• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.90.1-90.1
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• 2010

The design and fabrication of a metallic bipolar plate-gasket assembly for polymer electrolyte fuel cells (PEMFCs) is defined. This bipolar plate-gasket assembly was prepared by inserting a previously prepared bipolar plate in the specially designed gasket mold. For this aim, a proprietary fluoro-silicone based rubber was injected directly into the bipolar plate borders. Gaskets obtained like this showed the chemically / physically stable and the good sealibilty in typically operating PEM fuel cell conditions. And also, this bipolar plate-gasket assembly shows lots of advantages with respect to traditional PEMFCs stack assembling systems: useful application to automative stacking due to easy handling, reduced fabrication time, possibility of quality control and failed elements substitution. This bipolar plate-gasket assembly was evaluated in the short fuel cell stack and met the leakage requirement for normal operation both in short-term and in long-term operation. Especially, it was confirmed that this gasket could be applied successfully even in the high pressure FEM fuel cell systems(over 2.0 bar in absolute pressure).

• 한국수소및신에너지학회논문집
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• 제22권3호
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• pp.305-312
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• 2011

The use of a separator to control stack temperature in a molten carbonate fuel cell was studied by numerical simulation using a computational fluid dynamics code. The stack model assumed steady-state and constant-load operation of a co-flow stack with an external reformer at atmospheric pressure. Representing a conventional cell type, separators with two flow paths, one each for the anode and cathode gas, were simulated under conditions in which the cathode gas was composed of either air and carbon dioxide (case I) or oxygen and carbon dioxide (case II). The results showed that the average cell potential in case II was higher than that in case I due to the higher partial pressures of oxygen and carbon dioxide in the cathode gas. This result indicates that the amount of heat released during the electrochemical reactions was less for case II than for case I under the same load. However, simulated results showed that the maximum stack temperature in case I was lower than that in case II due to a reduction in the total flow rate of the cathode gas. To control the stack temperature and retain a high cell potential, we proposed the use of a separator with three flow paths (case III); two flow paths for the electrodes and a path in the center of the separator for the flow of nitrogen for cooling. The simulated results for case III showed that the average cell potential was similar to that in case II, indicating that the amount of heat released in the stack was similar to that in case II, and that the maximum stack temperature was the lowest of the three cases due to the nitrogen gas flow in the center of the separator. In summary, the simulated results showed that the use of a separator with three flow paths enabled temperature control in a co-flow stack with an external reformer at atmospheric pressure.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.180-184
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• 2005

An experimental study is performed to evaluate the performance and the efficiency by humidifying MEA and by making the double-tied catalyst layers in a fuel cell system which is taken into account the physical and thermal concept. An electrical output produced by PEFC(polymer Electrolyte Fuel Cell) is measured to assess the performance of the stack and the efficiency is also evaluated according to the different situation in which is placed with and without the humidification of MEA (Membrane Electrolyte Assembly). Subsequently, It is found that the measured values of stack voltage and current are influenced by the stack temperature, humidification, and the double-tied catalyst layers which gives more enhanced values to apply for electric units.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.89-90
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• 2006

The bipolar plate is a major component of the PEM fuel cell stack, which takes a large portion of stack cost. In this study, as alternative materials fur bipolar plate of PEM fuel cells, graphite composites were fabricated by compression molding. Graphite particles mixed with epoxy resin were used as the main substance to provide electric conductivity. Flow channels were fabricated by compression molding, and design of experiments (DOE) was applied to the tests to evaluate moldability. Results showed that land width and channel depth were two significant factors for moldability, and channel width had little influence on the moldability.

• 신재생에너지
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• 제1권2호
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• pp.41-52
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• 2005

The effects of internal manifold designs on the reactants feed-stream in Polymer Electrolyte Fuel Cells [PEFCs] is studied to figure out flow and thermal distribution patterns over an entire fuel cell stack. Reactants flows are modeled either laminar of turbulent depending on regions and the open channels in the bipolar plates are simulated by porous media where permeability should be pre-deter-mined for computational analysis. In this work, numerical models for reactants feed-stream In the PEFC manifolds are classified Into two major flow patterns: Z-shape and U-shape. Several types of manifold geometries are analyzed to find the optimal manifold configurations. The effect of heat generation in PEFC on the flow distribution is also Investigated applying a simplified heat transfer model in the stack level (i.e. multi-cell electrochemical power-generation unit). This modeling technique Is well suited for many large scale problems and this scheme can be used not only to account for the manifold flow pattern but also to obtain Information on the optimal design and operation of PEFC systems.

