• 청정기술
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• 제15권1호
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• pp.1-8
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• 2009

전 세계적으로 급성장하고 있는 자동차연료로 압축천연가스(CNG)의 사용이 일반화되고 있다. 1996년도에 100만 대이던 CNG자동차가 2006년도에는 5배가 증가하였으며, 지금도 계속 증가하고 있는 추세이다. CNG연료는 가솔린 및 디젤연료에 비하여 효율적이고 완전연소에 가까워 청정연료로서 적합하다. 또한 배출 가스로서 일산화탄소, 탄화수소 및 질소산화물 등이 다른 연료에 비하여 유리하며, 경제적인 면에서도 투자가치가 있다. 본 연구에서는 천연가스자동차의 환경적인 특성화 효율적이고 경제적인 면에서 고찰하고자 한다.

• 동력기계공학회지
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• 제12권5호
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• pp.27-33
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• 2008

Natural gas has been considered one of the most promising alternative fuels for transportation because of its abundance as well as its ability to reduce regulated pollutants. We measured emission characteristics of nanoparticles from lean burn H/D(Heavy-Duty) CNG (Compressed Natural Gas) engine equipped with oxidation catalysts. The experiments were carried out to measure the emission and engine performance according to the ESC test cycle. The CO and THC conversion efficiencies on the best catalyst in the ESC test cycle achieved about 91 % and 83 %, respectively. From the measurement by the SMPS, the number of nanoparticles emitted from H/D CNG engine is reduced by about 99 % which is more than that of 2.5 L diesel engine. The particle number concentrations of H/D CNG engine were almost nanoparticles. Nanoparticles smaller than 30 nm emitted from the H/D CNG engine and diesel engine equipped with a CDPF(Catalyzed Diesel Particulate Filter) were quite similar. However, the particles bigger than 30nm from the CNG engine were smaller than the particles from diesel engine equipped with a CDPF. The higher the CNG engine load, the lower the particle number from engine-out, but it increased slightly at full load.

• 동력기계공학회지
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• 제22권1호
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• pp.56-63
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• 2018

After the recent fabrication of diesel vehicle exhaust gas by Volkswagen, nitrogen oxides ($NO_x$) and particulate matter (PM) are drawing attention as representative pollutants included in exhaust gas. When gasoline and diesel fuels are combusted through direct injection into a combustion chamber at high pressure, PM emission is actually increased. To find a solution to this problem, a basic study was conducted to derive an optimized variable for combustion of compressed natural gas (CNG) by applying CNG, acknowledged as a clean fuel, to direct injection system. The essence of this study is in the introduction of a radical ignition technology for compressed natural gas (RI-CNG) in a sub-chamber type engine. The direct injection system was applied to a sub-chamber to remove residual gas from previous combustion cycle. In addition, optimal mixer distribution was achieved by precisely setting ignition timing based on fuel injection timing and excess air ratio.

• 대한조선학회논문집
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• 제42권2호
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• pp.142-150
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• 2005

Recently, the gas transportation system for CNG(Compressed Natural Gas) has been developed and several innovative approaches are presented from the aspects of commercial demand. In this study, a new type of 20ft container shape CNG tank with two and four cylinder intersections by using the intersecting spheres has been proposed. And the structural analysis of CNG tank with Mildsteel, API High Tensile Steel, Al-alloy and FRP has been carried out to compare the different types of pressure vessels of materials used. The analysis result shows that the proposed intersectional cylindrical type of CNG tank can be applied to the gas transportation system. And further study on the commercial analysis and associated equipments should be carried out for the practical applications.

• 한국가스학회지
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• 제19권1호
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• pp.12-17
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• 2015

CNG(Compressed Natural Gas)충전소의 주요 핵심설비는 압축기이며, 대부분의 압축기는 윤활이 필요하다. CNG압축기의 윤활유(oil)는 충전 중에 압력 레귤레이터, 엔진 연료공급시스템 등에 전이(Carry-over)되어 천연가스차량의 성능에 부정적인 영향을 미친다. 따라서 이러한 문제를 사전에 방지하기 위해서는 전이되는 오일의 양을 정량적으로 측정하여 공급되는 압축천연가스의 품질관리를 강화하는 것이 필요하다. 본 연구에서는 CNG오일전이를 측정하기 위해 중량법(Gravimetric method)을 사용한 샘플링 튜브 및 샘플링 장비를 개발하였다. 또한, CNG 충전소 6개소를 대상으로 CNG를 채취하였으며, 오일전이를 정량적으로 분석하였다. 측정된 전체 오일전이양은 2.569에서 6.509ppm 이었으며, 측정된 결과를 선행연구 결과와 비교 검증하였다.

