• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.157-160
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• 2007

The catalyst layer of a proton exchange membrane (PEM) fuel cell is a mixture of polymer, carbon, and platinum. The characteristics of the catalyst layer play critical role in determining the performance of the PEM fuel cell. This research investigates the role of catalyst layer composition using a Central Composite Design (CCD) experiment with two factors which are Nafion content and carbon loading while the platinum catalyst surface area is held constant. For each catalyst layer composition， polarization curves are measured to evaluate cell performance at common operating conditions, Electrochemical Impedance Spectroscopy (EIS), and Cyclic Voltammetry (CV) are then applied to investigate the cause of the observed variations in performance. The results show that both Nafion and carbon content significantly affect MEA performance. The ohmic resistance and active catalyst area of the cell do not correlate with catalyst layer composition, and observed variations in the cell resistance and active catalyst area produced changes in performance that were not significant relative to compositions of catalyst layers.

• Journal of Electrical Engineering and Technology
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• 제7권6호
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• pp.891-897
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• 2012

In this paper, the observer based nonlinear state feedback controller has been developed to control the pressures of the oxygen and the hydrogen in the PEM(Proton Exchange Membrane) fuel cell system. Nonlinear model of the PEM fuel cell system was introduced to study the design problems of the state observer and model based controller. A cascade observer using the filtering technique was used to estimate the pressure derivatives of the cathode and the anode in the system. In order to estimate the pressures of the cathode and the anode, the sliding mode observer was designed by using these pressure derivatives. To estimate the oxygen pressure and the hydrogen pressure in the system, the nonlinear state observer was designed by using the cathode pressure estimates and the anode it. These results will be very useful to design the state feedback controller. The validity of the proposed observers and the controller has been investigated by using the Lyapunov's stability analysis strategy.

• Composites Research
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• 제34권6호
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• pp.406-411
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• 2021

PEM(양성자 교환막) 연료 전지는 부산물로 물 만을 생성하여 친환경 에너지원으로 각광받고 있다. 이러한 연료전지의 스택을 이루는 여러 부품들 중 연료전지의 효율을 결정짓는 분리판에 관한 연구가 활발히 진행되고 있다. 복합재료 분리판은 높은 강도와 강성 및 내식성을 갖지만 상대적으로 낮은 전기 전도도를 갖는 단점이 있다. 본 연구에서는 이러한 단점을 극복하고자 가스확산층(GDL)-복합재료 분리판 조합체를 개발하고 그 성능을 실험적으로 확인하였다. 선행 연구에서 개발된 흑연 포일 코팅법을 분리판과 GDL 간의 접촉 저항을 줄이기 위해 적용하였다. 또한, 스택 내의 전자 이동경로를 향상시키고 GDL과 분리판 사이의 접촉저항을 최소화하기 위하여 금속 박막을 이용하여 GDL-분리판 조합체를 제작하였다. 실험 결과 개발된 GDL-분리판 조합체는 기존의 복합재료 분리판과 비교하여 98% 낮은 전기저항을 갖는 것을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제26권12호
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• pp.2171-2178
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• 2016

Polyester cloth (PC) was selected as a prospective inexpensive substitute separator material for microbial fuel cells (MFCs). PC was compared with a traditional Nafion proton exchange membrane (PEM) as an MFC separator by analyzing its physical and electrochemical properties. A single layer of PC showed higher mass transfer (e.g., for $O_2/H^+/ions$) than the Nafion PEM; in the case of oxygen mass transfer coefficient ($k_o$), a rate of $50.0{\times}10^{-5} cm{\cdot}s^{-1}$ was observed compared with a rate of $20.8{\times}10^{-5}cm/s$ in the Nafion PEM. Increased numbers of PC layers were found to reduce the oxygen mass transfer coefficient. In addition, the diffusion coefficient of oxygen ($D_O$) for PC ($2.0-3.3{\times}10^{-6}cm^2/s$) was lower than that of the Nafion PEM ($3.8{\times}10^{-6}cm^2/s$). The PC was found to have a low ohmic resistance ($0.29-0.38{\Omega}$) in the MFC, which was similar to that of Nafion PEM ($0.31{\Omega}$); this resulted in comparable maximum power density and maximum current density in MFCs with PC and those with Nafion PEMs. Moreover, a higher average current generation was observed in MFCs with PC ($104.3{\pm}15.3A/m^3$) compared with MFCs with Nafion PEM ($100.4{\pm}17.7A/m^3$), as well as showing insignificant degradation of the PC surface, during 177 days of use in swine wastewater. These results suggest that PC separators could serve as a low-cost alternative to Nafion PEMs for construction of cost-effective MFCs.

