Role of under-rib convection in in situ reactant and liquid water flows and current density distributions for polymer electrolyte membrane fuel cells

Novel flow-field approach by the under-rib convection (URC) aims to enhance polymer electrolyte membrane fuel cell (PEMFC) performance. This study presents the experimental and numerical results for single cells with a new serpentine flow-field (SFF) that stimulates URC by adding sub-channels and bypasses (SBs) to a conventional flow-field with five passes and four turns on an active area of 25 cm
²
. To characterize the role of under-rib convection for PEMFC performance, the performance-related parameters of the SFF with SBs are compared experimentally and numerically with those of conventional SFF without SBs. In the experimental evaluation of PEMFC performance, the area of the lower current density with the SFF without SBs become broader than that with the SFF with SBs. In the case of the SFF without SBs, the sub-channel changes the flow direction of the URC and the URC flow direction converges to the sub-channel. The enhancement of URC can reduce water flooding at the cathode and increase the electrochemical reaction, thus improving both the cell performance and the operating stability. URC would play an important role in improving PEMFC performance, as well as increasing the fuel cell lifetime.