• Advances in Energy Research
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• 제2권2호
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• pp.73-84
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• 2014

Fuel cells of proton exchange membrane type (PEMFC) working with hydrogen in the anode and ambient air in the cathode ('air breathing') have been prepared and characterized. The cells have been studied with variable thickness of the cathode catalyst layer ($L_{CL}$), maintaining constant the platinum and ionomer loads. Polarization curves and electrochemical active area measurements have been carried out. The polarization curves are analyzed in terms of a model for a flooded passive air breathing cathode. The analysis shows that $L_{CL}$ affects to electrochemical kinetics and mass transport processes inside the electrode, as reflected by two parameters of the polarization curves: the Tafel slope and the internal resistance. The observed decrease in Tafel slope with decreasing $L_{CL}$ shows improvements in the oxygen reduction kinetics which we attribute to changes in the catalyst layer structure. A decrease in the internal resistance with $L_{CL}$ is attributed to lower protonic resistance of thinner catalyst layers, although the observed decrease is lower than expected probably because the electronic conduction starts to be hindered by more hydrophilic character and thicker ionomer film.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.699-702
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• 2012

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.135.2-135.2
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• 2010

Carbon nanotube(CNT) has been spotlighted as a promising candidate for catalyst support material for PEMFC (proton exchange membrane fuel cell). The considerable properties of CNT include high surface area, outstanding thermal, electrical conductivity and mechanical stability. In this study, to fully utilize the properties of CNTs, we prepared directly oriented CNT on carbon paper as a catalyst support in the cathode electrode. The CNT layer was prepared by a chemical vapor deposition(CVD) process. And the Pt particles were deposited on the CNT oriented carbon paper by impregnation and eletro-deposition method. The potential advantages of directly oriented CNT on carbon paper can include improved thermal and charge transfer through direct contact between the electrolyte and the electrode and enhanced exposure of Pt catalyst sites during the reaction.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2005년도 수소연료전지공동심포지움 2005논문집
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• pp.93-96
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• 2005

고분자전해질형 연료전지에서는 수소이온의 이온전도성 저하를 방지하기 위하여 외부에서 가습하여 주는 방식이 일반적이지만, 가습에 소요되는 부품을 일부라도 제거할 경우 연료전지의 효율은 높이고 제작단가도 경감할 수 있다. 이를 위하여 저가습 및 무가습 실험을 수행하였으며, 정확한 data의 수집과 시험장비의 자동제어를 위하여 National Instrument사의 compact field point (cFP)를 사용하였다. Humidifier와 heater의 온도를 조절하여 공급유체의 상대습도 및 온도를 각각 조절하였으며, 이에 필요한 이론적 온도는 Antoine equation 을 사용하여 산정하였다. Anode와 cathode 양측 $100\%$ 가습 경우를 기준으로 가습량을 조절하면서 실험을 수행하였으며 성능 차이를 그래프로 도시하여 양측의 변화에 대한 영향을 볼수 있도록 하였다. Stack의 온도가 $70^{\circ}C$이고 양측 무가습일 경우에 성능 측정이 어려워서 stack의 온도를 저온에서부터 변화시키면서 무가습 성능을 실시간으로 측정하여 보았다. 일반적으로 hydronium ion은 anode측에서 cathode측으로 계속 이동하여야 전기를 생성할 수 있으므로 cathode측 무가습이 anode측 무가습보다 성능이 더 잘 나오는 것으로 예측하였으나 이와 반대되는 경향의 실험 결과를 얻었다. 양측 무가습의 경우에는 공기 중의 상대습도와 back diffusion 등에 영향을 받을 수 있으므로 각종 변수들의 영향을 분리하여 관찰할 수 있는 실험을 수행 중에 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.510-515
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• 2004

A proton exchange membrane fuel cells(PEMFC) operate at low temperature, allowing for faster startups and immediate response to change in the demand for power, and also deliver high power density. To maximize economical efficiency in PEMPC, it is necessary to the optimization. Response surface method(RSM) has non-gradient and fast convergency characteristics. Sampling points are extracted by design of experiments using Central Composite Method. In this paper, it is shown that the optimization is required for the design study of the PEMFC.

