• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.106-114
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• 1996

Extensive experiments were conducted to investigate the emission of DI diesel engine by using DMC(dimethyl carbonate) as an oxygenated fuel additives. The results indicate that smoke reduces almost linearly with fuel oxygen contents. Reductions of HC and CO were attained noticeably, while a small increase in NOx was encountered concurrently. The effective reduction in smoke with DMC was maintained with the presence of CO2, which suggested a low NOx and smoke operation could be obtained in combination of using oxygenated fuel and EGR. Further experiment was conducted a thermal cracking set-up for mechanism studies.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.79-86
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• 2003

In this paper, the effect of oxygen component in fuel on the exhaust emissions has been investigated fur direct injection diesel engine. It was tested to estimate change of engine performance and exhaust emission characteristics for the commercial diesel fuel and oxygenated blended fuel which has seven kinds of mixed ratio. And, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission have been investigated. Ethylene glycol mono-n-butyl ether(EGBE) contains oxygen component 27% in itself, and it is a kind of effective oxygenated fuel of mono-ether group that the smoke emission and unburned hydrocarbons of EGBE is reduced remarkably compared with commercial diesel fuel, that is, it can supply oxygen component sufficiently at higher loads and speeds in diesel engine. It was found that simultaneous reduction of smoke and NOx was achieved with oxygenated fuel and cooled EGR method.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.2
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• pp.80-86
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• 2002

A fuel injection system has an important role in the performance and emission gas in a diesel engine. In this paper, an experimental study has been performed to verify the effect of the performance and the emission gas with the factors such as diameters of an injection nozzle hole, diameters of an injection pipe, and injection timing in the fuel injection system. We have obtained the results that the fuel consumption ratio is reduced and NOx concentration is increased as the smaller diameter of injection nozz1e hole, the smaller diameter of injection pipe, and more advanced injection timing. They show that optimizing the factors of fuel injection system is significant to enhance the performance of the engine system and consumption ratio of fuel, smoke, and NOx.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.108-116
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• 2002

The diesel engine is one of the most effective transport options available in all sizes and covering a wide range of applications. But, many researchers developing the diesel engine are facing tough challenges in view of the increasingly lower emissions standards. Thus, this study will explore the possible fuel additive technology to further reduce the emissions from the IDI diesel engine. The purpose of this study is to investigate the effects of oxygenated fuels on the exhaust emissions and to attain a better trade-off relation between smoke and NOx in four cylinder diesel engine. Experiments were conducted with oxygenated fuels as an effective way to improve the combustion efficiency. Some of oxygenated fuel(Diglyme and DEE) were added to the conventional diesel fuel which had no an oxygen content. Also, EGR was adopted for reducing NOx without any strong adverse effects on other exhaust emissions. This study concluded that exhaust emissions in diesel engine could be reduced by adding the oxygenated fuels which had lower boiling point, and the combustion efficiency was also improved as the oxygen content in fuel increased.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.216-221
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• 2017

Diesel engines have the highest brake thermal efficiency among internal combustion engines. Therefore, they are utilized in medium and large transportation vehicles requiring large amounts of power such as heavy trucks, ships, power generation systems, etc. However, diesel engines have a disadvantage of generating large quantities of nitrogen oxides during the combustion process. Therefore, the authors tried to reduce the amount of nitrogen oxides in marine diesel engines using a wet-type exhaust gas cleaning system utilizing the undivided electrolyzed seawater method. In this method, electrolyzed seawater in injected into the harmful gas discharge from the diesel engine using real seawater. The authors investigated the reduction of NO and NOx from the pH value, available chlorine concentration, and the temperature of electrolyzed seawater. The results of this experiment indicated that when the electrolyzed seawater is acidic, the NO oxidation rate in the oxidation tower is higher than that when the electrolyzed seawater has a neutral pH. Likewise, the NO oxidation rate increased with the increase in concentration of chlorine. Further, it was confirmed that the electrolyzed seawater temperature had no effect on the NO oxidation rate. Thus, the NOx exhaust emission value produced by the diesel engine was reduced by means of electrolyzed seawater treatment.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.21-22
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• 2006

