• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.706-713
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• 1994

Isothermal vapor-Liquid equilibrium data have been measured for binary systems MTBE-methanol, MTBE-n-heptane, and methanol-n-heptane at $45^{\circ}C$ and $65^{\circ}C$ by using head space gas chromato-graphy (H.S.G.C). Among these systems a minimum azeotrope was observed in both of MTBE-methanol system and n-heptane-methanol system. Particularly n-heptane-methanol system has a heterogeneous minimum azotrope since it has an immisible region. These equilibrium data were correlated with the excess Gibbs energy model, and the thermodynamic consistency test was also carried out by using Redlich-Kister equation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.8
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• pp.710-719
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• 2001

Pool boiling heat transfer coefficients (HTCs) of HCFC123, HFC134a, HCFC22, HFC407C, HFC410A and HFC32 wre measured on a horizontal smooth tube, 26 fpi low fin tube, Turbo-B and Thermoexcel-E enhanced tubes. AN experimental apparatus was designed such that all tubes heated by cartridge heaters could be installed at the same time to save the refrigerant. Data were taken in the pool of $7^{\circ}C$ with the heat flux decreasing from 80 kW/$m^2\;to\;5kW/m^2$. Test results showed that HTCs of pure refrigerants and those of a azeotrope were greatly influenced by reduced pressure. HTCs of HFC407C were 21~25% lower than those of HCFC22 due to mass transfer resistance. For all refrigerants, enhanced tubes with sub-surface and sub-tunnels showed the largest heat transfer enhancement. Especially the largest heat enhancement was obtained for HCFC123 whose reduced pressure is the lowest among al the refrigerants tested. This indicates that either Turbo-B or Thermoexcel-E enhanced tube would be the best choice when used with a low vapor pressure refrigerant.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.6
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• pp.102-108
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• 2001

To prevent green house effect and destruction of an ozone layer, an ozone destruction potential(OBP) must be zero and a refrigerant for low global warming potential(GWP) is needed. HFC-l34a, in which hydrogen is mixed instead of chlorine is a refrigerant used for automobile conditioners and its destruction potential is ecologically zero. However, it is not consid- ered as a perfect substitutive refrigerant as its GWP is high. It is studied refrigerant mixtures in which HFC-l52a and $CF_3 I$ in HFC-l52a with low GWP and zero ODP are mixed by experimentally and concluded as follows: 1) With the variation of speed of compressor outside temperature and flow rate, 7he heat of evaporator and compressor and coefficient of perfor- mance was varied, and influenced the air conditioner. 2) The pressure of evaporator was decreased with increasing the speed of compressor and the pressure of evaporator with the refrigerant HFC-l52a was higher 24% than that of azotrope refrigerant mixed with $CF_3 I$

• Journal of Hydrogen and New Energy
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• v.18 no.4
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• pp.458-463
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• 2007

An experimental study on scale-up of Electro-electrodialysis(EED) to increase the efficiency of HI decomposition section in the IS(Iodine-Sulfur) process was carried out. The EED stack extends the effective area of the membrane to 20 times of that formerly used in a single EED unit cell. The experiment was carried out using HIx solution($HI:H_2O:I_2=1:8.4{\sim}9:1.85{\sim}1.9$) at $100^{\circ}C$ and various solution flow rates of 20, 30, 40 and 50 cc/min. The increased HI molality in catholyte after one-pass throughout from the EED stack was 3 mol/kg-$H_2O$, 2.2 mol/kg-$H_2O$, 2 mol/kg-$H_2O$ and 1.37 mol/kg-$H_2O$ at 20, 30, 40 and 50 cc/min, respectively. These values satisfied the target of HI molality(the increase of HI molality: 2 mol/kg-$H_2O$) in the IS process for hydrogen production of 20 L/hr.

• 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.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.29-41
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• 2018

Separating a mixture having an azeotrope or low relative volatility with single distillation column is difficult. Separating water-acetic acid mixture and water-ethanol mixture with a distillation column consumes a lot of energy. Pervaporation membrane can be used to separate the mixture in the concentration region where separation is difficult with distillation. We simulated a distillation-membrane hybrid process where membrane is located on the head of the distillation column for efficient separation of water-acetic acid and water-ethanol mixture. Permeability data were obtained from experiments and literature. We formulated an optimization problem for the process with total annual cost (TAC) as an objective function and major design variables as optimization variables. Major optimization variable affecting TAC of the hybrid process was shown to be distillate concentration. We also suggested a simplified optimization procedure to get a close-to-optimal solution.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3764-3773
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• 2012

In this study, modeling and optimization works were completed for the separation of 99.9 mol% of methyl ethyl ketone from water through a pressure-swing distillation process since the azeotropic composition varies very sensitively with the change of system pressure. PRO/II with PROVISION release 9.1 was used for the computer simulation and Wilson activity coefficient model was chosen as a modeling equation. A pressure-swing distillation process can be classified into a low-high pressure columns configuration and a high-low pressure columns configuration. In this work, each configurations were optimized for the minimization of steam consumptions, respectively and were compared.

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2336-2347
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• 2018

The azeotrope of methyl acetate methanol and water was isolated using extractive distillation with water as entrainer. The pressure-swing extractive distillation (PSED) process and vapor side-stream distillation column (VSDC) with the rectifier process were designed to separate the methyl acetate, methanol and water mixture. It was revealed that the VSDC with the rectifier process had a reduction in energy consumption than the PSED process. Four control schemes of the two process were investigated: Double temperature control scheme (CS1), $Q_R/F$ feedforward control of reboiler duty scheme for PESD (CS2), $Q_R/F$ feedback control scheme for VSDC (CS3), the feedback control scheme of sensitive plate temperature of side-drawing distillation column to dominate the compressor shaft speed (CS4). Feed flow and composition disturbance were used to evaluate the dynamic performance. As a result, CS4 is a preferable choice for separation of methyl acetate-methanol-water mixture. A control scheme combining the operating parameters of dynamic equipment with the control indicators of static equipment was proposed in this paper. It means using the sensitive plate temperature of side-drawing column to control the compressor shaft speed. This is a new control scheme for extractive distillation.

• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.698-705
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• 2016

Butyl acetate is produced from acetic acid and butanol via an esterification reaction in reactive distillation (RD). The product, butyl acetate, has been used as an internal entrainer until now. In this case, butyl acetate and water are removed at the top of column and separated into two different phases (organic and aqueous phases) after condensation, and butyl acetate rich organic phase is refluxed into the RD. This method makes butyl acetate remain high at the reactive zone, leading to lower equilibrium conversion and product yield. We introduced an extraneous entrainer to solve the problem. The extraneous entrainer forms a new azeotrope with water. The proposed process provides lower concentration of butyl acetate in the reactive zone than conventional RD processes using an internal entrainer. We compared the yield and production rate of butyl acetate between the proposed and conventional processes through pilot-scale experiments. Experimental and simulation results showed that the proposed process was more efficient than conventional process using internal entrainer.