流道擋板對高溫型質子交換膜燃料電池性能之影響

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Title:	流道擋板對高溫型質子交換膜燃料電池性能之影響 Effects of Channel Block on the Performance of a High Temperature Proton Exchange Membrane Fuel Cell
Authors:	黃彥傑 (Huang Yan jie)
Contributors:	機械工程學系數位機電碩士班
Keywords:	流道擋板空氣流速電化學阻抗 Channel block Air velocity Electrochemical impedance
Date:	2018
Issue Date:	2019-05-17 12:17:55 (UTC+8)
Abstract:	本研究成功建立了高溫型質子交換膜燃料電池的單條三維流道模型，並利用COMSOL多重物理耦合軟體探討陰極流道擋板及空氣流速對電池性能之影響，並且透過與實驗數據之比較證實了本研究之模擬結果具有可靠信。在本研究中除了極化曲線，亦探討電池內氧氣濃度分佈、水氣濃度分佈、空氣流速分佈及電流密度分佈等燃料電池基本特性。模擬結果顯示，加裝70%以上BR值之擋板可增加電池於高空氣流速下之性能。在低流速情形下，增加擋板BR值雖可提高流道前段部分區域之電流密度與氧氣利用率，但因導致流道後段之陰極質傳阻抗上升，造成電池整體質傳過電位上升，使得電池性能下降。在0.8 m/s空氣流速時，當擋板BR值由0%增加至100%情況下，電池於0.3 V之性能增加約8.8%；反之，在0.2 m/s空氣流速時，當擋板BR值由0%增加至100%情況下，電池於0.3 V之性能降低約23.1%。再者，提高擋板BR值提高了電池性能對於空氣流速之敏感度，這是因為提高擋板BR值會增加陰極質傳阻抗對於空氣流速之敏感度。 This research successfully developed a single channel three dimensional model of high temperature proton exchange membrane fuel cells. The effects of channel blocks and air velocity on the cell performance were studied via the multi-physics coupling software, COMSOL Multiphysics®. The simulation results were verified with experimental data and thus had good credibility. In addition to polarization curves, the fundamental characteristics, including the oxygen concentration distribution, water vapor concentration distribution, air velocity vector and the current density distribution, were discussed as well in this work. The simulation results show that installing the channel blocks with a blocking ratio higher than 70% increases the cell performance at high air velocities. Under low air velocities, increasing the blocking ratio of the channel block increases the local current density and oxygen utilization in the upstream flow channel, but however causes an increase in cathodic mass transport resistance in the downstream flow channel, leading to increasing the overall mass transport overpotential and decreasing the cell performance. At the air velocity of 0.8 m/s, the cell performance at 0.3 V increases by about 8.8% as the blocking ratio is elevated from 0% to 100%. By contrast, the cell performance at 0.3 V decreases by about 23.1% as the blocking ratio is elevated from 0% to 100% at an air velocity of 0.2 m/s. Moreover, the sensitivity of cell performance to the air velocity increases with increasing the blocking ratio of channel block because the sensitivity of mass transport resistance to the air velocity increases with increasing the blocking ratio.
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