• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.5
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• pp.68-75
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• 2010

The one of the major problems in the development of PEMFC was regarding to the assurance of sealing on stack. The failure on the sealing creates the problems of fuel leakage, mixing, internal combustion, damage on parts and can be a direct reason for the degrading the efficiency of fuel cell. This paper studies on the analytical approach for improving the contacting pressure distribution on the gasket at the evaluation on the sealing of fuel cell stack. So, the assembly analysis on multi layered fuel cell stack was performed. The research on the simplification of finite element model was performed for three dimensional analysis at the multi layered state. The improved contact pressure distribution was obtained through the case studies on gasket for better sealing. In addition, the number of the cell was determined for the effective analysis and the structural characteristics were evaluated based on this research.

• New & Renewable Energy
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• v.1 no.2 s.2
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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.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.3
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• pp.143-148
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• 2018

In this study the performance and humidity variation for 2 unit cells connected in series were experimentally measured. The relative flow direction of hydrogen and air was changed from parallel flow to counter flow. Internal humidity distribution was then measured by 5 embedded sensors on each channel. In all experimental conditions, the former unit cell showed a better performance and the gap is noted to be higher when counter flow is applied. The performance was noted to be higher at high humidification case in the parallel flow. However, in the counter flow, the difference of performance according to the humidification is negligible. Hydrogen and air are discharged from the PEMFC unsaturated with water vapor at parallel flow/low humidification condition, which explains lower performance of the PEMFC than other conditions. The humidities in hydrogen and air streams of counter flow were noted to increase rapidly even at low humidification condition and the consequential even hydration of membrane is the reason of higher performance.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.17-20
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• 2008

HYOSUNG manufactured and tested 1kW class PEFC systems to generate electrical and thermal energy for each residential usage. In particular, HYOSUNG developed power conditioning system that performs over 91% electrical conversion ratio specified in 1kW class PEFC systems. Prior to system integration, we tested each performances of components to derive control issues from it. In addition, we have been developing the adequate simulator to describe and predict system performance. In this paper, we verified HYOSUNG's 1kW class PEFC systems are valid for residential energy sources by testing the characteristics of systems and performances of main components.

• Journal of the Korean Institute of Gas
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• v.11 no.3
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• pp.40-43
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• 2007

The performance of PEMFC stack can be improved significantly by optimizing the design and operating conditions. As a result, the performance of daily operation showed slight deviation (0.02-0.9%) after accumulated DSS operation for 500 hrs but the stack performance was stable. Therefore, it is confirmed that it would be improved the life-time of stack and operation reliability for the commercialization of PEMFC system.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.751-760
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• 2014

The unmanned underwater vehicle(UUV) requires the highly dense energy source because of its limited space. Especially, for the UUV designed for long-term operation, it should be reviewed first whether it is possible to install the energy source against required total power. Therefore, this study identifies whether it is possible to install the energy source for the energy requirement of the UUV. And fuel and oxidizer requirement for the fuel cell system are calculated to determine its location and layout inside of the vehicle. Finally, we design the closed type 1kW polymer-electrolytic fuel cell system and check the applicability to underwater operations with UUV.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.346-347
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• 2012

