• 동력기계공학회지
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• 제20권2호
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• pp.32-42
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• 2016

Under part load condition of spark-ignition engine, pumping loss had great effect on engine efficiency. To reduce pumping loss, the study designed spark-ignited engines to make direct spray of gasoline to combustion chamber. In spark-ignited direct-injection engines, ignition probability is important for successful combustion and flame propagation characteristics are also different from pre-mixed combustion. This study designed a visualization testing device to study ignition probability of spark-ignited direct-injection LPG fuel and combustion flame characteristics. This visualization device consists of combustion chamber, fuel supply system, air supply system, electronic control system and data acquisition system. Ambient pressure, ambient temperature and ambient air flow velocity are important parameters on ignition probability of LPG-air mixture and flame propagation characteristics, and the study also found that sprayed LPG fuel can be directly ignited by spark-plug under proper ambient conditions. To all successful cases of ignition, the study recorded flame propagation image in digital method through ICCD camera and its flame propagation characteristics were analyzed.

• International Journal of Automotive Technology
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• 제8권3호
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• pp.269-274
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• 2007

A prior fundamental study was executed using a constant volume chamber (CVC) to improve the burning characteristics of lean pre-mixture by the injection of active radicals generated in the sub-chamber of the CVC. The Radical ignition (RI) technique shows remarkable progress in the burning velocity and combustible lean limit compared with the results of the spark ignition (SI) technique. The optimum design value of the sub-chamber geometry is near $0.11cm^{-1}$ for the ratio of the total area of the holes to the sub-chamber volume $(A_h/V_s)$. In this study, based on the former experimental results, the additional works have been performed to examine the effects of the geometry change in the number $(N_h)$, the total section area $(A_h)$, and diameter $(D_h)$ of the passage holes on the combustion characteristics in the CVC. Also ambient conditions such as the initial temperature and the initial pressure of the mixture were selected as experimental parameters and the effects of residual gas at the chamber on the combustion characteristics were investigated. As a result, the correlation between the passage hole number and overall passage hole area was grasped. The effects of the initial temperature were significant, but on the other hand, those of the initial pressure were weak. A more detailed analysis on the residual gas is required in the future.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.66-72
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• 2002

A premixed charge compression ignition engine is experimentally investigated for the reduction of NOx and smoke emissions from diesel engines. In this study, the premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber and then this pre-mixture is ignited by small amount of diesel fuel directly injected into the cylinder. In the premixed charge compression ignition engine, NOx and smoke concentrations of the exhaust emissions were reduced simultaneously as compared with the conventional diesel engine. But HC emission was increased with the increase of premixed ratio. Also, when EGR system was applied to the PCCI diesel engine, the effect of EGR rate on the combustion characteristics and the exhaust gas emissions was discussed.

• 한국분무공학회지
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• 제21권1호
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• pp.37-46
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• 2016

For the SI engines, at only full load, the pumping loss has a negligible effect, while at part load conditions, the pumping loss increases. To avoid the pumping loss, the spark-ignited engines are designed to inject gasoline directly into the combustion chamber. In the spark-ignited direct-injection engines, ignition probability is important for successful combustion and the flame propagation characteristics are also different from that of pre-mixed combustion. In this paper, a visualization experiment system is designed to study the ignition probability and combustion flame characteristics of spark-ignited direct-injection CNG fuel. The visualization system is composed of a combustion chamber, fuel supply system, air supply system, electronic control system and data acquisition system. It is found that ambient pressure, ambient temperature and ambient air flow velocity are important parameters which affect the ignition probability of CNG-air mixture and flame propagation characteristics and the injected CNG fuel can be ignited directly by a spark-plug under proper ambient conditions. For all cases of successful ignition, the flame propagation images were digitally recorded with an intensified CCD camera and the flame propagation characteristics were analyzed.

