• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.3
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• pp.66-73
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• 2005

The pressurization system in a liquid rocket propulsion system provides a controlled gas pressure in the ullage space of the vehicle propellant tanks. It is advantage to employ a hot gas heat exchanger in the pressurization system to increase the specific volume of the pressurant and thereby reduce over-all system weight. A significant improvement in pressurization-system performance can be achieved, particularly in a cryogenic system, where the gas supply is stored inside the cryogenic propellant tank. In this study liquid nitrogen was used instead of liquid oxygen as a simulant. The temperature characteristic of cryogenic pressurant is very important to develop some components in pressurization system. Numerical modeling and test data were studied using SINDA/FLUINT Program and PTF(Propellant-feeding Test facility).

• International Journal of Aerospace System Engineering
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• v.6 no.2
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• pp.11-16
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• 2019

A system analysis program has been developed for a gas generator cycle liquid rocket engine of 30 ton class. Numerical models have been proposed for a combustor, a turbopump, a gas generator and pressure drop through a regenerative cooling system. Numerical algorithm has been validated by comparing with the published data of MC-1. The major source of error is not the numerical algorithm but the imperfect performance models of subsystems. So the precision of the program can be improved by revising the performance models using experimental data. The sea level specific impulse and vacuum specific impulse have been demonstrated for a 30 ton class gas generator engine. The optimal condition of combustor pressure and mixture ratio for specific impulse which is a typical characteristic of a gas generator cycle engine has been illustrated.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.3
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• pp.174-179
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• 2016

To protect the ocean environment, the use of liquefied natural gas (LNG) carriers, bunkering ships, and fueled ships is increasing. Recently, Korean shipbuilders have developed and supplied a partial reliquefaction facility for boil-off-gas (BOG). Despite reasonable insulation, heat leakage in vessel storage tanks causes LNG to be continuously evaporated as BOG. This research analyzed the maximum liquid yield rate for various partial reliquefaction systems (PRS) and considered related factors affecting yields. The results showed a liquid yield of 48.7% from an indirect PRS system (heat exchanges between cold flash gas and compressed natural gas), and 41% from a direct PRS system (BOG is mixed with flash gas and discharged from a liquid-vapor separator). The primary factor affecting liquid yield was heat exchanger effectiveness; the exchanger's efficiency and insulation characteristics directly affect the performance of BOG reliquefaction systems.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.3
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• pp.137-142
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• 2013

A small air-conditioner or chiller for a constant temperature bath normally uses a constant speed compressor. The constant speed compressor is relatively inexpensive, but it uses on/off control for capacity modulation. The on/off control has several disadvantages, specifically energy loss and large temperature fluctuation. Continuous operation with a bypass system can be an alternative to on/off control, for capacity modulation. In this study, a heat pump system having a hot-gas bypass and a liquid bypass was adopted. The performance of the bypass-type heat pump was measured, by varying the bypass valve opening. The differences of the COP between the hot-gas bypass and the liquid bypass, in the cooling and heating operations, were within 2% and 1%, respectively. The liquid bypass showed a wider range of capacity control in the cooling operation but the hot-gas bypass showed a wider range of capacity control in the heating operation.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.4
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• pp.33-42
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• 1998

The optimum design and preliminary cost estimations of air stripping towers ASTs with granular activated carbon adsorption (GAC) systems as the off-gas treatment were done and compared to liquid-phase GAC system. The optimum design and preliminary cost estimations were done for either single or multicomponent systems. A computer program was developed for this study. 15 single compounds and their multicomponent systems were studies. Even with off-gas treatment, AST was generally a less expensive process for treatment of volatile organics than liquid-phase GAC system. Treatment costs of small systems were sensitive to system capacity. Accumulative effect of treatment costs was found in multicomponent systems. The cost of a multicomponent system was highly dependent on the least strippable component in ASTs even with gas-phase GAC or the least adsorbable component in liquid-phase GAC system.

