Systematic study of back pressure and anode stoichiometry effects on spatial PEMFC performance distribution
Systematic study of back pressure and anode stoichiometry effects on spatial PEMFC performance distribution
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DOI：
10.1016/j.electacta.2011.07.058
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发表时间：
2011-10-01
影响因子：
6.6
通讯作者：
Rocheleau, Richard
中科院分区：
文献类型：
--
作者：
Reshetenko, Tatyana V.;Bender, Guido;Rocheleau, Richard
采用分段电池系统研究了阳极和阴极背压以及氢的化学计量比对燃料电池性能的影响，考察了过电势沿流场的分布。分段式电池系统设计了闭环霍尔传感器和数据采集系统，允许同时测量空间电化学阻抗谱(EIS)。结果表明，对于试验的蛇形流场设计，背压的增加会导致电池性能的改善，但个别节段的性能改善并不均衡。总体而言，由于活化和传质损失的减少，随着背压的增加，下游的性能和过电位变得更加均匀。PEMFC在不同背压下的空间EIS数据支持过电位分析。在低电流密度下，氢化学计量比的变化不会影响电池或单个段的性能，因为流场中没有明显的氢浓度梯度。然而，在高电流密度下，氢化学计量比的降低会使进口段的性能略有下降，而出口段则表现出明显的性能损失。性能的下降归因于氮从阴极扩散到阳极导致的传质损失增加。由于下游氮的积累，这种影响对于出口段变得更加明显。在高电流密度条件下，电池局部燃料匮乏，即使高燃料化学计量比创造了导致电池因碳腐蚀而退化的条件。更重要的是，这种局部退化被基本不受影响的整体电池性能所掩盖。(C)2011爱思唯尔有限公司。保留所有权利。
A segmented cell system was applied to investigate the effects of the anode and cathode back pressure and hydrogen stoichiometry on fuel cell performance in terms of overpotential distributions along the flow field. The segmented cell system was designed with closed loop Hall sensors and a data acquisition system allowing simultaneous spatial electrochemical impedance spectra (EIS) measurements. It was determined that an increase in back pressure for the tested serpentine flow field design results in an improvement of the cell performance and uneven improvement of individual segments' performance. In general, the performance and the overpotentials become more uniform downstream with an increase in the back pressure due to a decrease in activation and mass transfer losses. Spatial EIS data for the PEMFC operated at different back pressures support the overpotential analysis. Hydrogen stoichiometry variations do not affect the performance of the cell or the individual segments at low current density because there is no significant hydrogen concentration gradient in the flow field. However, at high current densities a reduction in hydrogen stoichiometry produces a slight decrease in performance for inlet segments while outlet segments showed a noticeable performance loss. The decrease in performance is attributed to an increase in mass transfer losses due to nitrogen diffusion from the cathode to the anode. This effect becomes more pronounced for the outlet segments due to a downstream nitrogen accumulation. Under high current density conditions, the cell is locally fuel starved even with a high fuel stoichiometry creating conditions leading to cell degradation by carbon corrosion. More importantly, this local degradation is masked by the overall cell performance which remains largely unaffected. (C) 2011 Elsevier Ltd. All rights reserved.