• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.198-204
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• 2004

액화천연가스를 연료로 사용하여 물 냉각 및 천연가스와 액화천연가스 재생냉각 연소시험을 수행하였다. 연소시험과 CEC86을 이용한 연소해석 결과를 액체로켓엔진 성능인자로서, 특성속도와 비추력 관점에서, 추진제 혼합비와 연료의 연소실 유입온도의 영향을 분석하였으며, 엔진성능이 추진제 혼합비와 연료의 연소실 유입온도의 영향을 크게 받고 있음을 알 수 있었다. 엔진 성능으로서 특성속도는 추진제 혼합비가 0.72∼0.75일 때, 이론적 비추력은 추진제 혼합비가 0.75일 때 최대 값을 보여주었으며, 연료의 연소실 유입온도의 증가에 비례하여 엔진 성능이 향상되는 경향에서 재생냉각이 엔진 성능을 증대시키는 경향을 확인하였다.

• 천문학회보
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• 제36권2호
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• pp.105.1-105.1
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• 2011

We present the modeling results of deuterium fractionation of water ice, $H_2$, and the primary deuterium isotopologues of $H3^+$ in the physical conditions associated with the star and planet formation process. We calculated the deuterium chemistry for a range of gas temperatures (Tgas~10-30 K) and ortho/para ratio (opr ) of $H_2$ based on state-to-state reaction rates and explore the resulting fractionation including the formation of a water ice mantle coating grain surfaces. We find that the deuterium fractionation exhibits the expected temperature dependence of large enrichments at low gas temperature, but only for opr-H2<0.01. More significantly the inclusion of water ice formation leads to large D/H ratios in water ice (${\geq}10^{-2}$ at 10 K) but also alters the overall deuterium chemistry. For T<20 K the implantation of deuterium into ices lowers the overall abundance of HD which reduces the efficiency of deuterium fractionation at high density. Under these conditions HD will not be the primary deuterium reservoir in the cold dense interstellar medium and $H3^+$ will be the main charge carrier in the dense centers of pre-stellar cores and the protoplanetary disk midplane.

• 한국생산제조학회지
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• 제19권2호
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• pp.230-234
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• 2010

Hydrox gas which is the mixed gas of hydrogen and oxygen gained fromwater electrolysis is one of the new clean energy sources and thus is researched and commercialized actively. Especially, it can be replaced the fossil energy and shows the better quality compared to the conventional energy such as LPG or acetylene gas. The mixed gas of hydrogen and oxygen is gained from water electrolysis reaction. It has constant volume ratio 2:1 of hydrogen and oxygen, and it is used as a source of thermal energy by combustion reaction. Further, hydrox gas is nearly a mixed ideal gas combusting itself completely and its combustion shows anunique characteristics of implosion. In this study, temperature rise effects on hydrox gas content through mixed combustion test of kerosene and hydrox gas and LPG and hydrox gas are investigated. it is also confirmed that economy of mixed combustion of hydrox gas as effective energy is fairly probable.

• 한국정밀공학회지
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• 제5권3호
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• pp.71-80
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• 1988

This paper dealt with experimentally the effect of $N_2$ and $H_2$ gas mixtures ratio in the fatigue characteristics of SM45C on Ion-nitrided. The specimen were treated water cooling after Ion-nitriding at $500^{\circ}C$ and 5 torr. in 80% $N_2$and 50% $N_2$gas mixtures ratio in the atmosphere for 3 hrs. The hardness distribution and the depth of nitriding layer shows more increase in 80% $N_2$gas mixture ratio than 50% $N_2$. Ion-nitrided specim- en for 80% $N_2$gas mixture ratio show more increase infatigue strenght in the $>1.5{\times}10^5$ cycles region than 50% $N_2$. In the $<1.5{\times}10^5$cycles region, fatigue failure is due to cracking of the brittle nitrided case, and the propergation of the surface cracks into the core. But in the $>1.5{\times}10^5$cycles region, it is found that cracks propagate from the non-metallic inclusions in the subsurface.

• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1677-1688
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• 2020

In the sodium-cooled fast reactor, the steam generator is a heat exchange device between sodium and water, which may cause leakage, resulting in a sodium-water reaction accident, which in turn affects the safe operation of the entire nuclear reactor. To this end, the electromagnetic vortex flowmeter is used to detect leakage of the steam generator and its signal processing method is studied in this paper. The hydraulic experiment was carried out by using water instead of liquid sodium, and the sensor output signal of the electromagnetic vortex flowmeter under different gas injection volumes was collected. The bubble noise signal is reflected by the base line of the sensor output signal. According to the relationship between the proportion of the bubble noise signal in the sensor output signal and the gas injection volume, a signal processing method based on the energy ratio calculation is proposed to detect whether the water contains bubbles. The gas injection experiment of liquid sodium was conducted to verify the effectiveness of the signal processing method in the detection of bubbles in sodium, and the minimum detectable leak rate of water in the steam generator was detected to be 0.2 g/s.

