• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.1
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• pp.91-99
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• 1999

Vapor-liquid equilibrium apparatus is designed and set up. The equilibrium data of two binary systems, HFC-32/143a and HFC-143a/134a, are measured. Fifteen equilibrium data for HFC-32/143a and HFC-143a/134a systems are measured over the temperature range 263.15~283.15K at 10K interval and the composition range 0.10~0.80, respectively. And vapor-liquid equilibrium data are calculated using equation of state and correlation of activity coefficient and compared with the present data. Equation of state is used CSD and RKS equations and correlation of activity coefficient is used Margules' and Van Ness and Abbott's correlations. Real behavior of HFC-32/143a system has very large deviation with Raoult's rule which is ideal behavior. But real behavior of HFC-143a/134a system is similar to ideal behavior. The calculated data from CSD equation are compared with the data in the open literatures and the calculated data from REFPROP. In the results for REFPROP, the relative deviations of bubble point pressure for HFC-32/143a system are within -2.16~0.84% for CSD equation and within -0.20~1.10% for RKS equation. And the relative deviations of bubble point pressure for HFC-143a/134a system are within -0.45~0.12% and -0.20~2.8% for CSD and RKS equations, respectively.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.222-228
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• 2018

Benzene is one of the most widely used basic materials in the petrochemical industry. Generally, benzene exists as a mixture with alcohols rather than as a pure substance. Further, the alcohols-added mixtures usually exhibit an azeotropic composition. In this context, knowledge of the phase equilibrium behavior of the mixture is essential for its separation and purification. In this study, the vapor-liquid equilibrium data were measured in favor of a recirculating VLE apparatus under constant pressure for the 1 - propanol / benzene system. The measured vapor - liquid equilibrium data were also correlated by using the UNIQUAC and WILSON models and the thermodynamic consistency test based on the Gibbs/Duhem equation was followed. The results of the phase equilibrium experiment revealed RMSEs (Root Mean Square Error) and AADs (Average Absolute Deviation) of less than 0.05 for both models, indicating a good agreement between the experimental value and the calculated value. The results of the thermodynamic consistency test also confirmed through the residual term within ${\pm}0.2$.

• Korean Chemical Engineering Research
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• v.48 no.5
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• pp.632-637
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• 2010

Liquid-liquid equilibrium data for the quaternary system water +tetrahydrofuran + butyl acetate + isoamyl alcohol mixture were measured at 298.15 K and atmospheric pressure. Binodal curves, tie-lines, distribution, and selectivity for the quaternary system have been determined in order to investigate the effect of using binary solvents, butyl acetate and isoamyl alcohol, on extracting tetrahydrofuran from aqueous solution. In addition, these experimental tie-line data were also compared with the values predicted by the UNIFAC model. For the quaternary system, an average root-mean-square deviation for the system in 75/25, 50/50, and 25/75 mass ratios as mixed solvents are(3.35, 5.21 and 5.65) %, respectively.

• Bulletin of the Korean Chemical Society
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• v.12 no.3
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• pp.309-315
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• 1991

The thermal transport coefficients-the self-diffusion coefficient, shear viscosity, and thermal conductivity-of liquid argon at 94.4 K and 1 atm are calculated by non-equilibrium molecular dynamics (NEMD) simulations of a Lennard-Jones potential and compared with those obtained from Green-Kubo relations using equilibrium molecular dynamics (EMD) simulations and with experimental data. The time-correlation functions-the velocity, pressure, and heat flux auto-correlation functions-of liquid argon obtained from the EMD simulations show well-behaved smooth curves which are not oscillating and decaying fast around 1.5 ps. The calculated self-diffusion coefficient from our NEMD simulation is found to be approximately 40% higher than the experimental result. The Lagrange extrapolated shear viscosity is in good agreement with the experimental result and the asymptotic formula of the calculated shear viscosities seems to be an exponential form rather than the square-root form predicted by other NEMD studies of shear viscosity. The agreement for thermal conductivity between the simulation results (NEMD and EMD) and the experimental result is within statistical error. In conclusion, through our NEMD and EMD simulations, the overall agreement is quite good, which means that the Green-Kubo relations and the NEMD algorithms of thermal transport coefficients for simple liquids are valid.

