• Journal of Mechanical Science and Technology
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• 제17권9호
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• pp.1358-1370
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• 2003

The effects of anode, cathode, and cooling channels for a Proton Exchange Membrane Fuel Cell (PEMFC) on flow fields have been investigated numerically. Continuous open-faced fluid flow channels formed in the surface of the bipolar plates traverse the central area of the plate surface in a plurality of passes such as a serpentine manner. The pressure distributions and velocity profiles of the hydrogen, air and water channels on bipolar plates of the PEMFC are analyzed using a two-dimensional simulation. The conservation equations of mass, momentum, and energy in the three-dimensional flow solver are modified to include electro-chemical characteristics of the fuel cell. In our three-dimensional numerical simulations, the operation of electro-chemical in Membrane Electrolyte Assembly (MEA) is assumed to be steady-state, involving multi-species. Supplied gases are consumed by chemical reaction. The distributions of oxygen and hydrogen concentration with constant humidity are calculated. The concentration of hydrogen is the highest at the center region of the active area, while the concentration of oxygen is the highest at the inlet region. The flow and thermal profiles are evaluated to determine the flow patterns of gas supplied and cooling plates for an optimal fuel cell stack design.

• 한국수소및신에너지학회논문집
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• 제27권4호
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• pp.335-340
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• 2016

Hydrogen production through proton exchange membrane water electrolysis (PEMWE) is expeditiously receiving international attention for renewable energy sources as well as energy storage system applications due to its environmentally friendly uses. A series of $Ir_{0.2}Ru_{0.8}O_2$ $Ir_{0.5}Ru_{0.8}O_2$ & $IrO_2$ catalysts were synthesized and electrochemically evaluated by using linear sweep voltammetry (LSV) technique. Furthermore, the PEMWE performances of full cells were evaluated by recording I-V Curves. The developed PEMWE stack was also operated in combination with a proton exchange membrane fuel cell (PEMFC) to demonstrate the discrete regenerative fuel cell (DRFC) performances. Produced hydrogen and oxygen from PEMWE were used as a fuel to operate PEMFC to establish a DRFC system.

• Macromolecular Research
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• 제14권1호
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• pp.101-106
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• 2006

The transport of reactant gas, electrons and protons at the three phase interfaces in the catalytic layers of membrane electrode assemblies (MEAs) in proton exchange, membrane fuel cells (PEMFCs) must be optimized to provide efficient transport to and from the electrochemical reactions in the solid polymer electrolyte. The aim of reducing proton transport loss in the catalytic layer by increasing the volume of the conducting medium can be achieved by filling the voids in the layer with small-sized electrolytes, such as dendrimers. Generation 1.5 and 3.5 polyamidoamine (PAMAM) dendrimer electrolytes are well-controlled, nanometer-sized materials with many peripheral ionic exchange, -COOH groups and were used for this purpose in this study. The electrochemically active surface area of the deposited catalyst material was also investigated using cyclic voltammetry, and by analyzing the Pt-H oxidation peak. The performances of the fuel cells with added PAMAM dendrimers were found to be comparable to that of a fuel cell using MEA, although the Pt utilization was reduced by the adsorption of the dendrimers to the catalytic layer.

• 대한기계학회논문집B
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• 제32권5호
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• pp.359-366
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• 2008

A two-dimensional thermal model of proton exchange membrane fuel cell with large active area is developed to investigate the performance of fuel cell with large active area over various thermal management conditions. The core sub-models of the two-dimensional thermal model are one-dimensional agglomerate structure electrochemical reaction model, one-dimensional water transport model, and a two-dimensional heat transfer model. Prior to carrying out the simulation, this study is contributed to set up the operating temperature of the fuel cell with large active area which is a maximum temperature inside the fuel cell considering durability of membrane electrolyte. The simulation results show that the operating temperature of the fuel cell and temperature distribution inside the fuel cell can affect significantly the total net power at extreme conditions. Results also show that the parasitic losses of balance of plant component should be precisely controlled to produce the maximum system power with minimum parasitic loss of thermal management system.

• Journal of Electrochemical Science and Technology
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• 제14권3호
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• pp.283-292
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• 2023

Currently, spray coating has attracted interest in the mass production of anode catalyst layers for proton exchange membrane water electrolysis (PEMWE). The solvent in the spray ink is a critical factor for the catalyst dispersion in ink, the microstructure of the catalyst layer, and the PEMWE performance. Herein, various pure organic solvents were examined as a substitute for conventional isopropanol-deionized water (IPA-DIW) mixture for ink solvent. Among the polar solvents that exhibited better IrO₂ dispersion over nonpolar solvents, 2-butanol (2-BuOH) was selected as a suitable candidate. The PEMWE single cells were fabricated using 2-BuOH at various ionomer contents, spray nozzle types, and drying temperatures, and their performance was compared to the cells fabricated using a conventional IPA-DIW mixture. The PEMWE single cells with 2-BuOH solvent showed good performances comparable to the conventional IPA-DIW mixture case and highly durable performances under accelerated degradation tests.

