• Journal of ILASS-Korea
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• v.7 no.1
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• pp.1-6
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• 2002

This study has focused on using fuel injections as variables for measuring performance and reducing exhaust gas in turbo-charger diesel engine. In experiments, we changed nozzle hole diameter, diameter of an injection pipe, and injection timing as variable. The results show that torque. fuel consumption and smoke are reduced as nozzle hole diameter decreases, while NOx increases. When the diameter of injector is reduced, torque, fuel consumption and smoke are deteriorated, but NOx is decreased. In addition, when the time for injection is advanced. torque, fuel consumption and smoke are improved, but the density of NOx is increased.

• Journal of Power System Engineering
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• v.10 no.1
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• pp.5-11
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• 2006

During the SI engine starting up, starting conditions directly contribute to the harmful emissions in spark ignition engines. The effects of catalyst temperatures and fuel injection skip methods on HC emissions were investigated. The test was conducted on a 1.5L, 4-cylinder, 16 valve, multipoint-port-fuel-injection gasoline engine. To understand the formation of HC emissions, HC concentration was measured in an exhaust port using a Fast Response Flame Ionization Detector(FRFID). The result showed that HC emissions, which were generated during initial stage of the starting, could be reduced by coolant temperature and fuel injection skips. And through the vehicle test of ECE15+EUDC, it is convinced that the optimized fuel injection skip method according to coolant temperatures have favourable effects on the reduction of harmful exhaust emissions including HC during the SI engine start.

• Tribology and Lubricants
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• v.31 no.6
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• pp.245-250
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• 2015

This study investigates the lubrication characteristics of fuel injection pumps with reference to different fuel oils. Medium-speed diesel engines use fuel oils with various viscosities, such as heavy fuel oil (HFO, which is a high-viscosity fuel oil) and light diesel oil (LDO, which is a low-viscosity fuel oil). When fuel oil with a low viscosity is used, both fuel oil and lubricating oil lubricate the system. Thus, the lubrication of the fuel injection pump is in a multi-viscosity condition when the fuel oil in use changes. We suggest three cases of multi-viscosity models, and divide the fuel injection pump into three lubrication sections: a, the new oil section; b, the mixed oil section; and c, the used oil section. This study compares the lubrication characteristics with variation of the multi-viscosity model, clearance. The volume of Section b does not affect the lubrication characteristics. The lubrication characteristics of the fuel injection pump are poor when high-viscosity fuel oil transfers to low-viscosity fuel oil. This occurs because the viscosity in the new oil section (i.e., Section a) dominates the lubrication characteristics of the fuel injection pump. However, the lubricant oil supply in the used oil section (i.e., Section c) can improve the lubrication characteristics in this condition. Moreover, the clearances of the stem and head significantly influence the lubrication characteristics when the fuel oil changes.

• Journal of Power System Engineering
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• v.15 no.5
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• pp.10-15
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• 2011

This paper describes the engine performance and combustion characteristics of a CRDI diesel engine, operated by electronically controlled diesel fuel injector with variable injection timing. This experiment focused on fuel injection timing and pressure about combustion characteristics of CRDI diesel engine. EGR was excepted because it would be furtherly analyzed with additional experiments. The experiment was conducted under the circumstance of engine torque for 4, 8, 12 and 16 kgf-m and fuel injection timing for $15^{\circ}$, $10^{\circ}$ and $5^{\circ}$ BTDC, at the engine speed of 1100, 1400, 1700 and 2000 rpm. Fuel injection was controlled to retard or advance initiation of the injection event by electronically controlled fuel injection unit injector on the personal computer. When fuel was injected into the cylinders of a CRDI diesel engine it would go through ignition delay before starting of combustion. Therefore, fuel injection timing of CRDI diesel engine had a significant effect upon performance and combustion characteristics. Depending on the injection timing the fuel consumption rate following the rotational speed and torque was 3~78 g/psh (1.7~30.6%). The range of fuel injection timing that resulted in low fuel consumption overall was BTDC 15-10 degrees.

• Journal of ILASS-Korea
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• v.23 no.1
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• pp.36-41
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• 2018

Fuel wall film effects power output and cycle deviation by changing the amount of fuel flowing into cylinder in PFI gasoline engines. Reduction of wall film can reduce fuel consumption and improve combustion stability. In this research, the effects of injection strategies including injection pressure and dual injection system is investigated for reducing wall film formation. The CONVERGE software is used for numerical analysis tool and O'Rourke film splash model was used for wall film prediction model. Compared with the reference case wall film decreased with increase of injection pressures, and the film formation reduced when the dual injection system was used.

