• 동력기계공학회지
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• 제10권2호
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• pp.5-10
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• 2006

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 30vol-%(max. 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 commercial diesel fuel.

• 한국기계가공학회지
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• 제20권7호
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• pp.80-88
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• 2021

The behavior of the injection system was determined through FFT and PSD analysis of the pressure data of the common rail, and when the diesel fuel is mixed with water, the pressure data of the common rail, depending on the water content and engine rotation speed, represent a different frequency component distribution. Recently, a theory has been suggested that mixing diesel fuel with water controls engine overheating, fuel efficiency, NOx, CO, etc., but if water content exceeds 10%, it can have a fatal adverse effect on the engine's injection system. In the future, it is necessary to promote fault diagnosis and prediction studies of diesel engines using FFT and PSD results from common rail pressure data.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.30-37
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• 2004

The combustion and emission characteristics of a direct injection CI engine fuelled with DME(Dimethyl Ether) and diesel fuel were compared at idle engine speed(800 rpm) with various injection parameters. An optical single cylinder diesel engine equipped with a common-rail fuel injection system was constructed to investigate combustion processes of DME and diesel fuel. The combustion images were recorded with a high-speed video camera system. The results demonstrated that the DME-fuelled engine was superior to the conventional diesel engine in terms of engine performance and emissions. The optimal injection timing of DME was located around IDC(Top Dead Center), which was roughly same as that of diesel fuel. As the injection timing was advanced much earlier than TDC, NOx (Nitric Oxides) level increased considerably. NOx emission of DME was equal or a little higher than that for diesel fuel at the same injection pressure and timing because of higher evaporation characteristics of DME. Throughout all experimental conditions, DME did not produce any measurable smoke level.

• 한국자동차공학회논문집
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• 제18권6호
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• pp.145-151
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• 2010

The performance of a direct-injection diesel engine often depends on the strength of swirl or squish, the shape of combustion chamber, the number of nozzle holes, etc. This is natural because the combustion in the cylinder was affected by the mixture formation process. Since the available duration to make the mixture formation of air-fuel is very short, it is difficult to make complete mixture. Therefore, an early stage of combustion is violent, which leads to the weakness of noise and vibration. In this paper, the combustion process of a common-rail diesel engine was studied by employing two kinds of pistons. One has several grooves with inclined plane on the piston crown to generate swirl during the compression and expansion strokes in the cylinder in order to improve the atomization of fuel. The other is a toroidal piston, generally used in high speed diesel engines. To take photographs of flame and flaming duration, a four-stroke diesel engine was remodeled into a two-stroke visible single cylinder engine and a high speed video camera was used.

• 한국자동차공학회논문집
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• 제13권4호
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• pp.167-173
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• 2005

Thermal regeneration means burning-off and cleaning-up the particulate matters piled up in DPF(diesel particulate filter), and it requires both high temperature $(550\~600^{\circ}C)$ and appropriate concentration of oxygen at DPF entrance. However, it is not easy to satisfy such conditions because of the low temperature window of the HSDI(high speed direct injection) diesel engine(approximately $200\~350^{\circ}C$ at cycle). Therefore, this study is focused on the method to raise temperature using the trade-off relation between temperature, oxygen concentration, and the influence of many parameters of common rail injection system including post injection. After performing an optimal mapping of the common rail parameters for regeneration mode, the actual cleaning process during regeneration mode is investigated and evaluated the availability of the regeneration mode mapping through regenerating soot trapped in the DPF.

• 한국자동차공학회논문집
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• 제14권1호
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• pp.109-114
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• 2006

The reformed bio-diesel fuel irradiated by the ultrasonic wave is applied to the diesel engine of common rail in common use recently. This study has the object to examine the properties of engine performance and discharged materials. The bio-diesel fuel is mixed and used with the diesel fuel in common use at the ratio of $20\%\;or\; 100\%$. The ultrasonic energy is irradiated to the individually mixed fuel in order to reform the fuel. This fuel is applied to the engine in this experiment. And It is compared and analyzed from the experimental results with two cases irradiating the ultrasonic wave and no irradiating.

• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.225-230
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• 2003

The major purpose of this study is to find the optimized split injection quantities and dwell angles for PM reduction without increasing NOx. The tests were performed on a Common-Rail DI Diesel Engine to obtain optimum injection timing and duration. In this study, total injection quantities were divided into the ratio of 25-75%, 50-50% and 75-25%. NOx and PM were measured on the condition of the same bsfc by increasing dwell angles. It was found that the split injection reduced NOx with dwell angle increase. For 50_50, 75_25% split injection cases, PM was reduced with 10 to 12(CAD) dwell angles. For 25_75% split injection 33% PM reduction was achieved with 8 to 12(CAD) dwell angles.

• 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.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.9-15
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• 2004

The characteristics of combustion and emissions were investigated in a single cylinder DI diesel engine equipped with a common rail injection system. This study presents an experimental study of the effect of engine speed, injection timing, injection pressure and pilot injection timing on the combustion and exhaust emissions. The engine speeds were 1000 and 2000rpm and the corresponding injection pressures were 50 and 100MPa. Experimental results show that NOx emissions decrease with retarded injection timing, while HC and CO emissions increases. Higher injection pressure increases NOx with lower soot emissions. For the case with the pilot injection prior to main injection, the ignition delay is shortened and the premixed combustion ratio decreases. Also NOx and soot emissions are decreased with increase of pilot injection advance.

• Journal of Advanced Marine Engineering and Technology
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• 제33권2호
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• pp.252-258
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• 2009

Engine bench tests has been done on a common-rail diesel engine with bio-diesel fuel to study effects of B100 and B20 on output power, fuel consumption and emissions. Test results show that B100 and B20 could reduce PM, HC, CO emission and smoke, but power decrease, fuel consumption increase and NOx increase obviously, B100 reduce PM and DS with $50%{\sim}70%$ and $80%{\sim}85%$ compared with diesel fuel, while B20 reduce PM and DS with $25%{\sim}35%$ and $30%{\sim}40%$. NOx of B100 and B20 increase $5%{\sim}20%$ compare to diesel.