• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.73-77
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• 2019

Isothermal (vapor + liquid) equilibrium data measurements were undertaken for the binary mixtures of (propylene oxide + 1-pentanol) system at three different temperatures (303.15, 318.15, and 333.15) K. The Peng-Robinson-Stryjek-Vera equation of state (PRSV EOS) was used to correlate the experimental data. The van der Waals one-fluid mixing rule was used for the vapor phase and the Wong-Sandler mixing rule, which incorporates the non-random two liquid (NRTL) model, the universal quasi-chemical (UNIQUAC) model and the Wilson model, was used for the liquid phase. The experimental data were in good agreement with the correlation results.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2545-2552
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• 2018

$SF_6$ has been widely used in high voltage power equipment, such as gas insulated switchgear (GIS) and gas insulated transmission line (GIL), because of its excellent insulation and arc extinguishing performance. However, $SF_6$ faces two environmental problems: greenhouse effect and high liquefaction temperature. Therefore, to find the $SF_6$ substitute gases has become a research hotspot in recent years. In this paper, the liquefaction characteristics of $SF_6$ substitute gases were studied. Peng-Robinson equation of state with the van der Waals mixing rule (PR-vdW model) was used to calculate the dew point temperature of the binary gas mixtures, with $SF_6$, $C_3F_8$, $c-C_4F_8$, $CF_3I$ or $C_4F_7N$ as the insulating gas and $N_2$ or $CO_2$ as the buffer gas. The sequence of the dew point temperatures of the binary gas mixtures under the same pressure and composition ratio was obtained. $SF_6/N_2$ < $SF_6/CO_2$ < $C_3F_8/N_2$ < $C_3F_8/CO_2$ < $CF_3I/N_2$ < $CF_3I/CO_2$ < $c-C_4F_8/N_2$ < $C_4F_7N/N_2$ < $c-C_4F_8/CO_2$ < $C_4F_7N/CO_2$. $SF_6/N_2$ gas mixture showed the best temperature adaptability and $C_4F_7N/CO_2$ gas mixture showed the worst temperature adaptability. Furthermore, the dew point temperatures of the $SF_6$ substitute gases at different pressures and the upper limits of the insulating gas mole fraction at $-30^{\circ}C$, $-20^{\circ}C$ and $-10^{\circ}C$ were obtained. The results would supply sufficient data support for GIS/GIL operators and researchers.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.11
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• pp.859-866
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• 2006

This paper presents the vapor-liquid equilibrium (VLE) data measured for carbon dioxide and propane mixtures. Their mixtures were considered as promising alternative refrigerants due to good thermophysical properties and negligible environmental impact. The isothermal VLE data were measured at eight temperatures ranging from 253.15 to 323.15 K in the circulation type equipment with a view cell. The binary system was found to be a zeotropic mixture in the tested temperature range and could be correlated with sufficient accuracy by using the Peng-Robinson equation of state (PR EoS) with the van der Waals one fluid mixing rule. A comparison with published experimental VLE data has been carried out by means of the PR equation of state. In addition, the phase behaviors of carbon dioxide and propane mixtures were analyzed based on the measured VLE data.

• Korean Chemical Engineering Research
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• v.53 no.2
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• pp.193-198
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• 2015

The high-pressure phase behavior of a polycaprolactone (Mw=56,145 g/mol, polydispersity 1.2), dichloromethane, and carbon dioxide ternary system was measured using a variable-volume view cell. The experimental temperatures and pressures ranged from 313.15 K to 353.15 K and up to 300 bar as functions of the $CO_2$/dichloromethane mass ratio and temperature, at poly(D-lactic acid) weight fractions of 1.0, 2.0, and 3.0%. The correlation results were obtained from the hybrid equation of state (Peng-Robinson equation of state + SAFT equation of state) for the $CO_2$-polymer system using the van der Waals one-fluid mixing rule. The three binary interaction parameters were optimized by the simplex method algorithm.

• Clean Technology
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• v.11 no.3
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• pp.117-122
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• 2005

N-vinyl caprolactam (NVCL), a kind of N-vinyl amide monomer, must be dissolved in continuous phase ($scCO_2$) for dispersion polymerization in supercritical carbon dioxide. Phase behavior of $CO_2$+NVCL is very important and necessary for determining initial polymerization condition and for monomer extraction from final polymer. There is the limitation of experimental method for obtaining pure properties of the monomer because of the possibility of polymerization. And N-methyl caprolactam (NMCL) is the useful solvent for the gas treating process. In the viewpoint of molecular thermodynamics, NVCL and NMCL have same functional group i.e. ${\varepsilon}$-caprolactam. In the case of NVCL, hydrogen of amide group is substituted with vinyl group and for NMCL, hydrogen of amide group is substituted with methyl group. We suggested modified group contribution method for this ${\varepsilon}$-caprolactam derivatives. This new group contribution parameter was applied to correlate $CO_2$ + N-vinyl caprolactam or N-methyl caprolactam system.