• 한국자동차공학회논문집
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• 제12권1호
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• pp.32-38
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• 2004

To evaluate the durability of direct injection diesel engine using biodiesel fuel, a small D. I. diesel engine was operated on a blend(BDF 20) of 20％ biodiesel fuel and 80％ diesel fuel for 200 hours. Engine dynamometer test was performed at a load of 90％ and a speed of 1900 rpm to monitor the engine performance and exhaust emissions. Engine performance parameters and exhaust emissions were sampled at 1 hour interval for analysis. The combustion maximum pressure and the crank angle at this maximum pressure as a combustion variation factor were considered to study the combustion characteristics of BDF 20 in diesel engine during durability test. As the results, the standard deviations and errors of combustion variation factors on BDF 20 were very little and combustion characteristics were very stable during the durability test. BDF 20 resulted in lower emissions of carbon monoxide, carbon dioxide, and smoke emissions with special increase of nitrogen oxides compared to diesel fuel. There was no also unusual change in engine oil composition from using BDF 20. Most of engine parts were clean and showed little wear, but soots were detected around the hole of fuel injector when BDF 20 was used in direct injection diesel engine for 200 hours.

• 한국분무공학회지
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• 제1권4호
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• pp.54-62
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• 1996

Effect of reentrant type bowl geometry on combustion characteristics was investigated in a D.1.diesel engine. The main factor was the aspect ratio (Bowl Diameter/Bowl Depth) of bowl of combustion chamber, and the measured data include the cylinder pressure, engine performance and emissions of the engine using the 4 kinds of the combustion chamber. Experimental results indicate that the effect of dc/H and nozzle protrusion are relatively small and there exists an optimum dc/H according to the combustion conditions. It is also found that the smoke emission is quite sensitive the overall combustion time where the 90 percentage of the combustion heat is released. The smoke mission increases by shortening the 90% combustion time while it decreases by delaying the 90% combustion time.

• 한국자동차공학회논문집
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• 제11권2호
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• pp.48-55
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• 2003

The effects of pressure charge on combustion stability and emissions have been analyzed using a GDI single cylinder engine. A late injection mode of stratified condition at the air-fuel ratio of 40:1 for 1200∼2400 rpm was tested while the boosted pressure ratio was increased up to 1.5:1. In-cylinder CFD analysis was also performed for better understanding of in-cylinder flow and fuel spray behavior. With a higher boosted pressure ratio the IMEP was increased greatly due to the increased engine load, and the ISFC was improved by more than 10% at all engine speeds. The regime of stable stratified combustion was extended to a higher engine speed, but the spark ignition angle had to be more advanced for stable combustion. The emissions of ISHC and ISNOx did not show a particular trend for the increased engine speed but a general trend of lower ISHC and higher ISNOx for a gasoline engine.

• Journal of Advanced Marine Engineering and Technology
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• 제38권3호
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• pp.233-239
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• 2014

엔진성능 분석을 위해서는 기관의 정확한 출력이 기본적으로 중요한 인자이며, 또한 오늘날 내연기관에서 연소압력 분석 장치는 엔진의 연구와 개발, 환경규제 및 엔진의 유지관리를 위해서 필수 장비로 대두 되고 있다. 엔진의 출력뿐만 아니라 연소상태를 분석하여 엔진의 상태에 대한 올바른 판단을 유도하고, 구체적인 개선방법을 제시하여 실질적으로 연료소비량을 절감하여, 엔진의 유지관리 및 운항비 절감에 도움이 되도록 하기위해서는 이를 위한 도구가 절실히 필요하다. 따라서 본 연구는 개발된 측정 장치를 이용하여 선박용 발전기관인 실험엔진의 연소분석을 행하였으며, 실험기관의 불규칙적인 연소상태를 체크하고 재조정하여 안정된 운전 상태를 유지할 수 있었음은 물론 연료절감에 기여할 수 있었다. 이상의 결과로 엔진출력을 정확하게 측정할 수 있는 새로운 방법에 의한 측정 장치가 개발되었으며, 그 유용성이 입증되었다고 판단된다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.7-12
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• 2003

