A purge strategy for proton exchange membrane fuel cells under varying-load operations

Abstract

When a proton exchange membrane fuel cell is operated in a dead-ended anode mode, its performance gradually drops due to impurity accumulation in the anode channel. The performance can be recovered by purging the impurities from the anode channel. Developing a purge strategy for a fuel cell is challenging under varying-load operations because the measured or monitored signals vary with the load demand. To capture the local performance throughout the active area during dead-end operation, the local current density distribution was measured using a specially designed single cell. First, the single cell was operated at three different current density levels for the observation of the variation of the local current density. The ratio of the normalized local current density to the load current density can be employed as a characteristic value for the purge strategy. The purge strategy with different threshold values was applied to a single cell operated under varying-load conditions and was discussed. Finally, a procedure for implementing the purge strategy was presented in detail.