Determination of Temperature and Fuel Utilization Distributions in SOFC Stacks with EIS

摘要

Efficient operation of solid oxide fuel cell (SOFC) stacks requires uniform temperature and fuel utilization distributions in the stack. Especially high fuel utilizations necessitate uniform fuel flow distributions to avoid performance decrease or anode reoxidation. A uniform temperature distribution helps to prolong the life-time of the stack. This work presents a method to determine the fuel utilization and temperature distribution in SOFC stacks with electro-chemical impedance spectroscopy (EIS). The equations for relating the measured impedance and fuel utilization and temperature are derived from physical equations describing the SOFC stack. The method is demonstrated with an ElringKlinger AG 10-cell stack fuelled with 50%/50% H_2/N_2 at nominal operation conditions. The difference in temperature and fuel utilization between cells was determined. The calculated distributions are in line with cell voltage measurements. The method can be used to improve SOFC stack design and performance.