• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.4
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• pp.527-535
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• 1997

Vapor-liquid equilibrium apparatus is designed and set up. The vapor-liquid equilibrium data of the binary system HFC32/134a are measured in the range between 258.15 and 283.15K at compositions of 0.2, 0.4, 0.6 and 0.8 mole fraction of HFC32. Twenty-two equilibrium data are obtained. Based upon the present data, the binary interaction parameter for Carnahan-Starling-De Santis equation of state is calculated. Temperature range of data is extended to 313.04K using the data in the open literatures. Interaction parameters are determined at nine isotherms.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.127-132
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• 2003

A study of high-pressure n-heptane droplet vaporization is conducted with emphasis placed on equilibrium at vapor-liquid interface. General frame of previous rigorous model[1] is retained but tailored for flash equilibrium calculation of vapor-liquid interfacial thermodynamics. The model is based on complete time-dependent conservation equations with a full account of variable properties and vapor-liquid interfacial thermodynamics. The influences of high-pressure phenomena, including ambient gas solubility, thermodynamic non-ideality, and property variation on the droplet evaporation are investigated. The governing equations and associated moving interfacial boundary conditions are solved numerically using a implicit scheme with the preconditioning method and the dual time integration technique. And a parametric study of entire droplet vaporization history as a function of ambient pressure, temperature has been conducted. Some computational results are compared with Sato's experimental data for the validation of calculations. For low ambient temperatures, the droplet lifetime first increases with pressures, then decreases for high pressures. For higher ambient temperatures, the droplet lifetime increase with less amplitude than that of low ambient temperatures, which then decreases with more amplitude than that of low temperatures. The solubility of nitrogen can not be neglected in the high pressure and it becomes higher as the pressure goes up.

• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.513-519
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• 1988

The effect of pressure and temperature on the stabilities of hexamethylbenzene-1,3,5-trinitrobenzene charge transfer complex in carbon tetrachloride has been investigated by spectrophotometric measurements. The absorption spectra of charge transfer complexes were measured at 25, 40, $50^{\circ}C$ under 1, 200, 500, 1000, 1400 bar in this experiments. The equilibrium constants of the complex were increased with pressure and decreased with temperature rising. The absorption coefficients were increased with pressure and temperature. Change of volume, enthalpy, free energy and entropy for the formation of complexes were calculated from the equilibrium constants. The red-shift observed at a higher pressure, the blue-shift at a higher temperature and the relation between pressure and oscillator strength were discussed by means of thermodynamic fuctions.

• Journal of the Korean Chemical Society
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• v.27 no.2
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• pp.102-110
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• 1983

The effect of pressure and temperature on the stabilities of the benzene-iodine charge transfer complex have been investigated through ultraviolet spectrophotometric measurements in n-hexane. The stabilities of the complexes were measured at temperatures of 25, 40 and $60^{\circ}C$ up to 1600 bars. The equilibrium constant of the complex formation was increased with pressure and decreased with temperature raising. The absorption coefficient was increased with both pressure and temperature. Changes of volume, enthalpy, free energy and entropy for the formation of complexes were obtained from the equilibrium constants. The red-shift at a higher pressure, the blue-shift at a higher temperature and the relation between pressure and oscillator strength were discussed by means of thermodynamic functions.

• 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.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.2
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• pp.90-97
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• 2019

Sparkjet actuator, also known as plasma synthetic jet actuator (PSJA), is an active flow control device that has possibility of controling supersonic flow. This actuator utilizes arc plasma to deposit energy onto the gas inside the cavity to raise temperature and pressure. A change in the state of the fluid inside the cavity generates pressure waves and momentum jet, and they are exhausted through out the orifice exit and disturb external flow field. Since the cavity flow is affected by arc plasma, which is an equilibrium plasma and have generated equilibrium flow, the equilibrium state of air should be considered in order to analyze the flow of sparkjet actuator. In this study, numerical program for equilibrium flow was developed for the use of sparkjet actuator analysis. The developed program was validated by comparing the time - accurate jet front positions with the reference result. Then, impulse characteristics of the actuator in the atmospheric quiescent air were explained.

• Journal of computational fluids engineering
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• v.13 no.4
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• pp.50-57
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• 2008

The prediction of hydrate pellet decomposition characteristics is required to design the regasification process of GTS (gas to solid) technology, which is considered as an economic alternative for LNG technology to transport natural gas produced from small and stranded gas wells. Mathematical model based on the conservation principles, the phase equilibrium relation, equation of gas state and phase change kinetics was set up and numerical solution procedure employing volume averaged fixed grid formulation and extended enthalpy method are implemented. Initially, porous methane hydrate pellet is at uniform temperature and pressure within hydrate stable region. The pressure starts to decrease with a fixed rate down to the final pressure and is kept constant afterwards while the bounding surface of pellet is heated by convection. The predicted convective heat and mass transfer accompanied by the decomposed gas flow through hydrate/ice solid matrix is reported focused on the comparison of spherical and cylindrical pellets having the same effective radius.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.268-275
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• 2008

The prediction of hydrate pellet decomposition characteristics is required to design the regasification process of GTS (gas to solid) technology, which is considered as an economic alternative for LNG technology to transport natural gas produced from small and stranded gas wells. Mathematical model based on the conservation principles, the phase equilibrium relation, equation of gas state and phase change kinetics was set up and numerical solution procedure employing volume averaged fixed grid formulation and extended enthalpy method are implemented. Initially, porous methane hydrate pellet is at uniform temperature and pressure within hydrate stable region. The pressure starts to decrease with a fixed rate down to the final pressure and is kept constant afterwards while the bounding surface of pellet is heated by convection. The predicted convective heat and mass transfer accompanied by the decomposed gas flow through hydrate/ice solid matrix is reported focused on the comparison of spherical and cylindrical pellets having the same effective radius.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.268-275
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• 2008

The prediction of hydrate pellet decomposition characteristics is required to design the regasification process of GTS (gas to solid) technology, which is considered as an economic alternative for LNG technology to transport natural gas produced from small and stranded gas wells. Mathematical model based on the conservation principles, the phase equilibrium relation, equation of gas state and phase change kinetics was set up and numerical solution procedure employing volume averaged fixed grid formulation and extended enthalpy method are implemented. Initially, porous methane hydrate pellet is at uniform temperature and pressure within hydrate stable region. The pressure starts to decrease with a fixed rate down to the final pressure and is kept constant afterwards while the bounding surface of pellet is heated by convection. The predicted convective heat and mass transfer accompanied by the decomposed gas flow through hydrate/ice solid matrix is reported focused on the comparison of spherical and cylindrical pellets having the same effective radius.

• Transactions of Materials Processing
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• v.19 no.7
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• pp.423-428
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• 2010

Carbon nanotubes(CNTs) are expected to be ideal reinforcements of metal matrix composite materials used in aircraft and sports industries due to their high strength and low density. In this study, a high pressure torsion(HPT) process at an elevated temperature(473K) was employed to achieve both powder consolidation and grain refinement of aluminummatrix nanocomposites reinforced by 5vol% CNTs. CNT/Al nanocomposite powders were fabricated using a novel molecular-level mixing process to enhance the interface bonding between the CNTs and metal matrix before the HPT process. The HPT processed disks were composed of mostly equilibrium grain boundaries. The CNT-reinforced ultrafine grained microstructural features resulted in high strength and good ductility.