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LPDi 기관의 니들형상변화에 대한 인젝터내 기포발생현상의 해석
노기철(Kichol Noh),이종태(Jongtai Lee) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
One of the most important subjects to develop a LPDi engine is to suppress the bubble generated inside LPG direct injector. For the purpose of this, the bubbling phenomenon and behavior arc visualized and studied according to several needle configuration and the temperatures around an injector wall by using analogy visualization injector manufactured in this study. As the sac volume in LPDi injector is decreased, the generation of bubble is more active although the temperature around the injector wall is the same. Also, the number and rising velocity of bubble generated are increased with decrease of the sac volume.<br/>
디젤기관의 아트킨슨 사이클화에 따른 제반성능의 열역학적 해석
노기철(Noh Kichol),권오문(Kwon Ohmun),정양주(Jeong Yangjoo),이종태(Lee Jongtai) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
In order to recognize thermal efficiency and power in case diesel cycle is turned into diesel-atkinson cycle, the fuel-air diesel-atkinson cycle, which is considering intake and exhaust process, is analyzed non-dimensionally and thermodynamically. In Diesel-Atkinson cycle, as expansion ratio is increased as thermal efficiency is increased and the maximum value appears when expansion ratio is equal to compression ratio(Rec=1).<br/> When conventional diesel cycle is turned into diesel-atkinson cycle by high expansion with retard intake valve closing timing, thermal efficiency and power is decreased by reduction of effective compression ratio and intake air. This is compensated by increasing of effective compression ratio and over-charging of air with change of intake valve closing timing.<br/> In case of compensating compression ratio, Rec=1 appears around 100˚ ABDC, and it is expected that thermal efficiency is enhanced by 14.3% compared with conventional diesel engine. In case of over-charging and compensating compression ratio simultaneously. the over-charging pressure is 2.26bar at Rec=l.
노기철(Kichol Noh),윤재성(Jaeseong Yoon),박상욱(Sangwook Park),이종태(Jongtai Lee),임희수(Heesu Lim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The hydrogen fueled free piston engine is acknowledged as the next generation power system which is able to obtain high efficiency and low emission, concurrently. So, it is schemed to improve the performance of the hydrogen fueled free-piston engine in order to ensure the possibility to substitute the fuel cell. Hence the performance of the hydrogen fueled free-piston engine is analyzed by using linear RICEM for the change of fuel supply pressure and equivalence ratio. As the results, at fuel pressure Pf=6bar and equivalence ratio φ=0.5, respectively thermal efficiency is over 50% and hydrogen fueled free-piston engine is estimated to possible substitute for the fuel cell under this condition.
디젤기관의 아트킨슨 사이클화를 위한 실린더내 PIV 유동계측
노기철(Kichol Noh),정양주(Yangjoo Jeong),이종태(Jongtai Lee) 한국자동차공학회 2002 한국자동차공학회 Symposium Vol.2002 No.11
The adoption of Atkinson-cycle in disel engine with conventional piston type is considered as one of the methods to increase the thermal efficiency. The realization of atkinson-cycle in diesel engine can be realized by early or late intake valve closing timing same as otto engine. <br/> In this study, to suggest the appropriate intake valve closing timin for realizing diesel-atkinson engine, the in-cylinder flow is visualized by means of PIV method for the cases of advanced and retarded intake valve closing timings compared with conventional type.<br/> From the results, it is found that momentum is the largest and turbulent intensity is kept to the end of compression process due to the inertia effect and the increase of flow around the middle of compression process at 50?? retarded of closing timing.
LPDi 기관의 인젝터 내 기포발생 억제를 위한 기초연구
노기철(Kichol Noh),이제홍(Jehong Lee),이종태(Jongtai Lee) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
The one of the most important subject to develop a LPDi engine is to suppress the generation of bubble inside the liquid LPG direct injector. In this study, the preventing effect of bubble generation by cooling of the surrounding of injector and through by-pass under firing stop was analyzed.<br/> As results, it was found that the temperature of bubble generation increases about 4K by cooling 20K in the surrounding temperature of an injector at 30bars of fuel pressure. As the surround temperature of the injector increases after bubbles are generated, bubbles are awfully generated. The spray tip penetration decreases about 17% when the surrounding temperature increases 8K. It was seen that the generation of bubble is able to be prevented by menas of 60% of by-pass.
Huynh Thanh Cong,강준경(Joonkyoung Kang),노기철(Kichol Noh),이종태(Jongtai Lee) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In order to develop an external mixture type hydrogen engine with high performance, the characteristics of performance and combustion are investigated for various valve overlap period by using Hz engine installed a mechanical continuous variable valve timing system. In experiments, valve overlap periods are analogically varied for 0° to 400°CA by 10°CA with the same amount of supplied energy as valve overlap period of O°CA, fuel-air equivalence ratio of 0.3 to backfire limit equivalence ratio. The obtained results show that by using a similarly low supplied energy, the tendencies of the basic qualitative performance and combustion characteristics are similar to conventional engines using petroleum fuel, but quantitative results give a little difference. The backfire limit equivalence ratio (defined as the upper limit of fuel-air equivalence ratio just before backfire occurs) was also improved significantly with decrease of valve overlap period and/or for operating conditions with the same amount of supplied energy.