• 한국수소및신에너지학회논문집
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• 제14권2호
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• pp.138-145
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• 2003

There are high expectations for DME(Dimethyl Ether) as a new alternative fuel for diesel engine. Compared with the conventional diesel engine, nearly zero soot emission and high thermal efficiency have been reported from DME fuelled CI engines. However, higher NOx emission is one of the disadvantages from DME Engines. In the present study, cooled EGR(Exhaust Gas Recirculation) was applied to DME engine modified from conventional Dl diesel engine, and effects of EGR were examined under various EGR temperature. Finally, it was concluded that the cooled EGR is an effective solution to reduce NOx emission from DME engine.

• 에너지공학
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• 제18권3호
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• pp.163-168
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• 2009

이 논문은 새로운 개념의 엔진으로 균질혼합압축점화기관(HCCI)에 대해서 이야기 하고 있다. HCCI 엔진은 디젤기관과 가솔린기관의 미래대체엔진으로 고려되고 있다. HCCI엔진은 부분부하에서 높은 지시열효율과 매우 낮은 질소산화물을 배출하는 잠재력 있는 엔진이다.이 논문의 목적은HCCI 엔진에서 의 배기가스재순환(EGR)의 효과를 분명히 하는데 있다. 이러한 연구목적을 위해서 4실린더 압축점화기관이 HCCI 기관으로 개조가 되었다.이 작업은 일정한 회전속도에서 프로판과 부탄의 연료를 사용하였다.

• International Journal of Automotive Technology
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• 제2권4호
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• pp.123-133
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• 2001

An important goal in diesel engine research is the development of a means to reduce the emission of oxides of nitrogen ($NO_x$) and soot particulate. A phenomenological model based on the multizone concept is used in the current paper to analyze and compare the effects of exhaust gas recirculation (EGR) and split fuel injection on emission from a compression-ignited, direct-injection engine. The present results show that $NO_x$ can be reduced with a minimum penalty of soot particle emission with cooled EGR. Compared with EGR, split fuel injection has a higher soot penalty at a given level of $NO_x$ reduction.

• 한국자동차공학회논문집
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• 제17권3호
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• pp.62-67
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• 2009

In this study, the potential possibility of biodiesel fuel was investigated as an alternative fuel for a naturally aspirated indirect injection diesel engine. The smoke emission of biodiesel fuel was reduced remarkably in comparison with diesel fuel, that is, it was reduced approximately 36% at 2000rpm, full load condition. And, power, torque and brake specific energy consumption showed no significant differences. However, NOx emission of biodiesel fuel was increased compared with commercial diesel fuel. Also, the effects of exhaust gas recirculation(EGR) to reduce the NOx emission has been investigated. It was found that simultaneous reduction of smoke and NOx was achieved with biodiesel fuel(20vol-%) and cooled EGR method$(10{\sim}15%)$.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.124-129
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• 2010

The direct injection (DI) diesel engine has become a prime candidate for future transportation needs because of its high thermal efficiency. However, nitrogen oxides (NOx) increase in the local high temperature regions and particulate matter (PM) increases in the diffusion flame region within diesel combustion. Therefore, the demand for developing hybrid system consist of exhaust gas recirculation (EGR) and aftertreatment system as well as diesel particulate filter (DPF) or lean NOx trap (LNT) should be applied. The variation of EGR rate due to the malfunction of EGR valve can affect not only the combustion stability of engine but also the performance of aftertreatment system. In this research, 2.0 liter 4-cylinder turbocharged diesel engine was used to investigate the combustion and emission characteristics for various operating conditions with EGR. While the fuel consumption was increased with increase of EGR rate, NOx emission was improved by maximum 90% at low speed, low load operating condition. To achieve combustion stability and reliability of aftertrearment system with minimum penalty in fuel consumption and emissions, the fault diagnosis of EGR malfunction must be employed.

• 에너지공학
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• 제24권3호
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• pp.34-39
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• 2015

Recently, Air pollution is gradually increasing which are coming from the exhaust of the ICE vehicles in the world. ICE vehicle exhaust gas and $CO_2$ are widely suspected of contributing to the called greenhouse effect, fueling fears of global warming. Therefore, many countries are striving to decrease the vehicle exhaust gas and have developed a variety of policies as air pollution regulation plans. To comply with the regulations, automotive industry has developed hybrid vehicles, which have features of both ICE vehicles and electric vehicles. Hybrid car is eco-friendly and has lowered exhausting gases and improved fuel efficiency. This research has been written to show that break down cases with EGR valve in hybrid cars, steadily increasing in use, and to help with on-site maintenance.

