Effect of water distributions on performances of JARI standard PEFC by using neutron radiography

Murakawa, Hideki; Ueda, T.; Yoshida, Teru; Sugimoto, Katsuhisa; Asano, Hitoshi; Takenaka, Nobuyuki; Mochiki, Koh-ichi; Iikura, Hitoshi; Yasuda, Ryu; Matsubayashi, Masahito

doi:10.1016/j.nima.2009.01.142

Cited by 27 publications

(7 citation statements)

References 2 publications

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“…The water management is one of the most important issues for PEFCs, because the accumulation of water could flood the porous electrodes and gas-flow channels to deteriorate performance [1,2], whereas insufficiency in the proton conductivity and degradation of membranes could occur as a result of membrane drying out [3][4][5]. The generation and the distribution of liquid water inside the fuel cells has been actively studied and successfully visualized by direct optical observation [6][7][8][9][10][11], neutron radiography imaging [12][13][14][15][16][17][18][19], X-ray imaging [20][21][22][23], and magnetic resonance imaging [24][25][26]. The oxygen partial pressure (pO2) is also an essential factor, which is influenced by the consumption of oxygen for the power generation [27][28][29], the existence of the cross flows through the gas diffusion layer (GDL) [2,30], and the production of gaseous and liquid water [10,29,31,32].…”

Section: Introductionmentioning

confidence: 99%

Real-time visualization of oxygen partial pressures in straight channels of running polymer electrolyte fuel cell with water plugging

Nagase

Suga

Nagumo

et al. 2015

Journal of Power Sources

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Visualization inside polymer electrolyte fuel cells (PEFCs) for elucidating the reaction distributions is expected to improve the performance, durability, and stability. An oxygen-sensitive film of a luminescent porphyrin was used to visualize the oxygen partial pressures in five straight gas-flow channels of a running PEFC with liquid-water blockages formed at the end of the channels. The blockage greatly lowered and unstabilized the cell voltage. The oxygen partial pressure decreased nearly to 0 kPa in the blocked channel. With a water

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Section: Introductionmentioning

confidence: 99%

Real-time visualization of oxygen partial pressures in straight channels of running polymer electrolyte fuel cell with water plugging

Nagase

Suga

Nagumo

et al. 2015

Journal of Power Sources

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“…The start time for water evacuation from the GDL to the channel was earlier with the MPL than without the MPL, and the amount of water in the channels with the MPL was greater than that without the MPL at the same operation time. Droplets in the channel generally prevent gas supply to the channel, and water plugging in the channel causes sudden decreases in the cell voltage [2]. The PEFC could be operated for more than 25 min at i = 158 mA/cm 2 because the water accumulation in the channel was less than that at i = 316 mA/cm 2 .…”

Section: Two-dimensional Water Distributionsmentioning

confidence: 99%

“…(a) i = 158 mA/cm2 (b) i = 316 mA/cm Time series of the cell voltage.moisture content in the membrane, affects the resistance over potential of the PEFCs without and with the MPL.…”

mentioning

confidence: 99%

Visualization and Measurement of Water Distribution in Through-Plane Direction of Polymer Electrolyte Fuel Cell during Start-Up by Using Neutron Radiography

Murakawa

Sugimoto²,

Kitamura³

et al. 2015

JFCMV

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Water management in a polymer electrolyte fuel cell (PEFC) is a key topic for PEFC operation. A microporous layer (MPL) has been recently used to improve the water flooding in the gas diffusion layer (GDL) around the catalyst layer. However, the mechanisms of this MPL are not completely understood because of the difficulty of measuring the water distribution during operation. To clarify the water-accumulation phenomena with the MPL, visualization and measurement of the water distribution in the through-plane direction of a small fuel cell is carried out by using neutron radiography. The parallelism of the neutron flux is optimized by using a collimator to observe the transient change in the water distributions, and two-dimensional water distributions in the through-plane direction of the PEFC can be obtained every 60 s. The differences in the water accumulation processes in the GDL without and with the MPL under the lands and channels are compared. It is observed that the water accumulation in the GDL under the land is greater than that under the channel during the period of early PEFC operation. Water evacuation from the GDL to the channel mainly occurs around the land corners. Furthermore, one-dimensional water distributions are calculated from the visualized water distributions, and the results without and with the MPL in the cathode are compared. The water thickness in the through-plane direction attains its maximum value around the boundary between the catalyst layer and the GDL without the MPL, whereas it is attained between the MPL and the GDL with the MPL. The maximum water accumulation in the GDL under the land without the MPL is higher than that with the MPL. H. Murakawa et al.

