• 대한기계학회논문집B
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• 제26권9호
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• pp.1201-1208
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• 2002

A numerical flow-field analysis is performed to investigate flow configurations in the anode, cathode and cooling channels on the bipolar plates of a proton exchange membrane fuel cell (PEMFC). Continuous open-faced flow channels are formed on the bipolar plate surface to supply hydrogen, air and water. In this analysis, two types of channel pattern are considered: serpentine and spiral. The averaged pressure distribution and velocity profiles of the hydrogen, air and water channels are calculated by two-dimensional flow-field analysis. The equations for the conservation of mass and momentum in the two-dimensional fluid flow analysis are slightly modified to include the characteristics of the PEMFC. The analysis results indicate that the serpentine flow-fields are locally unstable (because two channels are cross at right angles). The spiral flow-fields has more stable than the serpentine, due to rotational fluid-flow inertia forces. From this study, the spiral channel pattern is suggested for a channel pattern of the bipolar plate of the PEMFC to obtain better performance.

• 한국재료학회지
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• 제20권4호
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• pp.187-193
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• 2010

Chromium nitride (CrN) samples with two different layer structures (multilayer and single layer) were coated on bipolar plates of polymer electrolyte membrane fuel cells (PEMFC) using the reactive sputtering method. The effects with respect to layer structure on corrosion resistance and overall cell performance were investigated. A continuous and thin chromium nitride layer ($Cr_{0.48}\;N_{0.52}$) was formed on the surface of the SUS 316L when the nitrogen flow rate was 10 sccm. The electrochemical stability of the coated layers was examined using the potentiodynamic and potentiostatic methods in the simulated corrosive circumstances of the PEMFC under $80^{\circ}C$. Interfacial contact resistance (ICR) between the CrN coated sample and the gas diffusion layer was measured by using Wang's method. A single cell performance test was also conducted. The test results showed that CrN coated SUS316L with multilayer structure had excellent corrosion resistance compared to single layer structures and single cell performance results with $25\;cm^2$ in effective area also showed the same tendency. The difference of the electrochemical properties between the single and multilayer samples was attributed to the Cr interlayer layer, which improved the corrosion resistance. Because the coating layer was damaged by pinholes, the Cr layer prevented the penetration of corrosive media into the substrate. Therefore, the CrN with a multilayer structure is an effective coating method to increase the corrosion resistance and to decrease the ICR for metallic bipolar plates in PEMFC.

• 한국수소및신에너지학회논문집
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• 제15권1호
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• pp.39-45
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• 2004

A 12-cell PEMFC stack was fabricated using the TiN-coated 316 stainless steel bipolar plates as substitute for the expensive and brittle graphite bipolar plates. Open cirtuit voltage and the maximum power of the stack was 12.08 V and 1.197 kW (199.5 A @ 6 V), respectively. Volumetric and gravimetric power density of the stack was calculated to be 373 W/L and 168 W/kg, respectively. Performance of each cell was quite uniform initially while degraded at a singnificantly different rate. During the 1,000 hr-operation at a constant load of 48 A, stack voltage decreased from 9.0 to 7.98 V at a degradation rate of 11 %/1,000 hr. However, degradation rate of each cell was in the wide rage from 1.2 to 31 %/1,000 hr.

• 전기화학회지
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• 제13권2호
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• pp.81-88
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• 2010

탄소복합소재 분리판의 연료전지 성능을 시험하기 위해 소형 고분자연료전지 스택을 제작하였으며 연료전지 운전에 따른 성능변화를 측정하여 탄소복합소재 분리판이 연료전지 스택의 성능에 미치는 영향을 조사하였다. 자체 설계한 가스유로로 디자인된 분리판과 MEA를 적층한 스택의 초기 성능과 장기간 운전에 따른 전압 감소를 측정하였다. 또한 장시간 운전 동안 각 셀의 전압 거동도 함께 측정하였으며 비교를 위해 흑연분리판을 이용하여 제작한 스택의 성능도 함께 시험하였다. 스택에서 각 셀의 성능은 단위전지에서의 성능과 유사하게 나타나 분리판과 스택의 구조가 셀의 성능을 충분히 보여줄 만큼 적절히 디자인된 것을 알 수 있었으며, 장시간 운전 동안 전류가 증가함에 따라 스택의 성능 감소도 점차 증가하였으며 두 종류의 스택이 유사한 성능 감소를 보여 자체 제작한 탄소복합소재 분리판이 흑연분리판과 유사한 성능을 보임을 알 수 있었다.