• Environmental Engineering Research
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• 제22권3호
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• pp.294-301
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• 2017

This paper is based on experiments conducted on a stationary, four stroke, naturally aspirated air cooled, single cylinder compression ignition engine coupled with an electrical swinging field dynamometer. Instead of 100% diesel, 20% Jatropha oil methyl ester with 80% diesel blend was injected directly in engine beside 25% pre-mixed charge of diesel in mixing chamber and with 20% exhaust gas recirculation. The performance and emission characteristics are compared with conventional 100% diesel injection in main chamber. The blend with diesel premixed charge with and without exhaust gas recirculation yields in reduction of oxides of nitrogen and particulate matter. Adverse effects are reduction of brake thermal efficiency, increase of unburnt hydrocarbons (UBHC), carbon monoxide (CO) and specific energy consumption. UBHC and CO emissions are higher with Diesel Premixed Combustion Ignition (DPMCI) mode compared to compression ignition direct injection (CIDI) mode. Percentage increases in UBHC and CO emissions are 27% and 23.86%, respectively compared to CIDI mode. Oxides of nitrogen ($NO_x$) and soot emissions are lower and the percentage decrease with DPMCI mode are 32% and 33.73%, respectively compared to CIDI mode.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.187-192
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• 2001

A homogeneous premixed charge compression ignition engine is experimentally investigated for the reduction of exhaust emissions in diesel engines. In this study, the premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber and then this pre-mixture is ignited by small amount of diesel fuel directly injected into the cylinder. In the premixed charge compression ignition engine, NOx and smoke concentration of the exhaust emissions were reduced simultaneously as compared with the conventional diesel engine. But HC and CO emissions were increased with the increase of premixed ratio. The combustion characteristics of premixed charged diesel engine such as the power output, the rate of heat release, and the other characteristics are discussed.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.9-14
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• 2002

A homogeneous premixed charge compression ignition engine has been experimentally studied far the reduction exhaust emissions of diesel engines. In this study, the gasoline fuel is injected into the intake manifold to from homogeneous pre-mixture in the combustion chamber and then this pre-mixture is ignited by small amount of diesel fuel directly injected into the cylinder. In the premixed charge compression ignition engine, NOx and smoke concentration of the exhaust emissions were reduced simultaneously as compared with the conventional diesel engine. The combustion characteristics of premixed charged diesel engine such as the power output, the rate of heat release, and the other characteristics are discussed.

• 한국자동차공학회논문집
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• 제17권3호
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• pp.8-14
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• 2009

Effect of heterogeneity of combustion chamber has been thought as one of the way to avoid dramatically generating heat in HCCI Combustion. The purpose of this research is to investigate the effect of heterogeneity, especially thermal stratification and fuel strength stratification on HCCI Combustion fueled with DME and n-Butane. Thermal stratification is formed in Combustion Chamber of Rapid Compression Machine with 3 Kinds of pre-mixture has different properties. The stratified charge mixture is adiabatic compressed and on that process, in cylinder gas pressure and two-dimensional chemiluminescence images are measured and analyzed.

• 한국자동차공학회논문집
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• 제2권3호
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• pp.85-93
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• 1994

The engine performance and combustion characteristics of diesel oil and fish oil blended with diesel oils were investigated at various blending rate of fish oil in a diesel engine. The maximum pressure showed no significant difference among test fuels at low load, but it was higher as the blending rate of fish oil increases at high load. Increasing the blending rate of fish oil, the rate of heat release and burned fraction were higher than those of diesel oil. The ignition delay became longer than that of diesel oil as the blending rate of fish oil increases, and its differences were larger at different loads. The combustion duration and density of smoke were shorter and lower as the blending rate of fish oil increases. The rate of fuel consumption showed no significant difference between diesel oil and fish blended with diesel oils.

• 한국자동차공학회논문집
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• 제11권1호
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• pp.49-54
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• 2003

The purpose of this work is to investigate the effect of premixed fuel on the reduction of exhaust emissions in premixed charge compression ignition engine. The premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber. The pre-mixture is ignited by a small amount of diesel fuel directly injected into the cylinder. In the case of gasoline as a premixed fuel of the engine, $NO_x$ and smoke concentration of exhaust emissions were reduced compared with the conventional diesel engine. But in the event of diesel fuel for premixed fuel, the rate of smoke reduction was small compared with the case of gasoline as a premixed fuel. HC and CO emissions were increased at high premixed ratio in the case of two premixed fuels. The combustion characteristics of the engine such as the combustion pressure, the rate of heat release, and other characteristics are compared.