• 멤브레인
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• 제26권6호
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• pp.432-448
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• 2016

최근 이온 교환 고분자 전해질 막을 활용한 고효율 에너지 전환 및 저장 장치에 대한 연구가 활발히 이루어지고 있다. 고분자 전해질 연료전지, 레독스 흐름전지 및 역전기투석 등 다양한 에너지 시스템에서 에너지 효율 향상을 위해 이온교환 전해질 막의 양/음이온의 선택적 수송 거동이 중요시되고 있다. 본 총설은 각각의 고효율 전해질 전지 시스템에 따라 요구되는 다양한 이온 교환막의 선택적 양/음이온 투과 거동의 한계점을 고찰하고, 한계를 극복하기 위한 다양한 구조의 고분자 이온 교환 복합막의 장점 및 단점을 정리하였다. 고분자 가교법 및 다공성 지지체 복합막 이외에 다양한 구조의 신규다공성 무기 나노입자를 유-무기 이온교환 복합막에 도입하는 시도가 이루어지고 있는 동시에, 이온 선택도 향상을 위한 다양한 형태의 표면 개질 방법이 개발되고 있으며, 이를 통해 이온 교환 복합막의 선택적 양/음이온 거동의 한계를 극복하는 전략을 제시하고 있다.

• Korean Membrane Journal
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• 제10권1호
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• pp.46-52
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• 2008

Optimization of ionomer solution was conducted in order to improve the performance of MEAs in PEMPC. The interface between membrane and electrodes in MEAs is crucial region determining fuel cell performance as well as ORR reaction at cathode. Through the modification of Nafion ionomer content at the interface between membrane and electrodes, an optimal content was obtained with Nafion 115 membranes. Two times higher current density was obtained with the outer Nafion sprayed MEA compared with the non-sprayed one. In addition, the symmetrical impedance spectroscopy mode (SM) exhibited that the resistances of membrane area, proton hydration, and charge transfer decreased as the outer Nafion is sprayed. From the polarization curves and SM, the highest current density and the lowest resistance was obtained at the outer ionomer content of $0.15\;mg\;cm^{-2}$.

• 멤브레인
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• 제16권4호
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• pp.276-285
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• 2006

술폰화 폴리아릴에테르벤즈이미다졸 공중합체를 $K_2CO_3$를 이용한 직접중합법으로 합성하고 인산도핑을 하여 고온운전 연료전지용 고분자전해질 막을 제조하였다. 최적의 전해질 막 제조를 위하여 술폰화도 $0{\sim}60%$ 및 도핑을 $0.7{\sim}5.7$의 범위에서 다양한 조성의 전해질 막 제조실험이 수행되었으며, 원자현미경분석 및 열중량분석, 수소 이온 전도도측정 등을 통해 전해질 막의 기본특성들을 평가하였다. 수소 이온 전도도는 도핑율에 따라 증가하는 것으로 나타났으며, $130^{\circ}C$의 비 가습환경에서 측정된 수소 이온 전도도는 도핑을 5.7의 전해질 막에서 최대 $7.3{\times}10^{-2}S/cm$의 값을 나타내었다.

• 한국수소및신에너지학회논문집
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• 제16권1호
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• pp.40-48
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• 2005

Until recently, only perfluorinated ionomer membrane such as Nation and Aciflex practically could be successfully used in water splitting. However, these membrane are limited by high cost and loss of membrane performance such as proton conductivity at elevated temperature above 80$^{\circ}C$. The sulfonated aromatic polymers such as PEEK and PSf, polyimides, and polybenzimidazoles are expected to have lower production cost as well as satisfactory chemical and electrochemical properties. HPAs and sulfonated polymers could have a significant influence on water electrolysis performance at elevated temperatures above 80$^{\circ}C$, but these phenomena have received relatively little attention until now. Therefore, it would be desirable to investigate the interrelation between the HPA and sulfonated polymer, such as SPEEK. The SPEEK membrane were prepared by the sulfonation of PEEK, and HPA was blended with SPEEK to increase the mechanical strength and electrochemical characteristics. As a results, electrochemical characteristics such as proton conductivity and ion exchange capacity were improved with the addion of 0.5 g HPA. And the properties of polymer electrolyte, SPEEK/HPA were better than Nation membrane at elevated temperature above 80$^{\circ}C$.

• Korean Chemical Engineering Research
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• 제54권5호
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• pp.593-597
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• 2016

고분자전해질 연료전지에서 전해질막의 이온전도도에 미치는 상대습도, 전류밀도, 온도의 영향에 대해 연구하였다. 전해질막의 물의 함량과 물의 이동은 이온전도도에 많은 영향을 미친다. 전기삼투와 역확산만으로 물 이동을 모사하고 해석하였다. 이온전도도는 셀 밖에서 측정 장비로 막 상태에서 그리고 막전극합체로 구동상에서 측정되었다. 상대습도 증가에 따라 막 내 물 함량이 증가하였고 물 함량 증가에 따라 이온전도도도 상승하였다. 전류밀도 증가에 따라 전기삼투와 역확산에 의한 물의 양이 증가해 물 함량이 선형적으로 증가하였고 그 결과 전류밀도 증가에 따라 이온전도도가 선형적으로 상승하였다. 온도가 $50^{\circ}C$에서 $80^{\circ}C$C로 증가함에 따라 이온전도도는 약 40% 증가하였다.