• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.75-81
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• 2001

This paper presents the atomization characteristics of single hole injector in the direct injection type diesel engine. The spray characteristics of fuel injector such as the droplet size and velocity were measured by phase Doppler particle analyzer. In this paper, the atomization characteristics of fuel spray are investigated for the experimental analysis of the measuring data by the results of mean diameter and mean velocity of droplet. The effect of fuel injection pressure on the droplet size shows that the higher injection pressure results in the decrease of mean droplet diameter in the fuel spray. The minimum size of fuel spray droplet appears on the location of 40mm axial distance from nozzle exit of diesel injector. Based on the experimental results, the correlation between the droplet diameter and mean velocity of the diesel spray due to the change of axial and radial distance from the nozzle tip were investigated.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.162-173
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• 1998

The high pressure common rail injection system offers a high potential for improving emmisions and performance characteristics in large direct diesel engines. High pressures in the common rail with electronic control allows the fuel quantity and injection timing to be optimized and controlled throughout a wide range of engine rpm and load conditions. In this study, high pressure supply pump, common rail, pipes, solenoid and control chamber, and nozzle were modeled in order to predict needle lift, rate of injection, and total injected fuel quantity. When the common rail pressure is raised up to 13.0 ㎫ and the targer injection duration is 1.0ms, the pressure drop in common rail is about 5.0㎫. The angle of effective pressurization is necessary to be optimized for the minimum pump drive torque and high pressure in common rail depending on the operating conditions. The characteristics of injection were also greatly influenced by the pressures in common rail, the areas of the inlet and exit orifice of the control chamber.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.140-156
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• 1997

The combustion characteristics of DI Diesel engine using turbocharging and EGR are numerically studied. Computations are carried out for the wide range of trubochyarged pressures, EGR ratios, and Ar/He dilution. Numerical results indicate that the Ar/He dilution in the intake gas significantly influence the engine performance, the spray combustion process, and the pollutant formation.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.3
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• pp.9-18
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• 1995

The substitution of conventional fuel oil by alternative fuels is of immense interest due to liquid oil shortage and requirements of emission control standard. Among the alternative fuels, natural gas may be the most rational fuel, because of its widespread resource and clean est burning. Meanwhile, engine simulation is of great importance in engine development. Hence a zero-dimensional combustion model was developed for dual-fuel system. Natural gas was injected directly into the cylinder and small amount of distillate was used to provide the ignition kernel for natural gas burning. The intake air and exhaust gas flow was modeled by filling and emptying method. Although the single zone approach has an inherent limitation, the model showed promise as a predictive tool for engine performance. Its simulation was also made to see how the engine performance was influenced by the fuel injection timings and amount of each fuel.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.1
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• pp.76-88
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• 1995

The effects of exhaust gas recirculation(EGR) on the characteristics of NOx emissions and specific fuel consumption rate have been investigated using an eight-cylinder. four cycle. direct injection diesel engine operating at several loads and speeds. The theoretical NO formation concentration is calculated with the equivalence ratio as a parameter of flame temperature to study the effect of EGR on NOx emissions in the diesel combustion. The experiments in this study are conducted on the fixed fuel injection timing of $38^{\circ}$ BTDC regardless of experimental conditions. It is found that the specific fuel consumption rate is slightly increased with EGR rate. and NOx emissions are markedly reduced owing to the drop of the incoming oxygen concentratio and the increase of equivalence ratio as the EGR rate increases.

• LP가스
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• s.96
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• pp.48-52
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• 2005

대기 질 악화를 둘러싼 논란으로 지연되어 오던 경유 승용차의 국내 시판이 4월부터 허용됨에 따라 경제적 기대와 환경적 우려가 현실화되고 있음. 경유 승용차의 시판에 따라 자동차 연료가격이 조정된다 해도 경유 승용차의 국내시장 점유율은 지속적으로 늘어나 2009년에는 10 %를 넘어설 전망임. 경유 차량은 환경에 직접적 피해를 주는 미세먼지, 질소산화물등을 많이 배출하는 반면, 지구온난화의 원인으로 알려진 이산화탄소는 적게 배출하는 환경적 양면성을 가지고 있음. 현재 대기오염 방지기술이 빠르게 발전하고 있어 경유 승용차의 시판과 함께 대기오염 방지를 위한 보완대책과 기술개발 투자가 병행된다면 대기의 질이 오히려 개선될 가능성이 큼. 정부가 마련 중인 자동차 대기오염 방지대책의 핵심은 경유 가격을 선진국 수준으로 높이고 차세대 제작차 환경기준을 강화하는 것임. 대기오염 개선대책이 순조롭게 시행될 경우 승용차 시판에도 불구하고 대기의 질이 개선되어 경제와 환경의 상생 기회가 될 것으로 기대됨.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.274-276
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• 2009

