• 한국가스학회지
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• 제19권2호
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• pp.29-36
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• 2015

본 연구는 발전용 디젤 엔진을 천연가스/디젤 혼소 엔진으로 개조하기 위한 선행 연구로 1.5MW급 발전용 디젤 엔진을 대상으로 상용 프로그램인 GT-Power를 이용해 수치해석을 진행하였다. 흡기 포트에 천연가스 분사 장치를 추가한 수치해석 모델을 통해 기존 엔진에서 천연가스와 디젤을 혼소시킬 경우 엔진 성능에 미치는 영향과 특성에 대해 분석하였다. 엔진 속도 720RPM, 혼소율 0%~40%까지 5개 조건에서 수치해석을 진행했다. 연구 결과 혼합 연소 시 천연가스의 비율이 증가할수록 출력이 감소하는 경향을 보였으며 혼소율 40%에서 출력이 18.4% 감소하였다. 이에 따라 실험계획법(Design of Experiment)을 통해 연료 분사시기와 연료 분사 기간에 대한 영향을 분석했다. 또한 이러한 영향을 고려해 연료 분사시기와 분사기간을 최적화시켜 혼소 엔진 출력과 디젤 엔진의 출력을 비교하여 혼소엔진으로의 개조에 따른 엔진의 출력과 효율에 대한 변화를 정량적으로 도출하였다. 그 결과 혼소율 40%에서 엔진 출력은 8.55% 감소하여 최적화 이전에 비해 12.5%의 개선 효과를 보였다.

• 동력기계공학회지
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• 제9권4호
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• pp.209-213
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• 2005

The effects of density change of ambient gas on mixture formation process have been investigated in high temperature and pressure field. To analyze the mixture formation process of evaporating diesel spray is important for emissions reduction in actual engines. Ambient gas density was selected as experimental parameter. The ambient gas density was changed from $r_a=5.0kg/m^3\;to\;r_a=12.3kg/m^3$ with a high pressure injection system(ECD-U2). For visualization of the experiment phenomenon, a CVC(Constant Volume Chamber) was used in this study. The ambient temperature and injection pressure are kept as 700K and 72MPa, respectively. The images of liquid and vapor phase in the evaporating free spray were simultaneously taken by exciplex fluorescence method. As experimental results, with increasing ambient gas density, the tip penetration of the evaporating free spray decreases due to the increase in the drag force from ambient gas.

• 대한기계학회논문집B
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• 제33권6호
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• pp.454-460
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• 2009

To analyze the mixture formation process of evaporating diesel spray is important for emissions reduction in actual engines. Then the effects of change in density of ambient gas on spray structure in high temperature and pressure field have been investigated in this study. The ambient gas density was changed from ${\rho}_a=5.0kg/m^3$ to ${\rho}_a=12.3kg/m^3$ with CVC(Constant Volume Chamber). Also, simulation study by modified KIVA-II code was conducted and compared with experimental results. The ambient temperature and injection pressure are kept as 700K and 72MPa, respectively. The images of liquid and vapor phase in the evaporating free spray were simultaneously taken by exciplex fluorescence method. As experimental results, with increasing ambient gas density, the tip penetration of the evaporating free spray decreases due to the increase in the drag force from ambient gas. The spatial structure of a diesel spray can be verified as 2-regions consisted of liquid with momentum decrease and vapor with large-scale vortex. The calculated results obtained by modified KIVA-II code show good agreements with experimental results.

• Journal of Advanced Marine Engineering and Technology
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• 제18권2호
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• pp.104-112
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• 1994

The scavenging efficiency has a great influence on the performance of a diesel engine, especially slow two-stroke diesel engines which are usually used as a marine propulsion power plant. And this is greatly affected by the conditions in the cylinder, scavenging manifold and exhaust manifold during the gas exchange process. There are many factors to affect on the scavenging efficiency and these factors interact each other very complicatedly. Therefore the simulation program of the gas exchange process is very useful to improve and predict the scavenging efficiency, due to the high costs associated with redesign and testing. In this paper, a three-zone scavenging model for two-stroke uniflow engines was developed to link a control-volume-type engine simulation program for performance prediction of long-stroke marine engines. In this model it was attempted to simulate the three different regions perceived to exist inside the cylinder during scavenging, namely the air, mixing and combystion products regions, by modeling each region as a seperate control volume. Finally the scavenging efficiency was compared with three type of scavenging modes, that is, pure displacement, partial mixing and prefect mixing.

