoromethane (R13B1). Experi-mental data [38]: � – 283.15 K, – 303.15 K, – 323.15 K. Predictions: SAFT + Cubic– solid lines, PC-SAFT – dashed lines.

72 I. Polishuk et al. / Fluid Phase Equilibria 316 (2012) 66– 73

P(bar)0 1800 3600 540 0.95

1.00

1.05

1.10

1.15

TT SAFT Cubic PC SAFT

PPvv

P P

V VSAFT Cubic PC SAFT

C CC C

vSAFT+Cubic /v

PC-SAFT

Fig. 18. Differences between SAFT + Cubic and PC-SAFT in predicting the constituentparts of Eq. (5) (R10 at T = 283.86 K.)

(GPa-1)1 10 100 100 0

0

250

500

750

1000

P (bar)

FeS

uabartdSo

Fdl

P(bar)

0.0 .2 .4 .6 .8 1.00

20

40

60

x1

Fig. 21. Bubble-points lines in the system R11(1)–R22(2). Experimental data [39]:� – 298.15 K, – 323.15 K, – 348.15 K, – 373.15 K. Modeling: SAFT + Cubic(k12 = 0.08) – solid lines, PC-SAFT (k12 = 0.05) – dashed lines.

(g/L)900 1200 1500 18000

200

400

600

800

P(bar)

Fig. 22. High pressure densities of the system R11(1)–R22(2) (x1 = 0.1664). Exper-imental data [40]: � – 230 K, – 320 K, – 400 K. Predictions: SAFT + Cubic

ig. 19. Isothermal compressibilities of carbon tetrafluoride (R14). Pseudo-xperimental data [31]: � – 120 K, – 220 K, – 320 K, – 420 K. Predictions:AFT + Cubic – solid lines, PC-SAFT – dashed lines.

And, finally, let us consider several mixtures of the compoundsnder consideration. Figs. 21 and 22 depict the bubble-points linesnd the high pressure densities of the system R11(1)–R22(2). Theinary adjustable parameter k12 has been fitted to the VLE datat 298.15 K for both models. As seen, SAFT + Cubic is a more accu-ate estimator of densities than PC-SAFT. The latter model exhibits

he characteristic under-prediction of the isotherms slopes in theensity-pressure projection. In addition, it appears that unlikeAFT + Cubic, PC-SAFT is incapable of accurate correlation of vari-us VLE isotherms with the same value of k12; smaller values of this

S (GPa-1).6 2.2 3.8 5.40

200

400

600

P (bar)

ig. 20. Isentropic compressibilities of chlorodifluoromethane (R22). Experimentalata [36]: � – 283.15 K, – 303.15 K, – 323.15 K. Predictions: SAFT + Cubic – solid

ines, PC-SAFT – dashed lines.

(k12 = 0.08) – solid lines, PC-SAFT (k12 = 0.05) – dashed lines.

parameters are required for fitting the data at higher temperatures.Once again, this result should be explained by the characteristicfor PC-SAFT overestimation of pure compound critical tempera-tures and pressures (see Figs. 23 and 24). These figures demonstrate

that thanks to the precise adjustment to the pure compound crit-ical data, SAFT + Cubic has a doubtless superiority over PC-SAFT incorrelating VLE in the symmetric mixtures under consideration.

x10.0 .2 .4 .6 .8 1.0

0

22

44

66

P(bar)

Fig. 23. VLE in the system R23(1)–R22(2). Experimental data [41]: � – 273.15 K,– 303.15 K, – 323.15 K, – 343.15 K, – 353.15 K. Modeling: SAFT + Cubic

(k12 = 0.04) – solid lines, PC-SAFT (k12 = 0.02) – dashed lines.

I. Polishuk et al. / Fluid Phase Eq

x10.0 .2 .4 .6 .8 1.0

0

18

36

54

P(bar)

Fig. 24. VLE in the system R14(1)–R13(2). Experimental data [42]: � – 199.82 K,– 222.04 K, – 244.26 K, – 266.48 K, – 288.71 K. Modeling: SAFT + Cubic

(

4

PmpPR

tebavact

A

ig

R

[

[

[[[[

[

[

[[[[

[[[

[

[

[[[

[[

[[[[

[[[

k12 = 0.03) – solid lines, PC-SAFT (k12 = 0.02) – dashed lines.

. Conclusions

In the current study the popular theoretically based modelC-SAFT and the recently proposed SAFT + Cubic have been imple-ented for correlating and predicting various thermodynamic

roperties of 11 halomethanes. The existing parameter matrix ofC-SAFT has been extended to four additional compounds (R10,40, R41 and R13B1).

It has been found that thanks to the correct estimation ofhe experimental critical temperatures and pressures, SAFT + Cubicxhibits a superior over-all robustness and reliability modelingoth pure compounds under consideration and their mixtures. Inddition, SAFT + Cubic has a clear advantage in predicting soundelocities and isochoric heat capacities. However PC-SAFT is moreccurate in modeling certain kinds of data, such as the isobaric heatapacities of the saturated liquids and vapor pressures away fromhe critical points.

cknowledgment

Acknowledgment is made to the Donors of the American Chem-cal Society Petroleum Research Fund for support of this research,rant No. PRF#47338-B6.

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[[

[[

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