Evaluation of Two Water Transports through Electrolyte Membrane of Polymer Electrolyte Fuel Cell Based on Water Visualization and Current Measurement

To alleviate membrane dehydration in polymer electrolyte fuel cells (PEFCs) during low‐humidity operations, it is essential to deeply understand two water crossover phenomena through electrolyte membranes. This study presented the quantitative method for separately evaluating the electro‐osmotic and back‐diffusion water transports in the electrolyte of an operating PEFC based on the measurements of water vapor and current distributions. Firstly, the water vapor distribution in the anode flow field was investigated by the visualization technique using humidity test paper (HTP). Subsequently, the detailed transport processes of water through the electrolyte membrane can be numerically estimated from the measurement results of water and current profiles by using a simple fuel cell model. In this work, the effects of inlet gas humidification, microporous layer (MPL) addition and flow configuration on the two water transports in the membrane were demonstrated under low‐humidity conditions to verify the validity of the proposed methodology. Results revealed that the introduction of MPL on the cathode side increases the water concentration in the anode channel due to the back‐diffusion effect. The counter‐flow configuration effectively improves the membrane hydration at the anode inlet because of the strong back‐diffusion from the wetted cathode outlet.