• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.100-106
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• 2012

This is a thesis about the experiment of comparison characteristic of power and exhaust gas in the same condition between diesel engine that is equipped turbocharger to increase effectiveness of the engine which is recently used in a lot of industry which requires high power. Resulting of the experiment with natural aspiration diesel engine and turbocharger diesel engine, difference in low speed is not significant, but in high speed, effectiveness of turbocharger diesel engine is much higher than the other one. In other hand, in exhaust gas experiment, turbocharger model exhausts more NOX and $O_2$, but it doesn't significantly affect the result when it comes with decreasing of $CO_2$ and effectiveness of increased power characteristic. As a result, the turbocharger diesel engine is economically effective comparing with the natural aspiration diesel engine.

• Journal of Power System Engineering
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• v.2 no.2
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• pp.27-34
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• 1998

The purpose of this study is to investigate the performance of swirl combustion chamber diesel engine by changing the jet passage area and its angle, the depth and shape of the piston top cavity(main chamber). The performance of diesel engine with newly changed swirl combustion chamber was tested through the experimental conditions as engine speed, load and injection timing etc. The test results were compared and analyzed. The rate of fuel consumption was affected significantly by the jet passage area at the high speed and load, by the depth of the piston top cavity at the low speed and load. The exhaust smoke density and exhaust gas temperature depended sensitively on variation of the injection timing rather than the shape of the combustion chamber within the experimental conditions.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.5
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• pp.565-572
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• 2002

The design concept of diesel engines for sea-going ships has been directed to Low-speed/Long-Stroke type to improve the efficiencies of combustion and propelling. But time-delay inevitable at low speed gives much difficulties for governors to control the engine speed because they would be apt to go into unstable region especially when operating at low speed. The purpose of this paper is to study the problem of how the governor gain can be calculated dynamically in accordance with the valiance of engine speed to locate the engine still on the properly stable condition. In this study, the property of diesel engine was described as composed of combustion element including dead time and rotating element, and the ultimate gain for the speed control system to be located on the condition of stability limit was proposed based on the frequency characteristics. And the target gains with optimized stability also were proposed by giving proper margin to these ultimate conditions. The results were applied to a model system and the availability was confirmed to be satisfactory.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.786-791
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• 2006

Two stroke low speed diesel engines are mainly used for marine propulsion or power plant prime mover. These have many merits such as higher thermal efficiency, mobility and durability. However various annoying vibrations sometimes occur in ships or at the plant itself. Of these vibrations, torsional vibration is very important and it should be carefully investigated during the initial design stage for engine's safe operation. In this paper authors suggest a new estimation method of for shaft's can be calculated equivalently from accumulated fatigue cycles number due to torsional vibration. The 6S70MC-C($25,320ps{\times}91rpm$) engine for ship propulsion was selected as a case study, and the accumulated fatigue cycles numbers for shafting life time converted from the measured angular velocity and torsional vibration stress was calculated. This new method can be realized and confirmed in test model ship with two stroke low speed diesel engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.120-127
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• 2014

Robustness and controllability are the key factors in internal combustion engine commercialization. This study focuses on the combustion strategy to commercialize the low temperature diesel combustion technology. Various LTC combustion methods such as PPCI, MK and highly diluted mixing controlled LTC were conducted on 6.0L heavy duty diesel engine. To find the best feasible LTC strategy, emission level, fuel consumption and combustion safety during the combustion mode change were considered. Experiments were carried out under various engine operating conditions; engine speed & load, EGR level, injection timing. Finally, this study suggests realizable LTC combustion strategy; moderate EGR level and slight early injection are possible to considerably lower PM, NOx emission and expand LTC operating range up to 50% load without CO and HC emission.

• Journal of Korean Society for Atmospheric Environment
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• v.1 no.1
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• pp.83-92
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• 1985

In odrder to survey the emission level of air pollutants from diesel vehicles, was measured CO, HC, NOx and smoke of 4 types of domestic-use diesel engines under various conditions. The emission of CO, HC and NOx tested by 6-Mode test method and smoke emission by full load test met the permissible vehicle emission standard. Pollutant emission rates of diesel engines were different according to engine operating conditions, that is, engine load and engine speed. Generally, CO and HC was emitted more at low load and NOx at high load but the trend was quite different by the type of engines. In exhaust gas, $NO_2$ portion of NOx emission was high, specially at low speed and low load. The correlation equation between CLD(NOx) and NDIR(NO) method of nitrogen of nitrogen oxides analysis was y = 1.10x - 3.48 (y: CLD method) as a result of 6-mode test.

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.395-402
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• 2007

Homogeneous Charge Compression Ignition (HCCI) shows great potential for low $NO_x$ emission but is hampered by the problem of no direct method to control the combustion process. Therefore, HCCI combustion becomes unstable easily, especially at lower and higher engine load. This paper presents a method to achieve diesel-fueled HCCI combustion, which involves directly injecting diesel fuel into the cylinder before the piston arrives at top dead center in the exhaust stroke and adjusting the valve overlap duration to trap more high temperature residual gas in the cylinder. The combustion stability of diesel-fueled HCCI combustion and the effects of engine load, speed, and valve overlap on it are the main points of investigation. The results show that: diesel-fueled HCCI combustion has two-stage heat release rate (low temperature and high temperature heat release) and very low $NO_x$ emission, combustion stability of the HCCI engine is worse at lower load because of misfire and at higher load because of knock, the increase in engine speed aids combustion stability at lower load because the heat loss is reduced, and increasing negative valve overlap can increase in-cylinder temperature which aids combustion stability at lower load but harms it at higher load.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.8
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• pp.827-836
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• 2006

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.47-56
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• 2001

Nitrogen oxides(NOx) and smoke emissions of diesel engine are regarded as a source of air pollution, and there is a global trend to enforce more stringent regulations on these exhaust gas emissions. However, the trade-off relation of NOx and smoke is a main obstacle to reduce both of them simultaneously. In this paper, experiments were conducted with an oxygenated fuel(diethyl ether) as an effective way to improve the trade-off relation of NOx and smoke. Exhaust emissions of diesel fuels with DEE were influenced by the additive content of DEE and the injection timing. Especially, DEE effected more at the high engine speed and load than at the low engine speed and load. Diesel fuel blended with DEE 10% was a desirable blend for the simultaneous reduction of NOx and smoke.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.376-381
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• 2009

The increasing needs for higher cargo capacity in the container vessels' fleet has led to ship builder's demand for higher power output rating engine to meet the propulsion requirement, thus, leading to the development of super large two stroke low speed diesel engines. This large sized bore engines with more than 12 cylinders are capable of delivering power output up to more than 100,000 bhp at maximum continuous rating. The thrust variation force due to axial vibration occurring in propulsion shafting of these ships are transmitted to ship structure via thrust bearing. This force may vibrate the super structure of ship in the fore-aft direction and the fatigue strength of crank shaft can be decreased by additional bending stress increase in crank shaft pin and journal. In this paper, the axial vibration of propulsion shafting system on the 14RT-flex96C super large diesel engine with 14 cylinders is identified by theoretical analysis and vibration measurement.