• Journal of ILASS-Korea
• /
• v.16 no.3
• /
• pp.134-139
• /
• 2011

Recent research has focused on engine combustion technology as well as application of after-treatment in order to comply with emission regulation. However, it is much more efficient way to control emissions from engine itself and furthermore research on engine control will provide the direction of after-treatment technology in future. Furthermore, emission standard regulation for passenger diesel vehicles has been stringent compared to others and nano-particles will be included in EURO6 regulation in Europe and similar emission standard will be introduced in Korea. A 3.0 liter high speed diesel engine equipped with by CRDI system of 160MPa injection pressure, and an intake/exhaust system of V type 6 cylinder turbo-intercooler was applied. The injection duration and injection quantity, pilot injection types which are related to CRDI and air/fuel ratio control applied by EVGT were changed simultaneously. Standard experiment procedure constituted dilution apparatus and CPC system to collect nano-particles and these test results were compared with regulated materials of CO, HC, NOx and investigated their relations and characteristics of nano-particles.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2006.06a
• /
• pp.67-68
• /
• 2006

This study suggests a precision flow control system that enables fluid injection of a few grams at a time in a few ms time duration. The fluid injection system suggested here consists of a high pressure fluid pump, a 3 way 3 position directional control valve, an injector and an orifice. The orifice is located between the directional control valve and the injector. By supplying current signal to the directional control valve, the prescribed small amount of fluid can be supplied to a plant through the injector. The control robustness of the suggested system against the disturbances like the pressure change in a plant and the viscosity variation of the injected fluid is secured easily by using an orifice with very small inside diameter and setting the supply pressure with comparatively high value. The control performances of the suggested system are verified by numerical simulations and experiments. The outcomes of this research could be applied to the common rail injection control of lubrication oil for large size marine diesel engines, and other industrial plants.

• Journal of Power System Engineering
• /
• v.17 no.6
• /
• pp.18-24
• /
• 2013

An experimental study was performed to investigate the characteristics of combustion pressure and exhaust emissions when the pilot injection timing and EGR rate were changed in a CRDI 4-cylinder diesel engine. The pilot injection timing and EGR rate have a significant impact on the combustion and emission characteristics of diesel engine. In this study, the pilot injection timing and EGR rate variation were conducted to 2000rpm of engine speed with torque 50Nm. Combustion pressure and heat release rate were decreased under high EGR rate conditions but increased under the pilot injection timing $20^{\circ}$(BTDC). IMEP and the maximum pressure in cylinder(Pmax) were decreased under the same injection timing with the increase of EGR rate. The NOx emission was decreased with increasing the EGR rate. On the other hand, in the same injection timing conditions, CO, HC, $CO_2$ emissions were increased with increasing the EGR rate.

• Journal of ILASS-Korea
• /
• v.14 no.3
• /
• pp.109-116
• /
• 2009

The purpose of this study is the experimental and numerical investigation on the DME spray characteristics in the combustion chamber according to the injection timing in a common-rail injection system. The visualization system consisted of the high speed camera with metal halide lamp was used for analyzing the spray characteristics such as spray development processes and the spray tip penetration in the free and in-cylinder spray under various ambient pressure. In order to observe the spray characteristics as a function of injection timing, the piston head shape of re-entrant type was created and the fuel injected into the chamber according to various distance between nozzle tip and piston wall in consideration of injection timing. Also, the spray and evaporation characteristics in the cylinder was calculated by using KlVA-3V code for simulating spray development process and spray tip penetration under real engine conditions. It was revealed that the high ambient pressure of 3 MPa was led to delay the spray development and evaporation of DME spray. In addition, injected sprays after BTDC 20 degrees entered the bowl region and the spray at the BTDC 30 degrees was divided into two regions. In the calculated results, the liquefied spray tip penetration and fuel evaporation were shorter and more increased as the injection timing was retarded, respectively.

