• 대한기계학회논문집B
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• 제22권2호
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• pp.205-212
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• 1998

Experiments were conducted to investigate the temperature profile and the emissions conversion efficiency of catalytic converters for natural gas vehicles. Two types of the catalyst structure and several transient engine operating conditions were used. The dual-bed catalyst effectively reduced the emissions in a transient period due to the low heat capacity of the front bed. The lanthanoid additives were effective in improving catalyst durability. When the natural gas fueled engine were operated outside of a very narrow window of excess air ratio (from 0.993 to 1.004), the HC and NOx conversion efficiency dropped off. The drop-off were especially fast on the lean side of the window.

• 한국가스학회지
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• 제19권6호
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• pp.8-14
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• 2015

합성가스(SNG)는 석탄 가스화를 통하여 얻어지는 가스연료로서, 고유가로 인한 천연가스가격 상승을 대비할 수 있는 대체연료 중의 하나로 주목받고 있다. 본 연구에서는 메탄 90.95%, 프로판 6.05%와 수소 3%의 조성비를 갖는 SNG연료 모사가스와 압축천연가스 (CNG)를 11리터 급 CNG 엔진에 적용하여 연소 및 배기 특성을 비교실험 하였다. 연료공급시스템, 분사시기 등 엔진의 연소제어인자를 일정하게 하고 전부하 운전조건에서 엔진회전수 변화에 따른 출력, 열효율, 연소 안정성 및 배기특성을 비교하였다. 1260rpm, 전부하 운전조건에서 노킹특성도 분석하였다. SNG 연료를 사용했을 때 출력 저하 없이 연소안정성이 향상되어 열효율이 증가하였다. 질소산화물($NO_x$)의 배출은 CNG연료의 경우에 비해 증가되었으나 이산화탄소($CO_2$)의 배출은 감소하였다. SNG 연료를 이용하여 운전할 경우 내노킹성이 향상되었다.

• 한국자동차공학회논문집
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• 제20권5호
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• pp.13-18
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• 2012

This research is about the exhaust gas and driving performance test which are for CNG-Diesel dual fuel engine. The CNG-Diesel dual fuel engine converted from 2500cc diesel has two steps of injection systems; small amount of diesel is injected to mixture CNG in cylinder to ignite before CNG is injected into each intake manifold to form mixture. The amounts of output power and emission in duel fuel consumption were measured by engine dynamometer and exhaust gas analyzer. Over 90% of diesel consumption reduction, similar driving performance to current diesel engine and reduced emission on $CO_2$ and PM, respectively, were indicated through the measurements. The two steps of system were applied to vehicle to investigate exhaust gas characteristics and driving performance via NEDC mode and real driving test. Additional oxidation catalyst was applied to reduce emission on the test vehicle and the NEDC mode test showed the reduction of Co, $CO_2$, Pm and THC.

• 한국대기환경학회지
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• 제16권2호
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• pp.159-164
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• 2000

A CNG dedicated engine one of the types in natural gas engine is assessed as the most effective mechanism for the reduction of exhaust emissions. This work described the measuring results of a CNG dedicated engine by the experiment, In this study the characteristics of the CNG engine was investigated and then measured exhaust gas by engine performance mode at maximum load condition with increasing the engine speed in the range of 1,000-2,200rpm. The exhaust emission was also measured at D-13 mode as well as AVL-8 mode.

• Journal of Mechanical Science and Technology
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• 제16권2호
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• pp.219-226
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• 2002

Natural gas is considered to be a promising alternative fuel for passenger cars, truck transportation and stationary engines providing positive effects both on the environment and energy security. However, since the composition of natural gas fuel varies with location, climate and other factors, it is anticipated that such changes in fuel properties will affect emission characteristics and performance of CNG (Compressed Natural Gas) engines. The purpose of the present study is to investigate the effects of the difference in gas composition on the engine performance and emission characteristics. The results show that THC (Total Hydrocarbon) decreases with increasing Wl (Wobbe Index) and MCP (Maximum Combustion Potential). On the other hand, it is observed that NOx slightly increases as Wl and MCP increase. The TLHV (Total Lower Heating Value of Intake) is proposed in this study as a potential index for compatibility of gas fuels in a CNG engine. There is a variation in power up to 20% depending on the composition of gas when the A/F ratio and spark timing are flexed for a specific gas fuel.

