• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.700-707
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• 2017

In the international natural gas market, natural gas has markedly low calories. The domestic calories standard of natural gas was changed and the performance and efficiency of many industrial machines using natural gas were affected because of low caloric natural gas. Therefore, in this study, a dual fuel engine fueled with natural gas and diesel was tested to examine the effects of the CNG substitution rate on the combustion characteristics, such as thermal efficiency, COVimep and heat release rate. The CNG substitution rate was defined as the ratio of CNG instead of diesel, which was calculated as the total energy. The conditions of the tested engine were fixed $1800rpm/500N{\cdot}m$. In addition, diesel fuel was injected at $16^{\circ}CA$ BTDC and the fuel pressure was fixed at 85 MPa; the lower heating value of CNG was $10,400kcal/Nm^3$. The results of the engine test showed that the amount of diesel fuel was changed according to the CNG substitution rate. Therefore, when the substitution rate was increased, the amount of diesel fuel was decreased, which affected the energy for ignition. In addition, the ignition delay duration was increased, which affected the thermal efficiency and torque. On the other hand, the COVimep was less than 5% and a stable combustion state of the engine was shown.

• Journal of the korean Society of Automotive Engineers
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• v.18 no.2
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• pp.18-28
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• 1996

메탄올이 자동차 연료로서 유망시 되고 있는 이유는 공급면과 이용면의 두 측면에서 장점을 가지고 있기 때문일 것이다. 공급면에 있어서는 원료가 천연가스나 석탄등 자원이 풍부하다는 점이 다른 연료에 비해 유리하며 특히 천연가스로 부터의 화학용 메탄올 제조기술이 거의 확립되어 있다는 점이다. 이용면에 있어서는 상온에서 운송, 저장 및 유량 제어 측면에서 취급이 비교적 용이하며 메탄올 연료의 특성상 옥탄가가 높고 희박연소한계가 넓어 고압축비 희박연소기관을 실현할 수 있으며, NOx나 매연 발생이 적은 저공해 연료인 점이 장점이다. 본 고에서는 본인의 실험실에서 이루어진 메탄올 연료에 대한 몇가지 실험결과들을 토대로 하여 메탄올 기관에 있어서의 일반적인 특성 및 문제점들에 대하여 소개하고자 한다.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.17-20
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• 2006

한국에너지기술연구원에서는 가정용 고분자연료전지 열병합 발전시스템을 위한 통합형 천연가스 연료처리 시스템을 개발해 왔다. 가정용 시스템으로서 필수적인 소형화와 고효율을 현실화하기 위해, 연료처리 시스템의 각 단위 공정 즉 수증기 개질, 수성가스 전이, 선택적 산화 공정 등을 이중 동 심관형 반응기에 통합하여 상호 열교환이 용이하도록 반응기를 설계하였다. 현재 시험 운전 중인 Prototype-I 연료 처리 시스템은 1kW급 고분자 연료전지 열병합 발전 시스템에 개질 가스를 공급하기 위해 설계되었으며, 기초 성능은 정격 부하 운전시 열효율 78% (HHV 기준), 메탄 전환율 91%이다. 개질 가스 내 일산화탄소 농도는 고분자 연료전지 전극의 피독을 피하기 위해 10ppm 이하로 유지되어야 하며, Prototype-I 연료 처리 시스템은 백금과 루테늄 촉매를 적용한 선택적 산화 반응기를 통해 개질 가스 내 일산화탄소 농도를 10ppm 이하로 제거하였다. 일반 가정에서는 고분자 연료전지 시스템의 부하 변동이 예상되기 때문에 연료 처리 시스템의 부하 변동 운전 특성도 살펴보았다 정격 부하에서 80%, 60%, 40%로 부하를 변동하며 운전하였고, 각 부하에서 안정한 메탄 전환율과 10ppm이하의 일산화탄소 농도를 보였다. 80%까지는 열효율이 77%로 큰 변화를 보이지 않았으며, 60%에서는 76%, 40%에서는 72%로 열효율이 감소하는 현상을 보였다 연료 처리 시스템의 일일 시동-정지 운전시 내구성을 테스트 중이다. 현재까지 50여회의 일일-시동 정지를 시도하였다 시동 후 약 세 시간가량의 정력 부하 운전을 실시한 후 부하 변동을 실시하였고, 총 운전 시간 8시간 정도 운전한 후 시스템을 정지하였다 메탄 전환율과 일산화 탄소 농도, 열효율을 모니터링 하고 있으며, 현재까지 초기 성능을 그대로 유지하고 있다. 앞으로 일일시동-정지 운전 시험을 지속하면서 초기 시동 특성 및 부하 변동에 따른 응답 특성 개선, 그리고 연료전지와의 연계 운전을 실시할 예정이다

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.3
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• pp.66-73
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• 2004

As a rocket propellent of hydrocarbon fuels, the characteristics of liquefied natural gas was evaluated with the viewpoint of the constituents and content, the cooling performance as a coolant, and characteristic velocity and specific impulse as parameters of the engine performance. Content of methane was a principal factor to determine the characteristics as a rocket propellant and more than 90% of it was needed as a fuel and coolant in the regenerative cooled liquid rocket engine. Some constituents of the liquefied natural gas can be frozen by the pre-cooling of the pipe lines, therefore they can be a factor disturbing the normal working of engine. In case the content of methane is around 90% in the liquefied natural gas, a normalized stoichiometric O/F mixture ratio of 0.75 is suggested for a nominal operation condition to get the maximum specific impulse and characteristic velocity.

