Evaporation-affected liquid water transport in intermediate-temperature PEMFC channels at 100 °C

Intermediate-temperature proton exchange membrane fuel cells (IT-PEMFCs) can simplify water-thermal management, but liquid water transport in channels remains poorly understood. This work combines ex-situ visualization and Volume of fluid simulations with interfacial evaporation-condensation to investigate water transport under 60-100 °C and 0-100% RH. Results show that liquid water accumulation is markedly reduced under IT conditions, and flow pattern transition boundaries shift toward lower gas velocities compared with low-temperature cases. At 100 °C, droplets reach maximum masses at 0.694 and 0.575 s under 65% and 100% RH, before removal, but remain trapped at 0% RH. Under 0% RH, removal occurs after maximum accumulated masses are reached at 1.141 and 1.399 s at 60 and 80 °C. Simulations reveal that enhanced evaporation suppresses droplet growth. When evaporation approaches supply rate, water growth becomes negligible and complete discharge is prevented. Three evaporation-affected transport modes are identified, providing guidance for water-thermal management in IT-PEMFCs.