Fluid flow manifold plays a significant role in the performance of a fuel cell stack because it affects the pressure drop, reactants distribution uniformity and flow losses, significantly. In this study, the flow distribution and the pressure drop in the gas channels including the inlet and outlet manifolds, with U‐ and Z‐type arrangements, of a 10‐cell PEM fuel cell stack are analyzed at anode and cathode sides and the effects of inlet reactant stoichiometry and manifold hydraulic diameter on the pressure drop are investigated. Furthermore, the effect of relative humidity of oxidants on the pressure drop of cathode are investigated. The results indicate that increase of the manifold hydraulic diameter leads to decrease of the pressure drop and a more uniform flow distribution at the cathode side when air is used as oxidant while utilization of humidified oxidant results in increase of pressure drop. It is demonstrated that for the inlet stoichiometry of 2 and U type manifold arrangement when the relative humidity increases from 25% to 75%, the pressure drop increases by 60.12% and 116.14% for oxygen and air, respectively. It is concluded that there is not a significant difference in pressure drop of U‐ and Z‐type arrangements when oxygen is used as oxidant. When air is used as oxidant, the effect of manifold type arrangement is more significant than other cases, and increase of the stoichiometry ratio from 1.25 to 2.5 leads to increase of pressure drop by 527.3%.

中文翻译：

---

PEM燃料电池堆气体通道和U型和Z型歧管的压降特性的数值研究

流体歧管在燃料电池堆的性能中起重要作用，因为它显着影响压降，反应物分布均匀性和流动损失。在这项研究中，分析了10格PEM燃料电池堆的气体通道（包括进，出口歧管以及U型和Z型布置）的气体通道中的流量分布和压降，以及在阳极和阴极侧的影响研究了入口反应物化学计量和歧管水力直径对压降的影响。此外，研究了氧化剂的相对湿度对阴极压降的影响。结果表明，当空气被用作氧化剂时，歧管水力直径的增加导致压降的减小和在阴极侧的更均匀的流量分布，而利用加湿的氧化剂导致压降的增加。结果表明，对于2和U型歧管装置的入口化学计量，当相对湿度从25％增加到75％时，氧气和空气的压降分别增加60.12％和116.14％。结论是，使用氧气作为氧化剂时，U型和Z型装置的压降没有显着差异。当使用空气作为氧化剂时，歧管类型布置的效果比其他情况更显着，化学计量比从1.25增加到2.5导致压降增加527.3％。