• Journal of the korean Society of Automotive Engineers
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• v.12 no.4
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• pp.66-74
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• 1990

Friction between piston-ring assembly and cylinder wall of a spark ignition engine was evaluated under various engine operating conditions utilizing a grasshopper linkage system. The friction force was estimated by the force balance relation at the small end of connecting rod. Three forces were chosen to be measured for the objective. They were gas pressure inside the cylinder, inertia force of the piston-ring assembly, and the force exerted by the connecting rod. These forces were measured by a piezo type pressure sensor, an accelerometer and strain gauges, respectively. Comparisons were made with the frictional force evaluated by the conventional method where the assumption of constant rotational speed of engines was adopted. Due to the variation of rotational speed of engines, the conventional method was found to lead to a large error in the evaluation of the frictional force.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.4
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• pp.39-56
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• 1988

In this study, the computer program was developed to predict the engine performances and exhaust emissions of a 4-cylinder 4-stroke cycle ignition engine including intake and exhaust system. The simulation models applied to each process were as follows. For the combustion process, two zone model which requires only one empirical constant was applied, and for the gas exchange process, the method of characteristics that allows the calculations of the time variation and spatial variation of properties along the pipes was used. Constant pressure perfect mixing model was applied to take into account of the interaction at manifold branches. To predict exhaust emissions, twelve chemical species were considered to be present in combustion products. These species were calculated through equilibrium thermodynamics and kinetic theory. The empirical constants reduced to least number as possible were determined through the comparison with the experimental indicator diagram of one particular operating condition and these constants were applied to other operating conditions. The predicted performances and emissions were compared with the experimental results over the wide range of operating conditions.

• Journal of Biosystems Engineering
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• v.28 no.4
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• pp.285-294
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• 2003

This study was carried out to propose a new-concept internal combustion engine which has great potential advantages to the conventional engines. Proposed new-concept engine is a kind of rotary engine. A rotor is rotating concentrically in a cylinder which is divided into two partitioning valves, and it makes four compartments in the cylinder. The volumes of each of four compartments are changing continuously with the rotor movement and performs the functions of intake, compression. expansion and exhaust simultaneously. Expected thermal efficiency for the real cycle is 26 percent at conditions of 1,000 rpm and compression ratio of 8.0, which is 3 to 4 percent higher than that of the conventional engines such as the piston engine, gas turbine and Wankel rotary engine. A simulation procedure proved that the new concept engine is functional, and has many potential advantages compared to the existing conventional engines.

• Journal of the Korean Society of Industry Convergence
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• v.6 no.2
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• pp.149-153
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• 2003

Besides the fuel spray behavior and combustion chamber shape. an air motion has a key role on exhaust gas emission and performance in a DI diesel engine. A swirl ratio represents the ratio of the intake swirl velocity to the engine speed. The main purpose in this work is to investigate the effects of the swirl ratio to the combustion characteristics. A shroud valve machined to change the swirl ratio. Test was carry out by changing the engine speed, nozzle diameter and swirl ratio in a single cylinder diesel engine. From this study, the optimized combustion was found at swirl ratio 2.7. And it was also found that the increasing the maximum cylinder pressure with an increasing swirl ratio lead to decrease a smoke and to increase NOx.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.147-154
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• 1996

An one-zone heat release analysis was studied for a 6 cylinder direct injetction compressionignition engine. The heat transfer constants in this anlysis were calibrated to match the measured fuel energy at 1,000 rpm full load, which was the fuel mass multiplied by the fuel's heating value. The integrated gross heat release values were close to the measured fuel energy at various full load operating conditions. The combustion inefficiency from this calculation was proportional to the smoke of exhaust gas.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.6
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• pp.25-38
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• 1988

As a mean of increasing engine power, great attention has been concentrated on the turbo-charging owing to better fuel economy, smaller engine size and lower emission. The performance in turbocharged engine depends not only on the efficiency of the engine and the turbocharger used, but also on the total characteristics of the system by the matching turbocharger to the engine. The matching of the turbocharger to the engine has been usually accomplished by the empirical techniques with a great deal of laborious work. It would be better to predict the performance and emission in the turbocharged engine using the effective simulation model. In this study, computer simulation program has been developed to predict the transient variation of properties of gas in the cylinder, intake and exhaust pipes, the engine performances and emissions.

• Journal of ILASS-Korea
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• v.22 no.4
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• pp.190-196
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• 2017

The aim of this work is to investigate the combustion and exhaust emission characteristics of low-temperature combustion (LTC) at various EGR test conditions using a single cylinder common-rail diesel engine. In high EGR rate combustion mode with DME fuel, 30% (${\Phi}=0.61$) and 50% (${\Phi}=0.86$) of EGR were respectively examined, and then the combustion, exhaust emissions, nano-particle characteristics of each cases were measured. From these results, it revealed that The ignition delay and combustion duration are prolonged as the increase of EGR rate. In addition, at an advanced injection timing (BTDC $30^{\circ}$), ignition delays were fairly increased because the dilution effect of EGR and also low charge in-cylinder temperature created a lean mixture, thus decreased the peak release rate.

• Journal of ILASS-Korea
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• v.2 no.2
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• pp.43-50
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• 1997

The purpose of this investigation is to carry out, the influence factor on the fuel spray characteristics for improve the engine combustion performance and exhaust omission in direct injection type diesel engine. The fuel properties, fuel spray structure and the shape or the piston surface of diesel engine play an important role of engine combustion process and exhaust emission. In order to obtain the effect of using auxiliary chamber and emulsified fuel on the fuel spray characteristics the experiment un conduct with single cylinder direct injection type diesel engine to examine the engine performance and gas emission. The results of this investigation showed that the increase auxiliary chamber volume and emulsified fuel give an effect on the fuel spray characteristics by reduced the concentration of nitric oxide emission in the combustion chamber. Also it can improve the combustion characteristics such as cylinder pressure, rate of pressure rise and rate of heat release.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.163-170
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• 2008

Auxiliary port which had been known to be used to reduce the expansion loss of a refrigeration system was applied to a R134a reciprocating compressor in a household refrigerator cycle with an intention of improving the compressor performance. Effects of the auxiliary port on the compressor performance was investigated by a computer simulation program. When a simple hole was made on the side wall of the cylinder as an auxiliary port and surrounding gas inside the compressor shell was assumed to be drawn into the cylinder through the hole, maximum COP improvement of 1.66% was obtained. With auxiliary port equipped with a plate type of check valve, maximum COP was raised to be 1.99%. COP improvement was more distinctive with decreasing the discharge pressure; COP improvement was 5% with discharge pressure of 7 bar.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.33-35
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• 2013

The present work is an experimental investigation on potential operating range using directly injected gasoline fuel in a single-cylinder compression ignition (CI) engine. The objectives of present study were to apply auto-ignited combustion to gasoline fuel and to evaluate potential operating range. In order to auto-ignite gasoline fuel in CI engine, the fuel direct-injection system and the intake air system were modified that a flow rate and temperature of intake air were regulated. The heat-release rate (HRR), net indicated mean effective pressure (IMEP), start of combustion (SOC), and combustion duration were derived from in-cylinder pressure data in a test engine, which has 373.33cc displacement volume and 17.8 compression ratio. The exhaust emission characteristics were obtained emission gas analyzer and smoke meter on the exhaust line system.