• Journal of Advanced Marine Engineering and Technology
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• 제39권9호
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• pp.870-875
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• 2015

디젤 엔진은 출력 및 연료소비율이 우수하여 많이 사용되고 있다. 그러나 디젤엔진은 가솔린엔진에 비하여 배출가스 저감 기술 등에서 아직 해결해야할 문제점들이 많고, 대기오염의 주범이다. 디젤엔진에 있어 배기가스 재순환(EGR; Exhaust Gas Recirculation) 기술은 여러 촉매 기술에 비해 질소산화물(NOx) 배출 저감을 위한 가장 효과적인 기술이며 또한 경제성, 적용 가능성 측면에서도 많은 장점을 갖고 있다. 본 연구에서는 EGR 시스템을 장착한 디젤 엔진을 대상으로 EGR이 디젤기관의 출력 성능 및 배기특성에 미치는 영향을 고찰하였고, 다음과 같은 결론을 얻었다. EGR율이 증가함에 따라 IHP 및 BHP는 감소하며, 순수EGR에 의한 영향은 엔진회전수에 따라 차이는 있지만, 순수 EGR에 의한 BHP는 저속 운전에서는 약 9%, 고속운전에서는 3.5% 정도 감소하였다. 그리고 NOx는 EGR율이 증가함에 따라 감소하고, 엔진회전수 증가할수록 증가한다. 또한 매연(smoke)은 EGR율이 증가함에 따라서 증가하고, 엔진회전수가 증가할수록 감소한다. EGR율에 따라 NOx와 매연 배출을 동시에 최소로 할 수 있는 최적의 운전 상태가 존재하며, EGR율이 증가할 수록 NOx 및 매연을 위한 최적운전 속도는 증가한다.

• Journal of Advanced Marine Engineering and Technology
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• 제24권2호
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• pp.57-62
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• 2000

The effect of exhaust gas recirculation(EGR) on the characteristics of exhaust gas emissions, and SFC are experimentally investigated by four-cylinder, four-cycle and direct injection marine diesel engine. In order to reduce the soot contents in the recirculated exhaust gas to intake system of the engines, a soot removal system of a cylinderical-type scrubber is specially designed and manufactured for the experimental system. (1) SFC is increased in downward convex curve style with increasing excess air ratio, it is increased with increasing EGR rate at the same excess air ratio. (2) NOx emission is reduced in downward convex curve style with increasing excess air ratio, it is reduced with increasing EGR rate at the same excess air ratio. (3) Soot emission is decreased in downward convex curve style with increasing excess air ratio, it is reduced with increasing EGR rate at the same excess air ratio. (4) CO emission is increased in nearly straight line style with increasing excess air ratio, it is increased with increasing EGR rate at the same excess air ratio. (5) HC emission is not constant tendency with increasing excess air ratio, it is increased with increasing EGR rate at the same excess air ratio.

• Journal of Advanced Marine Engineering and Technology
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• 제22권4호
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• pp.481-489
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• 1998

The effects of recirculated exhaust gas on the characteristics of fuel economy combustion and exhaust emissions have been experimentally investigated by a four-cylinder four cycle indirect injection water-cooled and marine diesel engine operating at several loads and speeds. in order to reduce the soot contents in the recirculated exhaust gas to intake system of the engine a novel diesel soot removal system with a cylinder-type scrubber which has 6 water injectors(A water injector has 144 nozzles in 1.0 mm diameter) is specially designed and manufactured for the experiment system The experiments in this study are performed at the fixed fuel injection timing of $15.3^{\circ}$ BTDC regardless of experimental conditions, The brake specific fuel consumption rate is slightly fluctuated with EGR in the range of experimental conditions, The maximum value of premixed combustion for the rate of heat release is decreased with EGR at engine load 25% and the ignition is slightly delayed with EGR at engine load 100% NOx emissions are markedly decreased with EGR especially at high loads while soot emissions are increased as the EGR rate rises.

• 한국자동차공학회논문집
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• 제3권1호
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• pp.76-88
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• 1995

The effects of exhaust gas recirculation(EGR) on the characteristics of NOx emissions and specific fuel consumption rate have been investigated using an eight-cylinder. four cycle. direct injection diesel engine operating at several loads and speeds. The theoretical NO formation concentration is calculated with the equivalence ratio as a parameter of flame temperature to study the effect of EGR on NOx emissions in the diesel combustion. The experiments in this study are conducted on the fixed fuel injection timing of $38^{\circ}$ BTDC regardless of experimental conditions. It is found that the specific fuel consumption rate is slightly increased with EGR rate. and NOx emissions are markedly reduced owing to the drop of the incoming oxygen concentratio and the increase of equivalence ratio as the EGR rate increases.

