• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.756-761
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• 2016

The objective of this study is to design and manufacture a fuel pump with the plunger diameter of 4 mm and stroke of 7 mm that can be mounted in a small single-cylinder four-stroke agricultural diesel engine, and to investigate the performance characteristics of the pump. The combustion pressure in a cylinder was reproduced by forming the back pressure of 1, 6, 11, 16 and 21 bar with a nitrogen gas in the home-manufactured modeling cylinder. In the experiment, the discharge pressure was measured at the spot of 1 cm away from the discharge port of a developed fuel pump. The delivery pressure and delivery flow rate were measured at the spot of 30 cm away from the discharge port of the pump, and the pump efficiency was calculated. The pump motor speed was changed from 600 to 800, 1000, 1200 and 1400 rpm. It is found that the delivery feed rate of fuel pump is increased as the rotational speed is raised, and is decreased as the back pressure, compression pressure in the cylinder, is increased. Also, the pump efficiency is reduced as the rotational speed and back pressure are increased.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.9
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• pp.1185-1194
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• 2000

The characteristics of intake port flow and engine performance with swirl ratio variance in a turbocharged D.I. diesel engine were studied in this paper. The intake port flow is important factor which have influence on the engine performance and exhaust emission because the properties in the injected fuel depend on the combustion characteristics. Through these experiments it can be expected to satisfy performance and emission by optimizing the main parameters; the swirl ratio of intake port, injection timing and compression ratio. The swirl ratio for ports was modified by hand-working and measured by impulse swirl meter. For the effects on performance and emission, the brake torque and brake specific fuel consumption were measured by engine dynamometer, NOx and smoke were measured by gas analyzer and smoke meter. The results of steady flow test are as follows; as the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased. Also we realized that there is a trade-off that the increase of swirl ratio decreases mean flow coefficient and increases the Gulf factor. And the optimum parameters to meet performance and emission through engine test are as follows; the swirl ratio 2.43, injection timing BTDC 13oCA and compression ratio 15.5.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.250-261
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• 1995

In this study, a rapid compression and expansion machine(RCEM) equipped with a swirl generator was designed and developed, in order to clarify normal and abnormal combustion(knocking phenomena). This RCEM is intended to simulate combustion process in actual automotive S.I.engines, having a high reproducibility in the compression stroke. Flame propagation and autoignition processes associated with normal and abnormal combustion were captured by the high speed schlieren photography. And swirl intensity. equivalence ratio and ignition position were varied to investigate the effect of turbulence, concentration in the unburnt gas region and flame propagation length. The knock intensity, knock mass fraction and knock mass fraction after autoignition were calculated by use of history of measured cylinder pressure.

• Journal of Power System Engineering
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• v.8 no.1
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• pp.24-29
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• 2004

In this study, a computer analysis has been developed for predicting the pipe pressure of the intake and exhaust manifold. To obtain the boundary conditions for a numerical analysis, one dimensional and non-steady gas dynamic calculation is performed by using the MOC(Method Of Characteristic). The main numerical parameters are the variation of the engine revolution to calculate the pulsating flow which the intake and exhaust valves arc working. The comparison of exhaust pressure in case of numerical results is quite matched with in case of experimental results. When engine revaluation is increased, the pressure amplitude showed a high value, but the pressure frequency was decreased.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.62-74
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• 2001

In this study, the prediction of performances and emissions of the gasoline engine of a light passenger car has been accomplished. The method of characteristics including friction, heat transfer, area change and entropy gradients was used to analyze the flow in the intake and exhaust systems. For in-cylinder calculation, the single-zone model was adopted for the periods of the intake, exhaust, compression and the expansion of the burnt gas and the 2-zone expansion model was applied to the period of combustion process. The simulation program was verified by comparison with the experimental values both for the naturally aspirated engine and the turbocharged engine showing good agreements. Using the simulation program, multi-valve system and turbocharging were examined as a means of increasing engine Performances.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.6
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• pp.39-47
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• 1988

