• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.10
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• pp.1370-1377
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• 2002

This study analyzed the design performance of the bottoming system of combined cycle power plants using a once-through heat recovery steam generator. For a parallel arrangement of the main heater and reheater, parametric analyses were carried out to present the criteria for determining the reheater pressure and the location of the starting point of the reheater in the HRSG. The performance of the bottoming system was presented fer a range from high subcritical to supercritical pressure. The steam turbine power is as high as that of conventional triple-pressure bottoming systems. The serial arrangement of heat exchangers with division of each heater into several segments can achieve similar power level.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.489-492
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• 2011

Supercritical fluid technology has been an alternative for purification and separation of biological compounds in cosmetic, food, and pharmaceutical products. Solubility information of biological compounds in supercritical fluids is essential for choosing a supercritical fluid processes. The equilibrium solubility of hinokitiol was measured in supercritical carbon dioxide with a static method in the pressure range from 8 to 40 MPa and at temperatures equal to 313.2, 323.2 and 333.2 K. The experimental data were correlated well by Peng.Robinson equation of state and quasi-chemical nonrandom lattice fluid model.

• Journal of Microbiology and Biotechnology
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• v.19 no.12
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• pp.1596-1602
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• 2009

A lipase-catalyzed esterification reaction of (S)-naproxen ethyl ester by CALB (Candida antarctica lipase B) enzyme was performed in supercritical carbon dioxide. Experiments were performed in a high-pressure cell for 10 h at a stirring rate of 150 rpm over a temperature range of 313.15 to 333.15 K and a pressure range of 50 to 175 bar. The productivity of (S)-naproxen ethyl ester was compared with the result in ambient condition. The total reaction time and conversion yields of the catalyzed reaction in supercritical carbon dioxide were compared with those at ambient temperature and pressure. The experimental results show that the conversion and reaction rate were significantly improved at critical condition. The maximum conversion yield was 9.9% (216 h) at ambient condition and 68.9% (3 h) in supercritical state. The effects of varying amounts of enzyme and water were also examined and the optimum condition was found (7 g of enzyme and 2% water content).

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.3.2-3.2
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• 2005

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.281-286
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• 2009

Bitumen extraction and sulfur removal from Athabasca oil sand were conducted using water in sub- and supercritical condition. Bitumen yield in micro reactor was investigated in the pressure range of 15~30 MPa, the temperature of 360 and $380^{\circ}C$ and water density $0.074{\sim}0.61g/cm^3$ for 0~120 min. Bitumen yield increased with reaction pressure irrespective of temperature and dramatically increased in especially supercritical region due to hydrogen formed from water gas shift reaction. Total amount of gas product decreased with reaction pressure but the portion of sulfur and hydrogen increased a little with increasing pressure to 25 and 30 MPa. It is seen that supercritical condition was favourable to the hydrogen formation and sulfur removal. Bitumen yield and sulfur removal from original oil sand reached a maximum 22% and 40% respectively in supercritical condition(the reaction time of 60 min at $380^{\circ}C$ and 25 or 30 MPa).

• Journal of ILASS-Korea
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• v.1 no.1
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• pp.35-43
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• 1996

A vaporization model for single component fuel droplet has been developed for applying to sub- and supercritical conditions. This model can account for transient liquid heat ins and circulation effect inside the droplet, forced and natural convection, Stefan flow effect, real gas effect and ambient gas solubility into the liquid droplet in high-pressure conditions. Thermodynamic and transport properties are calculated as functions of temperature and pressure in both phases. Numerical calculations are carried out for several validation cases with the detailed experimental data. Numerical results confirm that this supercritical vaporization model is applicable to the high-pressure conditions encountered in the combustion processes of diesel engine.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.6
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• pp.538-545
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• 2004

This paper presents the experimental data for the heat transfer and pressure drop characteristics obtained during the gas cooling process of carbon dioxide in a horizontal tube. The tube in which carbon dioxide flows is made of copper with an inner diameter of 7.73 mm. Experiments were conducted for various mass fluxes and inlet pressures of carbon dioxide. Mass fluxes are controlled at 225, 337 and 450 kg/$m^2$s and inlet pressures are adjust-ed from 7.5 to 8.8 ㎫. The experimental results in this study are compared with the existing correlations for the supercritical heat transfer coefficient, which generally under-predict the measured data. Pressure drop data agree very well with those calculated by the Blasius' equation. Based on the experimental data, a new empirical correlation to estimate the near-critical heat transfer coefficients has been developed.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.3
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• pp.21-29
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• 2013

Turbulent flow and thermal fields of gaseous hydrogen/liquid oxygen flames at supercritical pressure are investigated by turbulence models. The modified Soave-Redlich-Kwong (SRK) EOS is implemented into the flamelet model to realize real-fluid combustions. For supercritical fluid flows, the modified pressure-velocity-density coupling are introduced. Based on the algorithm, the relative performance of six convection schemes and the predictions of four turbulence models are compared. The selected turbulence models are needed to be modified to consider various characteristics of real-fluid combustions.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.2
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• pp.85-88
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• 2002

A study was carried out on the application of supercritical fluid to the hydrolysis of boll fibers of cotton (cultivar Tashkent-6 of Gossypium hirsutum L.) by cellulase enzymes from Trichoderma viride, Trichoderma reesei and Aspergillus niger. Conditions of the enzymatic process were optimized. The stabilities of cellulase enzymes were sustained at the pressure of up to 160 attn for 48 hours at 5$0^{\circ}C$ in supercritical carbon dioxide.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1429-1432
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• 2006

Polyaromatic hydrocarbons were separated by a capillary supercritical fluid chromatographic (SFC) column and detected by a UV detector at the wavelength of 280 $\mu$m. The temperature-controlled restrictor was designed for UV detection. The temperature-controlled restrictor is a 20 cm length of deactivated fused silica of 7 mm i.d. which is held right after UV detector of the capillary SFC. The temperature of the restrictor will control the flow rate of the supercritical carbon dioxide mobile phase through the capillary column in SFC. Thus as the pressure in the column is increased from 1500 psi to 4000 psi during a pressure program, the temperature of 7 $\mu$m fused-silica tube can be varied from 100 to 350 ${^{\circ}C}$ to maintain a constant flow rate.