• 한국생산제조학회지
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• 제9권1호
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• pp.53-59
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• 2000

Recently air pollution is increased according to increase of vehicle. So many countries are studying about compressed natural gas engine. Research on the development of CNG dedicated engine that has important meaning both as a clean fuel and an alterna-tive energy to reduce the exhaust emission from diesel engine are actively going on these days. In this study the character-istics of CNG engine was investigated and the engine performance experimented by changing the parameters such as boost pressure. The CNG engine performance and exhaust emission were measured by engine performance mode at maximum load condition with increasing the rpm in the range of 1,000-2,200rpm. The exhaust emission was also measured at D-13 mode and compared to the emission regulation.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.735-740
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• 2011

본 연구에서는 직접분사식 CNG기관의 희박한계를 보다 확장하여 고효율 및 저배기 공해를 실현시키고자 실린더 내에 고압의 천연가스를 직접분사함과 동시에 흡입과정 중 흡기관 내에 소량의 저압천연가스를 보조분사하는 경우의 희박한계 확장 및 제반특성에 대해 검토하였다. 그 결과, 흡기보조분사가 없을 경우 희박한계가 ${\lambda}$ = 1.4 까지였으나, 흡기보조분사율이 5~15% 정도에서는 희박한계가 ${\lambda}$ = 1.5 까지 확장되었다. 이는 흡기보조분사에 따른 혼합기의 혼합율 향상에 기인한 것으로 해석하였다. 연소기간은 줄어들었지만, 흡기보조분사의 효과는 주연소기간에서 조기연소기간보다 강하게 나타났다.

• Journal of Advanced Marine Engineering and Technology
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• 제34권5호
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• pp.632-637
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• 2010

천연가스는 메탄을 주성분으로 하는 청정한 대체연료로 자동차나 트럭 등에 압축천연가스와 액화천연가스 형태로 사용할 수 있다. 그리고, 천연가스만을 사용하는 전소엔진과 가솔린 및 천연가스를 동시에 사용할 수 있는 겸용엔진이 있으며, 특히, 겸용엔진의 경우 두가지 연료를 동시에 사용할 수 있는 것으로 정의할 수 있다. 본 연구에서는 선박용 가솔린 시스템을 인젝터, 레귤레이터, 연료탱크 및 전자제어장치로 구성된 압축 천연가스 겸용시스템으로 전환시켜 연료시스템과 동력값을 비교하였다. 그 결과, 천연가스엔진의 경우 적은 배출가스를 나타내었으며 최대동력은 가솔린엔진과 비교 약 7%정도 감소함을 확인할 수 있었다.

• 한국기계가공학회지
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• 제8권2호
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• pp.83-89
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• 2009

An air-fuel ratio control is essential in reducing hazardous exhaust emissions from a compressed natural gas(CNG) engine, and can be accomplished by accurate control of gas injection flow. In this study, theoretical research was conducted on injection characteristics of a solenoid gas injector, and injection experiments for calibration and analysis were performed. Various factors for gas injection flow such as injection pressure, gas temperature, and supply voltage are studied. A dynamic flow equation of the natural gas was proposed on the basis of flow dynamics theories and results of the injection experiment. The verification of the dynamic flow equation of the solenoid injector was carried out with a large CNG-engine applied to an urban bus. Air-fuel ratio control experiments were conducted in both steady and transient state. Results of injection experiments for the solenoid injector and the CNG-engine was proved the control method proposed herein to be effective.

• 한국자동차공학회논문집
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• 제11권2호
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• pp.16-21
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• 2003

Natural gas is one of the promising alternative fuels because of the abundant deposits and the cleanness of emission gas. It can be used in conventional gasoline engine without major modification. Natural gas has some advantages than gasoline i.e. the high octane number, good mixing condition because of gas and wide inflamable limit. In the present study, a $1.8{\ell}$ conventional gasoline engine is modified for using the CNG as a fuel instead of gasoline. Performance and emission characteristics are compared between gasoline and CNG with 4 cylinder SI Engine which is controlled by programable ECU. Parameters of experimentation are equivalence ratio, spark timing and fuels. We analyzed the combustion characteristics of the engine using the cylinder pressure i.e. ignition delay, combustion duration and cycle variation. As a result, CNG engine shows lower exhaust emissions but brake torque is slightly reduced compared to gasoline engine. Overall combustion duration is longer than that of gasoline because of lower burning speed.