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[가솔린엔진부문] 냉시동시 연료 분사 특성이 HC 배출에 미치는 영향에 대한 실험적 연구
우영민(Youngmin Woo),이용표(Youngpyo Lee),배충식(Choongsik Bae) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1999 No.11_1
Fuel system directly contributes to the unburned hydrocarbon formation in spark ignition engines. Depending on the injector type the spray characteristics is changed and subsequently affect following combustion. In port fuel injection SI engine most of the hydrocarbon(HC) emission is ascribed to the fuel behavior during cold starting and warm-up period. During this period it is said that intake port and cylinder wall wetting is significantly affect the combustion and HC emission characteristics. Spray behavior with regard to the injectors was characterized qualitatively and spray pattern was evaluated quantitatively with patternator. Using test rig, the wall wetting phenomena was experimentally investigated. HC emission was measured with varying coolant temperature by FR-FID(Fast Response Flame Ionization Detector) at steady idling engine operation.
EGR 성충화가 액상 분사 LPG 엔진의 희박연소에 미치는 영향
우영민(Youngmin Woo),배충식(Choongsik Bae),오승묵(Seungmook Oh),강건용(Kernyong Kang) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_1
Stratified EGR (Exhaust Gas Recirculation) achieves not only reductions in NOx emission and fuel consumption but also combustion stability improvement for highly diluted mixture. In this study, the timing and duration of a fast-response solenoid valve installed in the midst of EGR line was controlled to form the axial stratification of EGR within the cylinder. Lean burn of LPG with both stratified and homogeneous EGR was examined in terms of the rate of heat release, combustion stability (or EGR tolerance), fuel consumption and engineout emissions. Since stratified EGR showed faster combustion and improvement in combustion stability, more EGR amount was admitted and more reduction of NOx emission with less increase in HC emission was attained with stratified EGR than homogeneous EGR.
우영민(Youngmin Woo),장진영(Jinyoung Jang),표영덕(Young Dug Pyo),정용진(Yongjin Jung),고아현(Ahyun Ko),조종표(Chongpyo Cho),김강출(Gangchul Kim),신영진(Youngjin Shin) 한국자동차공학회 2022 한국자동차공학회 지부 학술대회 논문집 Vol.2022 No.5
After the IMO (International maritime organization) announced GHG (green-house-gas) reduction plans, marine engine makers were confronted with a serious challenges on their fixture businesses. According to the Plan, every ships in operation in the sea must reduce its GHG emissions by 70%. Thus, a radical transition is inevitable from the residual oils into the gas fuels, which is eventually hydrogen or ammonia rather than LNG fuel. Between the zero carbon fuels, ammonia is on the spotlights to abate GHG emission from ships. Ammonia emits only water and nitrogen theoretically but both unburned ammonia and nitric oxides are also found in reality. This can raise another emission issue. In this study, many low flash point fuels such as LPG, CNG, and hydrogen in addition to ammonia were investigated to draw a feasible option for the low GHG emissions from the internal combustion engine. As a result, ammonia can be easily supplied into the diesel engine and it substituted some diesel so that the same amount of carbon dioxide emission is reduced from the test engine without any significant increase of NOx emission. Not only ammonia but also different low flash fuel mix showed better combustion characteristics to reduce engine emissions than ammonia-diesel case.