• Journal of Mechanical Science and Technology
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• 제15권11호
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• pp.1524-1532
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• 2001

The effects of recirculated exhaust gas on the wear of cylinder liner and piston were experimentally investigated by a two-cylinder, four cycle, indirect injection diesel engine operating at 75% lo ad and 1600 rpm. For the purpose of comparison between the wear rates of the two cylinders with and without EGR, the recirculated exhaust gas was sucked into one of two cylinders after the soot in exhaust emissions was removed by an intentionally designed cylinder-type scrubber equipped with 6 water injectors(A water injector has 144 nozzles of 1.0 mm diameter), while only the fresh air was inhaled into the other cylinder. These experiments were carried out with the fuel injection timing fixed at 15.3$^{\circ}$ BTDC. It was found that the mean wear rate of cylinder liner with EGR was greater in the measurement positions of the second half than those of the first half, that the mean wear rate without EGR was almost uniform regardless of measurement positions, and that the wear rate of piston skirt with EGR increased a little bit, but the piston head diameter increased, rather than decreased, owing to soot adhesion and erosion wear, and especially larger with EGR.

• 한국자동차공학회논문집
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• 제19권2호
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• pp.105-110
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• 2011

Through this study, the performance evaluation on the addition of low-pressure loop EGR(Exhaust Gas Recirculation) in a 6.0 L commercial diesel engine was carried out using WAVE modeling and simulation. Since the key technology of advanced diesel engine combustion such as low-temperature combustion is to steadily supply high rates of EGR in a wide operating range, the current study could be effectively contribute to the design and development processes of up-to-date diesel engine systems as real-world reference data. The current simulation results show that the system in which low-pressure loop EGR is added shows almost 2.3 times increase in maximum EGR rate at 1000 rpm as well as almost 1.6 times increase at 2200 and 1600 rpm in comparison with an engine system employing high-pressure loop EGR only. Also, both turbocharger axis speed and charging pressure level did not deteriorate due to the addition of low-pressure loop EGR at 2200 and 1000 rpm, but they were fairly decreased at 1600 rpm.

• 한국자동차공학회논문집
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• 제19권5호
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• pp.76-81
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• 2011

Exhaust gas recirculation is the well-known and widely used NOx reduction technology for diesel engines. More effective EGR cooler has been developed and applied to diesel engines to meet the reinforced emission regulation. However, the contaminated EGR cooler by diesel exhaust gas reduces the performance of the engine and NOx reduction rate. The buildup of deposits in EGR coolers cause significant degradation in heat transfer performance, often on the order of 20~30%. Deposits also increase pressure drop across coolers and thus may degrade engine efficiency under some operation conditions. In this study, as a solution for this problem, DOC assisted EGR cooler is designed and then investigated to reduce fouling and its impact on cooler performance. A single channel EGR cooler fouling test apparatus and soot particle generator were developed to represent the real EGR cooler and exhaust gas of diesel engine. EGR cooler effectiveness of the case with catalyst of pt 30g/ft3 decreased just up to 5%. This value was 45% less compared to the case without catalyst which decreased up to 9% after 10hours experiments.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.448-453
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• 2003

In this study, the effects of oxygen component in fuel and exhaust gas recirculation(EGR) method on the exhaust emissions has been investigated for a D.I. diesel engine. It was tested to estimate change of exhaust emission characteristics for the commercial diesel fuel and oxygenate blended fuel which has five kinds of blending ratio. Dimethoxy methane(DMM) contains oxygen component 42.5% in itself. and it is a kind of effective oxygenated fuel for reduction of smoke emission. It was affirmed that smoke emission was decreased with increasing of DMM blending ratio. But, NOx emission was increased compared with commercial diesel fuel. It was needed a NOx reduction countermeasure that EGR method was used as a countermeasure for NOx reduction. It was found that simultaneous reduction of smoke and NOx emission was achieved with DMM blended fuel and cooled EGR method($10{\sim}15%$).