• Journal of the Korean Society of Combustion
• /
• v.15 no.4
• /
• pp.53-57
• /
• 2010

The purpose of the present work is to investigate the effect of gasoline-premixing on a combustion and emissions characteristics in a compression ignition engine. For studying combustion characteristics, a combustion pressure and rate of heat release (ROHR) were measured using a single-cylinder DI compression ignition engine with a common-rail injection system and premixed fuel injection system. In addition, exhaust emissions characteristics were studied using emission analyzers and smoke meter. The experimental results showed that the case of gasoline-premixing had longer ignition delay and lower combustion pressure compared to the cases of diesel direct injection. Furthermore, premixed gasoline-air mixture reduced NOx emissions due to low peak of ROHR.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.5
• /
• pp.84-91
• /
• 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.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.12
• /
• pp.1489-1495
• /
• 2013

High-pressure flows are ubiquitous in many industrial fields. A representative application is fuel injection using a common-rail control system in diesel engines, where the injection pressure in the injector exceeds 1000 bar. In high-speed injection, the fluid injected through the nozzle undergoes breakup owing to the interaction with the ambient gas. The breakup process influences mixture formation, which in turn influences combustion in diesel engines. Therefore, it is very important to analyze the breakup process of fuel spray. The Reitz and Diwakar model and cascade atomization and breakup (CAB) model were used in this study as sub-models for the numerical analysis of the breakup process of fuel spray. This study aims to precisely analyze the breakup process of spray and to investigate the breakup frequency of the injected fuel. Consequently, it proposes a suitable sub-model for analyzing the breakup process of a diesel spray by using CFX, a commercial CFD program.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.2
• /
• pp.54-62
• /
• 2009

The purpose of this study is to develop a piezo injector driver for common-rail direct injection diesel engines. In this research, we analyzed the electrical and mechanical characteristics of the piezo actuator through experiments. Current flow and charging voltage of the piezo injector are controlled by the PWM signal of variable duty ratio in order to realize both fast response and low peak current. The optimal switching duty ratio was designed by modeling and analyzing of the piezo driver circuit. In order to avoid resonance and unacceptably long settling time, appropriate frequency range of the PWM signal was derived based on the driver circuit model. The developed injector driver was validated by experiments under various fuel rail pressure, injection duration, and charging voltage.

• Journal of Power System Engineering
• /
• v.18 no.5
• /
• pp.156-163
• /
• 2014

Diesel engine is most suitable one for biodiesel fuel because the compression-ignition diesel engine has desirable fuel consumption due to higher thermal efficiency and in addition, the improvement of the fuel consumption also leads to a reduction of $CO_2$ emission and then it does not need to have spark-ignition system, which means that there is less charge on the technic and complexity. In this study, the spray behavior characteristics of the vegetable palm oil were analyzed by using a common-rail injection system of commercial diesel engine and the results were compared with those obtained for the diesel fuel. The injection pressures and blend ratios of palm oil and diesel(BD3, BD5, BD20, BD30, BD50, and BD100) were the main parameters. The experiments were conducted for different injection pressures: 500bar, 1000bar, 1500bar, and 1600bar by setting injection duration to $500{\mu}s$. Consequently, it was found that there is no significant difference in the macro characteristics of the spray behavior(spray penetration and spray angle) in response to change in the blend ratio of palm oil and diesel at a fixed injection pressure. In particular, all experiments showed the spray angle about $12^{\circ}{\sim}13^{\circ}$.

• 한국연소학회:학술대회논문집
• /
• 2004.11a
• /
• pp.146-151
• /
• 2004

The characteristics of combustion and emission of biodiesel fuel were investigated in a single cylinder DI diesel engine equipped with a common rail injection system. For investigating the effect of bio diesels, the experiments were conducted at various mixing ratio and engine operation conditions. Experimental results show that combustion pressure increased with the increase of mixing ratio and injection pressure. The HC and CO emissions are decreased and NOx emission is increased as the mixing ratio of biodiesels increases at 100MPa injection pressure. However the results of the emissions are shown the contrary to the results at 50MPa of injection pressure due to larger droplets of biodiesel sprays.