디젤엔진에서 배출되는 배기가스 중의 주요 오염물질 중의 하나인 NOx(질소산화물)는 대부분 고온의 연소 과정에서 발생하고, 발생량은 연소온도에 따라 결정되는 것으로 알려져 있다. 또한 연료의 연소 중에 물이 첨가되면 연소공기의 비열 증가에 의하여 연소온도가 감소하여 NOx 발생량이 급격하게 감소하게 되는데, 연소실에 물을 첨가하는 방법으로는 유화연료, 직접물분사, 흡기가습 등이 있다. 이중 흡기가습은 구조가 간단하면서 NOx 저감효율이 가장 높은 것으로 알려져 있다. 본 연구는 당사 고유모델 중형엔진인 힘센엔진에 흡기가습 기술을 적용하여 연소성능 및 NOx 저감효과 등을 시험하고, 흡기가습 시스템의 상용화 모델 개발을 위한 기초 데이터를 확보하기 위해 수행되었다.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.22-28
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• 2005

Exhaust gas emissions from internal combustion engines are one of the major sources of air pollution. And, it is extremely difficult to increase gasoline engine efficiency and to reduce $NO_X$ and PM(particulate matter) simultaneously in diesel combustion. This paper offers some basic concepts to overcome the above problems. To solve the problems, a recommended technique is CAI(controlled auto-ignition) combustion. In this paper, a flame trap was used to simulate internal EGR(exhaust gas recirculation) effect. An experimental study was carried out to find combustion characteristics using homogeneous premixed gas mixture in the constant volume combustion chamber(CVCC). Flame propagation photos and pressure signals were acquired to verify the flame trap effect. The flame trap creates high speed burned gas jet. It achieves higher flame propagation speed and more stable combustion due to the effect of geometry and burned gas jet.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.6
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• pp.896-902
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• 2009

EGR is applied in order to lower temperature of combustion chamber by using the specific heat of carbon dioxide in engine exhaust gas. However, the problem of EGR system in diesel engine is high PM concentration. Combined EGR system can be reduced it by mixing exhaust gas of gas engine into the intake air of diesel engine. This experimental study was designed for EGR system for both engines use. The results of EGR experimental study by using diesel engine and gas engine are as follows. 1) The pressure of combustion and rate of heat release decreased. 2) The specific fuel consumption increased. But, up to middle load, it little increased. 3) NO concentration has decreased up to 50% in almost all combustion area. 4) The variation of the PM concentration at low load is not so seen. But at high load, PM increased rapidly when concentration of oxygen is decreased and most of it caused the increasing of Dry Soot.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.5
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• pp.531-537
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• 2013

In this study, we conducted real-time measurement at the ship arrivals and departures at the port and at a constant speed of 150 rpm for exhaust emissions from a main engine installed on the training ship, HANBADA, of Korea Maritime University. The result showed that the concentration of nitrogen oxide was measured in the range of 800 ppm to 1,000 ppm at constant speed mode. On the other hand, the concentration of nitrogen oxide during ship arrivals and departures was significantly fluctuated between 210 ppm and 1,230 ppm. And, the concentration of carbon oxide at the arrivals and departures was also larger than that of at constant speed mode. These results show that the ship maneuvering skills to prevent a sudden load change of main engine at the arrivals and departures of ship is needed. Additionally, it means that the difference of exhaust emissions generated between the constant speed mode and the arrival/departure has to be considered when invented many technologies are adopted into the reduction technologies of air pollutants from ships.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.6
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• pp.128-139
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• 2000

Environmental concerns and shortage of petroleum have promoted considerable interest in the use of alternate fuels in stationary diesel engine. In this study, a heavy-duty, intercooler-turbocharged 6-cylinder stationary diesel engine was converted into stationary gas engine fueled with propane or natural gas for the cogeneration plants. One of the most important factors in the combustion features of a stationary gas engine is the fuel composition and operating parameters in terms of compression ratio, spark advance, and engine loads. Experiments with different fuel gas and load conditions were carried out with combustion pressure analysis and NOx measurement. Combustion analysis based on P-$\theta$ diagrams was also investigated by means of combustion duration and cycle variation. Compression ratio is 10.0 and ignition timing is set by using the gasoline setting as a base line and advanced toward BTDC. The results show that fuel composition and spark advance have dominant effects on combustion and NOx characteristics at operating conditions.