• 한국자동차공학회논문집
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• 제14권6호
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• pp.73-81
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• 2006

A commercial diesel engine was converted into a dedicated natural gas engine to reduce the exhaust emissions in a retrofit of a diesel-fueled vehicle. The cylinder head and piston were remodeled into engine parts suited for a spark ignition engine using natural gas. The remodeling of the combustion chamber changed the compression ratio from 21.5 to 10.5. A multi-point port injection(MPI) system for a dedicated natural gas engine was also adopted to increase the engine power and torque through improved volumetric efficiency, to allow a rapid engine response to changes in throttle position, and to control the precise equivalence ratio during cold-start and engine warm-up. The performance and exhaust emissions of the retrofitted natural gas engine after remodeling a diesel engine are investigated. The emissions of the retrofitted natural gas engine were low enough to satisfy the limits for a transitional low emission vehicle(TLEV) in Korea. We concluded that a diesel engine can be effectively converted into a dedicated natural gas engine without any deterioration in engine performance or exhaust emissions.

• International Journal of Aerospace System Engineering
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• 제5권2호
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• pp.16-22
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• 2018

An analysis has been made on the performance variation due to pressure drop change at propellant supply pipes of liquid rocket engine. The objective is to compare the effectiveness of control variables to tune the liquid rocket engine performance. The mode analysis program has been used to estimate the engine performance for different modes which is realized by controlling the flow rate of propellant. The oxidizer of combustion chamber, the fuel of combustion chamber, the oxidizer of gas generator and the fuel of gas generator are the independent variables to control engine thrust, engine mixture ratio and temperature of gas generator product gas. The analysis program is validated by comparing with the powerpack test results. The error range of compared variables is order of 4%. After comparison of tuning effectiveness it is turned out that the pressure drop at oxidizer pipe of gas generator and pressure drop at combustion chamber fuel pipe and the pressure drop at the fuel pipe of gas generator can effectively tune the thrust of engine, mixture ratio of engine and temperature of product gas from gas generator respectively.

• 한국환경과학회지
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• 제14권1호
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• pp.15-22
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• 2005

Natural gas possesses several characteristics that make it desirable as an engine fuel; 1)lower production cost, 2)abundant commodity and 3)cleaner energy source than gasoline. Due to the physics characteristics of natural gas, the volumetric efficiency and flame speed of a natural gas engine are lower than those of a gasoline engine, which results in a power loss of $10-20{\%}$ when compared to a normal gasoline engine. This paper describes the results of a research to improve the performance of a natural gas engine through the modification and controls of compression ratio, air/fuel ratio, spark advance and supercharging and method of measuring flame propagation velocity. It emphasizes how to improve the power characteristics of a natural gas engine. Combustion characteristics are also studied using an ion probe. The ion probe is applied to measure flame speed of gasoline and methane fuels to confirm the performance improvement of natural gas engine combustion characteristics.

• 한국정보통신학회논문지
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• 제11권1호
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• pp.75-82
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• 2007

선진국에서는 가스터빈엔진을 개발하여 항공기, 대형선박, 유도무기용으로 많이 사용한다. 국내에서도 엔진부품 생산단계를 넘어 소형 가스터빈엔진을 개발하고 있으나, 가스터빈엔진에서 가장 중요한 핵심기술인 엔진제어 관련기술은 선진국에서 기술이전을 기피하고 있다. 본 논문은 가스터빈엔진 시뮬레이터 개발에 대한 연구이다. 논문에서 제시하는 시뮬레이터는 가스터빈엔진의 성능데이터를 기반으로 한 엔진 수학적 모델을 통하여 엔진 시뮬레이터를 개발함으로서 가스터빈엔진 제어알고리즘 개발을 쉽게 할 수 있도록 하고, 엔진제어기 의 기능도 검증 할 수 있도록 한다. 본 시뮬레이터에는 엔진센서 신호변환 보드를 설계하여 시뮬레이션 할 때 엔진모델 센서신호가 실제 센서와 같은 신호가 생성되도록 하였다. 가스터빈엔진에 대한 실제 엔진시험 결과와 시뮬레이션 결과를 비교하여 시뮬레이터의 성능을 입증하였다.