• 한국수소및신에너지학회논문집
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• 제21권5호
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• pp.419-424
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• 2010

The 125kW external reforming (ER) type molten carbonate fuel cell (MCFC) system for developing a commercial prototype has been operated at Boryeong thermal power plant site since the end of 2009. The system consists of 125kW stack with $10,000 cm^2$ effective area, mechanical balance of plant (MBOP) with anode recycle system, and electrical balance of plant (EBOP). The 125kW MCFC stack installed in December, 2009 has been operated from January, 2010 after 20 days pre-treatment. The stack open circuit voltage (OCV) was 214V at initial load operation, which approaches the thermodynamically theoretical voltage. The stack voltage remained stable range from 160V to 180V at the maximum generating power of 120 kW DC. The stack has been operated for 3,270 hours and operated at rated power for 1,200 hours.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2005년도 수소연료전지공동심포지움 2005논문집
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• pp.103-110
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• 2005

Fuel cell systems are consisted of various parts, for example fuel cell stack, fuel supplier, electrical converters, controllers and so on. Each components of system should have appropriate specification for their applications as well as simplicity. Because thermal load can be managed simply by using fans without any water cooling system, the air-cooled PEMFC is widely used in sub kW and around 1kW systems. The performance of an air-cooled system is highly dependent on ambient temperature and humidity. In this paper, the air-cooled PEMFC systems are developed and investigated to study the operating characteristics in the aspect of the thermal and water coupled management by the control of the axial fans and compressors. Various experiments were also conducted to get the cell voltage distribution, the relative humidity of the reactant gas and the thermal management by axial cooling fans, which cannot be observed in single cell experiment. After then, as practical applications, portable fuel cell system and a hybrid electric cart were successfully integrated and operated by using this air-cooled stack.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.97-100
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• 2007

Fuel Cell Stack performance, which is influenced by the maintenance of a constant internal environment, requires high levels of air tightness. Used for analysis, gasket for fuel cell is made of elastic rubber materials and placed over separator, and shape of deformation of a gasket affects the transformation separator and airtightness while fastening structure. Separator as made of steel sheet isn't broken under pressure but can affect gas and cool water flow by the plastic deformation process. Therefore， it is understood that assembly process is well developed in case distribution of stress and shape of deformation is shown uniformly. This study is conducted on the assumption that a fuel cell maintenance is advantageous in that conditions. In this paper, analyses of unit cell and partial model were performed and distribution of stress and shape of deformation of Gasket and separator were analyzed to evaluate the airtightness while fastening structure.

• Journal of Advanced Marine Engineering and Technology
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• 제35권5호
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• pp.590-599
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• 2011

연료전지시스템의 고효율화를 목적으로 수소가 가진 화학적 에너지를 최대한 전력화하기 위하여 연료전지에서 발생하는 폐열을 적극 활용할 필요가 있다. 이런 목적에 폐열을 이용하는 증기터빈과 연료 전지를 결합시킨 SOFC/ST 하이브리드시스템이 적합하다. 본 논문은 SOFC/ST 하이브리드시스템에 대한 셀의 작동온도와 전류밀도, 연소기 출구 온도, 보일러 출구 가스온도가 시스템의 성능에 미치는 영향 등을 시뮬레이션을 통하여 검토한 것으로 증기터빈의 일정 조건에서는 연료전지 스택에서 다량의 폐열이 발생하는 경우가, 연료전지의 일정 조건에서는 연소기에 추가적 연료 공급을 억제하는 경우에서 하이브리드시스템의 효율이 증가됨을 확인하였다.

• 한국수소및신에너지학회논문집
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• 제30권5호
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• pp.401-410
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• 2019

The operating conditions greatly impact the efficiency and performance of polymer electrolyte membrane (PEM) fuel cell systems and must be properly managed to ensure better performance and efficiency. In particular, small variations in operating conditions interact with each other and affect the performance and efficiency of PEM fuel cell systems. Thus, a systematic study is needed to understand how small changes in operating conditions affect the system performance and efficiency. In this paper, an automotive fuel cell system (including cell stack and balance of plant [BOP]) with a turbo-blower was modeled using MATLAB/Simulink platform and the sensitivity analyses of main operating parameters were performed using the developed system model. Effects of small variations in four main parameters (stack temperature, cathode air stoichiometry, cathode pressure, and cathode relative humidity) on the system efficiency were investigated. The results show that cathode pressure has the greatest potential impact on the sensitivity of fuel cell system efficiency. It is expected that this study can be used as a basic guidance to understand the importance of achieving accurate control of the fuel cell operating conditions for the robust operation of automotive PEM fuel cell systems.