• International Journal of Automotive Technology
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• 제6권4호
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• pp.429-436
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• 2005

In this paper, operation algorithms are evaluated for a fuel cell hybrid electric vehicle (FCHEV). Power assist, load leveling and equivalent fuel algorithm are proposed and implemented in the FCHEV performance simulator. It is found from the simulation results that the load leveling algorithm shows poor fuel economy due to the system charge and discharge efficiency. In the power assist and equivalent fuel algorithm, the fuel cell stack is operated in a relatively better efficiency region owing to the battery power assist, which provides the improved fuel economy.

• International Journal of Automotive Technology
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• 제1권1호
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• pp.9-16
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• 2000

The growing concerns on environmental protection have been constantly demanding cleaner and more energy efficient vehicles without compromising any conveniences provided by the conventional vehicles. The recent significant advances in proton-exchange-membrane (PEM) fuel cell technology have shown the possibility of developing such vehicles powered by fuel cells. Several prototype fuel cell electric vehicles (FCEV) have been already developed by several major automotive manufactures, and all of the favorable features have been demonstrated in the public roads. FCEV is essentially a zero emission vehicle and allows to overcome the range limitation of the current battery electric vehicles. Being motivated by the laboratory and field demonstrations of the fuel cell technologies, variety of fuel cell alliances between fuel cell developers, automotive manufactures, petroleum companies and government agencies have been formed to expedite the realization of commercially viable FCEV. However, there still remain major issues that need to be overcome before it can be fully accepted by consumers. This paper describes the current fuel cell vehicle development status and the staggering challenges for the successful introduction of consumer acceptable FCEVS.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.550-553
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• 2008

In this paper, experiments of air-breathing proton exchange membrane fuel cell (PEMFC) for mobile devices were carried out according to the cathode conditions. These conditions are defined by the cathode flow field plate type (the channel type, the open type) and the cathode surface direction. Single cell and 6-cell stack were used in this experiments. The experimental results showed that the open type cathode flow field plate gave better performance for small size PEMFCs because the open type cathode plate allowed better air convection than the channel type cathode plate. In the experiments related to the direction of the slits on the cathode flow field plate, the horizontal slit cell was better than the vertical slit cell. With respect to the cathode surface direction, when the cathode surface is placed in the direction normal to the ground, PEMFC generated more stable power in the mass transport loss region.

• International Journal of Automotive Technology
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• 제5권4호
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• pp.287-295
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• 2004

A performance simulator for the fuel cell hybrid electric vehicle (FCHEV) is developed to evaluate the potentials of hybridization for fuel cell electric vehicle. Dynamic models of FCHEV's electric powertrain components such as fuel cell stack, battery, traction motor, DC/DC converter, etc. are obtained by modular approach using MATLAB SIMULINK. In addition, a thermodynamic model of the fuel cell is introduced using bondgraph to investigate the temperature effect on the vehicle performance. It is found from the simulation results that the hybridization of fuel cell electric vehicle (FCEV) provides better hydrogen fuel economy especially in the city driving owing to the braking energy recuperation and relatively high efficiency operation of the fuel cell. It is also found from the thermodynamic simulation of the FCEV that the fuel economy and acceleration performance are affected by the temperature due to the relatively low efficiency and reduced output power of the fuel cell stack at low temperature.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 추계학술대회 논문집
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• pp.90-93
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• 2007

본 연구에서는 전압품질에 민감한 설비를 위한 3상 하이브리드 Z-소스 동적 전압 보상기(Z-HDVR : Hybrid Z-Source Dynamic Voltage Restorer)을 제시하였다. 제안된 시스템은 수동필터와 Z-소스 토폴로지의 직렬형 능동필터로 구성된다. Z-HDVR의 ESS(Energy Storage System)로는 친환경적인 고분자 전해질 연료전지(PEMFC : Proton Exchange Membrane Fuel Cells)를 사용하였다. 고조파 검출 알고리즘은 동기좌표계의 $i_d-i_q$ 이론에 의하였으며, 부하전압 보상을 위하여 PI제어를 사용하였다. 전압swell 및 sag등 다양한 전원 조건하에서 제안된 시스템의 보상 성능을 검토하였다.