• Journal of Mechanical Science and Technology
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• v.18 no.1
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• pp.30-36
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• 2004

In this paper, operation algorithms for a parallel HEV equipped with a relatively small motor are investigated. For the HEV, the power assist and the equivalent fuel algorithms are proposed. In the power assist algorithm, an electric motor is used to assist the engine which provides the primary power source. Tn the equivalent fuel algorithm, the electric energy stored in the battery is considered to be an equivalent fuel, and an equivalent brake specific fuel consumption for the electric energy is proposed. From the equivalent fuel algorithm, distribution of the engine power and the motor power is determined to minimize the fuel consumption for a given battery state of charge (SOC) and a required vehicle power. It is found from the simulation results that the fuel economy and the final battery SOC depend on the motor discharge energy and it is the best way to charge the battery only by the regenerative braking, not by the engine to improve the overall fuel efficiency of the HEV with the relatively small motor.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.25 no.2
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• pp.82-86
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• 1989

This paper is concerned with the effects of temperature of diesel fuel on combustion characteristics and engine performance in a home-made precombustion diesel engine for small-sized fishing boat. The results may be summarized as follows: 1. The fuel injection timing was delayed with increase in temperature for diesel fuel, and remarkably delayed at low load. 2. The point of maximum pressure was delayed with increase in temperature for diesel fuel, the maximum pressure decreased with increase in temperature for diesel fuel but increased with increase in load. 3. The brake specific fuel comsumption (BSFC) decreased with increase in load, the optimum temperature of the heated fuel was about 15$0^{\circ}C$. 4. The smoke emissions increased with increase in load and temperature for diesel fuel.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.75-80
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• 2008

Biodiesel fuel(BDF) can be effectively used as an alternative fuel in diesel engine. However, BDF may affect the performance and exhaust emissions in diesel engine because it has different physical and chemical properties from diesel fuel such as viscosity, compressibility and so on. To investigate the effect of injection timing on the characteristics of performance and exhaust emissions with BDF in IDI diesel engine, it was applied the BDF derived from soybean oil in this study. The engine was operated at seven different injection timings from TDC to BTDC $12^{\circ}CA$ and six loads at a single engine speed of 1500rpm. When the fuel injection timing was retarded, better results were showed, which may confirm the advantages of BDF. The simultaneous reduction of smoke and NOx was achieved at some fixed fuel injection timings of an IDI diesel engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.35-40
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• 2007

Our environment is faced with serious problems related to the air pollution from automobiles in these days. In particular, the exhaust emissions of diesel engine are recognized main cause which influenced environment strong, In this study, the potential possibility of biodiesel fuel was investigated as an alternative fuel for a naturally aspirated common rail diesel engine. The smoke emission of biodiesel fuel 5vol-%(min. content) was reduced in comparison with diesel fuel, that is, it was reduced approximately 60% at 4000rpm, full load. But, power, torque and brake specific energy consumption didn't have no large differences. But, NOx emission of biodiesel fuel was increased compared with a commercial diesel fuel. Also, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission has been investigated. It was found that simultaneous reduction of smoke and NOx was achieved with biodiesel fuel(5vol-%) and cooled EGR method($5{\sim}10%$) in a common rail diesel engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.65-71
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• 2005

Our environment is faced with serious problems related to the air pollution from automobiles in these days. In particular, the exhaust emissions of diesel engine are recognized main cause which influenced environment strong. In this study, the potential possibility of biodiesel fuel was investigated as an alternative fuel for a naturally aspirated D.I. diesel engine. The smoke emission of biodiesel fuel was reduced remarkably in com parison with diesel fuel, that is, it was reduced approximately 48.5% at 2500rpm, full load. But, power, torque and brake specific energy consumption didn't have no large differences. But, $NO_X$ emission of biodiesel fuel was increased com pared with commercial diesel fuel. Also, the effects of exhaust gas recirculation(EGR) on the characteristics of $NO_X$ emission has been investigated. It was found that simultaneous reduction of smoke and $NO_X$ was achieved with biodiesel fuel(20vol-%) and cooled EGR method($5{\sim}15%$).