• Environmental Engineering Research
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• 제8권1호
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• pp.31-40
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• 2003

• 한국자동차공학회논문집
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• 제15권4호
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• pp.178-185
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• 2007

A study is improvement of power and emission in a inline-pump Dr diesel engine by using Dimethyl ether Fuel. Dimethyl ether (DME) is an oxygenated fuel with a cetane number higher than that of diesel oil. It meets the ULEV emission regulation and reduces the smoke to almost zero when used in a diesel engine. But NOx emission is almost same and CO, THC emissions are lower than that of diesel engine. The emissions aren't satisfied the stronger emission regulation in the further. Generally DOC (Diesel Oxidation Catalyst) is used to reduce CO & THC emissions and EGR (Exhaust Gas Recirculation) system is used to reduce NOx emission. Test results showed that the torque and the power with DME were almost same as those of pure diesel oil, but the brake thermal efficiency increased a little. also the BSEC (Brake Specific Energy Consumption) with DME was similar that of diesel. The test results showed that the DOC was the vary effective method to reduce the CO emission in case of Dimethyl Ether Fuel in diesel engine. But, THC emission is showed a little reduction rates. Also EGR system was the very effective method to reduce the NOx emission in case of Dimethyl Ether Fuel in diesel engine.

• 한국자동차공학회논문집
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• 제16권5호
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• pp.84-91
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• 2008

Due to increasing need for better emission characteristics and lower fuel consumption rate in automotive engines, alternative fuels are drawing more attentions recently. The GTL (gas to liquid) is the one of most favored candidates. In this study, emission characteristics are compared between diesel and GTL fuel in commercial 2.0 liter diesel engine and vehicle with CRDi(Common Rail Direct injection) system. The effects of injection timings on emission and fuel consumption rate are compared at various engine speeds and loads. Noticeable reduction in HC, CO and PM emissions are observed due to higher cetane number and low sulfur and aromatic contents in GTL. On the trade-off curve of NOx and PM(Particulate matter) GTL showed much more benefits than diesel, where about 30% of PM mass decreased at the same operating conditions. On CVS 75 mode test in vehicle, GTL showed an excellent emission enhancement, in which 50% of HC, 21% of PM, and 12% of NOx engine-out emissions are decreased compared to ULSD(Ultra low sulfur diesel) fuel.

• 미생물학회지
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• 제39권2호
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• pp.102-107
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• 2003

유류오염 토양으로부터 디젤에 대한 분해능이 있는 균주를 순수분리하였고, 이들 분리 균주의 액체 배양을통하여 균체 생육과 유화활성이 우수한 균주를 최종적으로 선별하였다. 생리,생화학적 특성 및 165 rDNA 염기서열 분석을 실시한 결과, Pseudomonas sp.로 분류 되었으며, Pseudomonas sp. GENECO 1으로 명명하였다. Bioscreen C를 이용하여 디젤 분해를 위한 배양 조건을 조사한 결과 최적 배양온도는 $30^{\circ}C$, 초기 pH는 7.0로 나타났다. Gas chromatography를 이용한 배양 시간별 잔류 디젤 성분분석 결과 96시간 이내에 1.0%의 디젤을 95%이상 분해하였다.

• 동력기계공학회지
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• 제12권5호
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• pp.34-39
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• 2008

The combustion purpose of diesel engine is to reduce the emission of green gas and to produce high output. Generally, the regulation matter of emission gas is largely diveded by 'THC', 'NOx', 'CO' and 'PM'. Among those matters, the most problem is to disgorge into 'PM', the character of diesel combustion. Diesel PM can be controlled using Diesel Particulate Filter, which can effectively reduce the level of soot emissions to ambient background levels. $NO_2$ generated by the DOC is used to combust the carbon collected in the DPF at low temperature. To certificate DPF device that is suitable to domestic circumstances, it is necessary to exactly evaluate the DPF devices according to the regulation of DPF certificate test procedure fur retrofit. To do carry out the above-mentioned description the understanding of that regulation like the standard of PM reduction is needed. In this study the test procedure including test cycle and BPT test condition was examined, and also the test result for specific DPF was analyzed. In every test like field test, PM reduction efficiency test and Seoul-10 mode test, no defect was showed.

• 한국자동차공학회논문집
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• 제15권3호
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• pp.35-40
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• 2007

Our environment is faced with serious problems related to the air pollution from automobiles in these days. In particular, the exhaust emissions of diesel engine are recognized main cause which influenced environment strong, In this study, the potential possibility of biodiesel fuel was investigated as an alternative fuel for a naturally aspirated common rail diesel engine. The smoke emission of biodiesel fuel 5vol-%(min. content) was reduced in comparison with diesel fuel, that is, it was reduced approximately 60% at 4000rpm, full load. But, power, torque and brake specific energy consumption didn't have no large differences. But, NOx emission of biodiesel fuel was increased compared with a commercial diesel fuel. Also, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission has been investigated. It was found that simultaneous reduction of smoke and NOx was achieved with biodiesel fuel(5vol-%) and cooled EGR method($5{\sim}10%$) in a common rail diesel engine.