• 한국가스학회지
• /
• 제15권1호
• /
• pp.9-14
• /
• 2011

대형 디젤엔진은 주행거리가 길고 배기량이 크기 때문에 차량의 대수는 상대적으로 적지만 대기환경에 미치는 영향은 크다. 시내를 주행하는 시내버스의 경우 한일 월드컵을 계기로 CNG 버스로 전환되었다. 그러나 대형트럭과 장거리 시외버스의 경우 주행거리가 길고 CNG 충전소가 대도시의 시내버스 차고지 위주로 설치되어 있어 이용이 불가능하였다. 단열용기의 적용으로 천연가스를 압축상태가 아닌 액체 상태로 보관이 가능해져 주행거리가 긴 대형트럭이나 장거리 시외버스로의 적용이 가능해졌으며, 혼소엔진의 경우 LNG 충전이 어려운 지역에서는 디젤로 운행이 가능하다. 이와 같은 장점으로 인하여 석유 의존도를 크게 낮출 수 있어 에너지원의 다변화가 가능하며, 디젤차의 고질적인 단점으로 여겨왔던 매연 및 질소산화물뿐만 아니라 저탄소 연료를 사용함으로서 대표적인 온실가스중의 하나인 이산화탄소도 10%이상 저감할 수 있었다.

• 한국생산제조학회지
• /
• 제8권2호
• /
• pp.94-94
• /
• 1999

Natural gas is considered to be on e of the most promising candidates for a clean substitute fuel and a great amount of research on the compressed natural gas(CNG) fueled vehicle has been performed. In this s tudy, we try to understand the property of CNG fuel with using CNG engine experiment. In order to present the direction and application of CNG, we experiment with various operating conditions that is, spark timing, A/F ratio, air quantity and fuel quantity, etc. 11,967 cc engine was used in the experiment and the engine fuel ratio was determined in the way that the performance of dedicated CNG engine is corresponded to that of existing diesel engine. The performance and dedicated CNG engine were measured by changing the fuel injection timing. The dedicated CNG engine was proved to be good in describing the experimental results and according to the actual road test, acceleration and constant speed driving for dedicated CNG engine was better than existing diesel engine.

• 한국자동차공학회논문집
• /
• 제4권6호
• /
• pp.11-17
• /
• 1996

Many researches on natural gas engines, with lean mixtures are being conducted for the purpose of preservation of global environment. Lean combustion is one of the most promising method for increasing engine efficiency and reducing the emission from SI engines. Due to the possibility of partial burn and misfire, however, under lean burn operation, stable flame kernel formation and fast burn rate, by use of swirl or tumble flow, are needed to guarantee a successful subsequent combustion. Experimental data were obtained on a 4-stroke, natural gas fueled SI engine to investigate the effect of compression ratio, swirl and spark plug electrode rotation on efficiency and emission under lean burn condition. Experimental results have displayed that higher compression ratio, presence of swirl vane and favorable direction of electrode gap brougth about the improvements in engine efficiency and its operational stability.

• Environmental Engineering Research
• /
• 제14권2호
• /
• pp.95-101
• /
• 2009

Natural gas is a promising alternative fuel of internal combustion engines. In this paper, the combustion and emission characteristics were investigated on a natural gas engine at two different fuel injection timings during the intake stroke. The results show that fuel injection timing affects combustion processes. The optimum spark timing (MBT) achieving the maximum indicated mean effective pressure (IMEP) is related to fuel injection timing and air fuel ratio. At MBT spark timing, late fuel injection timing delays ignition timing and prolongs combustion duration in most cases. But fuel injection timing has little effect on IMEP at fixed lambdas. The coefficient of variation (COV) of IMEP is dependent on air fuel ratio, throttle positions and fuel injection timings at MBT spark timing. The COV of IMEP increases with lambda in most cases. Late fuel injection timings can reduce the COV of IMEP at part loads. Moreover, engine-out CO and total hydrocarbon (THC) emissions can be reduced at late fuel injection timing.

• 한국분무공학회지
• /
• 제26권4호
• /
• pp.204-211
• /
• 2021

Lean combustion performance of natural gas and hydrogen was compared in a spark-ignition engine. The lean combustion engine operation with natural gas was limited due to combustion instability at an excess air ratio (EAR) above 1.8. The total hydrocarbon (THC) emissions increased significantly with increasing EAR. The nitrogen oxides (NO_X) emissions were also high due to the limitation of increasing EAR. The lean combustion engine operation with hydrogen showed superior combustion stability as well as low THC and NO_X emissions, even at high EARs. However, boosting technology was required to reach the high EARs.

• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2011년도 전기공동학술대회 논문집
• /
• pp.3-6
• /
• 2011

The utilization of gas as ship fuel requires a new set of regulations by IMO and society of classification. Maritime Safety Committee(MSC) and the subcommittee Bulk-Liquids and Gases(BLG) in IMO developed "Interim Guidelines on Safety for Natural Gas-fueled Engine Installation in Ships(Res.MSC.285(86))" for the use of natural gas in internal combustion engine. According to the requirement of Res.MSC.285(86) for natural gas-fueled engine installations in ships, several parts of ships should follow safety criteria in terms of Fuel bunkering, Gas safe Machinery spaces, Gas Fuel Storage and etc. In this thesis, details of the IGF code shall be described and development of the IGF code in IMO shall be illustrated.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2005년도 학술발표논문집
• /
• pp.592-597
• /
• 2005

Biogas is widely accepted as one of renewable energy. Raw biogas can be used in internal combustion engines either spark ignition or diesel engines. Since the gas has relatively low calorific values, engine power also is lower than rated power values. Modified engines or biogas-specific engines have been utilized in order to increase efficiency. Recently, gas engine/generators are provided for various purposes. They are mostly for LPG or natural gas. When biogas is fueled to the gas engines, de-rating is inevitable due to its lower calorific values. Meanwhile, massively produced commercial gas engines are more competitive in terms of initial investment for engines, compared to biogas-specific engines. Then, the characteristics of the commercial engine and power generation should be understood for better operation. A 5kW gas engine/generator(natural gas) was tested for determining an allowable maximum concentration of $CO_2$ in synthetic biogas, with respect to engine stating, power generation. Experimental results indicated that about 65% of methane concentration is required to start the gas engine. At this condition, the power generated was about 3 kW. It is about 60% of the nominal power, which is similar to the ratio of calorific values.

• 한국자동차공학회논문집
• /
• 제7권8호
• /
• pp.123-131
• /
• 1999

Natural gas is one of the most promising alternative fuels for automotive vehicles. However, natural gas varies in compositional between the originating fields and may be further modified due to processing and additional mixing. These variations are known to affect engine performance and emissions through changes in fuel metering and combustion characteristics. In the present study, the effect of gas compositions on vehicle performance such as fuel economy, driveability and exhaust emissions was examined. Analysis are made of using 3 types of NGVs which were made by automakers and 6 different fuels which are selected in consideration of the variation in fuel composition on the worldwide market. The results may be utilized to develop natural gas natural gas engine in automaekrs and/or to establish the fuel standard in the refueling stations.

• 한국가스학회지
• /
• 제23권6호
• /
• pp.90-96
• /
• 2019

셰일가스의 채굴량 확장과 러시아를 통한 PNG (Pipeline Natural Gas)의 도입은 천연가스가 유력한 대체 연료임을 시사해주고 있다. 따라서 향후 증대될 천연가스의 공급에 맞추어 해당 연료의 수요처 증대가 필수적인 상황이다. 이와 같은 상황에서 수송분야는 저탄소 기체 연료인 천연가스를 적용하기 적합한 분야이며, 이를 통해 이산화탄소와 입자상 물질 등의 유해 배기물질을 저감하는 데 큰 역할을 할 것으로 기대된다. 천연가스는 자발화 특성이 낮고, 내노킹(Anti-knocking)성이 우수하기 때문에 전기점화 방식에 적합하다. 최근 가솔린 엔진은 연비 개선을 위해 연소실에 직접 분사하는 방식을 주로 채택하고 있으나,연소실 내로 액상 직분사를 하는 반면 천연가스의 경우 액상분사 혹은 고압 분사가 어렵다. 따라서 포트에 분사하는 방식을 사용하므로 동등 흡기압력에서 연료의 분율이 흡입공기의 체적을 대체하여 가솔린 직분 방식에 비해 출력이 저하되는 현상을 피할 수 없게 된다. 이에 본 연구에서는 터보차저를 천연가스 포트 분사 엔진에 적용하여 흡기 압력 상향을 통한 출력 보상을 도모하고자 하였다.그 결과 천연가스 적용 시 흡기압력을 기존 가솔린 대비 5-27 % 상향 시 가솔린 직분사 엔진과 동등 출력을 확보함과 동시에 향상된 제동 열효율을 확인 할 수 있었다.

• 한국분무공학회지
• /
• 제24권4호
• /
• pp.194-202
• /
• 2019

A mixture preparation strategy was proposed and evaluated in a diesel-natural gas dual-fuel engine to reduce hydrocarbon (HC) and carbon monoxide (CO) emissions under low load conditions. An experimental investigation was conducted in a single-cylinder compression-ignition engine. Natural gas was supplied with air during the intake stroke, and diesel was injected directly into the combustion chamber during the compression stroke. First, effects of diesel start of energizing (SOE) and natural gas substitution ratio on the combustion and exhaust gas emissions were analyzed. Based on the results, the mixture preparation strategy was established. A low natural gas substitution ratio and a high exhaust gas recirculation (EGR) rate were effective in reducing the HC and CO emissions.