• 한국수소및신에너지학회논문집
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• 제15권2호
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• pp.159-165
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• 2004

Fuel cell makes electricity through chemical reaction. Bipolar-plate distribute hydrogen, oxidation using channel geometry condensation of water vapor inside channels of bipolar-plates lowers efficiency of fuel cell. Usually high pressured gas supply is used to solve the water condensation problem with serpentine type channel geometry. In this study, a new channel geometry shows feasible to minimize lowering efficiency due to water condensation through numerical and experimental analysis.

• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1177-1182
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• 2012

The corrosion resistance of 316L stainless steel coated with NiO-YSZ (Ni added yttria stabilized zirconia) was examined in a proton exchange membrane fuel cell (PEMFC) environment. The NiO-YSZ coating was carried out using a sol-gel dip coating method, and the corrosion resistance and interfacial contact resistance (ICR) were determined by the composition and morphology of the NiO-YSZ film. The corrosion resistance increased with increasing Ni content in the NiO-YSZ film, but rapid corrosion was observed when the YSZ film contained more than 15 wt % Ni due to surface cracks. The polarization resistance was improved by several orders of magnitude when 316L stainless steel was coated with a 15 wt % NiO-YSZ film compared to bare 316L. The ICR of the NiO-YSZ film was decreased to that of bare 316L when the YSZ film contained 25 wt % NiO, suggesting the possible application of NiO-YSZ coated stainless steel for a bipolar plate.

• 한국주조공학회지
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• 제31권2호
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• pp.71-78
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• 2011

This study aims to investigate the formability of bipolar plates for fuel cell fabricated by vacuum die casting of ALDC 6. Cavity shape of mold is thin walled plate (size: $200mm{\times}200mm{\times}0.8mm$) with a serpentine channel (active area: $50mm{\times}50mm$). Before bipolar plate was made by HPDC, computational filling behavior and solidification was performed by MAGMA soft. The final mold design for location and direction of channel was determined by computational simulation. Also, according to injection speed conditions, simulation result was compared to actual die casting experimental result. When vacuum pressure, injection speed of low and high region is 350 mbar, 0.3 m/s and 2.5 m/s respectively, products had few casting defects. On the other hand, at the same as injection speed, without vacuum pressure, products had many casting defects between end of the channel and overflow.

• 멤브레인
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• 제15권2호
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• pp.141-146
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• 2005

본 연구에서는 흑연, 열경화성 수지, 그리고 카본 블랙을 사용하여 조성과 제조 조건을 달리하여서 탄소 복합체를 제조하였다. 제조된 탄소 복합체의 고분자 전해질 연료전지용 bipolar plate로의 응용 가능성을 살펴보기 위하여 연속 흐름 기체 투과 장치를 사용하여서 산소의 투과도를 측정하였다 실험 결과 카본 블랙의 양이 증가할수록 산소 투과도가 증가하였으며, 탄소 복합체의 성형 시간이 증가할수록 투과도가 감소하였다 반면에 성형 압력은 산소 투과도에 큰 영향을 미치지 않음을 알 수 있었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.55.2-55.2
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• 2009

A polymer electrolyte membrane (PEM) fuel cell has been getting large interest as a typical issue in useful applications. The PEMFC is composed of a membrane, catalyst and the bipolar plate. SnOx:F films on SUS316 stainless steel were prepared as a function of substrate with using electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) in order to achieve the corrosion-resistant and low contact resistance bipolar plates for PEM fuel cells. The SnOx:F films coated on SUS316 substrate at surface plasma treatment for excellent stability, before/after heat treatment for good crystalline structure and microwave power for were characterized by X-ray diffraction (XRD), auger electron microscopy (AES) and field emission-scanning electron microscopy (FE-SEM). The SnOx:F film coated on SUS316 substrate with various process parameters were able to observe optimum interfacial contact resistance (ICR) and corrosion resistance. It can be concluded that fluorine-doping content plays an important function in electrical property and characteristic of corrosion-protective film.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.260-263
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• 2005

The effects of internal manifold designs the reactant feed-stream in Polymer Electrolyte Fuel Cells (PEFCs) is studied to figure out mass flow-distribution patterns over an entire fuel cell stack domain. Reactants flows are modeled either laminar or turbulent depending on regions and the open channels in the bipolar plates are simulated by porous media where permeability should be pre-determined for computational analysis. In this work, numerical models for reactant 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 a PEMC system.