A disk photo sensor system was constructed and installed on engine for the crank angle measurement. Statically measured TDC crank angle data were compared with those obtained from engine motoring. Two groups of cylinder pressure data were compared each other, one measured by pressure transducer mounted flush on the combustion chamber and the other obtained with the help of spark plug type adaptor. A simple analysis on the gas flow in the spark plug type pressure transducer displayed reasonably good agreement with those from engine motoring tests. In various firing tests, the IMERs obtained from the spark plug type pressure transducer turned out to be higher than those from the flush mounted one at low engine speed while those two were nearly the same at high engine speed. As the engine load decreased the relative difference in IMEP measurement between the two types tended to be enlarged.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.7
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• pp.90-97
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• 2014

The effects of high pressure and low pressure exhaust gas recirculation (HP/LP EGR) portion on diesel engine combustion and emissions characteristics were investigated in a 2.2 L passenger-car diesel engine. The po3rtion of HP/LP EGR was varied from 0 to 1 while fixing the mass flow rate of fresh air. The intake manifold temperature was lowered with the increasing of the portion of LP EGR, which led to the retardation of heat release by pilot injection. The lowered intake manifold temperature also resulted in low nitrogen oxide (NOx) emissions due to decreased in-cylinder temperature and prolonged ignition delay, however, the carbon monoxide (CO) emission showed opposite trend to NOx emissions. The brake specific fuel consumption (BSFC) was decreased as the portion of LP EGR increased due to lowered exhaust manifold pressure by wider open of turbocharger vane. Consequently, the trade-off relationship between NOx and BSFC could be improved by increasing the LP EGR portion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.393-396
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• 2007

EGR is well established and efficient means to reduce NOx emissions. The increase of EGR rate affects the ignition delay of the combustion due to the lower oxygen availability. The increasing of the ignition delay period causes large combustion noise. In this study, the effects of EGR and Induction Point on combustion noise are investigated by measuring cylinder pressure and noise. As a result, The Combustion noise is markedly increased under the application of EGR. The increased premixed distance by displacing EGR Induction point in flow direction causes the uniform EGR distribution and the modulation level of the combustion noise is reduced slightly.

• Journal of the Korean Society of Safety
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• v.14 no.3
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• pp.78-83
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• 1999

This work is the experimental study for NO and NOx removal by utilizing non-thermal plasma. To apply to moving pollution source such as diesel automobile, we suggested the metal packed-helical wire reactor(MPHW) and measured properties of MPHW by varying the peak voltage, frequency, NOx concentration and flow rate for simulated NOx gas balanced with $N_2$. And then we compared these results with the results of cylinder-wire(CW) which was one of popularly used reactor in nonthermal plasma applications. The results of MPHW show fairly good NO and NOx removal rate compare with CW around above 20%. However. the power consumption of MPHW is larger than that of CW as much as around 2.5Watt in all range.

• Journal of Hydrogen and New Energy
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• v.8 no.2
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• pp.91-97
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• 1997

The goals of this research are to understand the $NO_x$ emission in direct injected diesel engine with premixed hydrogen fuel. Hydrogen fuel was supplied into the test engine through the intake pipe. Amount of hydrogen-supplemented fuel was 70 percent basis heating value of the total fuel. The effects of intake air temperature on $NO_x$ emission were studied. The intake air temperature was controlled by flow rate of liquid nitrogen. The major conclusions of this work include : (i) the tested engine was run without backfire under 70 percent hydrogen fuel supplemented. (ii) radicals of nitrogen gas in the intake pipe were increased by 30 percent and cylinder gas temperature was decreased by 24 percent as the intake air temperature were changed from $23^{\circ}C$ to $0^{\circ}C$ ; and (iii) $NO_x$ emission per unit heating value of supplied fuel was decreased by 45 percent with same decrease of intake air temperature.