2
0
2017
sia
alg
0
journal
Original
Siahvashi, A.[Arman]
Al-Ghafri, S. Z. S.[Saif Z.S.]
Oakley, J. H.[Jordan H.]
Hughes, T. J.[Thomas J.]
Graham, B. F.[Brendan F.]
May, E. F.[Eric F.]
J. Chem. Eng. Data
2017
2020-09-29
Visual Measurements of Solid Liquid Equilibria and Induction Times for Cyclohexane + Octadecane Mixtures at Pressures to 5 MPa
A specialized apparatus designed for visual measurements of solid liquid equilibrium (SLE) and solid liquid vapor equilibrium (SLVE) was constructed and used to measure liquidus (melting) temperatures in binary mixtures of cyclohexane (C6H12) and octadecane (C18H38) across the entire range of composition and at pressures from about (0.004 to 5.3) MPa. A Peltier-cooled copper tip immersed in the liquid mixture was used to determine both freezing and melting temperatures by varying the temperature of the copper tip relative to the stirred, bulk liquid. With the bulk liquid held at the mixture s SLVE temperature, the induction time required to nucleate solid octadecane decreased exponentially as the subcooling of the copper tip increased, halving approximately every 0.25 K. At higher pressures, while the melting temperature of pure cyclohexane (cyC6) increased by about 0.55 K*MPa 1, at xcyC6 = 0.5675 it increased by only 0.15 K*MPa 1. The new data were compared with measurements reported in the literature, empirical correlations describing those literature data, and the predictions of models based on cubic equations of state (EOS), including the Peng Robinson Advanced (PRA) EOS implemented in the software Multiflash. The best description of the data was achieved by adjusting the binary interaction parameter in the PRA model from 0 to -0.0324, which reduced the deviation of the SLVE data at the eutectic point (xcyC6 0.95) from (12.8 to -0.2) K. Although the accuracy of predictions made with the SLVE-tuned PRA EOS deteriorated slightly at pressures around 5 MPa, they were still as good as, or better, than the empirical correlations available for this system. Furthermore, the SLVE-tuned PRA EOS was more accurate at describing literature VLE data for this binary than the default PRA EOS, reducing the root mean square deviation in bubble temperature predictions from (6.7 to 0.67) K.
Solid-Liquid Equilibrium (SLE)
Hydrocarbon mixtures
Cyclohexane
Octadecane
Induction time
Equation of state
10.1021/acs.jced.7b00171
9
62
2896-2910
1
InChI=1S/C6H12/c1-2-4-6-5-3-1/h1-6H2
XDTMQSROBMDMFD-UHFFFAOYSA-N
cyclohexane
C6H12
1
Commercial source
1
99
2
Stated by supplier
2
InChI=1S/C18H38/c1-3-5-7-9-11-13-15-17-18-16-14-12-10-8-6-4-2/h3-18H2,1-2H3
RZJRJXONCZWCBN-UHFFFAOYSA-N
octadecane
n-octadecane
C18H38
1
Commercial source
1
99
2
Stated by supplier
1
1
1
Principal objective of the work
BDH
TRC
9/28/2017
1
Solid-liquid equilibrium temperature, K
VISOBS
Crystal 1
Direct value, X
1
Data file compiler
Propagation of evaluated standard uncertainties
95
Crystal 1
Liquid
1
Pressure, kPa
Crystal 1
1
1310
3
1
280.31
5
1
0.26
1
3430
3
1
281.53
5
1
0.34
1
5310
3
1
282.52
5
1
0.41
2
2
1
1
1
Principal objective of the work
EP
EP
6/8/2017
1
Eutectic composition: mole fraction
Derived from phase diagram analysis
1
Crystal
Direct value, X
1
Data file compiler
Propagation of evaluated standard uncertainties
95
Crystal
2
Crystal 1
1
Liquid
Gas
1
0.9499
4
1
0.0048
3
2
1
1
1
Principal objective of the work
EP
EP
6/8/2017
1
Eutectic temperature, K
Derived from phase diagram analysis
Crystal
Direct value, X
1
Data file compiler
Propagation of evaluated standard uncertainties
95
Crystal
2
Crystal 1
1
Liquid
Gas
1
265.51
5
1
0.41
4
2
1
1
1
Principal objective of the work
EP
EP
6/29/2017
1
Triple point temperature, K
VISOBS
Liquid
Direct value, X
1
Data file compiler
Propagation of evaluated standard uncertainties
95
Liquid
Crystal
2
Gas
1
Mole fraction
1
Liquid
1
0
5
1
301.37
5
1
0.26
1
0.1004
4
1
300.49
5
1
0.44
1
0.2351
4
1
298.67
5
1
0.22
1
0.3574
4
1
296.26
5
1
0.33
1
0.4312
4
1
294.36
5
1
0.43
1
0.4986
4
1
292.73
5
1
0.31
1
0.5535
4
1
291.02
5
1
0.49
1
0.5937
4
1
289.37
5
1
0.44
1
0.6213
4
1
288.46
5
1
0.49
1
0.6728
4
1
286.49
5
1
0.45
1
0.7062
4
1
285.24
5
1
0.41
1
0.7613
4
1
282.58
5
1
0.5
1
0.7951
4
1
280.36
5
1
0.66
1
0.8367
4
1
278.02
5
1
0.45
1
0.8837
4
1
274.71
5
1
0.78
1
0.9231
4
1
270.69
5
1
0.86
1
0.9393
4
1
268.01
5
1
1.22
1
0.9499
4
1
265.51
5
1
1.16
5
2
1
1
1
Principal objective of the work
EP
EP
6/29/2017
1
Triple point temperature, K
VISOBS
Liquid
Direct value, X
1
Data file compiler
Propagation of evaluated standard uncertainties
95
Liquid
Crystal 1
1
Gas
1
Mole fraction
1
Liquid
1
0.9499
4
1
265.51
5
1
1.08
1
0.9605
4
1
267.84
5
1
1.22
1
0.9718
4
1
270.43
5
1
1.46
1
0.9805
4
1
273.46
5
1
2.9
1
0.9891
4
1
276.22
5
1
2.31
1
1
5
1
279.83
5
1
0.23
6
2
1
1
1
Principal objective of the work
BDH
TRC
9/28/2017
1
Solid-liquid equilibrium temperature, K
VISOBS
Liquid
Direct value, X
1
Data file compiler
Propagation of evaluated standard uncertainties
95
Liquid
Crystal
2
1
Mole fraction
1
Liquid
2
Pressure, kPa
Liquid
1
0.5675
4
2
1330
3
1
290.8
5
1
0.31
1
0.5675
4
2
3400
2
1
291.02
5
1
0.33
1
0.5675
4
2
5340
3
1
291.41
5
1
0.39
1
0.8573
4
2
1320
3
1
276.26
5
1
0.39
1
0.8573
4
2
3420
3
1
276.83
5
1
0.41
1
0.8573
4
2
5300
2
1
277.17
5
1
0.43