• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.257-262
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• 2003

Engine-out HC emissions were investigated during engine start. The tests were conducted on a 1.5L, 4-cylinder, 16 valve, multipoint-port-fuel-injection gasoline engine at different coolant temperatures and fuel injection-skip methods; no skip, 1 cycle-skip and 3 cycle-skip. To understand the characteristics of engine-out HC emissions, HC concentration was measured at a exhaust port using a Fast Response Flame Ionization Detector (FRFID). The result show that HC emissions were emitted at the cold coolant temperature much higher than those of the hot coolant. In additions, the fuel injection skip highly reduced engine-out HC emissions. It is convinced that optimized fuel injection skips according to coolant temperatures could be applied to reduce HC emissions during SI engine start.

• Journal of Power System Engineering
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• v.10 no.1
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• pp.5-11
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• 2006

During the SI engine starting up, starting conditions directly contribute to the harmful emissions in spark ignition engines. The effects of catalyst temperatures and fuel injection skip methods on HC emissions were investigated. The test was conducted on a 1.5L, 4-cylinder, 16 valve, multipoint-port-fuel-injection gasoline engine. To understand the formation of HC emissions, HC concentration was measured in an exhaust port using a Fast Response Flame Ionization Detector(FRFID). The result showed that HC emissions, which were generated during initial stage of the starting, could be reduced by coolant temperature and fuel injection skips. And through the vehicle test of ECE15+EUDC, it is convinced that the optimized fuel injection skip method according to coolant temperatures have favourable effects on the reduction of harmful exhaust emissions including HC during the SI engine start.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.2
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• pp.27-33
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• 1993

Using the solenoid driven gas injection valve, Hydrogen fuel supply system was made. It was attached to a single cylinder research engine and intake port injection type hydrogen fueled S.I. engine was constructed. Engine performance, emission characteristics, and abnormal combustion were studied through the engine test performed with the variations of fuel-air equivalence ratio and spark timing. Compared with gasoline, hydrogen burns so fast that cylinder peak pressure and temperature are higher and NO is emitted more at full load condition. IN the case of intake port injection type engine, COVimep becomes lower due to the well-mixing of air and fuel, and engine output is lower owing to the low volumetric efficiency. As fuel-air equivalence ratio goes up, the combustion speed increases, and COVimep decreases. NO emission peaks slightly lean of stoichiometric. As spark timing advances and fuel-air equivalence ratio goes up, the cylinder peak pressure and temperature become higher, so abnormal combustions take place easily.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.9
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• pp.1198-1206
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• 1997

The flow characteristics of an intermittent fuel injection into a stationary ambient air were investigated using gasoline. The measurements were made by two-channel, air cooling type Phase Doppler Anemometer(PDA) system (DANTEC, 750 MW). And a pintle type injector of MPI (Multi-point Port Injection) system was utilized as a fuel injector. The PDA receiver optic was set up in a 60.deg. C forward scatter arrangement to obtain the optimum scattering signal of fuel droplets. The data were obtained by synchronizing PDA system with the fuel injection period, and the axial and radial velocity and turbulent components of fuel droplets were mainly measured for the analysis of temporal and spatial distribution depending upon the fuel injection pressures.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.28-35
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• 2005

Fuel injection rate of an injector is affected by various injection conditions such as injection duration, fuel temperature, injection pressure, and voltage in LPG liquid injection systems for either a port-fuel-injection(PFI) or a direct injection(DI) in a cylinder. Even fuel injection conditions are changed, the air-fuel ratio should be accurately controlled to educe exhaust emissions. In this study, correction factor for the fuel injection rate of an injector is derived from the density ratio and the pressure difference ratio. A voltage correction factor is researched from injection test results on an LPG liquid injection engine. A compensation method of the fuel injection rate is proposed for a fuel injection control system. The experimental results for the LPG liquid injection system in a SI-engine show that this system works well on experimental range of engine speed and load conditions. And the fuel injection rate is accurately controlled by the proposed compensation method.

• 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.3 no.3
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• pp.42-48
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• 1998

This study describes the spray structure of gasoline port injectors by using phase Doppler particle analyzer(PDPA) and particle motion analysis system(PMAS). The characteristics of fuel spray such as the spray penetration, spray angle and breakup processes were obtained by PMAS and the droplet size and mean velocity were measured by PDPA system. Pintle type and two-hole type injectors were used as gasoline port fuel injectors under various injection pressures. The effect of injection pressure on the droplet mean diameter and axial mean velocity of droplet were investigated under the various injection conditions. In addition the comparison of breakup processes for the two types of injectors was also conducted. It Is shown that pintle type injector has smaller droplet size than that of two-hole type injector.

• Journal of ILASS-Korea
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• v.26 no.2
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• pp.81-87
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• 2021

This study was performed to calculate the swirl ratio of a diesel engine intake port by a 1D computer simulation under actual engine operating conditions. The swirl ratio of the intake port was simulated according to the change of the engine speed during the operation of the motoring without fuel injection. The swirl ratio of the intake port was simulated according to changes in the crank angle during the four-cycle operation of intake, compression, expansion and exhaust. The swirl ratio represented by the three regions of the piston, center and squish was simulated. Among the three regions, the piston-region swirl ratio is important for effective air-fuel mixing in the engine cylinder. In particular, it was confirmed during the simulation that the piston swirl ratio before and after the compression top dead center (TDC) point when fuel is injected in the DI diesel engine can have a significant effect on the mixing of air and fuel. It was desirable to set the average piston swirl ratio over a crank angle section before and after compression TDC as the representative swirl ratio of the cylinder head intake port according to the change of the engine speed.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.796-801
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• 2001

During cold operation period, fuel injection system directly contributes the unburned hydrocarbon formation in spark ignition engines. The relationship between injection parameters and HC emission behavior was investigated through a series of experiments. Spray behavior of port fuel injectors was characterized through a quantitative evaluation of mass concentration of liquid fuel by a patternator and PDA. 6-hole injector was found to produce finer spray than single hole one. Using a purpose-built test rig, the wall wetting fuel was measured, which was mostly affected by wall temperature. Varying coolant temperature($20{\sim}80^{\circ}C$), HC emissions were measured in a production engine. With respect to the different types of injectors, HC emission was also measured. In the 6-hole injector application, the engine produced less HC emission in low coolant temperature region. Though it produces much more amount of wetting fuel, it has the advantages of finer atomization quality. In high coolant temperature region, there was little effect between different types of injectors. The control schemes to reduce HC emissions during cold start could be suggested from the findings that the amount of fuel supply and HC emission could be reduced by utilizing fine spray and high intake wall temperature.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.3
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• pp.1-9
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• 2004

During the SI engine starting up, starting conditions directly contribute to the unburned hydrocarbon emissions in spark ignition engines. The effects of catalyst temperatures and fuel injection skip methods on HC emissions were investigated. The test was conducted on a 1.5 L, 4-cylinder, 16 valve, multipoint-port-fuel-injection gasoline engine. To understand the formation of HC emissions, HC concentration was measured in an exhaust port using a Fast Response Flame ionization Detector (FRFID). The result showed that HC emissions, which were emitted at the cold coolant and catalyst temperature, were generated much higher than those of hot coolant and catalyst temperatures. In additions, fuel injection skips reduced highly HC emissions. It is convinced that optimized fuel injection skip method according to coolant and catalyst temperatures could be applied to reduce HC emissions during the SI engine starts.