• 대한기계학회논문집B
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• 제35권9호
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• pp.869-874
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• 2011

CNG/diesel dual-fuel 엔진은 CNG 를 주 연료로 사용하고 소량의 디젤을 착화제로서 실린더 내에 분사한다. 본 연구에서는 기존의 디젤엔진을 커먼레일직접분사(CRDI)를 통하여 고압으로 디젤을 분사하고, 예혼합을 위하여 CNG 를 흡기포트에 분사하는 CNG/diesel dual-fuel 엔진으로 개조하였다. CNG/diesel dualfuel engine 은 기존의 디젤엔진과 동등한 수준의 토크 및 출력성능을 나타내었다. 또한, CNG 대체율은 CNG/diesel dual-fuel 엔진의 전체 운전영역에 대하여 89% 이상을 만족시켰다. Dual-fuel 엔진의 PM 배출농도는 디젤엔진보다 94% 더 낮게 나타났지만, NOx 배출농도는 더 높게 나타났다.

• 한국자동차공학회논문집
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• 제19권3호
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• pp.38-43
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• 2011

A CNG/diesel dual-fuel engine uses CNG as the main fuel and injects a small amount of diesel as an ignition priming. This study proposed the modification of the existing diesel engine into a dual-fuel engine that injects diesel with a high pressure by common rail direct injection (CRDI) and by injecting CNG at the intake port for premixing. And experiment was progressed for understanding about effect of CNG mixing ratio. The CNG/diesel dual-fuel engine showed equally satisfactory coordinate torque and power regardless of CNG mixing ratio. The PM emission was low at any CNG mixing ratio because of very small diesel pilot injection. In case of NOx and HC, high CNG mixing ratio showed low NOx and HC emissions at low speed. At medium & high speed, low CNG mixing ratio showed low NOx and HC emissions. Therefore, it would be optimized by controlling CNG mixing ratio.

• 한국자동차공학회논문집
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• 제19권2호
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• pp.142-147
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• 2011

Compressed natural gas (CNG) is well known as one of the cleanest burning alternative fuels. Bi-fuel CNG vehicle can also run on gasoline or another fuel while dedicated natural gas vehicle is designed to run on natural gas only. Recently, increased attention has been focused on bi-fuel CNG/LPG taxi because of good fuel economy of CNG. A number of LPG taxis modified to CNG Bi-fuel vehicles are running in many cities. In this paper, the emissions characteristics of in-use passenger cars running on CNG and LPG were investigated. Chassis dynamometer test was used to measure exhaust emissions from an in-use fleet of 5 cars. Exhaust emissions were collected for CVS-75 driving mode. The test results showed that for CNG fuel mode, CO, $CO_2$ and NMHC emissions decreased to 9%, 12% and 14% respectively, and $CH_4$ and $NO_x$ emissions increased to 317% and 47% respectively.

• 한국분무공학회지
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• 제19권1호
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• pp.33-39
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• 2014

Due to persist of high oil prices, LPG price stabilization and CNG modification project will be conducted. Present study describes the fuel efficiency and $CO_2$ emission characteristics on driving cycle mode and ignition advance condition change of CNG/LPG Bi-Fuel vehicle. In case of LPG Base and CNG Base condition, considerable $CO_2$ emissions are generated within range of high acceleration on FTP-75 and HWFET driving mode. However previous phenomena does not appear in CNG fuel $10^{\circ}CA$ and $15^{\circ}CA$ spark advance condition. As a result of analyzing the experimental data CNG $S/A10^{\circ}CA$, CNG $S/A15^{\circ}CA$, CNG Base, and LPG Base sequentially measured high fuel economy and low $CO_2$ emission characteristics.

• 한국분무공학회지
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• 제21권2호
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• pp.95-103
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• 2016

