Relationship of local current and two-phase flow in proton exchange membrane electrolyzer cells

A macro segmented Proton exchange membrane electrolyzer cell (PEMEC) with visualized endplates is designed and assembled to investigate the internal performance inhomogeneities. The local current density distribution (CDD) of the four segments of the PEMEC is measured, and the flow in the channel is observed and recorded by visualizing the endplates. The effect of varying operating conditions on the two-phase flow type distribution and performance are analyzed. It is found that the variations of the two-phase flow type from the inlet to the outlet of the electrolyzer cell lead to significant differences in the internal local performance. Large bubbles have a positive effect on the performance improvement, due to they are able to carry bubbles moved backwards along the flow direction, resulting in the region with the best performance moving from the inlet segment to the middle segment. In addition, the electrolytic current density increases as the increase of voltage, and the variation of the two-phase flow type lead to the increase of inhomogeneity. The above investigation provides a better understanding on the internal inhomogenrity of the electrolyzer cell, which is related to the two-phase flow behavior. • A macroscopic segmented PEMEC was designed and assembled. • It was confirmed that the performance inside the cell was inhomogeneous. • Different two-phase flow types had different effects on performance. • Three analytical indexes were proposed to quantify the two-phase flow.