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“…村川英樹 *1 ，橋本迪矩 *2 ，杉本勝美 *1 ，浅野等 *1 竹中信幸 *3 ，持木幸一 *4 ，安田良 *5 は，金属内の水分布が計測可能な中性子ラジオグラフィが有効である．著者らは日本自動車研究所(Japan Automobile Research Institute, JARI)準拠の PEFC 単セルで二次元水分布計測 (7), (8) を行い，発電性能に及ぼす結露水挙動の解明を行ってきた．実機では，複数のセルをスタックして用いられる．中性子ラジオグラフィは透過手法であるため，中性子透過方向の水の積算量が取得できるが，1 枚の中性子透過画像では PEFC スタックに存在する水分布をセル毎に把握することができない．そこで PEFC スタックの水分布計測には CT 計測が必要である． CT 技術は X 線計測などで広く用いられ，等角度刻みで 180°以上の角度からの透過画像を取得し再構成することで，三次元分布を計測するものである．各角度からの計測には，線源の機械的な回転，複数の線源を使用，電子ビーム走査型などの手法が用いられ，フレームレート 1000 fps による二相流の X 線高速 CT 計測も実現されている (14) ．中性子ラジオグラフィでは原子炉や加速器で発生する中性子を用いるため線源が固定され，CT 計測には一般的に計測対象を回転させる必要があるで 180°分の画像を各々往路・復路で取得した．実験は，日本原子力研究開発機構の実験用原子炉 JRR-3(中性子束：1.5 × 10 8 n/cm 2 s，ビームの平行度 L/D：176) (18) で実施した． Fig.1 Setup of the imaging system and the PEFC stack.…”

Section: Development Of a Dynamic Ct System For Neutron Radiography Aunclassified

Development of a Dynamic CT System for Neutron Radiography and Consecutive Visualization of Three-Dimensional Water Behavior in a PEFC Stack

Murakawa

Hashimoto²,

Sugimoto

et al. 2011

Trans.JSME, Ser.B

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A dynamic CT system was developed for visualization of consecutive three-dimensional water behavior in a PEFC stack for neutron radiography. The system is composed of a neutron image intensifier and a C-MOS high speed video camera. An operating stack with three cells based on the Japan Automobile Research Institute standard was visualized using the neutron radiography system at a research reactor JRR-3 in Japan Atomic Energy Agency. The dynamic water behavior in channels in the operating PEFC stack was clearly visualized every 15 seconds by using the system. The water amount in each cell was evaluated by the CT reconstructed images. It was shown that a cell voltage decreased gradually when the water increased and increased rapidly when the water was evacuated. It was estimated that the power generation stopped when the channel of a cell was partly filled with the water because the air supply was blocked to a cell in the stack.

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Effect of water distributions on performances of JARI standard PEFC by using neutron radiography

Cited by 27 publications

References 2 publications

Real-time visualization of oxygen partial pressures in straight channels of running polymer electrolyte fuel cell with water plugging

Real-time visualization of oxygen partial pressures in straight channels of running polymer electrolyte fuel cell with water plugging

Visualization and Measurement of Water Distribution in Through-Plane Direction of Polymer Electrolyte Fuel Cell during Start-Up by Using Neutron Radiography

Development of a Dynamic CT System for Neutron Radiography and Consecutive Visualization of Three-Dimensional Water Behavior in a PEFC Stack

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