The effects of channel depth on the performance of miniature proton exchange membrane fuel cells with serpentine-type flow fields

Flow channels are one of the key components of a fuel cell, because they perform various essential functions that enable the system to operate correctly. In this study, three-path serpentine and parallel-serpentine flow fields with various depths were analyzed experimentally. Die-sinking microelectrical discharge machining was applied to fabricate miniature SUS316L bipolar plates, of which both the rib and channel widths were 500 μm and the channel depths varied among 200, 300, 400, and 600 μm in an active area of 20 mm × 20 mm. The clamping test was performed to examine the magnitude of membrane electrode assembly deformation and the contact resistance. The pressure drops for each cell were analyzed to determine the effects of channel depth. The results revealed that a deep channel is required to leave sufficient space for reactant transportation and water removal; however, too low flow velocity reduces the convective mass transport and cell performance when the channel is too deep.