• 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.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.539-546
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• 2008

A study on the selection of an optimal entrainer as the third component among water, aniline, 1,3-diethylbenzene, furfural, and MEK, for the extractive distillation of an azeotropic acetone/methanol system was performed using both the entrainer effect vapor-liquid equilibrium (VLE) and the relative volatility. In the case of water as the entrainer, a VLE curve without azeotropic point in the range of water composition from 0.3 up to 0.7 mole fraction could be obtained by both the experiment and the calculation using modified-UNIFAC model. For aniline and 1,3-diethylbenzene, however, VLE curve without azeotropic point could be obtained only at compositions above 0.7 mole fraction, which exhibited that they could be hardly utilized as the entrainer. Moreover, both furfural and MEK were verified to be improper entrainer since they formed an azeotropic phase. Relative volatility of water showed greater than 1.0 and increased with compositions, while those of the others decreased non-linearly, exhibiting that only water could be utilized as the proper entrainer for the extractive distillation of azeotropic acetone/methanol system.

• Clean Technology
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• v.11 no.4
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• pp.165-170
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• 2005

The aim of this study is to provide vapor-liquid equilibrium (VLE) information for the study of process which directly synthesize dimethyl carbonate (DMC) from $CO_2$. For this study we collected some necessary VLE systems data of Methanol-Water, Methanol-DMC, $CO_2$-DMC, $CO_2$-Methanol, $CO_2$-Methanol, and performed VLE calculation with Peng-Robinson equation of state, Wong-Sandler mixing rules that widely used in chemical industry. These calculation results relatively agreed with VLE data well. Optimized Parameters of EoS given through this calculation will be used as some valuable information for fundamental study, process development and process optimization of DMC direct synthesis.

• Macromolecular Research
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• v.14 no.2
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• pp.220-229
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• 2006

Several equations of state for hard-sphere chains with various perturbation terms are reviewed. For each model, three characteristic parameters are required to represent phase equilibria of normal fluids and obtained from thermodynamic properties of pure saturated liquids. The models are then compared with computer simulation data to show the effect of attractive contribution forms employed. Calculated values of vapor-liquid equilibria (VLE) of hydrocarbons that can be reproduced for each model are also compared with experimental results. An additional parameter, ${\zeta}_{KB}$, is required to represent the VLE of pure water, which is ascertained to have a strong influence on the theoretical coexistence curve.

• Journal of the Korean Institute of Gas
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• v.4 no.4 s.12
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• pp.1-5
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• 2000

Cubic and non-cubic equations of state are used to calculate the vapor-liquid equilibrium(VLE) compositions for liquified natural gas(LNG) containing hydrogen sulfide. Modified Benedict-Web-Robin EOS is chosen as a non-cubic equation of state while Peng-Robinson, Soave-Redlich-Kwong EOS are used for a cubic EOS. Modified Benedict-Web-Robin EOS. showed better predictability than the cubic EOS used for the systems $H_2S/CH_4,\;H_2S/iC_4H_{10},\;H_2S/N_2$. specially for liquid composition.

• Journal of Energy Engineering
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• v.17 no.4
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• pp.241-246
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• 2008

Increase of $CO_2$ by using fossil fuels makes mainly global warming and the international efforts to reduce the $CO_2$ emission is being promoted. Absorption process using aqueous alkanolamine solution to remove acid components in the mixed gases has been used commercially. This method was used to remove $CO_2$ in the flue gas in recent years. $CO_2$ Absorption characteristics of several aqueous alkanolamine solutions such as MEA, DEA and AMP was studied by measuring vapor-liquid-equilibrium(VLE) and absorption velocity in this study. VLE measuring equipment, shell and reactor type, was used to acquire VLE data, equilibrium $CO_2$ pressure(${P_{CO_2}}^*$) and time at each pulse gas input. We also acquired the $CO_2$ absorption velocity by measuring the time to arrive the VLE at $40{\sim}80^{\circ}C$ and first gas input. The $CO_2$ absorption capacity of MEA 10wt% solution was higher than two alkanolamine solutions at $40^{\circ}C$ and the equilibrium $CO_2$ loading was 0.5. Absorption capacity was excellent as follows; AMP>DEA>MEA. But absorption velocity was fast as follows; MEA>AMP>DEA. Though good absorbent was considered by many variables, absorption velocity and capacity was more important factor.

