• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.31-38
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• 2006

Cylinder liner rotation is a new concept for reducing piston assembly friction in the internal combustion engine. The purpose of cylinder liner rotation is to reduce the occurrence of boundary and mixed lubrication friction in the piston assembly. This paper reports the results of experiments to quantify the potential of the rotating liner engine. A GM Quad-4 SI engine was converted to single cylinder operation and modified for cylinder liner rotation. The hot motoring method was used to compare the friction loss between the baseline engine and the rotating liner engine. Additionally, tear-down tests were used to measure the contribution of each engine component to the total friction torque. The cycle-averaged motoring torque of the RLE represents a $23\~31\%$ friction reduction compared to the baseline engine for hot motoring tests. Through tear down tests, it was found that the piston assembly friction of the baseline engine is reduced from $90\%$ at 1200 rpm to $71\%$ at 2000 rpm through liner rotation.

• Journal of the Korean Society of Visualization
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• v.9 no.4
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• pp.16-21
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• 2011

The effects of stroke change on turbulent kinetic energy for the in-cylinder flow of a four-valve SI engine were studied. For this study, the same intake manifold, head, cylinder, and the piston were used to examine turbulence characteristics in two different strokes. In-cylinder flow measurements were conducted using three dimensional LDV system. The measurement method, which simultaneously collects 3-D velocity data, allowed a evaluation of turbulent kinetic energy inside a cylinder. High levels of turbulent kinetic energy were found in regions of high shear flow, attributed to the collisions of intake flows. These specific results support the more general conclusion that the inlet conditions play the dominant role in the generation of the turbulence fields during the intake stroke. However, in the absence of two counter rotating vortices, this intake generated turbulent kinetic energy continues to decrease but at a much faster rate.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.1-12
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• 1997

In an SI engine, the characteristics of the air flow is important not only for the design of the intake system geometry but also for the accurate measurement of the induction air mass. In this study, an air flow rate measurement using the ultrasonic flow meter and hot wire flow meter was conducted at the upstream of the intake port and the throttle. At the upstream of the intake port, the pulsating flow into the cylinder affected by the pressure wave was detected directly with the flow meters instead of pressure sensors. At the upstream of the throttle, the reverse flow phenomena were showed by comparing the flow pattern measured by the hot wire air flow meter and the ultrasonic air flow meter. The results of this study can be used for the analysis of the tuning effect in the intake manifold and estimation of the error in real time measurement for the air flow rate.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2126-2130
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• 2008

Gasoline engine have proved its utility in light, medium and heavy duty vehicle in every sector of the world community. The concern about long term availability of petroleum and the increasing threat for the environment by the increasing load of vehicular emission, compel the technology to upgrade itself for meeting the challenges. CNG is environmentally clean alternative to the existing SI Engines with out much change in the hardware. Many researchers have found this as a potential substitute to meet the energy requirement. Higher octane number and higher self ignition temperature make it a good gaseous fuel. Although power output is slightly lesser than the gasoline it's thermal efficiency is better than the gasoline for the same SI Engine. Results showed that reduced CO, hydrocarbon emissions is a favorable outcome, with slight increase in $NO_x$ emission when compared with gasoline fuel to dual fuel mode in the existing SI Engines.

• Journal of Hydrogen and New Energy
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• v.21 no.5
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• pp.435-441
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• 2010

To verify the possibility of a power generation system using biogas from the waste of pig farm for rural electric production, a SI gasoline engine is modified to use biogas fuel and was installed in a 20 KVA power generation system. An electronic speed regulation unit is developed to keep the system speed at 1500 rpm. Experimental investigations have been carried out to examine the performance characteristics of power generation system (such as: system frequency, phase output voltage,$\ldots$). In addition, the operating parameters and output emissions ($NO_x$, HC, and $CO_2$) of biogas-fueled engine are preliminary evaluated and analyzed for the change of system load. Results indicated that the researched power generation system shows a high stability of output voltage and frequency with help of speed regulator. Biogas fuel (mainly $CH_4$ and $CO_2$) has an environmental impact and potential as a green alternative fuel for SI engine and they would not require significant modification of existing engine hardware. Output emissions of biogas-fueled engine are found to be relative low. $NO_x$ emission increases with the increase of output electric power of the power generation system.

