A model-based approach for current voltage analyses to quantify degradation and fuel distribution in solid oxide fuel cell stacks

作者：Linder Markus^*; Hocker Thomas; Meier Christoph; Holzer Lorenz; Friedrich K Andreas; Iwanschitz Boris; Mai Andreas; Schuler J Andreas

来源：Journal of Power Sources, 2015, 288: 409-418.

DOI：10.1016/j.jpowsour.2015.04.136

• Solid oxide fuel cell (SOFC)
• Current voltage characteristic
• Stack degradation
• Fuel distribution
• Hydrocarbon fuels
• Local thermodynamic equilibrium

Reliable quantification and thorough interpretation of the degradation of solid oxide fuel cell (SOFC) stacks under real conditions is critical for the improvement of its long-term stability. The degradation behavior is often analyzed based on the evolution of current voltage (V,I) curves. However, these overall resistances often contain unavoidable fluctuations in the fuel gas amount and composition and hence are difficult to interpret. Studying the evolution of internal repeat unit (RU) resistances is a more appropriate measure to assess stack degradation. RU-resistances follow from EIS-data through subtraction of the gas concentration impedance from the overall steady-state resistance. In this work a model-based approach where a local equilibrium model is used for spatial discretization of a SOFC stack RU running on hydrocarbon mixtures such as natural gas. Since under stack operation, fuel leakages, uneven fuel distribution and varying natural gas composition can influence the performance, they are taken into account by the model. The model extracts the time-dependent internal resistance from (V,I)-data and local species concentration without any fitting parameters. RU resistances can be compared with the sum of the resistances of different components that allows one to make links between laboratory degradation experiments and the behavior of SOFC stacks during operation.

• 出版日期2015-8-15