FreeStanMix

The complete thermodynamic model implemented in FreeStanMix is documented in the following references:

  1. Colonna, P., June 1995. Properties of Fluid Mixtures for Thermodynamic Cycles Applications.Tech. rep., Stanford University, Stanford, CA.

  2. Angelino, G. and Colonna, P., 1998. ''Multicomponent Working fluids for Organic Rankine Cycles (ORCs).'' Energy , 23, pp. 449-463.

The PRSV cubic equation of state, which is a modified Peng Robinson equation of state particularly suited for the accurate estimation of saturation properties, is described in

  1. Stryjeck, R. and Vera, J. H., 1986. ``PRSV: An Improved Peng-Robinson Equation Of State For Pure Compounds And Mixtures.'' Can. J. Chem. Eng. , 64, pp. 323-333.

The Wong and Sandler mixing rules which are suitable for the modeling of highly non-ideal mixtures are documented e.g. in:

  1. Wong, D. S. H., Sandler, S. I., and Orbey, H., 1992. ``Equation Of State Mixing Rule For Nonideal Mixtures Using Available Activity Coefficient Model Parameters And That Allows Extrapolation Over Large Ranges Of Temperature And Pressure.'' Ind. Eng. Chem. Res. , 31, pp. 2033-2039.

  2. Wong, D. S. H. and Sandler, S. I., 1992. ``A Theoretically Correct Mixing Rule for Cubic Equations of State.'' AIChE Journal , 38, pp. 671-680.

  3. Huang, H. and Sandler, S. I., 1993. ``Prediction of Vapor-Liquid Equilibria at High Pressures Using Activity Coefficient Parameters Obtained from Low Pressure Data: A comparison of Two Equation of State Mixing Rules.'' Ind. Eng. Chem. Res. , 32, pp. 1498-1503.

  4. Orbey, H. and Sandler, S. I., 1993. ``Accurate Equation of State Predictions at high temperatures and pressures using the existing UNIFAC model.'' Fluid Phase Equilib. , 85, pp. 41-54.

  5. Sandler, S. I. et al. , 1994. Models For Thermodynamic And Phase Equilibria Calculations . Marcel Dekker, New York.

  6. Orbey, H. and Sandler, S. I., 1995. ``On the Combination of Equation of State and Excess Free Energy Models.'' Fluid Phase Equilib. , 111, pp. 53-70.

  7. Orbey, H. and Sandler, S. I., 1995. ``Reformulation of Wong-Sandler Mixing Rules for Cubic Equations of State.'' AIChE J. , 41.

  8. Orbey, H. and Sandler, S. I., 1995. ``Equation of State modeling of Refrigerant Mixtures.'' Ind. Eng. Chem. Res. , 34, pp. 2520-2525.

  9. Orbey, H. and Sandler, S. I., 1997. ``A Comparison of Huron-Vidal Type Mixing Rules of Mixtures of Compounds with Large Size Differences, and a New Mixing Rule.'' Fluid Phase Equilib. , 132, pp. 1-14.

  10. Shiflett, M. B. and Sandler, S. I., June 1998. ``Modeling Fluorocarbon Vapor Liquid Equilibria using the Wong-Sandler model.'' Fluid Phase Equilib. , 147, pp. 145-162.

IMPORTANT NOTE: FreeStanMix implements a simple Successive Substitution Model for the solution of saturation calculations that is known to fail for close-to-critical states and performs worse for highly non-ideal mixtures. The critical point calculation for a mixture is implemented as the pseudo-critical point calculation if the user specifies the composition, therefore the result is highly inaccurate, but an estimate is necessary for all other type of calculations. For predefined mixtures the critical point is calculated with a "climbing" method, that is the bubble point calculation is repeated by increasing the temperature in ever-small steps until it does not converge anymore. This is also an inaccurate estimate even if much better than the pseudo-critical point calculation. Refer to StanMix for improved versions of these algorithms.

The critical point calculation for a mixture is implemented as the pseudo-critical point calculation if the composition is specified by the user, therefore the result is highly inaccurate, but an estimate is necessary for all other type of calculations. For predefined mixtures the critical point is calculated with a "climbing" method, that is the bubble point calculation is repeated by increasing the temperature in ever small steps until it does not converge anymore. This is also an inaccurate estimate even if much better than the pseudo-critical point calculation. We plan to improve these calculations.

