• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.2
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• pp.137-143
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• 2012

Currently, in order to meet the reinforced emissions regulations for harmful exhaust gas including carbon dioxide ($CO_2$) as a greenhouse gas, technologies for reducing $CO_2$ emission and fuel consumption are being developed. Gasoline direct injection (GDI) systems have the advantage of improved fuel economy and higher power output than port fuel injection gasoline engine systems. The aim of this study is to examine the performance and emission characteristics of a lean burn GDI engine equipped with spray-guided-type combustion system. Stable lean combustion was achieved with a late fuel injection strategy under a constant operating condition. Further improvement in specific fuel consumption is possible with the introduction of multiple fuel injection strategies, which also increases hydrocarbon (HC) and nitrogen oxide ($NO_x$) emissions and decreases carbon monoxide (CO) emission.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.2
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• pp.105-113
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• 2017

Recently the direct injection diesel engine is the most efficient one available for road vehicles, so this fundamental advantage suggests the compression injection diesel engine are a wise choice for future development efforts. The compression ignition diesel engine, with its bigger compression ratios if compared to the SI engine, offers a higher thermodynamic efficiency, also additionally the diesel engine with its less pumping losses due to the throttled intake charge as in a SI engine has higher fuel economy. But the largest obstacle to the success of this engine is meeting emission standards for Nitric oxides and particulate matter while maintain fuel consumption advantage over currently available engines. Thus its use should be largely promoted, however, diesel engine emits more Nitric oxides and particulate matter than other competing one. There has been a trade-off between PM and NOx, so efforts to reduce NOx have increased PM and vice versa, but trap change this situation and better possibility emerge for treating NOx emission with engine related means, such as injection timing, equivalence ratio, charge composition, and engine speed. The common rail direct injection system is able to adjust the fuel injection timing in a compression ignition engine, so this electronically controlled injection system can reduce the formation of NOx gas without increase in soot. In this study it is designed and used the engine test bed which is installed with turbocharge and intercooler. In addition to equipped using CRDI by controlling injection timing with mapping modulator, it has been tested and analyzed the engine performance, combustion characteristics, and exhaust emission as operating parameters.

• Journal of ILASS-Korea
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• v.21 no.1
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• pp.20-28
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• 2016

This paper presents an experimental study on the GDI injector with Bosch method. The injection characteristics, such as the injection quantity, the injection rate, the maximum velocity of the nozzle exit and the injection delay were studied through the change of the injection pressure, the tube pressure and energizing duration in injection rate measurement device using nheptane. The injection quantity is increased by increasing injection pressure, decreasing tube pressure or increasing energizing duration. As the difference of the injection quantity changed, the shape of injection rate was moved with a constant form. The maximum velocity of the nozzle exit showed a tendency to increase as the injection pressure is increased. However, tube pressure did not affect. Overall, it was confirmed that the closing delay is longer than the opening delay in all conditions. As the injection pressure increased, the result has a tendency to decrease the closing delay, it did not affect the opening delay. Reduction of the closing delay showed the reduction of the injection duration. the tube pressure and energizing duration did not affect the injection delay (opening delay, closing delay).

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.4
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• pp.55-62
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• 2009

As an experiment investigation, the effects of ethanol blended gasoline fuel with different injection method on nano-sized particle emission characteristics were examined in a 0.5L spark-ignited single-cylinder engine with a compression ratio of 10. Because this engine nano-particles are currently attracting interest due to its adverse health effects and their impact on the environments. So a pure gasoline and an ethanol blended gasoline fuels, namely E85 fuel, used for this study. And, as a particle measuring instrument, a fast-response particle spectrometer (DMS 500) with heated sample line was used for continuous measurement of the particle size and number distribution in the size range of 5 to 1000nm (aerodynamic diameter). As this research results, we found that the effect of ethanol blending gasoline caused drastic decrease of nano-particle emissions when port fuel injection was used for making better air-fuel mixture than direct fuel injection. Also injection timing, specially direct fuel injection, could be a dominant factor in controlling the exhaust particle emissions.

