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2행정 싱글형 프리피스톤 수소 기관의 구동 안정성 확보를 위한 실험적 연구
변창희(CHANGHEE BYUN),안병호,이종태(JONGTAI LEE),이용균(YOUNGGYUN LEE) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5
Potential advantages of the free-piston engine are optimized combustion by realizing variable compression ratio, leading to higher efficiency at part load and less frictional losses due to a simple design without crank system. It has also advantage of the low emission and high performance by using hydrogen fuel. The structure of a single free-piston engine with hydrogen fuel is relatively so simple as compared with a dual piston type adapted conventionally in a free piston engine researches. But driving characteristics of a single type free piston engine is greatly influenced by the piston compression energy. In this study, as an initial step for the driving stability of single type 2-stroke free-piston engine with hydrogen fuel, it was analyzed about the piston compression dynamic. The method compressing the piston by the spring causes the in-cylinder pressure variation due to the piston vibration at TDC, but the method by the static air pressure is appropriate in terms of driving the stability. In order to improve the driving stability of single type free piston engine should be applied the proper compression energy.
역단류 소기방식을 갖는 2행정 프리피스톤 수소기관의 점화시기 변화에 따른 역화 특성
변창희(Changhee Byun),조관연(Gwanyeon Cho),백대하(Daeha Back),이종태(Jongtai Lee) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
In order to develop two-stroke free-piston hydrogen engine to obtain high thermal efficiency and low emission , it is necessary to use reverse uni-flow scavenging type to prevent backfire occurrence. In this research, the engine combustion and backfire occurrence were studied by using RICEM for researching combustion characteristics of the reverse uni-flow scavenging two-stroke free-piston hydrogen fueled engine. As a result, Ignition timing change of the two-stroke free-piston hydrogen fueled engine with reverse uni-flow scavenging have influence on piston displacement and backfire occurrence. Because delaying ignition timing increase combustion pressure and ignition timing exceeded stroke 82㎜ decrease combustion pressure.
프리피스톤 수소기관의 고효율 및 NOx 저감 가능성에 관한 연구
백대하(Daeha Baek),변창희(Changhee Byun),이종태(Jongtai Lee) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
In order to grasp the feasibility of high efficiency and low NOx emissions for H2 engine with free-piston, characteristics were analyzed by using ultra lean mixture in case of changing scavenging valve opening timing and scavenging pressure. As the results, it was shown that using ultra lean mixture is the feasibility of increasing efficiency and zero-level of NOx emissions without backfire. The other side, it was confirmed that efficiency and NOx remarkably depend on scavenging valve opening timing.
HCCI 수소기관에서 탄소계 배기성분 첨가에 의한 수소 EGR 특성분석
이건식(Keonsik Lee),변창희(Changhee Byun),이종구(Jonggoo Lee),양 취엔 조우(Yang Chuanzhou),이종태(Jongtai Lee) 한국자동차공학회 2015 한국자동차공학회 부문종합 학술대회 Vol.2015 No.5
In a HCCI engine with hydrogen, NOx increases and operating region decreases by increasing rate of pressure rise due to high compression ratio. EGR in a HCCI-hydrogen engine can decrease NOx and increase operating region by decreasing rate of pressure rise. However, like the case of using diesel or gasoline engine with EGR, when carbon exhaust composition is applied to a HCCI-hydrogen engine with EGR, the characteristics of hydrogen-EGR are uncertain. In this research, engine performance is analysed with EGR and CO₂ rate including compression ratio in HCCI-hydrogen research engine for evaluating adaptability carbon exhaust composition for a HCCI-hydrogen engine with EGR. When comparing with a HCCI-hydrogen engine with normal EGR, application of carbon exhaust composition for a HCCI-hydrogen engine with EGR has a little positive effects such as increasing operating region, decreasing knock frequency and NOx.
수소 HCCI 기관의 역화현상 규명을 위한 실린더 내 순간 열 유속 해석
김진구(Jingu Kim),변창희(Changhee Byun),이종태(Jongtai Lee) 한국자동차공학회 2016 한국자동차공학회 학술대회 및 전시회 Vol.2016 No.11
To investigate phenomenon of backfire in the cylinder of Hydrogen HCCI engine, instantaneous wall-surface temperature and heat flux of the cylinder head are measured and analyzed. As the results, there is a no possibility of hot-surface ignition in hydrogen HCCI engine. and, there is a chance to occur back-fire that burned gas goes in crevice volume of piston and comes out of the crevice volume to cylinder during intake preocess