최근 화석연료 대체 에너지원으로서 자동차용으로 연구 개발 및 응용되고 있는 고분자 전해질 연료전지(PEMFC: Proton exchange membrane fuel cells)에서 분리판(Bipolar Plate)은 스택 전체 무게의 80%, 스택 가격의 60% 정도로 가장 높은 비중을 차지한다. 분리판은 연료와 산화제를 공급해주는 통로 및 전지 운전 중에 생성된 물을 제거하는 통로 역할과 anode, cathode로서 전극 역할을 통해 스택 전력을 형성하는 핵심 기능과 전지와 전지 사이의 지지대 역할을 한다. 따라서 분리판은 전기전도성, 내부식성 및 기계적 특성이 우수해야함은 물론이고, 얇고 가벼우며 가공성이 뛰어나야 한다. 현재 가장 많이 사용되고 있는 금속 분리판 소재 중 스테인리스 스틸은 전기적, 기계적 특성 및 내부식성이 우수한 반면, 가격이 비싸고, 중량이 무거운 단점이 있다. 따라서 본 연구에서는 DC 반응성 마그네트론 스퍼터링법으로 전기적, 기계적 특성 및 내부 식성이 우수한 TiN, TiCN 박막을 스테인리스에 비해 중량이 1/3, 소재 단가가 1/4인 알루미늄 기판 위에 증착하여 박막 물성을 평가하였다. DC Power는 400 W, 기판과 타겟 사이의 거리는100 mm, 공정 압력은 0.5 Pa로 고정하였고, 3 inch의 지름과 순도 99.95%를 갖는 티타늄 타겟을 사용하였다. 공정 가스는 Ar을 주입하였으며, 질소와 탄소의 공급원으로는 질소($N_2$)와 메탄($CH_4$) 가스를 사용하여 챔버 내 주입혼합가스의 전체 유량을 50 sccm으로 고정시켰다. 증착된 박막의 전기적, 기계적 특성을 측정하였고, X-ray diffraction (XRD), Scanning electron microscope (SEM)을 이용하여 박막의 미세구조 및 표면 상태를 확인하였다. 또한, 내부식 특성을 평가하기 위해 potentiostatic, potentiodynamic 법을 이용하여 박막의 부식저항을 측정하였다. 증착된 TiN 박막의 경우 질소 함량의 증가에 따라 박막 증착속도는 감소하는 경향을 보였다. 이는 타겟 부근의 질소 라디칼 비율이 증가함에 따라 질화반응이 촉진된 것으로 생각된다. 또한, 증착된 TiN과 TiCN 박막은 반응성 질소 유량과 탄소 유량에 따라 각각 다른 미세구조를 가지는 것을 확인하였다. TiN과 TiCN은 NaCl형의 면심입방격자(FCC)로 같은 구조이며, 격자상수가 비슷하여 전율고용되어 TiCN을 형성하고, 탄소와 질소의 비에 따라 전기적 기계적 특성이 달라짐을 확인하였다.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.5
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• pp.465-477
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• 2023

In proton exchange membrane fuel cell (PEMFC), proper thermal management of the stack and moisture generation by electrochemical reactions significantly affect fuel cell performance. In this study, the PEMFC dynamic characteristic model was developed through Simcenter AMESim, a development program. In addition, the developed model aims to understand the thermal resin balance of the stack and performance characteristics for input loads. The developed model applies the thermal management model of the stack and the moisture content and permeability model to simulate voltage loss and stack thermal behavior precisely. This study extended the C based AMESet (adaptive modeling environment submodeling tool) to simulate electrochemical reactions inside the stack. Fuel cell model of AMESet was liberalized with AMESim and then integrated with the balance of plant (BOP) model and analyzed. And It is intended to be used in component design through BOP analysis. The resistance loss of the stack and thermal behavior characteristics were predicted, and the impact of stack performance and efficiency was evaluated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.2
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• pp.155-161
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• 2013

In this study, a metal-plated polycarbonate was adopted as a material for bipolar plates in a polymer electrolyte membrane fuel cell (PEMFC). The coated layers included 40-${\mu}m$-thick copper, 10-${\mu}m$-thick nickel, and 0.3-${\mu}m$-thick gold that respectively played the roles of current conduction, adhesion between copper and gold, and minimization of surface corrosion. The maximum power of the air-breathing PEMFC with polycarbonate bipolar plates was $120mW/cm^2$, which was similar to that of graphite bipolar plates. Finally, the maximum power of a 12-cell stack of polycarbonate bipolar plates was $132.7mW/cm^2$, and it had an operating time of 12 h. Therefore, this was considered a suitable material for bipolar plates in PEMFCs.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.149-154
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• 2011

In order to explore properties of various rubber compounds after thermal aging under the condition similar to the operating environment of a fuel cell-stack, heat resistance and compression set of those compounds were investigated for a long term operation in $H_2SO_4$, $H_2O$, and LLC (ethylene glycol : $H_2O=50:50$) solution. It was assumed that aging Acrylonitrile butadiene rubber (NBR) and Elthylene Propylene diene rubber (EDPM) compound in the solution resulted in discoloration as time passed. It was also found that hydrolysis was developed on the Silicone rubber (VMQ) compound intentionally aged under acidic condition by means of TGA, SEM, and EDS analysis.