Behavior of a single direct methanol fuel cell in stacks at air maldistribution conditions

Air maldistribution through different individual cells is frequently encountered in direct methanol fuel cell (DMFC) stacks since most stacks utilize parallel flow configuration. This air maldistribution has been recognized as an important cause for the performance and durability loss of DMFC stacks. To better understand the impact of air maldistribution, the behavior of a single DMFC at various air flow rates (AFRs) is investigated both experimentally and numerically. Special attention is paid to the variation of cell voltage with AFR, which is found to be characterized into three ranges. The voltage varies little at high AFRs, but drops dramatically in middle-range AFRs, and becomes negative at ultralow AFRs. Detailed behavior of the cell at each AFR range is investigated via a two-dimensional computational model. Meanwhile, the effects of various operating conditions such as methanol concentration and operating temperature over the voltage-AFR dependence are also addressed in this work.