• Journal of Environmental Science International
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• v.1 no.2
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• pp.105.1-113
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• 1992

The present study was performed to develop the removal system of the offensive gases, including hydrogen sulfide of acid gas, ammonia or amice of base gas, from the nightsoil treatment plant. In order to remove the offensive gases, the Fe-EDTA system liquid phase catalytic oxidation method with the bubble lift column reactor was employed. From the results obtained, it was confirmed that the offensive gases can be deodorized simultaneously and also hydrogen sulfide of acid gas, ammonia of base gas completely removed at pH 6.45. In addition, as input gases feed rate the efficiency of acid gas did not change but the efficiency of base gases decreased to approximately 90 % at pH 6, 0. From the result of particle size analyzer, it was found that the particle sizes including sulfur and other impurites grew up to $21{\mu}m$ over 72hour reaction time.

• Journal of Mechanical Science and Technology
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• v.14 no.12
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• pp.1365-1375
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• 2000

Two phase flows have been numerically calculated to analyze plume characteristics and liquid circulation in gas injection through a porous plug. The Eulerian approach has been for formulation of both the continuous and dispersed phases. The turbulence in the liquid phase has been modeled using the standard $textsc{k}$-$\varepsilon$ turbulence model. The interphase friction coefficient has been calculated using correlations available in the literature. The turbulent dispersion of the phase has been modeled by the "dispersion Prand시 number". The predicted mean flows is compared well with the experimental data. The plume region area and the axial velocities are increased with the gas flow rate and with the decrease in the inlet area. The turbulent intensity also shows the same trend. Also, the space-averaged turbulent kinetic energy for various gas flow rates and inlet areas has been obtained. The results are of interest in the design and operation of a wide variety of materials and chemical processing operations.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.223-226
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• 2012

Biomass to Liquid (BTL) is an attractive option for using biomass as an renewable energy. A syngas supplying system has been designed for BTL system, based on the Fischer-Tropsche (FT) process, and long-term operation test was conducted. The syngas supplying system is composed of a fluidized bed gasifier, gas cleaning and compression system, and methanol absorption system. Stable operation of more than hundred hours was achieved with several champaigns. In addition, a pilot scale biomass gasifier has been developed for 1 bbl/day BTL system and its performance was evaluated. Some preliminary results and current status of the development of BTL system will be presented.

• Journal of Hydrogen and New Energy
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• v.35 no.4
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• pp.353-362
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• 2024

In this study, several studies were conducted on the construction of gas conversion process system for a pilot plant using a small-scale hydrogen liquefaction system. The pilot plant considered in this study includes a liquefier, a storage tank, an evaporator, a gas booster, and a gas storage tank. First, the suspected leak area of the container was checked using the sprayed method of helium gas. The small-scale hydrogen liquefaction system was designed based on the analysis results of the pre-cooling system and the liquefaction system. Additionally, the program was developed to maintain pressure within vessel for an automatic production of liquid hydrogen. The evaporator for liquid hydrogen was manufactured based on the designed analysis data, and the pollution of gas in the vessel was analyzed through a gas recovery line system.

• Preventive Nutrition and Food Science
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• v.1 no.2
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• pp.179-185
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• 1996

Extraction yields of thiosulfinates from garlic were studied by using gas-in-liquis-dispersion(GLD) system to maxmize the thiosulfinate extraction. Extracted thiosulfinates were spectrophotometically quantified using synthesized dially1 thiosulfinate. The conditions for maximum extraction were optimized by response surface methodology. The volatile components extracted by various methods, such as hexane extraction, simultaneous steam distillation and GLD system, were compared by using gas chromatography. The results indicated that the thiosulfinate yield was increased by incresaing temperature and nitrogen gas flow rate, while the effects of bubble sizes on thiosulfinate extraction were not significant at the ranges tested. Application of GLD system resulted in extraction of more volatile components than other extraction methods, Therfore, it was suggested that GLD system was one of the efficient extraction methods among the ever introduced ones, for thiosulfinate extraciton.