• Journal of ILASS-Korea
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• v.12 no.4
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• pp.211-219
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• 2007

The liquid film thickness inside a pressure-swirl nozzle was measured, and then the measured liquid film thickness was compared with the results from previous empirical equations. The liquid film inside the nozzle was visualized using extended transparent nozzles and a microscopic imaging system, and then the measurement error was evaluated using optical geometry analysis. The high injection pressures up to 7MPa were adopted to simulate the injection conditions of the direct-injection spark-ignition engines. The totally different two injectors with different fuels, nozzle lengths, nozzle diameters and swirlers were utilized to obtain the comprehensive equations. The results showed that the liquid film thickness very slightly decreased at high injection pressures and the empirical equations overestimated the effect of injection pressure. Most of empirical equations did not include the effect of nozzle length and swirler angle, although it caused significant change in liquid film thickness. A new empirical equation was suggested based on the experimental results with the effects of fuel properties, injection pressure, nozzle diameter, nozzle length and swirler angle.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.32-42
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• 1998

Lean burn gasoline engine is recognized as a promising way to meet better fuel economy. Lean burn engine is classified into port injection and direct injection(DI), DI is more active technique for improving fuel economy with ultra-lean operation, Nowadays, port injected lean burn engine has been produced by many Japan maker. Also, DI engine is also possible for production owing to improvement in control technique of spray, flow air fuel ratio. DI engine uses either homogeneous stoichiometric mixture or stratified mixture by controlling injection timing to be early or late respectively. HM(homogeneous mixture) is worse than SM(stratified mixture) in view of ultra-lean operation in partical load and Nox reducion by using EGR control. But, HM has advanteges in cold starting and emission reduction during transient operation, This paper describes experimental variables and bench test results of HM GDI engine.

• Journal of Mechanical Science and Technology
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• v.18 no.4
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• pp.597-605
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• 2004

Turbulent temperature field in a channel subject to strong wall injection has been investigated via direct numerical simulation technique. These flows are pertinent to internal flows inside hybrid rocket motors. A simplified model problem where a regression process at the propellant surface is idealized by wall injection has been investigated to understand how the temperature field is modified. The effect of strong wall injection displaces thermal boundary layer away from the wall and this causes a sharp drop of friction temperature. Turbulent diffusivity and dissipation time scale for temperature field are found to show large variations in the streamwise direction under application of wall blowing. It is, thus, expected that more sophisticated turbulence models would be required to predict the disturbed temperature field accurately.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.4
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• pp.46-57
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• 1996

The direct injection stratified charge(DISC) engine enhances the fuel tolerance and the antiknock tendency. This enhanc3d antiknock tendency allows use of a higher compression ratio which results in higher thermal efficiency. But its actual utilization is prevented by high emission combustion time and wall quenching will be the main causes of increasing unburned hydrocarbons in DISC system. In order to solve this problem, small aount of hydrogen was added to the charging air or injected fuel. The effects of hydrogen addition were examined experimentally by radial fuel injection using a pancake-type constant volume bomb. In case of the hydrogen addition to the charge of air, the combustion the amount of hydrogen. In case of the hydrogen addition to the fuel, the combustion pressure was significantly increased.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.500-510
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• 1996

A Direct injection -mixing total -flow -control sprayer was developed and evaluated . The system provided precise application rates and minimized operator exposure to chemicals as well as providing a possibility for recycling container so f unused chemicals that can causes environmental contamination. Chemicals were metered and injected proportionally to the diluent flow rate to provide constant concentrations. The main diluent flow was varied in response to changes in travel speed. Experimental variables of the sprayer were the control interval, the sensitivity of flow regulating valve, the tolerance of control object and the sensitivity of the injection pump system. The optimal performance of the flow control system was with an average response time of 8.5 sec at an absolute steady state of error of 0.067 L/min (0.8% of flow rate). The average response time of the injection rate was -0.53 sec and the coefficient of variation (CV) of concentration was 3.2%.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.8
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• pp.1101-1110
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• 1998

Computational investigation was conducted to examine the performance of a high pressure common-rail fuel injection system which is used to power a passenger car direct injection (Dl) diesel engine. The pipe flows were modeled by one dimensional wave equation and solved by implicit FDM Each volume of injector was considered as chambers with orifice nozzle in connections. These simulation results were compared with the experimental data of Ganser Hydromag. The comparison of needle life and rate of injection between simulation data and experimental data showed quite a good agreement Different shape of injection rate can be made by adjusting the size of inlet orifice and exit orifice in the piston chamber The pilot injection was accomplished by adjusting command signal.