• Journal of the Korean Institute of Gas
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• v.21 no.5
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• pp.9-15
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• 2017

Natural gas fuel has known to be very promising in terms of abundancy and economic value. Therefore it is widely treated as research topics in a variety field of production, storage and utilization. Natural gas has become one of the major sources for the power generation by using internal combustion engines(ICE). Development of natural gas fuel injection device should be preceded to realize a reliable natural gas fuel supply system for a MW class power generation reciprocating ICE. In this research, an injection valve which consists of solenoid and body part with a moving plate was designed and its dynamic performance was experimented in the engine-like environment. Displacement length and diameter of an armature and diameter of a solenoid coil were tested at former study. In this research the effect of materials of solenoid core, size of main housing inlet and supply gas pressure are examined.

• Journal of the Korean Institute of Gas
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• v.4 no.2 s.10
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• pp.20-26
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• 2000

In this experimental study, we examined gas engine characteristics of a small high-speed engine in various ways. And we studied performance of natural gas, hydrogen gas and gasoline fuel engines, as emission characteristics and process of combustion. For the purpose of preventing back-fire occurred in case of high-speed and high load in hydrogen engine, we controlled air quantity by installing throttle valve in gas fuel engine. We performed experiment by mixing nitrogen to hydrogen fuel. As a result, we could find out characteristics which of a high speed small engine by applying gas fuels.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.05a
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• pp.73-78
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• 2002

대부분의 산업용 가스터빈은 고발열량의 액체 및 가스연료를 사용하도록 설계되었다. 그러나 이러한 고발열량 에너지원인 석유나 천연가스등은 자원의 고갈, 가격문제 및 환경문제 등으로 인해 점차적으로 사용량이 줄어들 전망이다. 그러므로, 최근 들어 석유 및 천연가스를 대체할 수 있는 대체연료에 대한 맡은 연구가 이루어지고 있으며, 그 중에서도 중발열량 또는 저발열량 연료인 석탄가스 및 중잔사유 가스의 활용성에 대한 연구가 활발히 진행되고있다.(중략)

• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.15-21
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• 2015

Natural gas fuel has known to be very promising in terms of abundancy and economic value. Therefore it is widely treated as research topics in a variety field of production, storage and utilization. Natural gas has become one of the major sources for the power generation by using internal combustion engines(ICE). Development of natural gas fuel injection device should be preceded to realize a reliable natural gas fuel supply system for a MW class power generation reciprocating ICE. In this research, an injection valve which consists of solenoid and body part with a moving plate was designed and its dynamic performance was experimented in the engine-like environment. As a result of the experiments, linearity of flow rate was obtained and overall around 2ms of response time was observed at the pressure difference of 1bar. In addition, more than 100Liter/min(@2Hz) of gas flow rate was witnessed, which is expected to be adequate for the fuel supply system of a MW class natural gas engine.

• Journal of the Korean Institute of Gas
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• v.13 no.6
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• pp.15-20
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• 2009

The number of compressed natural gas (CNG) vehicles have increased gradually by virtue of korea government's urban air quality improvement policy since 1998. Although the use of CNG as transportation fuel gives environmental benefits, there is a possibility of huge accidents from unexpected fire. Therefore, needs for the guarantee of safety are indispensible for the reliable operation of CNG vehicles. A check valve is a safety device which prevents leakage of the pressurized fuel charged in a fuel tank. Durability of this component should be guaranteed in spite of repeated operation. This research has performed durability tests of a CNG check valve regarding the repeated usage, extreme chattering, and the effect of compressor oil.Although a check valve used for CNG vehicle satisfies validation requirements in the test results, it has been found that problem in the function of leakage prevention in a check valve could take place in the case of prolonged exposure to compressor oil.

• Journal of the Korean Institute of Gas
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• v.11 no.4
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• pp.12-16
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• 2007

The fuel pressure regulator mounted on CNG vehicles is used to maintain a constant pressure in the fuel injection system. It needs precise fuel pressure control to obtain benefits of high efficiency and low emissions in CNG vehicles. In this study, a high pressure test rig for the performance evaluation of CNG regulators was introduced. Two different CNG regulators were tested and compared each other at various test conditions. Results showed that dynamic response and creep characteristics are directly effected by the valve assembly design. Gas temperature was dramatically dropped at hish supply pressure conditions, so that effective design for coolant bowl is needed to prevent icing problem.