The purpose of this work is to investigate the effect of premixing condition on the combustion and exhaust emission characteristics in a HCCI diesel engine. To form homogeneous charge before intake manifold, the premixed fuel is injected into premixed tank by GDI injection system and the premixed fuel is ignited by direct injected diesel fuel. But in the case of high intake air temperature, premixed fuel is auto-ignited before diesel combustion and soot emission is increased. In the case of light load condition, the BSFC is improved by intake air heating because increased air temperature promoted the combustion of premixed mixture. NOx and smoke concentration of exhaust emissions are reduced compared to conventional diesel engine. The combustion characteristics of the HCCI diesel engine such as combustion pressure, rate of heat release, and exhaust emission characteristics are discussed.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.291-294
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• 2012

The research and development status of combustion chamber of liquid rocjet engine for Korea Space Launch Vehicle(KSLV-II) are briefly described. The cold and hot firing tests of uni-element injector, the performance/heat flux measurement/hot firing tests of subscale combustion chamber and the performance/stability rating/regenerative cooling/hot fire tests of 30ton-class combustion chamber were successfully performed. Based on these results, the research and development of combustion chamber for 75ton-class liquid rocket engine are underway.

• 한국분무공학회지
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• 제22권3호
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• pp.116-121
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• 2017

Pre-combustion chamber type indirect diesel engines have different combustion characteristics compared with those of common rail direct injection engine. The CONVERGE, specific engine CFD program, was used to simulate hollow cone spray model and combustion. The air-fuel mixture flow propagating from pre-combustion chamber to cylinder was concentrated at top half and center of the pre-combustion chamber throat. Stronger mixture flow was formed at smaller and longer throat cases. As a result, thermal efficiency and fuel consumption were improved for modified throat shape and the soot emission was also reduced.

• 한국자동차공학회논문집
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• 제12권4호
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• pp.31-35
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• 2004

A new combustion strategy called LIFC(Late Injection ＆ Fast Combustion) was developed for simultaneous reduction of particulate matter(PM) and nitrogen oxides(NOx) in exhaust emission of diesel engines, In this study, effects of injection timing and injection pressure under relatively high EGR rate were investigated. The experiments were conducted in a conventional engine over a range of commercial engine speed. The test engine could be operated in LIFC up to 2000rpm / bmep 5 bar condition with significant reduction of NOx and PM. The experimental results showed potential for the mechanism of the simultaneous reduction of NOx and PM from HSDI diesel engines.

• 한국연소학회지
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• 제16권2호
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• pp.9-15
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• 2011

Homogeneous charge compression ignition(HCCI) is the best concept able to provide low NOx and PM in diesel engine emissions. This new alternative combustion process is mainly controlled by chemical kinetics in comparison with the conventional combustion in internal combustion engine. In this paper, combustion characteristics of HCCI engine with suggested diesel surrogate(heptane/toluene mixture fuel) reaction mechanism were numerically investigated by heptane/toluene mixture ratio and EGR ratio. As results, the ignition timing became faster with increasing of heptane, and an initial oxidation and the ignition timing of the mixture fuel were affected by heptane and toluene, respectively.

• International Journal of Automotive Technology
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• 제8권1호
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• pp.19-25
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• 2007

This experimental study was carried out to obtain both low emissions and high thermal efficiency by rapid bulk combustion. Two kinds of experiments were conducted to obtain fundamental data on the operation of a RI engine by a radical ignition method. First, the basic experiments were conducted to confirm rapid bulk combustion by using a radical ignition method in a constant volume chamber (CVC). In this experiment, the combustion velocity was much higher than that of a conventional method. Next, to investigate the desirable condition of engine operation using radical ignition, an applied experiment was conducted in an actual engine based on the basic experiment results obtained from CVC condition. A sub-chamber-type diesel engine was reconstructed using a SPI type engine with controlled injection duration and spark timing, and finally, converted to a RI engine. In this study, the operation characteristics of the RI engine were examined according to the sub-chamber's specifications such as the sub-chamber volume and the diameter and number of passage holes. These experimental results showed that the RI engine operated successfully and was affected by the ratio of the passage hole area to the sub-chamber volume.