• 한국수소및신에너지학회논문집
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• 제32권5호
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• pp.308-314
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• 2021

Chemical durability issue in polymer electrolyte membranes has been a challenge for the commercialization of polymer electrolyte membrane fuel cells (PEMFCs). In this study, we proposed a manufacturing method of Nafion composite membrane containing a stable polyimide antioxidant to improve the chemical durability of the membrane. The thermal casting of the Nafion solution with poly (amic acid) induced polyimide reaction. We evaluated proton conductivity, oxidative stability with ex-situ Fenton's test, and fluoride ion emission to analyze the effect of polyimide antioxidants. We confirmed that incorporating the polyimide antioxidant improves the chemical durability of the Nafion membrane while maintaining inherent proton conductivity.

• 한국항공우주학회지
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• 제32권3호
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• pp.22-29
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• 2004

박막연의 변형은 고분자 전해질 연료전지의 성능에 상당한 영향을 미친다. 탄소공기판의 응력 분포는 고분자 전해질 연료전지의 안정성과 작동 효율의 중요변수이다. 본 논문에서는 작동 조건에서의 공기판과 박막면의 구조해석을 수행하였다. 박막면의 구조적 변형은 연료전지의 변수들의 분포에 영향을 미친다. 본 연구에서는 두 가지 모델에 대한 해석을 수행하였다. 한가지는 박막면의 물성치를 비선형으로 가정한 것이고, 나머지 한가지는 박막면의 물성치를 비선형으로 가정하고 공기판과 박막면의 접촉면에 접촉 조건을 적용한 경우이다. 이 두 가지 경우에 대해서 해석해본 결과 각각의 응력과 변형율의 분포에서 차이가 있음을 알 수 있었다. 이 결과를 통해 연료전지의 연구에서 비선형 접촉 해석이 필요함을 알 수 있다.

• Korean Chemical Engineering Research
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• 제52권6호
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• pp.695-700
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• 2014

고분자전해질 연료전지로 물을 전기분해하여 수소와 산소를 발생시킬 수 있다. 그러나 1.7V 이상의 높은 전압에서 수전해 반응이 일어나므로 전극과 고분자 전해질 막의 열화가 빠르게 진행된다. 수전해 과정에서 anode의 열화를 방지하기 위해 촉매로 지지체 없는 $IrO_2$를 보통 사용하는데 본 연구에서는 고분자전해질 연료전지용 Pt/C 촉매를 수전해 반응에 그대로 사용했을 때 전극과 막의 열화 현상을 분석하였다. 1.8~2.0 V 전압 범위에서 수전해 반응 후 고분자 전해질 연료전지 구동 조건에서 I-V, CV, 임피던스, LSV를 측정했다. 수전해 전압이 높을수록 전극과 막의 열화 속도가 증가하였다. 2.0 V에서 1분 동안 수전해 반응했을 때 수소 수율은 88%였고, 전극과 고분자 막이 열화되어 0.6 V에서 성능이 49% 감소하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3423-3428
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• 2007

This paper shows that inlet humidity condition at cathode side is one of dominant parameters affecting the performance of PEMFC. To investigate effects of inlet humidity condition, the performance measurements were conducted for a single PEMFC with two operating variables : cathode relative humidity and dry condition in anode dry. The fuel cell employed for the experiments is a unit PEMFC with a 25$Cm^2$, Nafion$^(R)$112 membrane. As a result of this study, the cell performance is getting higher by increasing inlet humidity condition at cathode side. The cell performance is different from each operating temperature an it has maximum30% higher than dry condition at 60$^{\circ}C$ operating temperature with 80% relative humidity.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.93-96
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• 2009

In the cathode channel of a PEM fuel cell, the local concentration of oxygen near the gas diffusion layer (GDL) decreases in streamwise direction due to chemical reactions, which degrades the efficiency of the oxygen consumption and overall fuel cell efficiency. We numerically studied the influence of the swirling flow generated by a slanted groove mixer (SGM) on the concentration distribution of oxygen. We found that the swirling flow can increase the concentration of oxygen near the GDL, and subsequently improves the oxygen consumption rate.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.69-72
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• 2008

The local water contents and water transfer characteristics in the PEMFC system were investigated by numerical simulations and experiments. The performance of a lab-scale PEMFC is measured for fully humidified gases conditions and non-humidified ones. In order to observe the local water contents and water transfer characteristics inside PEMFC, the numerical simulation using CFD module on STAR-CD(es-pemfc) were conducted. The results show that the water content was increased as increasing current density, whereas it was decreased in high current density region. Then there was close correlation between high water content and internal temperature inside of MEA, and high current density was observed when internal temperature was dramatically increased.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.374-377
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• 2009

The operating temperature of Proton Exchange Membrane Fuel Cell (PEMFC) usually has to be limited under $100^{\circ}C$ to maintain the proper ionic conductivity. Therefore, the only product from reaction, water, is in the liquid phase. Two-phase flow makes the flow phenomenon in the channel difficult to understand and predict. Water blocking in the PEMFC channel or the pore of Gas Diffusion Layer (GDL), called flooding, is known as the main effect of PEMFC degradation. To analyze two-phase flow, the PEMFC with transparent acrylic plate was used. Two-phase flow patterns were observed by varying the current density. When the PEMFC is mounted horizontally, water in the cathode is mainly transported on the interface between the channel and GDL.

• 신재생에너지
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• 제4권1호
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• pp.31-36
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• 2008

Stainless steels have been widely considered as metallic bipolar plates, due to their passive surface film, which is good for corrosion resistance. However, the high resistivity of the passive film increases interfacial contact resistance between the bipolar plates and the electrodes. Stainless steels thermal spray coated with a mixture of tungsten carbide and stainless steel powders showed that the coated layer safely combined with the matrix but they suffered many internal defects including voids and cracks. Many cracks were formed in the coated layer and the interface of the matrix and the coated layer during the rolling process. The coated and rolled stainless steels showed lower interfacial contact resistance and corrosion resistance than bare stainless steel because of low resistivity of tungsten carbide and numerous defects, which caused crevice corrosion, in the coated layer.

• 대한기계학회논문집B
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• 제30권8호
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• pp.756-763
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• 2006

PEMFC has several technical problems such as water management, long term stability and performance degradation as. PEMFC has been studied not only to solve water management, but also to generate power in stable manner to system by using a hybrid system with auxiliary energy storage device. The purpose of this study is to couple PEMFC with supercapacitor to make a hybrid system and to design and test control strategies for stable power generation in case of changing output power. The polarization curve and dynamic behaviors while changing power were investigated to find out characteristics of PEMFC stack. A DC/DC converter was fabricated in order to increase fuel cell and supercapacitor voltage and to charge supercapacitor. We found that the operation strategy 2 was recommended to the system because of solving water management problem and increasing the dynamic behavior.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.320-323
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• 2006

A numerical study is made of a manifold and bipolar plate in polymer electrolyte fuel cells, the aim of the present study is to describe the characteristics of flow pattern In manifold and bipolar plate. The present work shows that the flow pattern in the bipolar plate is affected by the penetration flow through GDL characterized by clamping pressure and GDL intrusion in to a channel area. Manifold geometry also affects the flow distribution. The recirculation flow by bent duct destroy even distribution In manifold, the present work shows that corner rounding can improve the manifold performance.