최근 화석연료의 연소로 인해 발생되는 이산화탄소에 의한 환경오염이 크게 대두가 되고 있으며, 특히나 내연기관 자동차의 배출가스는 이산화탄소의 배출량이 매우 높은 실정이다. 따라서 정부에서는 친환경자동차 분야를 하나의 성장사업으로 선정하였으며, 이에 대한 많은 연구 개발이 진행 중에 있다. 본 논문에서는 출퇴근용으로 사용할 수 있는 근거리 전기자동차용 10kW급 BLDC 모터 제어기 개발에 대하여 제안을 한다. 제안된 근거리 전기자동차용 10kW급 BLDC 모터 드라이브 제어기는 한정된 공간 및 배터리 전원에서도 고토크, 고출력, 고효율, 경량화의 장점을 가지도록 개발을 하였다. 또한, BLDC 모터는 회전자 위치 정보가 필수적으로 요구되기 때문에 다양한 위치 센서를 사용할 수 있도록 홀센서, 엔코더, 레졸버를 사용할 수 있도록 모터제어기를 개발 하였다. 제안된 방식의 타당성 검증을 위해 PSIM을 이용하여 시뮬레이션 수행하였으며, 10kW급 BLDC 모터 드라이브 제어기를 제작하여 성능을 검증하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.60-69
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• 2000

In order to obtain underwater or underground power sources, the closed cycle diesel engine is operated in the non air-breathing circuit system where the major species of the working fluid include oxygen, argon, and recycled exhaust gas. In the present study, the closed cycle diesel engine is designed to operate at the intake pressure between 2 and 3 bar. For operating in the open-cycle and closed-cycle situations, experimental apparatus using this diesel engine is made with ACAP as data acquisition system. In open, semi-open, and closed cycle modes, the predicted p-$\theta$ and P-V are compared with load bank power. Computation have been performed for wide range of major experimental parameters such as the specific fuel and oxygen concentrations, fuel conversion efficiency and polytropic exponent, IMEP and maximum cylinder pressure.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.33-42
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• 2002

Recently, our world is faced with very serious and hard problems related to the air pollution due to the exhaust emissions of the diesel engine. In this paper, the effect of oxygen component in fuel on the exhaust emissions has been investigated fur direct injection diesel engine. It was tested to estimate change of engine performance and exhaust emission characteristics for the commercial diesel fuel and oxygenate blended fuel which has three kinds of mixed ratio. And, it was tried to analyze not only total hydrocarbon but individual hydrocarbon components from Cl to C6 in exhaust gas using gas chromatography to seek the reason far remarkable reduction of smoke emission. This study was carried out by comparing the chromatogram with diesel fuel and diesel feel blended DGM(diethylene glycol dimethyl ether) 5%. The results of this study show that individual hydrocarbon(C1∼C6) as well as total hydrocarbon of oxygenated fuel is reduced remarkably than that of diesel fuel.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.32-41
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• 1999

Natural gas is an attractive fuel in view of environment benefits due to its flow carbon-to-hydrogen ratio. However, its compositions and properties are varied depending upon production regional groups. Therefore, study on the combustion characteristics of natural gas engines with a variety of compositions has been demanded for the efficient application of gas engines. This study aims to investigate the effects of gas composition on engine combustion characteristics. It was found that , by controlling an engine with fixed fuel nozzle area, power and heat release were subject to Wobbe Index. And at fixed excess air ratios, power and heat release were subject to low heating value of unit mixture . In addition, in case of constant nozzle area, combustion duration was found to be inversely proportional to CP(Combustion Potential), and the condition of fixed excess air ratios showed no change in combustion duration, regardless of CP.