Probing water transport in polymer electrolyte fuel cells with neutron radiography

In this work, the characteristic water removal from a full-sized fuel cell is analyzed with coolant-controlled thermal boundary conditions. High frequency resistance (HFR) along with neutron radiography (NR) is used to elucidate the characteristic variation of water content in the membrane and in other components in the fuel cell during operation and purge, respectively.During operation, the variation in stored water content was also investigated for different relative humidity (RH) and power conditions. The effect of purge was analyzed by shutting the current off and by holding the reactant flow rate constant during polarization, and the change of water content was investigated for the whole fuel cell and the membrane, respectively. Interestingly, it was determined that water removal from the membrane can be, to some extent, separately controlled from the flow field and porous media by utilizing proper purge conditions.