Proper water management plays an essential role in the performance and durability of Polymer Electrolyte Fuel Cells (PEFCs), but it is challenged by the variety of water transport phenomena that take place in these devices. Previous experimental work has shown the existence of fluctuations between low and high current density levels in PEFCs operated with wet hydrogen and dry air feed. The alternation between both performance states is accompanied by strong changes in the high frequency resistance, suggesting a cyclic hydration and dehydration of the membrane. This peculiar scenario is examined here considering liquid water distributions from neutron imaging and predictions from a 3D two-phase non-isothermal model. The results show that the hydration-dehydration cycles are triggered by the periodic condensation and shedding of liquid water at the anode inlet. The input of liquid water humidifies the anode channel and offsets the membrane dry-out induced by the dry air stream, thus leading to the high-performance state. When liquid water is flushed out of the anode channel, the dehydration process takes over, and the cell comes back to the low-performance state. The predicted amplitude of the current oscillations grows with decreasing hydrogen and increasing air flow rates, in agreement with previous experimental data.

适当的水管理在聚合物电解质燃料电池（PEFC）的性能和耐用性中起着至关重要的作用，但是，这些设备中发生的各种水传输现象给它带来了挑战。先前的实验工作表明，在使用湿氢气和干空气进料运行的PEFC中，低电流密度水平和高电流密度水平之间存在波动。两种性能状态之间的交替伴随着高频电阻的强烈变化，表明膜的循环水合和脱水。这里考虑来自中子成像的液态水分布和来自3D两相非等温模型的预测，来研究这种特殊情况。结果表明，水的脱水循环是由阳极入口处的液态水的周期性凝结和脱落触发的。液态水的输入加湿了阳极通道并抵消了由干燥空气流引起的膜干燥，从而导致了高性能状态。当液态水从阳极通道中冲出时，脱水过程就接管了，电池又回到了低性能状态。与先前的实验数据一致，电流振荡的预测幅度随着氢气的减少和空气流速的增加而增加。脱水过程接管了工作，电池又回到了低性能状态。与先前的实验数据一致，电流振荡的预测幅度随着氢气的减少和空气流速的增加而增加。脱水过程接管了工作，电池又回到了低性能状态。与先前的实验数据一致，电流振荡的预测幅度随着氢气的减少和空气流速的增加而增加。