• 한국산학기술학회논문지
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• 제17권2호
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• pp.137-146
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• 2016

EGR율이 증가할수록 $NO_X$ 저감에는 효과적이나, 과도한 EGR율은 오히려 불완전 연소의 주원인이 된다. 엄격한 배기규제를 만족하기 위해서는 엔진의 운행 조건에 최적화된 정밀한 EGR 밸브의 위치 제어가 뒷받침 되어야 한다. 따라서 본 연구에서는 EGR 밸브 용 모터 특성 분석을 위해 수학적 모델링과 제어 이론에 대해 연구하고, 마이크로칩 개발 툴을 이용하여 EGR 밸브용 모터의 위치를 제어하기 위한 단계로서 PWM(Pulse Width Modulation)의 듀티(duty)비의 입력 값에 따른 밸브 위치를 측정하여 개폐 구간 별 EGR 밸브 모터 특성을 분석하였다.

• 수산해양교육연구
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• 제29권2호
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• pp.586-592
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• 2017

This study analyzed the effect of four control factors, RPM, load, EGR rate and cooling water temperature on the exhaust emissions of the small DI diesel engine. The amount of NOx and smoke emissions were measured through experiments for three levels of four control factors according to orthogonal array table, and the effect of four factors on NOx and smoke emissions was analyzed quantitatively. The main results obtained in this study are summarized as follows: 1. RPM, load and EGR rate have a great influence on NOx and smoke emissions, and the effect of cooling water temperature is negligible. 2. As RPM and load increases NOx emission increases and decreases sharply as the EGR rate increases. 3. Smoke emission decreases or increases randomly according to RPM and load, but increases sharply in proportion to the EGR rate. 4. EGR rate has the greatest effect on NOx and smoke emissions by more than 60% of contribution to variance, especially in the case of NOx emission, EGR rate represents a significant result even under the confidence level of 99% on ANOVA.

• Journal of Advanced Marine Engineering and Technology
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• 제23권2호
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• pp.184-191
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• 1999

Th effects of exhaust gas recirculation(EGR) on the characteristics of combustion exhaust emissions and specific fuel consumption(SFC) are experimentally investigated by four-cylin-der four-cycle and direct injection marine diesel engine. In order to reduce soot contents in the recirculated exhaust gas to intake system of the engines a novel diesel soot removal system with a cylinder-type scrubber which has water injector(4 nozzles in 1.0mm diameter)is specially designed and manufactured for the experi-mental system. The obtained results are as follows; The combustion pressure in cylinder is decreased and ignition is delayed with increasing EGR rate. The accumulated quantity of heat release is slightly decreased and the tendency of heat release rate is not constant. NOx and Soot emissions are decreased by maximum 7% and 540% with scrubber tan without scrubber in the range of experimental conditions. Those are increased at the lean burn area with increasing equivalence ration in the constant value of engine speed and EGR rate. Also those are decreased with increasing EGR rate in the constant value of engine speed and equivalence ratio.

• 한국분무공학회지
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• 제22권4호
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• pp.190-196
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• 2017

The aim of this work is to investigate the combustion and exhaust emission characteristics of low-temperature combustion (LTC) at various EGR test conditions using a single cylinder common-rail diesel engine. In high EGR rate combustion mode with DME fuel, 30% (${\Phi}=0.61$) and 50% (${\Phi}=0.86$) of EGR were respectively examined, and then the combustion, exhaust emissions, nano-particle characteristics of each cases were measured. From these results, it revealed that The ignition delay and combustion duration are prolonged as the increase of EGR rate. In addition, at an advanced injection timing (BTDC $30^{\circ}$), ignition delays were fairly increased because the dilution effect of EGR and also low charge in-cylinder temperature created a lean mixture, thus decreased the peak release rate.

• 한국산학기술학회논문지
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• 제8권2호
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• pp.185-188
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• 2007

최근 디젤 차량의 NOx와 PM의 동시 저감을 위해 EGR 밸브와 EGR 쿨러로 구성된 modulated EGR 시스템이 디젤엔진에 장착되고 있다. 본 연구에서는 modulated EGR 시스템의 성능 평가를 위한 test bench를 설계, 제작한 후 2.0 L 디젤엔진용 전자식 EGR 밸브를 시험하였다. 또한 전자식 EGR 밸브의 성능을 밸브양정의 거동, 밸브 개폐시의 응답성, 밸브 통과 유량을 통하여 평가하였다. PWM 신호의 듀티율에 따른 밸브 양정의 거동은 비선형적이었으며, 밸브 개방과 폐쇄의 경로가 상이한 히스테리시스 현상을 나타냈다. 밸브 개방시 응답성은 통상의 기준을 만족하여 적절하였다. 끝으로 밸브 통과 유량은 듀티율 $40{\sim}60%$에서 듀티율과 밸브 전후의 차압에 의해 결정되나, 듀티율 60%이상에서는 차압에만 의존하였다.

• 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.