• 산업기술연구
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• 제26권A호
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• pp.39-46
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• 2006

As an automobile fuel, LPG has many environmental advantages compared to gasoline or diesel. However, current LPG engine which is provided with LPG fuel as gas form has lower power and worse fuel efficiency than gasoline engine. These problems of low power and bad fuel efficiency come from lower volumetric efficiency. Also there is a new rising problem of high failure ratio in an engine emission test. Although there are many factors which affect engine performance of exhaust gas emission, one believes that the fact that ECM of gasoline engine is used for LPG engine when retrofitting gasoline engine to LPG engine is one of the main problems, which lower engine power and emit more noxious gas due to wrong ignition timing. To solve these problems, one studied the effects of ignition timing on the exhaust gas to find out the optimum condition of ignition timing. The experimental results show that noxious exhaust gas is reduced and engine power is increased if the optimum control of ignition timing is applied in accordance to the revolution speed of engine.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2003년도 춘계 학술발표회 논문집
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• pp.595-600
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• 2003

This paper presents the applicability of low caloric synthetic gas from coal gasification to a gas engine system. A commercial LPG engine is modified to use the low caloric synthetic gas from coal gasification as the gas engine fuel. The modification is focused on the fuel supplying system, which includes air flowrate adjusting orifice, gas mixer, vaporizer, preheater, regulators, and fuel tank. The electrical system and others for the alternative fuel are also redesigned and replaced. From the results of engine performance data, we have demonstrated that the engine modified by using coal gasification gas is well operated from idle to wide open throttle conditions although the engine power is somewhat reduced relative to LPG fueled engine. This paper addresses the need to determine the practical potential for such a concept and to identify further research and development efforts that may be necessary.

• 한국자동차공학회논문집
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• 제10권6호
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• pp.11-18
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• 2002

Residual gas fraction in an engine cylinder affects engine performance, efficiency and emission characteristics. With high residual gas fractions, a flame speed and maximum combustion temperature are decreased and these are deeply related with combustion stability especially at idle and NOx emission at relatively high engine load. In this work, the residual gas fraction was calculated by an engine simulation code, which was validated by the experimental data (cylinder pressure and emissions) obtained from 4-cyliner spark ignition engine. A comparison between experimental and computational calculation results was made. The residual gas is generated mostly at low engine speed by the larger pressure difference between the intake and exhaust port. As the valve overlap duration was increased, the amount of residual gas in the cylinder, the amount of HC emission in the exhaust gas and the variation of power output increased.

• 한국기계가공학회지
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• 제8권3호
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• pp.13-20
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• 2009

Development of a dynamic engine model is essential to predict and analyze of dynamic characteristics from a natural gas engine. Reducing the harmful exhaust emissions can be accomplished by a precise air-fuel ratio control. In this paper, the dynamic engine model was proposed and included mixture formation and intake process because the dynamic characteristics can be affected by the mixture components such as an air and a gaseous fuel. The air mass flow, the partial pressure ratio, and the gas constant are changed by variations of the components in the mixture formation and intake process. The dynamic engine model is applied to the natural gas engine for validation test. Experimental results show that the dynamic engine model is effective to predict the dynamic characteristics of the natural gas engine.

• Journal of Biosystems Engineering
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• 제30권6호통권113호
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• pp.354-359
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• 2005

This is a fundamental study to develop a bio-gas utilization technology using livestock manure. Especially, this study was carried out to develop an engine using bio-gas. A bio-gas engine was designed and manufactured by modification of a diesel engine of 3 cylinders powering 13.31 kW/2800 rpm, changing the fuel supplying system fit for bio-gas. The result showed that, when the Air/Fuel ratio was controlled with fixed spark timing, the power of biogas-fueled engine is about $10.6{\~}14.6\%$ lower then that of LNG-fueled engine because of low volumetric efficiency. The engine output and torque was $11.85{\~}13.3$ kW, $39.5{\~}40.8\;N{\cdot}m$, respectively at the engine speed of 2600 rpm. Bio-gas consumption rate was 260.20 g/kW/hr, 315.20 g/kW/hr in engine speed or 1000 rpm, 2800 rpm, respectively.

• 한국가스학회지
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• 제4권2호
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• pp.20-26
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• 2000

본 실험 연구에서는 소형 고속기관의 가스엔진 특성을 다양한 방법으로 수행하였다. 그리고, 가스연료인 천연가스, 수소연료 및 휘발유 연료를 사용한 기관의 성능을 분석하고, 그에 대한 배기특성과 연소과정에 대하여 고찰하였다. 수소기관의 높은 회전과 고부하로 운전할 때 발생하는 역화를 방지하기 위하여 가스연료기관에 교축밸브를 설치하여 공기량을 조절하였다. 그리고 수소연료에 질소를 혼합하여 실험을 수행하였다. 그 결과 소형고속기관에 가스연료를 적용하여 운전하였을 때 여러 특성을 파악할 수 있었다.