Spatial distribution characteristics of various physical quantities in PEM fuel cells: Entire morphology investigation based on bifurcated gas distribution zones

The gas distribution zone (GDZ) plays a crucial role in ensuring the efficient operation of proton exchange membrane fuel cells (PEMFCs), particularly in cells with larger active areas. Its well-considered design effectively mitigates concentration gradients before the gases reach the electrochemical reaction zone, thereby preventing issues such as local oxygen starvation, overheating, and decreased reaction rates that may result from uneven gas distribution. However, suboptimal GDZ design can lead to obstructed gas flow, significant mass distribution disparities, and increased pressure losses. This study conducts a comparative analysis of the overall performance of fuel cells (FCs) with and without the GDZ. The results indicate that in the absence of the GDZ, a significant accumulation of liquid water occurs in the central flow channels, leading to a marked disparity in oxygen molar concentration (OMC) and a 4.6 % reduction in output voltage. Conversely, when the GDZ occupies 21 % of the total area, the average current density (ACD) reaches its peak value, with the electrochemical reaction rate (ERR) and proton conductivity increasing by 1.2 % and 6.8 %, respectively. Additionally, the trends in OMC discrepancies of each flow channel are found to be consistent with those of ACD. Further analysis of the spatial distribution of physical quantities within the empty chamber distribution zone (ECDZ) and the bifurcated distribution zone (BDZ) reveals a significant increase in pressure drop (33.5 %) for the BDZ. Nevertheless, the oxygen value in the gas flow field (GFF) improves by 3.1 %, resulting in a 2.3 % increase in output voltage and a notable mitigation of water flooding issues. The study also explores the relationship between the bending angles of the inner and outer corners of the BDZ. Simulation results suggest that when the inner angle exceeds the outer angle by 10°, an optimal OMC distribution is achieved, leading to a uniform liquid concentration across the entire GFF and the elimination of local water blockages at the outlet of GDZ.