FreeStanMix provides thermodynamic properties for the pure fluids listed in Table 1 and 2. The listed FluidProp names (either short or long) must be used to specify the fluid name the SetFluid method. For a given fluid, the FluidProp name is the same in all thermodynamic libraries in which the fluid is available.

 

Table 1

FluidProp Name (short) FluidProp Name (long) Tc [°C] Pc [bar] MW [g/mol] Tmin[°C] Tmax[°C]
1-C4H10O
1-butanol
74.1200
289.83
44.13
-50.00
1226.85
1-C8018O
1-octanol
130.2279
411.65
28.60
0.00
400.00
1-C3H8O
1-propanol
60.0960
263.56
51.70
59.85
350.00
2-C4H10O
2-butanol
74.1200
289.90
44.23
-73.15
1226.85
2-C3H8O
2-propanol
60.0960
235.25
47.64
-75.00
350.00
C3H6O
acetone
58.0800
234.95
46.96
-94.95
1500.00
NH3
ammonia
17.0305
132.45
112.98
-78.15
350.00
Ar
argon
39.9480
-122.29
48.98
-190.00
1226.85
C6H6
benzene
78.1140
289.01
48.98
5.85
350.00
C12H10
biphenyl
154.2100
496.00
31.21
19.85
350.00
C4H10
butane
58.1240
152.01
37.97
-91.15
400.00
C10H14
butylbenzene
134.2182
387.35
28.90
-87.85
1226.85
CO2
carbon dioxide
44.0100
31.06
73.82
-57.15
400.00
C6H12
cyclohexane
84.1620
280.49
40.75
6.85
400.00
D3
D3
222.4640
281.05
16.63
64.00
400.00
D4
D4
296.6180
313.35
13.32
17.65
400.00
D5
D5
370.7697
346.00
11.60
-4.65
400.00
D6
D6
444.9270
372.65
9.61
-1.15
400.00
CH3OCH3
dimethylether
46.0680
126.95
52.40
-141.50
700.00
C12H10O
diphenyl ether
170.2072
503.65
30.80
15.00
600.00
C12H26
dodecane
170.3348
295.61
24.86
-9.55
700.00
diethylbenzene
Dowtherm J
170.3348
295.61
24.86
-9.55
700.00
C2H6
ethane
30.0700
29.28
48.80
-153.15
350.00
C2H5OH
ethanol
46.0690
240.77
61.48
-114.15
700.00
C8H10
ethylbenzene
106.1680
344.05
36.06
32.85
329.85
C2H6O2
ethylene glycol
62.0678
446.85
82.00
-13.00
1000.00
C5H4O2
furfural
96.1000
396.85
58.90
-50.00
160.00
C7H16
heptane
100.2019
267.05
27.40
-73.15
1226.85
C6F6
hexafluoro benzene
186.0000
243.52
33.38
0.00
400.00
C6H14
hexane
86.1780
234.15
30.12
-41.15
400.00
H2
hydrogen
2.0160
-229.55
20.47
-259.15
350.00
i-C4H10
isobutane
58.1240
135.05
36.50
-108.15
135.05
i-C5H12
isopentane
72.1510
187.25
33.90
-53.15
187.25
MD2M
MD2M
310.6900
326.25
11.79
-10.15
400.00
MD3M
MD3M
384.8430
355.25
9.96
2.85
400.00
MD4M
MD4M
458.9933
380.05
8.77
13.85
400.00
MD5M
MD5M
533.1500
398.65
7.63
21.85
400.00
MD6M
MD6M
607.3100
415.75
6.77
29.85
400.00
MDM
MDM
236.5315
290.94
14.15
-25.15
400.00
CH4
methane
16.0425
-82.59
45.99
-182.46
351.85
CH4O
methanol
32.0420
239.43
80.96
-85.00
700.00
MM
MM
162.3790
245.60
19.39
-45.15
400.00
C10H8
naphthalene
128.1740
475.20
40.51
86.85
249.85
N2
nitrogen
28.0130
-146.95
34.00
-209.15
350.00
C8H18
octane
114.2200
295.61
24.86
0.00
400.00
O2
oxygen
31.9990
-118.38
50.90
-217.15
350.00
C5H12
pentane
72.1510
196.55
33.68
-77.15
400.00
C6F12
PFCH
79.1645
217.20
32.32
-41.15
400.00
C7F14
PP2
350.0000
211.85
20.60
0.00
600.00
C10F18
PP5
462.0000
291.85
17.88
0.00
400.00
C3H8
propane
44.0970
96.67
42.50
-187.62
400.00
C8H10
p-xylene
106.1680
344.05
36.06
32.85
329.85
R113
R113
187.3800
214.15
34.10
-34.95
400.00
R114
R114
170.9400
145.75
32.70
-94.00
400.00
R116
R116
138.0120
19.85
30.18
-100.75
400.00
R12
R12
120.9140
111.85
40.70
-140.00
273.15
R125
R125
120.0200
66.25
36.31
-40.15
400.00
R134a
R134a
102.0300
101.06
40.56
-63.15
400.00
R14
R14
88.0050
-45.55
37.40
-183.15
400.00
R142b
R142b
100.4960
136.45
43.30
-130.15
136.45
R22
R22
86.4800
96.05
49.80
-73.15
400.00
R23
R23
70.0130
25.91
48.41
-163.15
400.00
R245fa
R245fa
134.0488
154.05
36.40
-73.15
226.85
R32
R32
52.0240
78.41
58.30
-124.15
78.41
silox 1
silox 1
199.4554
266.49
17.37
-10.15
400.00
silox 2
silox 2
192.0394
245.60
19.39
-25.15
400.00
silox 3
silox 3
206.8723
280.54
17.09
-10.15
400.00
C7H8
toluene
92.1410
318.65
41.06
12.85
399.85
C9H12
trimethylbenzene
120.1900
364.10
31.27
56.85
359.85
C4H6O2
vinyl acetate
86.0900
246.05
41.40
-73.15
1226.85
H2O
water
18.0150
374.14
220.90
0.00
750.00
xx
xxxxxx
16.0425
-82.59
45.99
-182.46
351.85

