• Journal of the Korean Institute of Gas
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• v.12 no.3
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• pp.7-12
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• 2008

In this study, a spark ignition engine operated with the DME blended LPG fuel was investigated experimentally. Performance, emissions characteristics including hydrocarbon, CO, NOx, and combustion stability of an SI engine fuelled with DME blended LPG fuel were examined at $1200{\sim}5200\;rpm$. Results showed that stable engine operation was possible for a wide range of engine loads within 20% mass content of DME fuel. Also, engine output power within 10% mass content of DME fuel was comparable to that of pure LPG fuel operation. However, engine output power was decreased and break specific fuel consumption (BSFC) was severely increased with the amount of blended fuel as the energy content of DME was much lower than that of LPG. DME blended LPG fuel is expected to be potential for enlarging DME market.

• Journal of the korean Society of Automotive Engineers
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• v.8 no.2
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• pp.31-42
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• 1986

The prediction of performance, exhaust emissions and EGR effect is made by the SI engine cycle simulation. In this simulation several models are employed - two zome, thermodynamic combustion, mass fraction burned, heat transfer, chemical equilibrium, chemical kinetics for NOx, laminar flame speed for ignition delay. The chemical species in burned gas considered are 13 species-CO$_{2}$, CO, $O_{2}$, H$_{2}$O, H$_{2}$,OH, H, O, N$_{2}$, NO$_{2}$, N, Ar - and the cylinder pressure, burned and unburned zone temperature and composition of gas are calculated at each crank angle through the compression, ignition delay, combustion and expansion process. To check the validity of the model, experimental study is done for measuring emissions, combustion pressure and engine output. The predicted values for pressure and emissions show qualitative agreement with the measured data and the EGR effect also shows similar tendency.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.153-161
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• 1998

The knock in a spark ignition engine has been investigated to avoid the damage to the engine and unpleasant feeling caused by the pressure waves propagating across the combustion chamber. Knock intensity and knock onset angle were used as physical parameters to quantify the knock characteristics. The knock intensity is defined as a peak to peak value of the bank pass filtered combustion pressure signal and the knock onset angle is determined as the crank angle at which this signal exceeded the threshold level on each cycle. The cyclic variation of knock in four valve single cylinder engine was investigated with these two parameters. The location of autoignition was also examined by ion probes in the cylinder head gasket and squish region in the combustion chamber. For this measurement, a single cylinder engine was modified to accept the pressure transducer, 18 ion probes in the squish region and 8 ion probes in the specially designed PCB (Printed \ulcornerCircuit Board) cylinder head gasket.

• 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.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.2
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• pp.175-182
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• 2008

In this study, a spark ignition engine operated with LPG and DME blended fuel was studied experimentally. Performance and emissions characteristics of a LPG engine fuelled by LPG and DME blended fuel were examined. Results showed that stable engine operation was possible for a wide range of engine loads within 20% mass content of DME fuel. Also, engine output power within 10% mass content of DME fuel was comparable to pure LPG fuel operation. Exhaust emissions measurements showed that hydrocarbon and NOx were increased with the blended fuel at low engine speed. Engine output power was decreased and break specific fuel consumption (BSFC) was severely increased with the blended fuel since the energy content of DME was much lower than that of LPG. Considering the results of engine output power and exhaust emissions, the blended fuel within 20% mass content of DME could be used as an alternative fuel for LPG.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.16-21
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• 2003

Natural gas is one of the promising alternative fuels because of the abundant deposits and the cleanness of emission gas. It can be used in conventional gasoline engine without major modification. Natural gas has some advantages than gasoline i.e. the high octane number, good mixing condition because of gas and wide inflamable limit. In the present study, a $1.8{\ell}$ conventional gasoline engine is modified for using the CNG as a fuel instead of gasoline. Performance and emission characteristics are compared between gasoline and CNG with 4 cylinder SI Engine which is controlled by programable ECU. Parameters of experimentation are equivalence ratio, spark timing and fuels. We analyzed the combustion characteristics of the engine using the cylinder pressure i.e. ignition delay, combustion duration and cycle variation. As a result, CNG engine shows lower exhaust emissions but brake torque is slightly reduced compared to gasoline engine. Overall combustion duration is longer than that of gasoline because of lower burning speed.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.11-18
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• 2002

Residual gas fraction in an engine cylinder affects engine performance, efficiency and emission characteristics. With high residual gas fractions, a flame speed and maximum combustion temperature are decreased and these are deeply related with combustion stability especially at idle and NOx emission at relatively high engine load. In this work, the residual gas fraction was calculated by an engine simulation code, which was validated by the experimental data (cylinder pressure and emissions) obtained from 4-cyliner spark ignition engine. A comparison between experimental and computational calculation results was made. The residual gas is generated mostly at low engine speed by the larger pressure difference between the intake and exhaust port. As the valve overlap duration was increased, the amount of residual gas in the cylinder, the amount of HC emission in the exhaust gas and the variation of power output increased.

• The KSFM Journal of Fluid Machinery
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• v.19 no.6
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• pp.43-49
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• 2016

A performance analysis of a gasoline engine with a 2-stage turbocharger system for unmanned aerial vehicle(UAV) was conducted. One dimensional system analysis was conducted for the requirements of turbochargers and adequate turbochargers were selected from commercially available models for automobiles. Modeling and simulation were performed by Ricardo WAVE. Gasoline engine modeling was based on a 2.4 L 4-cylinder engine specification. The selected turbochargers and intercoolers were added to the engine model and simulated at 40,000 ft altitude condition. The results of the engine model and 2-stage turbocharger system model simulation showed break power 93 kW which is appropriate power required for the engine operation at the ambient conditions of 40,000 ft altitude.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.3
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• pp.83-93
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• 1985

The prediction of emission concentrations in a 4cycle spark ignition engine was made by considering nonuniform model with thermodynamics, chemical equilibrium and kinetic mechanism of nitric oxide. Calculation of this model shows that a temperature difference of the order of 500K can be established across he cylinder. Results of the kinetic calculation of nitric oxide show that the temperature gradient across the cylinder has a profound effect on the nitric oxide formation. The predicted values for nitric oxide, carbon dioxide and carbon monoxide agree with measured ones for a variety of equivalence ratio.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.1-10
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• 2001

In order to reduce hydrocarbon emissions of spark ignition engine, it is important not only to improve catalyst conversion efficiency but also to reduce direct engine out hydrocarbon emissions, during cold starting and warm up process. Tjerefore many researchers have been attracted to develop an early fuel evaporator (EFE) by introducing a ceramic heater for a solution of engine out hydrocarbon emissions in SI engine. But, the performance of the EFE in MPI engine to reduce the exhaust emissions and to improve the cold startability has nat been clarified yet. The purpose of this study is to evaluate the feasibility of a glow plug for EFE.