فهرست نشریات علمی دسترسی آزاد ایران

Effective water management is critical for achieving high performance and operational stability in proton exchange membrane fuel cells (PEMFCs), as both membrane dehydration and cathode flooding can significantly reduce cell efficiency. This study experimentally investigates the combined effects of reactant stoichiometry and inlet relative humidity on PEMFC performance and liquid-water accumulation using a transparent single-serpentine PEM fuel cell with a 25 cm² active area. Simultaneous electrochemical measurements and digital image processing were employed to quantify the cathode wetted length ratio (WLR) and correlate liquid-water accumulation with cell performance. The results show that both stoichiometry and relative humidity strongly influence membrane hydration, water transport, and electrochemical behavior. Increasing the cathode stoichiometric ratio improves oxygen transport and water removal; however, excessive stoichiometry promotes membrane dehydration and reduces performance. The anode stoichiometric ratio was found to exert a greater influence on performance stability because of its stronger impact on membrane water balance. Under dry anode conditions, increasing cathode relative humidity continuously enhanced membrane hydration and power output. In contrast, excessive cathode humidification under fully humidified anode conditions increased liquid-water accumulation and caused flooding, leading to performance degradation. The results demonstrate that optimum PEMFC performance is achieved at an intermediate WLR that balances membrane hydration and reactant transport. The proposed visualization and image-processing approach provides an effective experimental tool for quantitative investigation and optimization of PEMFC water management.