• 한국항공우주학회지
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• 제32권3호
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• pp.66-73
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• 2004

탄화수소 계열의 액체로켓엔진용 연료로서의 액화천연가스의 특성을 성분 및 함량 분석, 냉각제로서의 특성과 엔진 성능 인자로서 특성속도와 비추력 관점에서 평가하였다. 액화천연가스내의 메탄의 함량이 연료로서의 특성을 결정짓는 주요한 인자이었으며, 재생냉각형 액체로켓엔진의 연료로 사용되기 위해서는 최소 90% 이상의 메탄 함량이 요구되는 것으로 판단된다. 한편, 예비 냉각에 의한 액화천연가스의 일부 성분의 응결이 예상되어 정상적인 엔진 작동을 방해하는 요소가 될 수 있다. 약 90%의 메탄 체적 함량을 가지는 액화천연가스의 액체로켓엔진의 작동 조건은 화학 당량비적 혼합비로 표준화한 추진제 혼합비로 0.75가 최적이었다.

• 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.

• 한국가스학회지
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• 제25권6호
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• pp.66-73
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• 2021

본 연구에서 인증을 위한 표준가스 종류의 변화가 대형 천연가스 엔진에 미치는 영향을 살펴보기 위해 전부하 시험과 WHTC 모드 시험 조건에서 엔진 성능 및 배기 특성을 비교하고 그 결과를 분석하였다. 실험에 사용된 연료는 표준 가스 두 종류(G_r, G₂₃)와 시중에 유통되고 있는 천연가스, 총 3종류를 적용하였다. 연료 조성이 다른 3가지 천연가스의 실험결과 엔진 성능 특성은 질소 함유율이 높은 G₂₃ 연료에 대해서 토크, 연료소모율, 열효율 결과가 모두 다른 연료에 비해 악화되는 결과를 보였다. 또한 인증시험모드인 WHTC 모드에서 평가하였을 때, G₂₃ 연료를 적용한 경우 다른 두 연료에 비해 이산화탄소 및 일산화탄소 배출량은 감소하고 메탄, 질소산화물 및 입자상물질의 개수 배출량은 증가하여 질소산화물의 경우 EURO VI 규제치를 만족할 수 없었다.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.65-77
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• 1996

A small-sized industrial diesel engine was converted to a spark ignited engine and then adapted for fuelling with natural gas. After conversion work, general combustion characteristics of the gas engine(such as ignition delay, main and total combustion durations, and heat release characteristics) were studied as a functio of major engine operating variables such as air to fuel ratio, spark timing, and spark plug type. Some other studies on cyclic variation characteristics in IMEP, Pmax and (dp/dφ)max, and also optimum combustion phasing angle were performed.

• 한국자동차공학회논문집
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• 제11권1호
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• pp.7-17
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• 2003

Highly accurate control of an air-fuel ratio is very important to reduce exhaust gas emissions of gaseous-fuel engines. In order to achieve this purpose, a precise engine model is required to estimate engine performance from the engine design process which is applied to the design of an engine controller. Engine dynamics are considered to develop a dynamic engine model of a gaseous-fuel engine. An effective air mass ratio is proposed to study variations of the engine dynamics according to the water vapor and the gaseous-fuel in the mixture. The dynamic engine model is validated with the LPG engine under steady and transient operating conditions. The experimental results in the LPG gaseous-fuel engine show that the estimation of the air flow and the air-fuel ratio based upon the effective air mass ratio is more accurate than that of a normal engine model.