• Journal of Environmental Science International
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• v.9 no.6
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• pp.517-522
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• 2000

Separation of strontium ion from synthetic seawater in the contained liquid membrane permeator with two micro-porous films was performed. The permeator consisted of a liquid membrane and two cells for aqueous solutions. The liquid membrane consisted of $D_2EHPA(di-2-ethylhexy1-phosphoric acid)$ and DCH18C6 (dicyclohexano-18-crown-6),diluted to 30 vol% with kerosine and was trapped between two micro-porous hydrophilic films. This liquid membrane separated two aqueous solutions, one of which was synthetic seawater and the other of which was the stripping solutions consisting of 1mol/L $H_2SO_4$ solution. The effects of various operating parameters on the extraction rate and equilibrium extraction ratio of strontium ion from synthetic seawater were experimentally examined. The addition of DCH18C6 to the $D_2EHPA$ solution caused synergy effect on the extraction of strontium ion. The permeator extracted strontium ion from synthetic seawater effectively with high membrane life time.

• Journal of Environmental Science International
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• v.9 no.2
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• pp.159-164
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• 2000

For the purpose of development of a liquid membrane permeator which separates metal ions from aqueous solutions continuously and effectively, a continuous membrane permeator with the membrane solution trapped between extraction and stripping phases by two micro-porous hydrophilic films was manufactured. Experimental researches on the separation of zinc ion from aqueous solutions were performed in the liquid membrane permeator with 30 vol % D2EHPA solution in kerosine as liquid membrane. As results, the liquid membrane permeator separates zinc ion from aqueous solutions continuously and effectively in the wide range of operating conditions. A simple mass transfer rate model using equilibrium constant of the extraction reaction for the system used were proposed, and the model was compared with experimental results of separation of zinc ion in the permeator. And the effects of operating factors, such as space time, pH of extraction solution, extraction temperature, on the separation rate of zinc ion in the permeator were experimentally examined.

• Korean Journal of Metals and Materials
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• v.56 no.12
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• pp.870-877
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• 2018

Cyanex 272 shows the highest separation factor for the rare earth elements from hydrochloric acid solution among the organophosporus acidic extractants, D2EHPA and PC 88A. Solvent extraction of Tb(III) from weak hydrochloric acid solution with an initial pH 3 to 6 was compared with Cyanex 272, its mixture with Alamine 336, and ionic liquid with Aliquat 336. The solvent extraction reaction of Tb(III) using Cyanex 272 was the same as that of light rare earth elements. Synergism was observed for the extraction of Tb(III) by the mixture with Alamine 336 when the initial concentration ratio of Cyanex 272 to Alamine 336 was higher than 5. Use of the ionic liquid led to a great increase in the extraction percentage of Tb(III) from the same initial extraction conditions. While the equilibrium pH of the mixture was always lower than the initial pH, under some conditions extraction with the ionic liquid resulted in a higher equilibrium pH than the initial pH. The loading capacity of the mixture and the ionic liquid was the same and 2.6 times larger than that using Cyanex 272 alone. Ionic liquid was recommended as a suitable extractant for the extraction of Tb(III) from hydrochloric acid solution based on the ease of handling and higher extraction percentage.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.241-248
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• 2002

In this work, we calculated the vapor-liquid equilibrium of aqueous polymer solutions by using PRSV equation of state combined with $G^{ex}$ mixing rules(HVO, MHVL, MHV2, LCVM). From the comparison of calculated results with experimental data obtained from literature, we found that calculation results by using MHV1 mixing rule have showed small range of error than HVO, MHV2 and LCVM mixing rules. Calculation results by using the combination of MHV1 mixing rule and UNIFAC-FV model have showed the best result for selected aqueous polymer solutions.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.157-161
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• 2008

This study introduce a newly developed program to calculate the combustion process of combustion chamber and gas generator of liquid rocket engine by use of Gibbs free energy minimization method based on chemical equilibrium. The simulation results of the new program and CEA code of NASA were compared and showed good agreement, thus proving the validity of the newly developed in-house program for combustion analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.1 s.232
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• pp.159-168
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• 2005

In recent studies, it was reported that there existed the temperature discontinuity at a liquid-vapor interface in an equilibrium state. However, from the viewpoint of the classical thermodynamics, it is highly questionable result although considering that the experiments related with a boundary layer is very difficult due to the extremely thin thickness of it. To clarify whether the temperature discontinuity over a liquid-vapor interface really exists, the computer simulations were performed. From the simulation results, it could be concluded that the misconception in a temperature calculation might result in non-uniform temperature distributions over an interface under an equilibrium state.