PLANAR AND TUBULAR SOLID OXIDE FUEL CELLS: A COMPARISON OF TRANSIENT PROCESS BEHAVIORS

摘要

Two typical configurations of solid oxide fuel cells (SOFCs) are planar cross-flow and tubular counter-flow. Even though their performance is based on the same physical principles, their operation characteristics and parameters vary considerably due to different geometries. The goals of this paper are to detect the particularities of the cell geometries at transient operation and to identify their applicability for stationary power generation. This has been achieved by investigating the thermal and electrochemical performance of a planar and a tubular cell at different operation modes, i.e. load change, start-up, and shut-down. As the most relevant results of the transient SOFC analysis, the comparison of relaxation times and transient temperature gradients within the cell as well as the transients of the power density are presented and discussed. Relaxation times for different processes are shorter for the planar geometry, caused by its compactness. However, due to its longer spatial extension the tubular geometry is more advantageous concerning the level of temperature gradients within the cell.