• 한국수소및신에너지학회논문집
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• 제16권2호
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• pp.191-198
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• 2005

Adding hydrogen gas in natural gas leads to stable combustion in internal combustion engine and its performances rely on compression ratio. To analyze the effects of compression ratio and rate of hydrogen addition on the engine performance, the characteristics of overall engine performance including emission were investigated by using the medium duty natural gas fueled engine. As results, it was found that compression ratio occurred knock was nearby compression ratio, $\varepsilon$=14 for the case that hydrogen was enriched in the natural gas fueled engine. But slight knock was occurred at $\varepsilon$=14.7 in the case of neat natural gas. Also HC and $CO_2$ were reduced around 80% and 20% respectively when the rate of hydrogen addition was increased to 50% and compression ratio from $\varepsilon$=13 to $\varepsilon$=14.7.

• 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.

• 한국분무공학회지
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• 제26권4호
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• pp.204-211
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• 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.

• 에너지공학
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• 제9권2호
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• pp.83-88
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• 2000

In this study, the performance and pollutant emission of CNG engine using diesel oil as a source of ignition, so called CNG dual fuel diesel engine is considered by experiment. One of the unsolved problems of the natural gas dual fuel engine is that there is too much exhaust of total hydrocarbon (THC) at a low equivalent mixture ratio. To fix it, a natural gas mixed with hydrogen was applied to engine test. The results showed that the higher the mixture ratio of hydrogen to natural gas, the higher the combustion efficiency. and when the amount of the intake air is reached to 90% of WOT, the combustion efficiency was promoted. But, like a case making the injection timing earlier, the equivalent mixture ratio for the knocking limit decrease and the produce of NOx increases.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.104-109
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• 2006

Improvements in internal combustion engine and aftertreatment technologies are needed to meet future environmental quality goals. Plasmatron fuel converters provide a rapid response, compact means to transform a wide range of hydrocarbon fuels (including gasoline, natural gas and diesel fuel) into hydrogen-rich gas. Hydrogen-rich gas can be used as an additive to provide NOx reductions of more than 80% in diesel engine vehicles by enabling very lean operation or heavy exhaust engine recirculation. For diesel engines, use of compact plasmatron reformers to produce hydrogen-rich gas for the regeneration of NOx absorber/absorbers and particulate traps for diesel engine exhaust after-treatment could provide significant advantages. Recent tests of conversion of diesel fuel to hydrogen-rich gas using a low current plasmatron fuel converter with non-equilibrium plasma features are described.

• 한국자동차공학회논문집
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• 제19권4호
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• pp.78-83
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• 2011

Natural gas is one of the most promising alternatives to gasoline and diesel fuels because of its high thermal efficiency and lower harmful emissions, including $CO_2$. Although the high octane value of natural gas increases engine output and efficiency due to the high compression ratio, this fuel is prone to such difficulties as a narrow limit of inflammability and a slow combustion speed in the lean burn operation domain, leading to unstable combustion and higher emissions of harmful exhaust gases. Hydrogen blended with natural gas can extend the lean burn limit while maintaining stable, efficient combustion and achieving lower NOx, hydrocarbon and green house gas emissions. In this study, the effect of hydrogen addition on an engine performance and NOx emission characteristics was investigated in a heavy duty natural gas engine. The results showed that thermal efficiency was increased and NOx emissions were reduced due to the expansion of lean operation range under stable operation. NOx emission can be significantly reduced with the retard of spark advance timing.

• 한국가스학회지
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• 제14권4호
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• pp.12-17
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• 2010

자동차 연료로서의 천연가스는 고옥탄가, 넓은 연소 한계, 낮은 미연탄화수소 배출 특성, 지구 온난화 물질인 $CO_2$배출 저감 등 디젤과 가솔린을 대신할 수 있는 현실성 있는 대체연료이다. 그러나 희박운전 영역에서는 느린 연소속도 등으로 연소가 불안정해지고 유해 배기가스가 증가하는 단점이 있다. 수소의 첨가는 연소속도를 빠르게 하고 가연한계를 확장시켜 초희박 영역에서도 안정된 운전을 가능하게 하며, NOx의 저감에 유리하다. 본 연구에서는 대형 수소-천연가스 혼합연료 엔진에서 수소 첨가에 따른 기본 연소특성과 희박영역 확장, 배기성능 및 효율 특성에 대해 검토하였다.

• 한국수소및신에너지학회논문집
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• 제31권4호
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• pp.380-386
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• 2020

This paper represents an analysis of the economic impact of firing natural gas/diesel and natural gas/by-product oil mixtures in diesel engine power plants. The objects of analysis is a power plant with electricity generation capacity (300 kW). Using performance data of original diesel engines, the fuel consumption characteristics of the duel fuel engines were simulated. Then, economic assessment was carried out using the performance data and the net present value method. A special focus was given to the evaluation of fuel cost saving when firing natural gas/diesel and natural gas/by-product oil mixtures instead of the pure diesel firing case. Analyses were performed by assuming fuel price changes in the market as well as by using current prices. The analysis results showed that co-firing of natural gas/diesel and natural gas/by-product oil would provide considerable fuel cost saving, leading to meaningful economic benefits.

• 한국수소및신에너지학회논문집
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• 제14권3호
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• pp.276-282
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• 2003

A hydrogen enriched CNG engine can be stably operated at ultra lean condition and reduce emission extremely. It also has advantage to increase gradually the use of hydrogen for the coming hydrogen-energy age. In this studies, the combustion and emission characteristics of heavy-duty hydrogen-CNG engine were investigated to verify the enhancement of performance by enriched hydrogen into natural gas. The results showed that a hydrogen-CNG engine could achieve ultra lean operation and low emission, while power was reduced by the decrease of intake air flow.

• 한국자동차공학회논문집
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• 제21권2호
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• pp.146-153
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• 2013

CNG buses has contributed to improve air quality in cities. But it is difficult to meet the next emission regulations such as EURO-VI without the help of additional post-processing device. Hydorgen has higher flame speed and lower combustion temperature that make it thermal efficiency increase with leaner operation. Using hydrogen natural gas blend (HCNG) fuel is promising technology which can reduce $NO_x$ and $CO_2$ emissions for a natural gas vehicle. However, fuel flow rate of HCNG should be increased since hydrogen's energy density per volume is much smaller than natural gas. In the present study, the characteristics of fuel supply system and its applicability were evaluated in a heavy duty natural gas engine. The results showed that the potential of fuel pressure regulator and fuel metering valve had enough capacity with HCNG. Employed mixer did not affect the distribution characteristics of mixture.