Large-scale current fluctuations in PEM fuel cells operating with reduced feed stream humidification

The effects of systematic dehydration of the fuel and oxidant feed streams on the performance of a proton exchange membrane (PEM) membrane electrode assembly (MEA) were investigated in an attempt to understand the effects of feed stream humidification on cell operation. A significant but expected performance loss was observed when the feed stream humidification was diminished. In addition, strong periodic fluctuations in current and cell resistance were also observed as the feed stream humidification was decreased. A cyclic mechanism is proposed that may offer a qualitative explanation for these unusual fluctuations.