More fluids can easily be added. The necessary data are the critical temperature, the critical pressure, the saturation curve and the specific heat in the ideal gas state.

Moreover the mixtures listed in Table 2 are available as predefined mixtures. The listed FluidProp names (either short or long) must be used to specify the fluid name the SetFluid method. Other mixtures can be added if pure and binary interaction data are available.

A large collection of binary interaction parameters data is available, for example, on:

  1. Various authors. DECHEMA Chemistry Data Series, Frankfurt am Main (1977 and thereafter).

  2.  DETHERM: Thermophysical properties of pure substances & mixtures

  3.  Infotherm: Experimental thermodynamic and physical properties of mixtures and pure substances

  4.  DIPPR: Evaluated Process Design Data of the AIChE Design Institute of Physical Properties

Please contact us if you need to add a fluid or a mixture.

 

Table 2

FluidProp Name (short) FluidProp Name (long) Tc [°C] Pc [bar] MW [g/mol] Tmin[°C] Tmax[°C]
1-C3H8O/C6H14
1-propanol/hexane
60.0960
263.56
51.70
59.85
350.00
C3H6O/CH4O
acetone/methanol
58.0800
234.95
46.96
-94.95
1500.00
C3H6O/H2O
acetone/water
38.0475
275.30
97.40
0.00
750.00
air
air
28.8501
-142.14
35.89
-209.15
350.00
NH3/H2O
ammonia/water
17.5235
278.09
156.67
0.00
350.00
Ar/CH4
argon/methane
39.9480
-122.29
48.98
-190.00
1226.85
C6H6/C6H12
benzene/cyclohexane
81.1380
284.72
45.89
6.85
350.00
C6H6/C6H12/C6H14
benzene/cyclohexane/hexane
83.1540
254.73
36.91
6.85
350.00
C6H6/C8H10
benzene/ethylbenzene
92.1410
321.63
43.77
32.85
329.85
C6H6/C6H14
benzene/hexane
82.1460
260.72
40.03
5.85
350.00
C6H6/C7H8
benzene/toluene
85.1275
305.36
45.52
12.85
350.00
C6H6/H2O
benzene/water
48.0645
341.16
146.89
5.85
350.00
C4H10/C6H14
butane/hexane
72.1510
202.08
36.84
-41.15
400.00
C4H10/C5H12
butane/pentane
65.1375
177.02
37.67
-77.15
400.00
C4H10/C5H12/C6H14
butane/pentane/hexane
65.1375
177.02
37.67
-77.15
400.00
CO2/1-C4H10O
carbon dioxide/1-butanol
44.0100
31.06
73.82
-57.15
400.00
CO2/C6H6
carbon dioxide/benzene
44.0100
31.06
73.82
-57.15
400.00
CO2/C4H10
carbon dioxide/butane
44.0100
31.06
73.82
-57.15
400.00
CO2/furfural
carbon dioxide/furfural
44.0100
31.06
73.82
-57.15
400.00
CO2/C6H14
