http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
홍성은,강환국 대한설비공학회 2006 설비공학 논문집 Vol.18 No.11
Considering heat pipe design principles in fabrication and operational performances, water is one of the most recommended working fluids to make mid to low temperature heat pipes. But the conventional water heat pipes might encounter the failure in a cold start-up operation when socked at a chilling temperature lower than the freezing point. If they are subjected to a heat supply for start-up at a temperature around -20℃, the rate of the vapor flow and the corresponding heat transfer from the evaporator to the condenser is so small that the vapor keeps to stick on the surface of the chilling condenser wall, forming an ice layer, resulting in a liquid deficiency in the evaporator. This kind of problems was resolved by Kang et al. in 2004 by adopting a gas loading heat pipe technology to the conventional water heat pipes. This study was conducted to examine a chilling start-up procedure of gas loading heat pipes by investigating the behaviors of heat pipe wall temperatures. And the thermal resistance of the gas loaded heat pipe that depends on the operating temperatures and heat loads was measured and examined.Two water heat pipes were designed and fabricated for the comparison of performances, one conventional and the other loaded with N2 gas. They were put on start-up test at a heat supply of 30W after having been socked at an initial temperature around -20℃. It was observed that the gas loaded one had succeeded in chilling start-up operation.
Axiomatic Design 기법을 이용한 연료전지 냉시동 특성 개선에 관한 연구
서정도(Suh, Jung-Do),이성호(Lee, Sung-Ho),안병기(Ahn, Byung-Ki),임태원(Lim, Tae-Won),유하나(Yu, Ha-Na),이대길(Lee, Dai-Gil) 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.10
Cold start of a fuel cell system is a major obstacle should be overcome as to commercialize it, especially for passenger vehicle applications. However, the cold start characteristics is so complicated since it involves various phenomenon such as ice-blocking in GDL, ionic conductivity in membrane affected by water activity with phase change, heat transfer through components such as bipolarplates or endplates, electro-chemical reactions affected by circumferential temperature and humidity as well. Axiomatic design provides a systematic method to investigate the complex phenomenon although it was developed as a methodology to establish logical design procedure by Nam P. Suh in 1990s. This paper presents a framework to approach the complex cold start problem using Axiomatic Design which features simplifying a problem through hierarchical decomposition and decoupling from the view of functional requirements and design parameters.
냉시동 환경에서 thermal cycle이 FEMFC의 MEA 열화에 미치는 영향
이준기(Rhee, Jun-Kee),서동호(Seo, Dong-Ho),전유권(Jeon, Yu-Kwon),설용건(Shul, Yong-Gun) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06
In recent times, starting up polymer electrolyte membrane fuel cells(PEMFC) in sub-zero condition is a great challenge of fuel cell electric vehicle(FCEV). The water produced in a cathode during PEMFCs operate. The water changes into the form of solid/ice in sub-zero temperatures and this makes trouble in PEMFC cells. Voltage of PEMFC drops and cold startup is failed. This paper describes an experimental study on the effect of thermal cycle to degradation of MEA in PEMFC.
냉시동 시 포트 마스킹이 실린더 내부의 HC와 NOx 생성 및 배출에 미치는 영향
전우주(Wooju Jeon),최관희(Kwanhee Choi),김주원(Ju-Won Kim),박심수(Simsoo Park),이경환(Kyung-Hwan Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Emission characteristics at cold start condition with different intake charge motions by port masking schemes in the CVVT (Continuously Variable Valve Timing) engine was investigated. Time resolved in-cylinder and exhaust emissions were measured by the fast response HC and NOx analyzers to examine their formation mechanism and exhaust characteristics. As a result, in-cylinder HC decreased with the enhanced intake charge motion. However, charge motion improvement caused an increment of combustion temperature thus in-cylinder NOx increased. Exhaust HC decreased with port masking schemes due to the increment of lean misfire limit. However exhaust NOx increased by the addition of intake air to replace the engine output power down. It was confirmed that swirl and tumble improved the intake charge motion and had an effect on the stability of combustion in the cylinder. This effect caused a reduction of HC however NOx increased.
CFD를 이용한 냉시동 조건에서의 GDI 엔진 내 분무거동 및 혼합기 분포에 관한 연구
김주한(Joohan Kim),이경현(Kyeonghyeon Lee),권혁선(Hyuksun Kwon),민경덕(Kyoungdoug Min) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
Gasoline Direct Injection (GDI) engine is in the spotlight as the next generation engine technology since it is possible to reduce fuel consumption and increase engine performance. However, under the cold start of engine, high injected fuel amount and the low vaporization result the wall wetting problem and unstable combustion. Compare to the conventional Port Fuel Injection (PFI) engine, the mixing process depends largely on the spray behavior and the combustion process is relying on the mixture formation. Since the experimental approach has limitation to investigate the in-cylinder physical phenomena, the CFD analyses can be an alternative approach to gain a full insight of the overall process. In this research, a numerical study on mixing process of a GDI engine under cold start condition was carried out, and the effects of fuel injection timing were investigated
고재준,이종현,김세훈,임태원,안병기 한국수소및신에너지학회 2009 한국수소 및 신에너지학회논문집 Vol.20 No.3
The improvement of cold start capability is one of the most challenging tasks to be solved for commercialization of fuel cell vehicle. In this study, cold start test and ice blocking test(IBT) of fuel cell stack were carried out under various operating conditions. This fuel cell stack can be thawed from -20℃ within 25s and the voltage change was found to be comprised of 4 steps; the first step is the voltage decrease by overpotential, the second step is the voltage increase by the cell temperature increase, the third step is the voltage decrease by ice blocking, and the last step is the voltage increase by thawing. Bootstrap startup was failed after shutdown at temperature under 40℃ because of much condensed water in the fuel cell. Quantitative estimation of cold start capability have been demonstrated by ice blocking test(IBT). In the results, it was found that cold start capability was improved double every 10℃ from 30℃ to 65℃ and enhanced by 30% at the condition of SR 3/4 compared to SR 1.5/2.0 and enhanced by 20% with dry purge condition compared to with RH 50% purge condition.
고재준(Ko, Jae-Jun),권순길(Kwon, Soon-Kill),금영범(Kum, Young-Bum),이종현(Lee, Jong-Hyun) 한국신재생에너지학회 2007 한국신재생에너지학회 학술대회논문집 Vol.2007 No.11
The startup behaviour of PEM fuel cells at subfreeze zero is one of the most challenging tasks to be solved before PEM fuel cell vehicle is commercialized. Automotive companies are trying to increase cold statup capability of fuel cell. In this study, we found out the design factor of the stack to increase cold startup capability using 4kW stack and then cold startup test was performed at the various shutdown condition and the various current. In order to test the cold startup possibility and capability in vehicle, we installed 80kW stack in the vehicle and this 80kW fuel cell vehicle was housed in an environmental chamber to investigate the characteristics of cold startup and driving. We found that it is possible for fuel cell vehicle with 80kW stack to self-heated cold startup and drive at -15?C.