• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.550-553
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• 2008

In this paper, experiments of air-breathing proton exchange membrane fuel cell (PEMFC) for mobile devices were carried out according to the cathode conditions. These conditions are defined by the cathode flow field plate type (the channel type, the open type) and the cathode surface direction. Single cell and 6-cell stack were used in this experiments. The experimental results showed that the open type cathode flow field plate gave better performance for small size PEMFCs because the open type cathode plate allowed better air convection than the channel type cathode plate. In the experiments related to the direction of the slits on the cathode flow field plate, the horizontal slit cell was better than the vertical slit cell. With respect to the cathode surface direction, when the cathode surface is placed in the direction normal to the ground, PEMFC generated more stable power in the mass transport loss region.

• 한국수소및신에너지학회논문집
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• 제19권4호
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• pp.283-290
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• 2008

In this paper, experiments with an air-breathing proton exchange membrane fuel cell (PEMFC) for mobile devices were carried out according to cathode conditions. These conditions are defined by the cathode flow field plate type (the channel type, the open type) and the cathode surface direction. Single-cell and 6-cell stack were used in the experiments. The experimental results showed that the open-type cathode flow field plate gave a better performance than the small channel type. In the experiments related to the direction of the slits on the cathode flow field plate, the horizontal slit cell was better than the vertical one. With respect to the cathode surface direction, when the cathode surface is placed in the direction normal to the ground, the PEMFC generated more stable power in the mass transport loss region. Since stable power in the mass transport region is closely related to the air supply, computational fluid dynamics (CFD) analysis for air-breathing PEMFC of different cathode surface directions was performed.

• 한국수소및신에너지학회논문집
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• 제28권4호
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• pp.369-376
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• 2017

Temperature and humidity regulations of an open-cathode PEM fuel cell with balance of plant (BOP) are developed in this study. The axial fan, a bubble humidifier, set of solenoid valves and a controller are used to perform temperature and humidity control simultaneously. A fuzzy controller is designed, and it shows its superiority in real-time controlling for strong non-linear dynamical fuel cell system. The axial fan speed is used for temperature control and solenoid valve on/off signal of the bubble humidifier is used for humidity control. The axial fan speed is controlled to keep the fuel cell temperature within the desired point. Meanwhile, the bubble humidifier is utilized to moisture hydrogen to manage the water content of membrane. The results show that the proposed fuzzy controller effectively increases the output power of 10% for a PEM fuel cell.

• Korean Chemical Engineering Research
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• 제60권1호
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• pp.12-19
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• 2022

소형 이송형 고분자전해질 연료전지 (PEMFC)에 많이 사용되는 cathode 개방형 PEMFC 스택은 내구성이 약한 문제점이 있다. 13개의 셀로 이루어진 PEMFC 스택의 가속 내구성 평가를 통해 스택의 열화 원인을 찾고 cathode 개방형 스택의 내구성 향상에 기여하고자 하였다. Cathode가 대기에 개방되어 있고, 기밀 유지가 어려운 cathode 개방형 스택의 구조적 문제점 때문에 시동/정지 (SU/SD)시 수소/공기 경계가 형성되어 cathode를 열화시킨다. 본 연구에서는 cathode 개방형 스택에 SU/SD 1,800회 반복 후 초기 성능의 54%가 감소하여 비교적 짧은 시간에 내구성을 평가할 수 있었다. 스택 해체 후 각 셀을 2등분하여 성능분석하였다. 전체적으로 공기 유입이 용이한 anode 출구부 MEA가 유입부 MEA보다 전극 열화가 더 심해서 SU/SD시 수소/공기 경계 형성이 주요 열화 원인임을 확인했다.

• 대한기계학회논문집B
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• 제27권7호
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• pp.963-972
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• 2003

Performance characteristics of the planar-type solid oxide fuel cell (SOFC) are investigated by the analysis of flow fields coupled with heat and mass transfer phenomena in anode and cathode channels. For these purposes, performance analysis of the SOFC is conducted based on electrochemical reaction phenomena in electrodes and electrolyte coupled with flow fields in anode and cathode channels. In the present study, the isothermal model adopted in the previous paper prepared by the same authors is extended to the non-isothermal model by solving energy equation additionally with momentum and mass transfer equations using CFD technique. It is found that the difference between isothermal and non-isothermal models come from non-uniform temperature distribution along anode and cathode electrodes by solving energy equation in non-isothermal model. Non-uniform temperature distribution in non-isothermal model contributes to the increase of average temperature of the fuel cell and influences its performance characteristics.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.567-571
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• 2008

PEM Fuel Cell operation mode can be classified into dead-end mode or open mode by whether the outlet port is blocked or not. Generally, dead-end type fuel cell has some merits on the pressure drop and system efficiency because it can generate more power than the open type fuel cell due to high operating pressure condition. However, the periodic purging process should be done for removing water which is formed as product of a reaction in the gas diffusion layer. In this study, cathode side dead-end type operation has been conducted. Moreover, pulsating flow generator at the outlet of cathode side has been suggested for increasing the period to purge the formed water because the pulsating flow can make formed water scattered uniformly over the whole channel. As a result, the purging period with pulsation increased by 1.5-2 times longer than that without pulsating.