carbon dioxide/hexane
44.0100
31.06
73.82
-57.15
400.00
CO2/C5H12
carbon dioxide/pentane
44.0100
31.06
73.82
-57.15
400.00
CO2/C3H8
carbon dioxide/propane
44.0100
31.06
73.82
-57.15
400.00
CO2/C7H8
carbon dioxide/toluene
44.0100
31.06
73.82
-57.15
400.00
CO2/C4H6O2/2-C4H10O
carbon diox/vinyl ace/2-butanol
44.0100
31.06
73.82
-57.15
400.00
D3/D4/D5/D6
D3/D4/D5/D6
222.4640
281.05
16.63
64.00
400.00
D4/D3
D4/D3
259.5410
297.00
15.00
64.00
400.00
D4/D5
D4/D5
333.6955
330.00
12.50
17.65
400.00
D4/D6
D4/D6
370.7725
342.00
11.50
17.65
400.00
D4/CP28
D4/CP28
241.3363
295.17
24.97
17.65
400.00
D4/PFCH
D4/PFCH
298.3325
0.00
0.00
17.65
400.00
D5/D3
D5/D3
296.6185
314.00
14.10
64.00
400.00
D5/D6
D5/D6
407.8500
360.00
10.60
-1.15
400.00
D6/D3
D6/D3
333.6955
327.00
13.10
64.00
400.00
C2H5OH/H2O
ethanol/water
32.0420
304.64
135.01
19.85
350.00
C8H10/C7H8
ethylbenzene/toluene
99.1545
332.28
38.84
32.85
329.85
C7H16/C2H5OH
heptane/ethanol
100.2019
267.05
27.40
-73.15
1226.85
C6H14/C6H12
hexane/cyclohexane
85.1700
256.70
35.50
6.85
400.00
i-C4H10/i-C5H12
isobutane/isopentane
65.1375
164.99
36.39
-53.15
135.05
MD2M/MD3M
MD2M/MD3M
347.7665
340.00
10.00
2.85
400.00
MD2M/MD4M
MD2M/MD4M
384.8450
353.00
10.30
13.85
400.00
MD2M/MD5M
MD2M/MD5M
421.9200
362.00
9.70
21.85
400.00
MD2M/MD6M
MD2M/MD6M
459.0000
371.00
9.30
29.85
400.00
MD2M/PP2
MD2M/PP2
330.3713
0.00
0.00
29.85
400.00
MD3M/MD4M
MD3M/MD4M
421.9215
368.00
9.30
13.85
400.00
MD3M/MD5M
MD3M/MD5M
458.9965
377.00
8.80
21.85
400.00
MD3M/MD6M
MD3M/MD6M
496.0765
386.00
8.40
29.85
400.00
MD3M/PP2
MD3M/PP2
367.4478
0.00
0.00
29.85
400.00
MD4M/MD5M
MD4M/MD5M
496.0750
389.00
8.20
21.85
400.00
MD4M/MD6M
MD4M/MD6M
533.1550
398.00
7.80
29.85
400.00
MD4M/PP2
MD4M/PP2
404.5229
0.00
0.00
29.85
400.00
MD5M/MD6M
MD5M/MD6M
570.2300
407.00
7.20
29.85
400.00
MDM/MD2M
MDM/MD2M
273.6100
309.00
13.10
-10.15
400.00
MDM/MD3M
MDM/MD3M
310.6865
323.00
12.20
2.85
400.00
MDM/MD4M
MDM/MD4M
347.7650
336.00
11.60
13.85
400.00
MDM/MD5M
MDM/MD5M
384.8400
345.00
11.00
21.85
400.00
MDM/MD6M
MDM/MD6M
421.9200
354.00
10.60
29.85
400.00
MDM/PP2
MDM/PP2
293.2920
0.00
0.00
29.85
400.00
CH4/CO2
methane/carbon dioxide
16.0425
-82.59
45.99
-182.46
351.85
CH4O/C6H6
methanol/benzene
55.0780
269.75
76.23
14.85
350.00
CH4O/C7H8
methanol/toluene
55.0780
269.75
