The Impact of Flow Rate Variations on the Power Performance and Efficiency of Proton Exchange Membrane Fuel Cells: A Focus on Anode Flooding Caused by Crossover Effect and Concentration Loss

This study investigates the effects of anode and cathode inlet flow rates (ṁ) on the power performance of bipolar plates in a polymer electrolyte membrane fuel cell (PEMFC). The primary objective is to derive optimal flow rate conditions by comparatively analyzing concentration loss in the I−V curve and crossover phenomena at the anode, thereby establishing flow rates that prevent reactant depletion and water flooding. A single-cell computational model was constructed by assembling a commercial bipolar plate with a gas diffusion layer (GDL), catalyst layer (CL), and proton exchange membrane (PEM). The model simulates current density generated by electrochemical oxidation-reduction reactions. Hydrogen and oxygen were supplied at a 1:3 ratio under five proportional flow rate conditions: hydrogen ( m ˙ H 2 = 0.76–3.77 LPM) and oxygen ( m ˙ O 2 = 2.39–11.94 LPM). The Butler–Volmer equation was employed to model voltage drop due to overpotential, while numerical simulations incorporated contact resistivity, surface permeability, and porous media properties. Simulation results demonstrated a 24.40% increase in current density when raising m ˙ H 2 from 2.26 to 3.02 LPM and m ˙ O 2 from 7.17 to 9.56 LPM. Further increases to m ˙ H 2 = 3.77 LPM and m ˙ O 2 = 11.94 LPM yielded a 10.20% improvement, indicating that performance enhancements diminish beyond a critical threshold. Conversely, lower flow rates ( m ˙ H 2 = 0.76 and 1.5 LPM, m ˙ O 2 = 2.39 and 4.67 LPM) induced hydrogen-depleted regions, triggering crossover phenomena that exacerbated anode contamination and localized flooding.