Investigation of mass spatial distribution characteristics in proton exchange membrane fuel cells: Full-morphology simulation considering “mixed structure” gas distribution zones

Improper structural design of the GDZ can result in non-uniform spatial distribution of mass, leading to localized gas starvation and hotspot formation. In response to these challenges, this study proposes a novel mixed structure (MS) GDZ, which combines the “bifurcation” and “dot matrix” (DM) structures, and compares its performance with that of empty chamber distribution zones (ECDZs) and various bifurcated distribution zones (BDZs). The simulation results reveal that as the fill volume within the GDZ increases, the variation in oxygen molar concentration (OMC) distribution within each channel also increases, however, overall output performance improves. Notably, the mixed structure distribution zone (MSDZ) exhibits a higher net output power density (with a decrease of only 0.37 %), while significantly reducing OMC distribution error and pressure drop. Moreover, a moderate increase in liquid flow velocity in the channels facilitates the removal of excess liquid, thereby reducing mass transfer resistance. In contrast, a higher pressure drop enhances gas transport, improving the electrochemical reaction rate by 5.02 %. The introduction of coolant (with an optimal flow rate of 5m∙s−1) increases the OMC distribution error but significantly boosts output performance. Nevertheless, the presence of localized high temperatures (with increased water vapor) dilutes oxygen, leading to localized oxygen starvation.