The influence of channel wettability on two-phase flow and polymer electrolyte membrane fuel cell performance

Water management is one of the critical issues affecting polymer electrolyte membrane fuel cell (PEMFC) performance, durability and cost. Modifying the surface wettability of flow field channels in PEMFC can improve the water management and consequently the fuel cell performance. In the present work, an ex-situ investigation of the effects of channels with different surface wettability on the two phase-flow characteristics has been conducted. Horizontal graphite channel (slightly hydrophobic) and other four channels coated with polytetrafluoroethylene (PTFE) (hydrophobic), silica/ Polydimethylsiloxane (PDMS) (superhydrophobic), silica/PDMS at the bottom wall but with the side walls being raw graphite (combined surface wettability channel), and silica coated channel (superhydrophilic), are tested and visualized at room temperature and atmospheric pressure. Pressure drop measurements and two-phase flow visualization using high speed camera have been performed. Superhydrophobic channel has shown desirable positive effect on the two-phase flow and on the PEMFC's performance compared with the other channels, especially at high current densities.