Quantification of water in hydrophobic and hydrophilic flow channels subjected to gas purging via neutron imaging

摘要

Water removal from an idle fuel cell is an important issue for start-up/shutdown down under cold temperature conditions. In our study, we performed an in-situ neutron imaging for a PEM fuel cell with bipolar plates, treated with a super-hydrophobic and super-hydrophilic coating on the flow channels. The coatings were applied to the channels but not on the landings in contact with the GDL. The cells were run at a constant voltage prior to shutdown, then sets of neutron images were taken with purge velocities varied from 1ms~(-1) to 4 m s~(-1), in intervals of 1 m s~(-1). It was found that changing the wettability of the flow channels can improve the dynamics of water removal during purging. The super-hydrophilic and super-hydrophobic coating had better performance in removing water on the landings and in the channels, respectively. Based on our test cells, we used the amount of water remaining as a metric and found no significant improvement by purging the cell at velocities greater than 3ms~(-1).