Enhanced transport phenomena and performance in proton exchange fuel cells using triangular flow field obstacles with...

This study numerically investigates the influence of triangular obstacles with different aspect ratios (AR = 0.25, 0.5, 0.75, and 1) on transport phenomena and electrochemical performance of a proton exchange membrane fuel cell (PEMFC). A comprehensive set of simulations was conducted to analyze polarization behavior, oxygen velocity distribution, reactant mass fraction consumption, temperature field, membrane water content, and overall power density. The results demonstrated that obstacle structures significantly improved reactant distribution through enhanced local convective mixing, leading to more than a 35% increase in maximum oxygen velocity compared to the baseline channel. Polarization and power density curves confirmed notable performance enhancement, with AR = 1 providing up to 24% higher maximum power density. Water management analysis revealed that the presence of obstacles not only prevented membrane dehydration but also mitigated cathode flooding, thereby ensuring favorable water distribution under a wide range of operating conditions. Sensitivity studies of operating parameters further highlighted the robustness of the obstacle design. Increasing the cell temperature from 333 to 363 K improved the maximum power density by approximately 24% in the optimized AR = 1 case. At moderate operating pressure (2 atm), the use of obstacles yielded more than a 60% enhancement in cell performance compared to the baseline, while excessively high pressures (≥ 3 atm) caused a 10-15% reduction due to elevated hydrodynamic losses. Similarly, under dry conditions (0% relative humidity), obstacle-enhanced channels achieved a 27% improvement in power density, and even at 100% RH, performance remained about 24% higher than the baseline. Overall, the findings demonstrate that optimized triangular obstacles not only enhance oxygen accessibility and water management but also ensure stable and efficient PEMFC operation, making them a promising design modification for next-generation fuel cell systems.