Visual Measurements of Solid-Liquid Equilibria and Induction Times for Cyclohexane + Octadecane Mixtures at Pressures to 5 MPa

Arman Siahvashi, Saif Z.S. Al-Ghafri, Jordan H. Oakley, Thomas J. Hughes, Brendan F. Graham, Eric F. May

Research output: Contribution to journalArticle

2 Citations (Scopus)
225 Downloads (Pure)

Abstract

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.

Original languageEnglish
Pages (from-to)2896-2910
Number of pages15
JournalJournal of Chemical and Engineering Data
Volume62
Issue number9
DOIs
Publication statusPublished - 14 Sep 2017

Fingerprint

Cyclohexane
Equations of state
Phase equilibria
Liquids
Melting point
Copper
Binary mixtures
octadecane
Freezing
Temperature
Eutectics
Chemical analysis

Cite this

@article{b5c794e0c0794ea4b923f47b96483369,
title = "Visual Measurements of Solid-Liquid Equilibria and Induction Times for Cyclohexane + Octadecane Mixtures at Pressures to 5 MPa",
abstract = "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.",
author = "Arman Siahvashi and Al-Ghafri, {Saif Z.S.} and Oakley, {Jordan H.} and Hughes, {Thomas J.} and Graham, {Brendan F.} and May, {Eric F.}",
year = "2017",
month = "9",
day = "14",
doi = "10.1021/acs.jced.7b00171",
language = "English",
volume = "62",
pages = "2896--2910",
journal = "Journal of Chemical & Engineering Data",
issn = "0021-9568",
publisher = "American Chemical Society",
number = "9",

}

TY - JOUR

T1 - Visual Measurements of Solid-Liquid Equilibria and Induction Times for Cyclohexane + Octadecane Mixtures at Pressures to 5 MPa

AU - Siahvashi, Arman

AU - Al-Ghafri, Saif Z.S.

AU - Oakley, Jordan H.

AU - Hughes, Thomas J.

AU - Graham, Brendan F.

AU - May, Eric F.

PY - 2017/9/14

Y1 - 2017/9/14

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85029453044&partnerID=8YFLogxK

U2 - 10.1021/acs.jced.7b00171

DO - 10.1021/acs.jced.7b00171

M3 - Article

VL - 62

SP - 2896

EP - 2910

JO - Journal of Chemical & Engineering Data

JF - Journal of Chemical & Engineering Data

SN - 0021-9568

IS - 9

ER -