76.23
14.85
350.00
CH4O/H2O
methanol/water
25.0285
308.12
149.91
14.85
350.00
MM/PP2
MM/PP2
256.2158
0.00
0.00
-45.15
400.00
MM/CP28
MM/CP28
174.2168
0.00
0.00
-45.15
400.00
MM/D3
MM/D3
192.4215
263.00
18.00
64.00
400.00
MM/MD2M
MM/MD2M
236.5345
286.00
15.60
-10.15
400.00
MM/MD3M
MM/MD3M
273.6110
300.00
14.70
2.85
400.00
MM/MD4M
MM/MD4M
310.6895
313.00
14.10
13.85
400.00
MM/MD5M
MM/MD5M
347.7645
322.00
13.50
21.85
400.00
MM/MD6M
MM/MD6M
384.8445
331.00
13.10
29.85
400.00
MM/MDM
MM/MDM
199.4545
268.00
16.90
-25.15
400.00
MM/MDM/MD2M
MM/MDM/MD2M
199.4554
266.49
17.37
-10.15
400.00
MM/MDM/MD3M
MM/MDM/MD3M
251.3635
306.00
16.00
2.85
400.00
MM/MDM/MD4M
MM/MDM/MD4M
273.6106
306.00
16.00
13.85
400.00
MM/MDM/MD2M/MD3M
MM/MDM/MD2M/MD3M
273.6106
306.00
16.00
13.85
400.00
MM/MDM/MD2M/MD3M/MD4M/MD5M/MD6M
MM/MDM/MD2M/MD3M/MD4M/MD5M/MD6M
273.6106
306.00
16.00
13.85
400.00
N2/O2
nitrogen/oxygen
28.8102
-140.72
37.94
-209.15
350.00
C5H12/C6H14
pentane/hexane
79.1645
217.20
32.32
-41.15
400.00
C3H8/C4H10
propane/butane
44.0970
96.67
42.50
-187.62
400.00
C3H8/C5H12
propane/pentane
58.1205
160.08
44.82
-77.15
400.00
c8H10/c6H14
p-xylene/hexane
106.1680
344.05
36.06
32.85
329.85
R113/C2H5OH
R113/ethanol
116.7245
229.85
60.56
19.85
350.00
R114/C2H5OH
R114/ethanol
108.5045
204.18
59.05
19.85
350.00
R125/R134a
R125/R134a
120.0200
66.25
36.31
-40.15
400.00
R134a/R116
R134a/R116
120.0210
65.92
31.53
-63.15
101.06
R134a/R142b
R134a/R142b
101.2630
119.27
43.19
-63.15
101.06
R14/R23
R14/R23
79.0090
-1.65
57.24
-163.15
400.00
R32/R125
R32/R125
52.0240
78.41
58.30
-124.15
78.41
R32/R134a
R32/R134a
52.0240
78.41
58.30
-124.15
78.41
R407a
R407A
90.1095
75.78
41.83
-40.15
78.41
R410a
R410A
72.5853
74.83
51.42
-40.15
78.41
R410b
R410B
75.5717
74.31
50.42
-40.15
78.41
H2O/2-C3H8O
water/2-propanol
34.8474
292.45
98.70
51.85
350.00
H2O/2-C4H10O
water/2-butanol
34.8474
292.45
98.70
51.85
350.00

 

The limits for the calculation of properties are as follows:

For a pure fluid:

Pmin = Psat at freezing temperature, i.e. P(Tmin, q=1)

Pmax = P(Tmax, v = 1/2 vc)

 

For a mixture:

Tmin = Max[Tmin (i)]; i = 1,2,..., ncomponents

Tmax = Min[Tmax(i)]; i = 1,2,..., ncomponents

Pmin = P(Tmin, q = 0)

Pmax = P(Tmax, v = 1/2 vc,min),

vc,min = Max[vc (i)] ; i = 1,2,..., ncomponents