• 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 Institute of Gas
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• v.23 no.6
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• pp.90-96
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• 2019

Natural gas has been regarded as one of major alternative fuels, because of the increment of mining shale gas and supplying PNG(Pipeline Natural Gas) from Russia. Thus, it needs to broaden the usage of natural gas as the increasing its supplement. In this situation, application of natural gas on the transport area is a good suggestion to reduce exhaust emissions such as CO₂(carbon dioxides) and soot from vehicles. For this reason, natural gas can be applied to SI(spark ignition) engines due to its anti-knocking and low auto-ignitibility characteristics. Recently, since turbocharged SI engine has been widely used, it needs to apply natural gas on the turbocharged SI engine. However, there is a major challenge for using natural gas on turbocharged SI engine, because it is hard to make natural gas direct injection in the cylinder, while gasoline is possible. As a result, there is a loss of fresh air when natural gas is injected by MPI (multi-point injection) method under the same intake pressure with gasoline-fueled condition. It brings the power reduction. Therefore, in this research, intake pressure was increased by controling the turbocharger system under natural gas-fueled condition to improve power output. The goal of improved power is the same level with that of gasoline-fueled condition under the maximum torque condition of each engine speed. As a result, the maximum power levels, which are the same with those of gasoline-fueled conditions, with improved brake thermal efficiency could be achieved for each engine speed (from 2,000 to 6,000 rpm) by increasing intake pressure 5-27 % compared to those of gasoline-fueled conditions.

• 한국연소학회:학술대회논문집
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• 2004.11a
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• pp.206-212
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• 2004

It is necessary to consider the stability, economic environmental-friendly problems by the development of the road, supply of the automobile, environmental problem as designing the exhaust system. To reduce the noise and the vibration of the automobile, it is needed to consider the pulsation noise, air current noise, vibration of air pipe which generate the intake and exhaust noise of the automobile. Moreover, the discharge sounds, intake sound, radiation sound, transmitted sound are occurred. To reduce this influence, the variable valve is needed and to control these factors, path transformation muffler and active type muffler are needed. While engine efficiency could be reduced with this transformationand resistance by the pressure, thermal property. In this study, how to design exhaust systems yielding higher condversion efficiency, lower backpressure and optimize the performance. this study is recommended for exhaust system and designers and engineers involved in SI engine exhaust system and it will furnish information for you to design more efficient.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.8
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• pp.718-723
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• 2007

The new concept spark plug was developed to study its influence on the combustion characteristics of SI engine. It has pre-ignition chamber in the lower end of spark plug and flame hole, in which fresh mixture gas can be introduced without any fuel supply system. This spark plug was tested with a commercial SI engine. Fuel consumption rate, emission gas and MBT timing were measured in the engine dynamometer for various flame hole numbers, hole positions, hole sizes of the pre-ignition chamber of the spark plug. And average flame propagation speed was measured by using the head gasket ionization probe in single cylinder engine. The new concept spark plug induces fast bum in combustion compared with the conventional spark plug, and MBT(Minimum advance for Best Torque) timing was retarded about $3{\sim}5^{\circ}$ crank angle. The flame hole number, hole direction and volume of pre-ignition chamber were found to influence the combustion characteristics.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.108-121
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• 1998

Using gas chromatography, the light hydrocarbon emissions were analyzed from SI engine fueled with methane and liquified petroleum gas(LPG), and the effects of fuel and engine operating condition were discussed. For this purpose, 14 species of light hydrocarbon including 1, 3-butadiene were separated, calibrated with standard gas, and measured from undiluted emissions. The brake specific hydrocarbon emission(BSHC) and ozone forming potential(BSO)3 were calculated and discussed with the changes of fuel, engine speed, load, fuel/air equivalence ratio, coolant temperature, and spark timing. As a result, exhaust emission was composed of mainly fuel composed of mainly fuel comp- onent and other olefin components of similar carbon number. The olefin components such as ethylene and propylene determine most of the ozone forming potential. The fraction of fuel component in total hydrocarbon emission was bigger with methane fuel than with LPG fuel. Also fuel fraction increased at high speed or high speed or high temperature of exhaust gas, and to lesser extent with high coolant temperature and retarded spark. However, the effect of equivalence ratio had different tendency according to fuels.