• 한국물환경학회지
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• 제28권6호
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• pp.917-922
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• 2012

In order to improve applicability of a microbial fuel cell the laboratory-scaled study has been performed by adopting an air-cathode MFC system with high concentrated anaerobic slugies in this study. The concentrations of microbes are grouped into three types, Type A (TS 1.7%), Type B (TS 1.1%) and Type C (TS 0.51%). The open circuit voltage $(V_{oc})$ characteristics showed that the medium microbes concentration of 1.10% (Type B) kept a constant voltage of 1.0 V for 150 hours, which showed the longest time among three types (Type A and Type C). The discharge charge curves for a closed circuit with $500 \Omega$ also showed that Type B generated a stable discharge voltage of 0.8 V for a longer time as in the open circuit voltage case. This could be explained by the relatively large amount of the attached microbes. Under the $V_{oc}$condition the COD removal efficiency of Type B was found to be low for a long time, but those of Type A and C were found to be high for a short period of time. Therefore, the suspended microbes could decrease the coulombic efficiency. It was concluded that the high $V_{oc}$ was caused by low COD and the $V_{oc}$ became low after the COD removal. The COD reduction resulted in an unstable and low working voltage. From the polarization characteristics Type A was found to show the highest power density of $193\;mW/m^2$ with a fill factor of 0.127 due to the relatively high remaining COD even after the MFC reaction.

• 대한기계학회논문집B
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• 제27권5호
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• pp.635-643
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• 2003

Parametric study for the analysis of performance characteristics of a planar -type solid oxide fuel cell(SOFC) using computational flow analysis is conducted. A planar -type SOFC, which is composed by two gas channels (fuel and ai.) and one set of anode-electrolyte-cathode assembly, is modeled as a two -dimensional isothermal case. Results of computational analysis of flow field including distributions of mass fractions in gas channels are used to the performance analysis of the fuel cell. Flow analysis makes it possible to consider current density distributions along the length of the cell in the process of performance analysis of the SOFC. As results of parametric study, it is found that the mole fraction of fuel at the inlet of fuel channel, operating pressure and temperature are closely related to the performance characteristics of SOFC.

• 공업화학
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• 제28권1호
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• pp.118-124
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• 2017

공랭식 고분자전해질 연료전지는 개방된 cathode구조로 인하여 시스템의 단순화와 부품 수 저감의 장점이 있다. 공랭식 연료전지는 최근에 많이 연구되고 있지만, 성능이 외부 환경에 영향을 받으며, 공기의 상대습도가 낮은 경우 전해질막의 건조로 인한 성능 감소가 발생할 수 있다. 본 연구에서는 공랭식 연료전지의 성능에 영향을 주는 요인인 cathode 측 공기 유량과 anode 측 purge interval영향에 대해 분석하였으며, 스택을 운전하지 않는 상태로 장기간 보관하는 것이 성능에 미치는 영향에 대하여 실험을 수행하였다. 연료전지 외부에 설치한 fan의 전압을 조절하면 cathode 측 공기의 공급유량을 변화시킬 수 있고 스택의 온도도 제어할 수 있으므로, fan전압은 공랭식 연료전지의 성능에 영향을 주는 중요한 인자이다. 연료전지 시스템을 단순화하고 수소의 사용률을 높이기 위하여 anode 측은 dead ended anode (DEA) 기법을 사용하였다. 주기적인 purge를 실행하여 생성된 물과 가스를 배출하였으며, purge 주기를 변경하면서 스택의 성능에 미치는 영향에 대하여 실험을 수행하였다. 스택의 보관기간이 길어질수록 membrane dehydration으로 인해 성능이 감소하는 것을 실험을 통해 파악하였고, 단시간에 성능을 회복할 수 있는 기법을 제시하였다.

• 전기화학회지
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• 제12권4호
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• pp.329-334
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• 2009

본 연구는 연료전지 운전시 전극 촉매 및 전해질막 내에서 발생하는 연료 및 산화제의 산화/환원 반응 메커니즘, 이동현상, 구성품 열화현상 등을 핵자기 공명 (NMR, Nuclear Magnetic Resonance)을 이용하여 연료전지의 분해나 시료 채취 없이 제자리 (in situ) 분석할 수 있는 진단장치용 연료전지 개발에 관한 것이다. NMR에 사용되는 연료전지는 특수하게 제작된 TCD (Toroid Cavity Detector) 탐침 내부에서 작동하여야 하며, TCD 탐침이 가지는 기하학적 제한 요소들로 인해 일반적인 평판형 연료전지와 달리 원통형으로 제작된다. 이로 인해 반응물의 공급이나 생성물의 제거가 어려우며 누수 현상 및 불균일한 압력 분배가 발생하여 성능이 낮다. 따라서, in situ NMR 분석용 연료전지가 가지는 구조상의 특징인 원통형에 적합한 유로를 설계하고 제작하여 물질 전달 특성을 개선해야 할 필요성이 있다. 본 연구에서는 NMR 장비 내의 자기장에 영향을 미치지 않는 비자성 물질을 이용해 원 통형 공기극 유로를 개발하여, 산소의 공급 및 반응물의 제거를 원활하게 하였다. 또한, 체결 압력을막-전극 접합체에 균일하게 분배하여 누수 및 누액을 차단하였다. 이를 통해, 상온에서 약 $36mW/cm^2$의 우수한 성능을 나타내는 in situ NMR 진단용 직접 메탄올연료전지 시스템을 개발하였다.