Investigation of Locally Resolved SOFC Characteristics along the Flow Path

Solid oxide fuel cells (SOFCs) are characterized locally in a segmented cell arrangement. The tests were performed in counter flow operation for hydrogen concentrations from 2% to 100% to identify concentration limitations and to optimize fuel utilization. Cell characterisations were obtained for different cell concepts by voltage/current density U(i) and temperature measurements as well as gas chromatography measurements at 16 distinct points across the cell. The results show a substantial variation of current density and voltage distribution along the flow path with varying hydrogen content and fuel utilization. Especially at high fuel utilizations approaching 100% a dramatic dependence of power density along the flow path occurs which is associated with increasing degradation. The observation of inhomogencous temperature distribution emphasizes the importance of thermal management adapted to the cell operation characteristics, particularly when the stack itself only has a low thermal mass.