The flow-field design of the uniform distribution of reacting gas generates broad scientific interest,especially among those who study the performances of proton exchange membrane fuel cell (PEMFC)in relation to pressure drop, discharge of condensed water, maximization of cell voltage, anduniformity of current density over the entire surface area. In this study, we characterize numericallytwo serpentine flow-fields of a new serpentine flow field with sub-channel and by-pass (SFFSB)driven by under-rib convection, and a conventional advanced serpentine flow field (CASFF). Under- rib convection enables a more effective utilization of the electrocatalysts by increasing the masstransport rates of the reactants from the flow channel to the inner catalyst layer and by significantlyreducing the water flooding at the cathode. Four combinations of CASFF and SFFSB applied on theanode and cathode bipolar plates were compared each through a detailed numerical study of thedistribution of temperature, pressure, water content, and local current density. In two flow-fieldconfigurations that SFFSB is applied at the cathode, the pressure drop is decreased because of thegreater cross-sectional area for gas flow, and the decreased pressure drop results in the reduction of theload of BOP and accumulation of liquid water at the outlet. The anode liquid water mass fractionincreases with increasing channel height because of increased back diffusion, while the cathode liquidwater mass fraction does not depend upon the sub-channels which are ascribed mainly to the electro- osmotic drag. The current and power densities in the flow-field configuration that CASFF and SFFSBis applied at the anode and the cathode respectively are slightly higher than those in the flow-fieldconfiguration that SFFSB is applied at both the anode and the cathode. The findings in this work maymake it possible to optimize the design of under-rib convection driven flow-field for efficient PEMFC.
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