우영민(Youngmin Woo),배충식(Choongsik Bae),오승묵(Seungmook Oh),강건용(Kernyong Kang) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Lean bum was considered to overcome high thermal load and improve fuel economy in heavy duty SI engine. However, lean bum generally causes unstable engine operation due to combustion instability such as cyclic variation, misfire, or partial burning. To overcome such undesirable phenomena charge stratification inside the engine cylinder through fuel injection strategy was utilized and flow field enhancement through intake port and piston shape was adopted.<br/> In this study, tile effects of swirl ratio and piston bowl shape on tile mixture preparation were investigated. High intensity of squish flow as well as swirl flow was acquired by the enlarged piston squish area and helical intake port. To obtain two dimensional fuel distribution planar ~laser induced fluorescence (PLIF) was used. Acetone was excited by KrF excimer laser (248nm) and its fluorescence image was acquired by ICCD camera. Fuel injection strategy with respect to the intake process was found to have the key role of tile whole stratification process. The intense squish flow was found to be effective to place relatively rich mixture to tile vicinity of spark plug in tile end period of compression process.<br/>
우영민(Youngmin Woo),염기태(Kitae Yoem),장진영(Jinyoung Jang),배충식(Choongsik Bae) 한국자동차공학회 2002 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2002 No.5_1
Exhaust Gas Recirculation (EGR) system was used to reduce NOx emissions, to improve fuel economy and to suppress knock since it offers the benefits of charge dilution. In this research EGR was adopted to reduce the thermal load on the exhaust manifold, since the reduced gas temperature is desirable for the reliability of an engine in light of both thermal efficiency and material issue of exhaust manifold. However, the occurrence of excessive cyclic variation with high EGR rates brings about an undesirable combustion instability within the engine cylinder resulting in the deterioration of both engine performance and emissions.<br/> For a LPG fueled engine, use of mixer and vaporizer gives its way to liquid phase port injection. Improved volumetric efficiency gives more power and accurate air-fuel ratio gives less amount of hazardous emission. In this research, the investigation of the effects of EGR on the reduction of thermal loading at exhaust manifold was performed in a single cylinder liquid-phase LPG injection engine. The effects of EGR variables (a wide range of EGR rates and EGR Temperature) on power and emission characteristics were also investigated As a result, the optimum EGR rate was derived effectively as a function of the operating conditions.
우영민(Youngmin Woo),배충식(Choongsik Bae),오승묵(Seungmook Oh),강건용(Kernyong Kang) 한국자동차공학회 2002 한국자동차공학회 Symposium Vol.2002 No.11
Lean burn was considered to overcome high thermal load and improve fuel economy in heavy duty SI engine with<br/> large bore size. Fuel stratification in the cylinder was utilized to acquire the feasibility of lean burn. Measurement of<br/> fuel distribution is one of the possible ways to identify the extent of fuel stratification. To obtain two dimensional fuel<br/> distribution planar laser induced fluorescence (PLIF) was used. Acetone was excited by KrF excimer laser (248nm)<br/> and its fluorescence image was acquired by ICCD camera.<br/> In this study the effects of various parameters such as fuel injection timing, swirl ratio and piston bowl shape were<br/> investigated. They were considered to have the direct effects on the mixture motion. Fuel injection strategy with<br/> respect to the intake process was found to have the key role of the whole stratification process. The optimal value in<br/> each parameter was sought that made the mixture well prepared for lean burn.
우영민(Youngmin Woo),김강출(Gangchul Kim),권오석(Ohseuk Kwon),표영덕(Youngdug Pyo),이영재(Youngjae Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Since hybrid electric vehicles(HEV) use a secondary battery as well as an internal combustion engine, their on road performance shows quite different characteristics compared with the conventional vehicles. The objective of this on road performance test is to provide the collection of operating data from HEV evaluation fleets(the Toyota PRIUS and Honda CIVIC) and the analysis of these data to provide an evaluation of fleet operation. As a result, different characteristics of the on road performance of each vehicle were analyzed through a statistical process on the basis of the ensemble average of each short trip interval. The relationship between the measured SOC change and battery current balance was investigated for the two hybrid electric vehicles.
우영민(Youngmin Woo),이영재(Youngjae Lee),김윤영(Yunyoung Kim),김종혁(Jong-Hyuk Kim),민병두(Byung-Du Min) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The characteristics of spray diesel injected into the cylinder provide crucial clues to the perception of the combustion performance in a compression ignition engine. In this study, five different diesel 커먼레일 injectors were examined which have different hole number, jet cone angle, and hydraulic flow rates. Both the macroscopic and microscopic characteristics of diesel sprays were compared through Mie-scattered light imaging and PDA (Phase-doppler anemometry) measurements. Seven hole injector with smaller hole was found to give better air/fuel mixing and favorable droplet size compared with other injectors. To evaluate the feasibility of achieving lower emission level with the different diesel sprays, the combustion and emission characteristics in case of 6 and 7 hole injectors were investigated under the same fuel flow rate condition in a light duty DI diesel Engine. The results showed that 7 hole injector with pilot injection had shorter combustion delay and combustion duration, but these effects were not found in high speed and high load condition with no pilot injection. The Seven hole injector could be utilized to achieve lower emission compared with six hole one because of more improved spatial distribution of fuel in combustion chamber. The full load performance such as brake torque and thermal efficiency of 6 and 7 hole injectors were slightly different according to engine speed.