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.899-905
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• 2000

The characteristics of air flow and engine performance with swirl ratio variance of intake port In a turbocharged DI diesel engine was 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. 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 and NOx, smoke were measured by gas analyzer and smoke meter. As a result of steady flow test, when the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased. And as the swirl ratio is increased, the mean flow coefficient is decreasing, whereas the gulf factor is increasing. Also, through engine test its can be expected to meet performance and emission by optimizing the main parameters; the swirl ratio of intake port, injection timing and compression ratio.

• Journal of Energy Engineering
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• v.17 no.4
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• pp.198-203
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• 2008

The objective of the research was to study the effects of Miller cycle in a modified using diesel engine. The engine was dedicated to natural gas usage by modifying pistons, fuel system and ignition systems. The engine was installed on a dynamometer and attached with various sensors and controllers. Intake valve timing, engine speed, load, injection timing and ignition timing are main parameters. The results of engine performances and emissions are present in form of graphs. Miller Cycle without supercharging can increase brake thermal efficiency and reduce brake specific fuel consumption. The injection timing must be synchronous with valve timing, speed and load to control the performances, emissions and knock margin. Throughout these tested speeds, original camshaft is recommended to obtain high volumetric efficiency. Retard ignition timing can reduce $NO_x$ emissions while maintaining high efficiency.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.3
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• pp.143-148
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• 2010

In this study, the potential possibility of biodiesel fuel(BDF) and oxygenated fuel(ethylene glycolvmono-n-butyl ether; EGBE) was investigated as an effective method of decreasing the smoke emission. The smoke emission of blending fuel (BDF and EGBE 0~20 vol-%) was reduced in comparison with diesel fuel and it was reduced approximately 64% at 2000 rpm, full load in the 20% of blending rate. But torque and brake specific energy consumption( BSEC) didn't have no large differences. Also, the effects of exhaust gas recirculation(EGR) for the reduction of NOx emission has been investigated. Consequently, It was found that simultaneous reduction of smoke and NOx emission was achieved with BDF(90 vol-%) and EGBE(10 vol-%) blended fuel and cooled EGR method(5~10%).

• Magazine of the Korean Society of Agricultural Engineers
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• v.18 no.4
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• pp.4259-4264
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• 1976

This paper, is about the test on the operating performance of diesel engine by using of soybean oil which farmers could supply in their farm yard. The diesel engine used is a swirl-chamber type, four stroke cycle with single cylinder, air cooling and its rated horse power is 2 PS per 1300 rpm. Several results obtained are as follows; 1. The starting performance of diesel engine with soybean oil is almost the same as that with light oil. 2. The variation of engine speed according to various engine load is small when soybean oil is used compared with light oil. It is considered that soybean oil is desirable for the purpose of industerial power machine fuel. 3. The specific fuel consumption increases approximately 10 percent high in the condition of rated horse power and maximum horse power and shows less or same during the load test in low velocity, when soybean oil is used 4. Though the brake thermal efficiency in the condition of rated horse power and maximum horse power is inclined to decrease when soybean oil is used compared during the load test in low velocityt shows good inclination.

• Journal of ILASS-Korea
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• v.23 no.2
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• pp.96-101
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• 2018

The purpose of this study is to investigate the effect of water injection on combustion characteristics of gasoline direct injection (GDI) engine with turbo-charger under low-load operating condition. The test engine used in this study has four-cylinder and 10.2 of compression ratio. In order to study the effect of water injection ratio on combustion characteristics, the water was injected into the intake port from 10% to 50%, based on fuel injection quantity. From the experiment, it revealed that the water injection induced the improvement of fuel economy because of the advance of spark-timing by the reduction of in-cylinder temperature. In addition, the water injection caused the prolong of extension of the ignition delay and slight increase of burn duration.