• Journal of the Korean Institute of Gas
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• v.14 no.5
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• pp.32-37
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• 2010

In this study, vapor-liquid equilibrium (VLE) data at several isothermal temperatures for carbon dioxide and ethane binary systems were estimated using binary interaction parameters (BIP's) in Peng-Robinson (PR) equation of state built-in PRO/II with PROVISION (PRO/II) process simulator. Moreover, BIP's in PR equation of state were newly determined by regressing the experimental VLE data for carbon dioxide and ethane systems for each different isothermal temperatures using the summation of squares of the bubble point deviations as an objective function. Comparative works have been performed for absolute average deviation % (AAD(%)) between experimental and predicted bubble pressures using built-in BIP's in PRO/II and newly regressed one, respectively. Our calculation results gave a better estimation result than the simulation result using an existing parameter built-in PRO/II.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.993-998
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• 2011

The absorption capacity and initial absorption rate of $CO_2$ into aqueous $K_2CO_3$ solutions were measured by using VLE(Vapor-Liquid-Equilibrium) equipment in the pre-combustion condition. Absorption experiments were conducted within the temperature range of $40{\sim}80^{\circ}C$ while increasing the $CO_2$ pressure from 0 to 50bar. The effect of $K_2CO_3$ concentration was investigated by varying in the range of 5~20%. As a results, the absorption capacity and initial absorption rate were increased with increasing $K_2CO_3$ concentration in the absorbents. Also, the initial absorption rate was highest at $40^{\circ}C$. Further more, we have studied the effect of adding piperazine and homopiperazine to $K_2CO_3$ solutions. The results showed that absorption capacity of $CO_2$ was somewhat increased by adding piperazine.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.755-761
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• 2009

To a first approximation, phase behavior of a system becomes increasingly skew in proportion to the boiling point difference of system-forming constituents. Therefore, phase behavior data of a system of a large boiling point difference are to be experimentally measured for thorough understanding of the thermodynamic characteristics of such system. In this work, isobaric vapor-liquid equilibrium of a mixture consisting of toluene and cresol, which shows a large boiling point difference of nearly $100^{\circ}C$ and is consequently expected to be considerably nonideal, was measured by using a recirculating equilibrium cell at various subatmospheric pressures ranging from 10 kPa to 60 kPa. The measured VLE data were correlated with NRTL and UNIQUAC models in a satisfactory manner and the accompanying thermodynamic consistency test represented soundness of the measurements. In addition, the excess molar volume of the mixture was also measured with a vibrating densitometer and correlated with a Redlich-Kister polynomial. A negative excess volume prevailed over the whole concentration range, which indicates a favorable attraction between toluene and cresol isomers and results in an extensive miscibility.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.295-300
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• 2010

A binary system of 1-propanol and bromochloromethane which exhibits an azeotropic point and a considerable nonideal phase behavior probably due to the large boiling point difference is not amenable in the actual chemical processes such as the distillation tower and absorber. Therefore, experimental data of phase behavior data of this mixture are indispensable in understanding the inherent thermodynamic characteristics for an efficient application of the system in the industrial processes. In this work, the isobaric vapor-liquid equilibrium of a binary mixture consisting of 1-propanol and bromochloromethane was measured by using a recirculating equilibrium cell at various pressures ranging from 30 to 70 kPa. The measured VLE data were correlated in a satisfactory manner by using the UNIQUAC and NRTL models along with the thermodynamic consistency test based on Gibbs/Duhem equation. In addition, the excess molar volume of the mixture was also measured by using a vibrating densitometer and correlated with a Redlich-Kister polynomial.