• 한국분무공학회지
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• 제21권1호
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• pp.13-19
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• 2016

Atmospheric spray characteristics were experimentally compared between liquid-gas and liquid-liquid sprays of a pintle injector. In order to study spray characteristics, water and air were used as the simulants and the visualization technic was adopted. Spray images were acquired by using a backlight method by a high-resolution CMOS camera. As a result, when the pintle opening distance increased, liquid sheets became unstabled and fluttering droplets increased. In the liquid-gas case, the breakup performance increased as the pressure of gas injected from the annular orifice increased. In the liquid-liquid case, atomization efficiency decreased as the pressure of liquid injected from the annular orifice increased. Spray angles presented a similar trend between two cases. At the same momentum ratio, the spray angle of liquid-liquid case was lower than the angle of liquid-gas case.

• 상하수도학회지
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• 제24권3호
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• pp.319-332
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• 2010

In general, wastewater treatment systems consume high-energy consumption depending on operation characteristics of the facilities. Therefore, greenhouse gas(GHG) reduction activities that are application of digestion gas, induction of renewable energy etc. are conducted to reduce energy consumption and to increase energy independence ratio. In this study, GHG reduction in wastewater treatment system identified, searched application of Clean Development mechanism(CDM) approved methodology. If the methodologies apply to GHG reduction activities such as application of digestion gas, heat pump system using the wastewater as heat source, hydropower using the methodology determined CDM applicability, otherwise through several assumptions calculated expectable GHG reduction emissions and determined CDM applicability. As a result, the order of calculated GHG reduction emission showed that collected and energy generation of digestion gas is 66,775 $tCO_2$/yr, gas engine cogeneration system is 8,182 $tCO_2$/yr, heat pump system using the wastewater as a heat source is 72,715 $tCO_2$/yr, and hydropower is 561 $tCO_2$/yr. Consequently, the order of calculated Certified Emission Reductions(CERs) benefit showed that heat pump system using the wastewater, as a heat source is 1,381 million won/yr was estimated as the highest, followed by a collected and energy generation of digestion gas is 1,268 million won/yr.

• 오토저널
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• 제13권5호
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• pp.81-88
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• 1991

Combustion characteristic, concentration of NOx and exhaust smoke opacity was experimentally tested, according to fuel injection timing, mixing ratio of water and methanol for the driving condition of 2000 rpm of engine revolution and constant load(7.5kg/cm$^{2}$) using emulsified fuel of gas oil-water methanol. The result obtained was as following. Thermal efficiency indicated highly 0.4-2.7% for emulsified fuel then gas oil, and injection timing when maximum thermal efficiency, slicily risen then gas oil. For constant fuel injection timing ignition lag was increased, combustion duration decreased, maximum heat release rate indicated high, and concentration of NOx and exhaust smoke opacity is decreased, as function of water and methanol content y was higher.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.91.1-91.1
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• 2010

The Reforming system is an effective method to generate hydrogen which uses for fuel cell system. The purpose of this study is to present characteristics of an autothermal reformer at various operating conditions and to investigate ideal conditions for reforming efficiency. Dominant chemical reactions are Full Combustion, Steam Reforming reaction, Water-Gas Shift reaction and Direct Steam Reforming reaction. Operating parameters of the autothermal reformer are inlet temperature, Oxygen to Carbon Ratio, Steam to Carbon Ratio and Gas Hourly Space Velocity. Autothermal reformer is filled with catalysis of a packbed-bed type. Using numerical approach, we have investigated on various reaction conditions.

• Journal of Mechanical Science and Technology
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• 제17권4호
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• pp.581-589
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• 2003

Film absorption involves simultaneous heat and mass transfer in the gas-liquid system. While the non-absorbable gas does not participate directly In the absorption process. its pretence does affect the overall heat and mass transfer. An experimental study was performed to investigate the heat and mass transfer characteristics of LiBr-H$_2$O solution flow ing over 6-row horizontal tubes with the water vapor absorption in the pretence of non-absorbable gases. The volumetric concentration of non-absorbable gas, air, was varied from 0.17 to 10.0%. The combined effects of the solution flow rate and its concentration on the heat and mass transfer coefficients were also examined. The presence of 2％ volumetric concentration of air resulted in a 25% reduction in the Nusselt number and 41% reduction in the Sherwood number Optimum film Reynolds number was found to exist at which the heat and mass transfer reach their maximum value independent of air contents. Reduced Nusselt and Sherwood numbers. defined as the ratio of Nusselt and Sherwood numbers at given non-absorbable gas content to that with pure water vapor, were correlated to account for the reduction in the heat and mass transfer due to non-absorbable gases in a falling film absorption process.