• International Journal of Automotive Technology
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• 제8권1호
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• pp.119-126
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• 2007

Because of the low temperature operation, proton exchange membrane (PEM) fuel cell has a water phase transition. Therefore, water management is an important operation issue in a PEM fuel cell because the liquid water in the fuel cell causes electrode flooding that can lower the cell performance under high current density conditions. In this study, in order to understand the reactant distributions in the cathode channels of the PEM fuel cell, an experimental technique that can measure the species concentrations of reactant gases by using gas chromatograph (GC) is applied for an operating PEM fuel cell. The oxygen distribution along the cathode flow channels of PEM fuel cell is mainly investigated with various operating conditions. Also, the relations between cathode flooding and oxygen concentrations and oxygen consumption pattern along the cathode channel configurations of the unit cell adopted for this study are discussed using GC measurement and visualization experiment of cathode flooding. It is found that the amount of oxygen consumption is very sensitive to various operating conditions of the fuel cell and was much affected by the flooding occurrence in cathode channels.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.460-465
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• 2003

The modeling of PEM (Proton Exchange Membrane) fuel cell system consisting of fuel cell stack and BOP (Balance of Plant) is presented in this paper. The effects of temperature, pressure (air, hydrogen), and humidity on the fuel cell system performance were mainly investigated using thermo-dynamical and electro-chemical equations. To understand the power distribution characteristics of fuel cell system, the effects of operating temperature and air pressure on maximum power and system power were also demonstrated. Through this study, we can get the basic insight into the fuel cell stack and BOP component sizing and it can be used effectively for the optimization of the practical fuel cell systems in purpose.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 추계학술대회 논문집
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• pp.39-41
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• 2008

본 논문에서는 PEM(Proton Exchange Membrane) 연료전지 스택의 동적 특성에 관한 시뮬레이션에 대하여 기술한다. 연료전지의 출력은 부하 변동에 따른 가스 압력의 변화와 동작 온도의 변화 등에 민감하게 반응하는 특성을 갖고 있다. 본 논문에서는 부하 변화에 따른 스택 내부 채널의 가스 압력 변화를 계산하고 이를 Nernst 방정식에 적용하여 출력전압의 변동을 계산한 뒤 부하에 따른 손실을 계산하는 방법으로 동적 모델링을 수행하고 이를 이용한 시뮬레이션을 실시하였다. 스택의 각종 파리미터는 실험을 통해 추출되었고, 이를 적용한 Matlab/Simulink 시뮬레이션을 통해 제안된 모델이 연료전지 스택의 정특성 및 동특성을 적절하게 추종함을 확인하였다.

• 한국물환경학회지
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• 제26권4호
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• pp.681-686
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• 2010

Two different MFC designs were evaluated in batch mode: single compartment combined membrane-electrodes (SCME) design and twin-compartment brush-type anode electrodes (TBE) design (single chamber with two air cathodes and brush anodes at each side of the reactor). In SCME MFC, carbon anode and cathode electrodes were assembled with a proton exchange membrane (PEM). TBE MFC was consisted of brush-type anode and carbon cloth cathode electrodes without the PEM. A brush-type anode was fabricated with carbon fibers and was placed close to the cathode electrode to reduce the internal resistance. Substrates used in this study were glucose, leachate from cattle manure, or sucrose at different concentrations with phosphate buffer solution (PBS) of 200 mM to increase the conductivity thereby reduce the internal resistance. Hydrogen generating bacteria (HGB) were only inoculated in TBE MFC. The peak power densities ($P_{peak}$) produced from the SCME systems fed with glucose and leachate were 18.8 and $28.7mW/m^2$ at external loads of 1000 ohms, respectively. And the $P_{peak}$ produced from TBE MFC were 40.1 and $18.3mW/m^2$ at sucrose concentration of 5 g/L and external loads of 470 ohms, with a mediator (2-hydroxy-1, 4-naphthoquinone) and without the mediator, respectively. The maximum power density ($P_{max}$) produced from mediator present TBE MFC was $115.3mW/m^2$ at 47 ohms of an external resistor.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.96.1-96.1
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• 2005

• Advances in Energy Research
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• 제8권4호
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• pp.203-211
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• 2022

The aim of this paper is to analyze the performance of commercial fuel cell (rated capacity 1000W) with the help of resistive load and output power variation with change in H₂ flow rate and calculate the maximum power point (MPP) of the proton exchange membrane (PEM) while changing AC and DC load respectively. The factors influencing the output power of a fuel cell are hydrogen flow rate, cell temperature, and membrane water content. The results show that when the H₂ flow rate is changed from 11, 13, and 15 Lpm, MPP is increased from lower to higher flow rate. The power of the fuel cell is increased at the rate of 29% by increasing the flow rate from 11 to 15 lpm. This study will allow small-scale industries and residential buildings (in remote or inaccessible areas) to characterize the performance of PEMFC. Furthermore, fuel cell helps in reducing emission in the environment compared to fossil fuels. Also, fuel cells are ecofriendly as well as cost effective and can be the best alternative way to convert energy.