• Journal of the Korean Society of Industry Convergence
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• v.19 no.1
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• pp.31-38
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• 2016

Since the oil shock of 1970's there was a strong upward tendency for the use of the high viscosity and poorer quality fuels. Therefore the misfiring engine occurs due to the decrease of quantity injected for lean burn and emission control in Compression Ignition Common Rail Direct Injection diesel engine. In this study, it is designed and used the test bed which is installed with fuel injector controller. In addition to equipped engine using CRDI by controlling the injection timing with mapping modulator, it has tested and analyzed the engine performance and combustion characteristics, as it is varied that they are the operating parameters: fuel injected quantity, engine speed and injection timing.

• 한국연소학회:학술대회논문집
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• 2002.06a
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• pp.33-38
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• 2002

An optical single cylinder diesel engine equipped with a common-rail injection system has been built to investigate diesel combustion and emission characteristics. Three optical widows (piston crown quartz for bottom view of the cylinder, upper piston quartz for allowing laser sheet and liner quartz for side view) have been placed in the optical engine to visualize spray characteristics and combustion process inside the cylinder. Before doing further research using various optical diagnostics with the optical engine, fundamental combustion experiments and flame visualization incorporating a high speed motion analyser have been carried out with a wide range of engine operating conditions.

• Journal of the Korean Society of Combustion
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• v.15 no.1
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• pp.1-11
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• 2010

In this study, the coupled simulation of fuel injection model and three-dimensional KIVA-3V code was tried to develop an algorism for predicting the effects of varying fuel injection parameter on the characteristics of fuel injection and emissions. The numerical simulations were performed using STAR-CD code in order to calculate the intake air flow, and the combustion characteristics is examined by KIVA-3V code linked with the conditional moment closure(CMC) model to predict mean turbulent reaction rate. Parametric investigation with respect to twelve relevant injection parameters shows that appropriate modification of control chamber orifice diameter, needle valve spring constant and nozzle chamber orifice diameter can significantly reduce NOx and soot emissions. Consequently, it is needed to optimize the fuel injection system to reduce the specific emissions such as NOx and soot.

• Journal of ILASS-Korea
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• v.12 no.1
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• pp.30-37
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• 2007

Dimethyl ether (DME) as an alternative fuel for compression ignition engine was investigated by measuring spray development processes, injection rate profiles, engine performance, and exhaust emission characteristics. The results of DME fueled engine were compared with those obtained by fueled with diesel. The experimental results showed that DME has approximately 0.03ms shorter injection delay and higher maximum injection rate than those of diesel fuel at a constant injection pressure of 50MPa. The spray visualization indicates that DME has shorter spray tip penetration due to its low density and faster evaporation. The combustion characteristics of DME operated engine provided faster ignition delay and three times shorter combustion duration. It is believed that the better evaporation and atomization characteristic of DME contributes the faster combustion. At all operating condition, soot emission was not detected due to the clean combustion of DME.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.137-140
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• 2001

This paper shows an asynchronous comparator circuit for 1.2Gbps signal receiver that converts 1.2Gbps data rate input signals with less than 100㎷ swing to on-chip CMOS compatible voltage levels in a 0.35${\mu}{\textrm}{m}$ CMOS process. Folded-cascode nMOS input stage with source-coupled pMOS input stage cover rail-to-rail input common-mode range. Drastic gain-bandwidth increment due to gain-boosting stage with positive-feedback latch as well as wide input common-mode range make designed circuit be suitable for a fully differential signal receiver. HSPICE simulation results show that worst-case sensitivity is less than 20㎷ and maximum propagation delay is 640-psec. And also we verified 3.97㎽ power consumption with 150㎷ differential swing amplitude at 1.2Gbps.

• Journal of ILASS-Korea
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• v.9 no.1
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• pp.1-7
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• 2004

This paper describes the characteristics of injection rate and macroscopic behavior of fuel spray injected from common-rail type diesel injectors with different nozzle geometries. The injection rates according to the nozzle geometries were measured at different energizing duration of the injector solenoid and injection pressure by using the Bosch's injection rate meter based on the pressure variation in the tube. The spray behaviors injected from the different nozzles were visualized using the spray visualization system composed of an Ar-ion laser, an ICCD camera, and a synchronization system at various injection and ambient pressures. It is revealed that VCO nozzle has higher spray tip velocity at the early stage of injection duration and wider spray cone angle than the mini-sac nozzles. Also the spray cone angle is increased with the increase of nozzle diameter.

• Journal of Biosystems Engineering
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• v.32 no.2 s.121
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• pp.97-101
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• 2007

A CRDI diesel engine used to commercial vehicle was fueled with diesel fuel and 5% biodiesel blended fuel (BDF 5%) and tested at the Seoul-10 mode for 150 hours. Engine dynamometer testing was completed at regularly scheduled intervals to monitor the engine performance and exhaust emissions. To check the engine parts (valve, injector), the engine was inspected after 150 hours running test. It was concluded that there was no unusual deterioration of the engine, or the changes in engine power (below 2.6%), smoke (below 6.2%), NOx (below 2%) and durability characteristics in spite of operation of 150 hours run with BDF 5%. The difference of kinetic viscosity for engine oil (before and after durability testing) was below 0.36%

• Journal of ILASS-Korea
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• v.7 no.3
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• pp.18-23
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• 2002

An evaporating diesel spray of a common rail lnjector was visualized by LIEF technique. This technique makes it possible to separate the vapor and liquid phase images. The experiment was conducted in a constant volume vessel to make a high temperature and high pressure condition. Three images(vapor and liquid phase images from LIEF and a liquid phase image from Mie scattering) were taken simultaneously in one spray event. The major experimental parameters are the injection pressure and the ambient gas pressure. Also, a relative SMD distribution in a liquid phase was obtained by the ratio of the intensities of the fluorescence and the Mie scattering. The results show that the injection pressure and the ambient gas pressure have a close relation with the spray development and air-fuel muting process.

• Journal of ILASS-Korea
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• v.8 no.4
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• pp.31-38
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• 2003

Constant volume combustion chamber has been designed to investigate diesel spray characteristics with Common-Rail injection system to realize high pressure injection. In this study, two methods of measurements, Schlieren shadowgraphy and Mie scattering imaging method ate applied experimentally to study spray form and liquid phase zone in high pressure, high temperature conditions. Diesel fuel is injected at the point which ignited mixture gas is completely burned. The effect of injection pressure, injector hole diameter, ambient gas temperature and density are investigated experimentally.

• Journal of ILASS-Korea
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• v.12 no.3
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• pp.166-171
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• 2007

Recently, many studies on HSDI diesel engines have been performed to reduce the fuel consumption and $CO_2$ emission. One of the prominent technique to reduce emission is a high pressure multiple injection. For this technique, the injection rate is a critical parameter in order to determine precise injection duration and timing for combustion control. Thus the purpose of this study was to investigate relationship between the injection rate and the time-signature of chamber pressure at different injection pressure conditions in a common rail direct injection type injector using the Zeuch method. Using the measured correlation constants, estimated fuel injection rates are presented at many different injection conditions.