• 한국자동차공학회논문집
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• 제7권6호
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• pp.49-56
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• 1999

The effects of the internal flow in a D.I. Diesel injection nozzle on the atomization of a spray were analyzed experimentally. Flow visualization studies were made using a transparent acrylic model nozzle as a diesel nozzle . Water instead of disel fuel was used as the injection liquid. The geometry of the model nozzle was scaled up 10 times of the actual nozzle and the injection pressure for the model nozzle was adjusted so as to achieve a Reynolds number at the discharge hole that was the same as the actual nozzle. Experimental results show that when the needle lift was small, the high turbulence in the sac chamber generated by the high velocity seat flow made the spread angle of the spray plume large. Cavitation, which arose from the sac chamber, makes the spread angle of the spray plume large but the discharge coefficient small.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.3013-3018
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• 2008

Supercharging system was adopted to investigate the influence of boost pressure on operating range, brake specific fuel consumption (BSFC) and exhaust emissions by using a supercharger at low temperature diesel combustion (LTC) condition in a 5-cylinder 2.7 L direct injection diesel engine. The experimental parameters such as injection quantity, injection timing, injection pressure and exhaust gas recirculation (EGR) rate were varied to find maximum operating range. The result showed that operating range with boost was expanded up to 41.9% compared to naturally aspirated LTC condition due to increased mixing intensity. The boosted LTC engine showed low BSFC value and dramatically reduced soot emission under all operating range compared with high speed direct injection (HSDI) mode. Finally, this paper presents the boosted LTC map of emission and the strategy of improved engine operating range.

• 한국전산유체공학회지
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• 제5권3호
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• pp.1-7
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• 2000

In high-pressure diesel engine, the injected fuel spray impinges on the piston cavity surface due to the short distance between the injection nozzle and the cavity wall. The behavior of the impinging spray has the great influence on the dispersion of fuel, the evaporation, and the mixture formation process. In this study, the numerical simulation using the GTT code was performed to study the gas flows, the spray behaviors, and the fuel vapor distributions in the combustion of a D.I engine for variation of spray angle and swirl ratio.

• 한국지하수토양환경학회지:지하수토양환경
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• 제11권4호
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• pp.10-17
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• 2006

본 연구에서는 실험실 규모의 2D air/bio-sparging 장치를 이용하여 공기주입량과 공기주입방식이 디젤오염 토양/지하수의 복원에 미치는 영향을 평가하고 최적 조건을 도출하였다. 최적의 공기주입량과 공기주입방식은 1,000 ml/min의 공기주입과 15 min 간격의 간헐적인 공기주입 패턴이 효율적으로 관찰되었고, 실험기간동안 TPH와 DO 감소, $CO_2$ 생성은 오염원인 디젤이 효과적으로 생분해에 의해 제거가 이루어지고 있음 보여주었다. 즉, 최소한의 공기주입으로도 포화층에서의 디젤 분해를 효과적으로 증진시킬 수 있었으며, 간헐적인 공기주입방식은 대수층내에서의 공기 전달을 증진시킬 수 있었다. 또한 Air/bio-sparging공법의 대부분의 운전비가 blower와 off-gas 처리 시스템에 사용되는 전력비라는 것을 감안 할 때, 최적의 공기주입량과 간헐적인 공기주입방식은 운전비 절감의 효과를 가져다 줄 것으로 판단된다.

• 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.