The effect of pilot injection quantity on the combustion and emissions characteristics of a compression ignition engine with a biodiesel-compressed natural gas (CNG) dual fuel combustion (DFC) system is studied in this work. Biodiesel is used as a pilot injection fuel to ignite the main fuel, CNG of DFC. The pilot injection quantity is controlled to investigate the characteristics of combustion and exhaust emissions in a single cylinder diesel engine. The injection pressure and injection timing of pilot fuel are maintained at approximately 120 MPa and BTDC 17 crank angle, respectively. Results show that the indicated mean effective pressure (IMEP) of biodiesel-CNG DFC mode is similar to that of diesel-CNG DFC mode at all load conditions. Combustion stability of biodiesel-CNG DFC mode decreased with increase of engine load, but no notable trend of cycle-to-cycle variations with increase of pilot injection quantity is discovered. The combustion of biodiesel-CNG begins at a retarded crank angle compared to that of diesel-CNG at low load, but it is advanced at high loads. Smoke and NOx of biodiesel-CNG are simultaneously increased with the increase of pilot fuel quantity. Compared to the diesel-CNG DFC, however, smoke and NOx emissions are slightly reduced over all operating conditions. Biodiesel-CNG DFC yields higher $CO_2$ emissions compared to diesel-CNG DFC over all engine conditions. CO and HC emissions for biodiesel-CNG DFC is decreased with the increase of pilot injection quantity.

• 융복합기술연구소 논문집
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• 제3권2호
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• pp.57-60
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• 2013

The purpose of this study is to analysis of how to calculate fuel efficiency in major development countries (U.S. and Europe) and energy consumption formular derivation of domestic CNG fuel and prove by vehicle test. The formula of fuel consumption is different in mpg(mile per gallon), l/100km, and km/l each countries. CNG fuel has a significant impact on fuel density, composition, and Hydro-Carbon ratio. So, this study how to measurement and calculation procedures of CNG gaseous fueled vehicle energy consumption rate.

• 한국가스학회지
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• 제19권6호
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• pp.28-33
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• 2015

2012년 7월부터 우리나라 천연가스 열량에 대한 기준이 기존의 표준열량제에서 열량범위제로 변경되면서 가정이나 산업체로 공급되는 가스 열량 변화가 가스기기 성능에 미치는 영향을 규명하고자 하는 노력이 이루어지고 있다. 특히 천연가스를 주 연료로 사용하는 열병합 발전용 엔진의 경우 이러한 열량 변화에 의해 엔진 성능 전반에 걸쳐 영향이 있을 것으로 예상된다. 따라서 이번 연구에서는 열량범위제를 고려한 CNG 열량 변화가 디젤-CNG 혼소엔진의 효율 및 연소특성에 미치는 영향에 대해 조사하였다. CNG 모사 연료의 발열량은 $10,400kcal/Nm^3$에서 $9,400kcal/Nm^3$까지 질소 가스를 CNG에 희석하는 방식으로 변경을 하였다. 우선 디젤연료의 분사시기와 혼소율을 80%로 고정한 조건에서 가스연료의 발열량 변화가 엔진 효율 및 출력 변화에 미치는 영향을 살펴보았으며, 열방출율 및 연소압력 등의 변화를 측정하였다. 실험 결과로부터 가스 열량이 낮아질수록 엔진 출력과 효율이 모두 감소함을 알 수 있었으며, 점화지연시간과 연소기간은 가스 열량 감소에 관계없이 일정하게 유지되는 반면 최대연소압력은 낮아짐을 볼 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3288-3293
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• 2007

Compressed natural gas has good potential for alternative vehicle fuel due to its economical and clean characteristics. However, the composition of natural gas based on production location is known to affect performance and emissions of CNG engine. Thus, the objective of this paper is to clarify the effect of fuel composition on combustion and emissions of CNG engine. This paper presents combustion characteristics obtained from running a 2.5L, 4-cylinder CNG engine retrofitted IDI diesel engine with engine dynamometer. BSFC, emissions, fuel consumption and combustion pressure were measured under steady state operating conditions especially at partial load for CNG engine. Based on the experimental results, we found that CNG composition affects engine performance, fuel conversion efficiency and burning rate.

• 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.

• 한국자동차공학회논문집
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• 제15권6호
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• pp.23-29
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• 2007

In Korea, the number of LPG vehicles is increasing continuously because LPG is cheaper than Gasoline. Also in Europe, the CNG fuel is a good solution to meet $CO_2$ regulation. In order to use LPG/CNG fuel, new EMS ECU must be developed for every type of vehicles and it requires huge development cost. In order to reduce development cost and time, SIEMENS VDO has developed an Interface Box. It supports EMS ECU in the car and manages LPG/CNG fuel injection system. Basically the Interface box can be used with any kind of EMS ECU. The Interface Box controls LPG/CNG injector through the injection command of gasoline EMS ECU. It calculates required amount of based on the fuel temperature and pressure and sends feedback signal to ECU for fuel correction. Also, it controls LPG/CNG specific actuator such a Shut off valves and LPG switch inputs.