• Journal of Power System Engineering
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• v.11 no.4
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• pp.26-31
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• 2007

Recently, study on the improvement of combustion performance for the diesel engine by using the impinging spray in the combustion chamber has been actively studied. The purpose of this study is to examine the variation of exhaust emission between the trial engine with impinging plate and the prototype engine in accordance with change of fuel injection timing and fuel injection pressure. The concentration of nitrogen oxide of trial engine decreased more than 50% compared to prototype engine. However, smoke of trial engine indicated very high concentration compared to prototype engine. The effect of fuel injection timing on the nitrogen oxide and smoke indicated different results, that is, the concentration of nitrogen oxide decreased as the degree of fuel injection start become slower, whereas the concentration of smoke decreased as the degree of fuel injection start become faster.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.4
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• pp.444-453
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• 2015

In the previous study, several problems were observed in a NG conversion vehicle, which were fail of air-fuel ratio closed loop control, aggravated fuel economy, increased harmful emission and declined roadability. It was provisionally supposed that the mismatch of injection system with the engine caused these performance deterioration. In this context, the characteristics of fuel injection system of commercial conversion kit for NG were investigated experimentally varying the engine speed, fuel rail pressure and volume. The results are as follows; The injection quantity decreases as the engine speed increases due to the extremely small rail volume of the presenting system and flow rate of No. 2 injector are always lower than that of the other ones regardless of the speed under the dynamic operation condition. Furthermore the existing system does not meet the required fuel quantity for the normal engine operation over 3000 RPM. On the other hands, the large rail volume systems ease and/or eliminate the difference of injection quantity between the injectors according to the speed variation, however, these systems decrease injection flow rate and still cannot supply sufficient fuel. Finally, suitable combination of the higher rail pressure and the larger rail volume might be a solution about these problems.

• Journal of ILASS-Korea
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• v.2 no.1
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• pp.29-35
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• 1997

Many technologies have been developed to improve diesel emissions or performance, however NOx/PM trade-off occurs because normal methods that reduce NOx emissions tend to increase PM emissions. On the other hand many measures used to control PM emissions tend to increase NOx emissions. Thus, simultaneously controlling both NOx and PM emissions has become a significant challenge for diesel engine manufacturers. As one of the measures, the technology using emulsified fuel has recently become important under the stringent emission regulations of diesel engines. This paper investigates injection characteristics of emulsified fuel and its effect on a combustion performance in a diesel engine. In order to supply emulsified fuel into injection system a mixing unit produced by Harrier is used, then the fuel mixed with water is supplied into injector directly. The spray injected is investigated with a shadowgraph photo system and injection analyzing apparatus, then applied into a diesel engine. Those results showed that the emulsified fuel has an effect on reducing both NOx and PM.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.1-5
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• 2008

An experimental study was performed to develop the rotational fuel injection system of the micro turbojet engine. In this system, fuel is sprayed by centrifugal forces of engine shaft. The test rig was designed and manufactured to get droplet information on combustion space. This experimental apparatus consist of a high speed rotational device(Air-Spindle), fuel feeder, rotational fuel injector and acrylic case. To understand spray characteristics, spray droplet size, velocity and distribution were measured by PDPA (Phase Doppler Particle Analyzer) and spray was visualized by using Nd-Yag laser-based flash photography. From the test results, the length of liquid column from injection orifice is controlled by the rotational speeds and Sauter Mean Diameter(SMD) is decreased with rotational speed. Also, Sauter Mean Diameter is increased as increasing mass flow rate at same rotational speeds.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.89-95
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• 2013

In this work, the evaluation of swirl nozzle injector performance was conducted by investigating effective area ($A_{eff}$), injection mass ($m_{inj}$), injection rate ($Q_{inj}$), and injection delay ($t_{delay}$) under various test conditions. To achieve these, fuel injection analysis system which was composed of fuel supply system, injection system, and control system was installed. At the same time, the swirl nozzle that had 12 orifice hole with $120^{\circ}$ injection angle was used in this work. It was revealed that the difference of injection mass ($m_{inj}$) between base and swirl nozzle injector increased as the injection pressure ($P_{inj}$) and energizing duration ($t_{eng}$) decreased under the same test conditions. The maximum injection rate ($Q_{inj}$) of swirl nozzle injector was higher than base nozzle injector about 2~5%. The injection performance of swirl nozzle was better than base nozzle at low injection pressure ($P_{inj}$) and short energizing duration ($t_{eng}$) conditions.