Transportparameter dünner geträgerter Kathodenschichten der oxidkeramischen Brennstoffzelle

Wedershoven, Christian

Dissertation / PhD Thesis/Book

Transportparameter dünner geträgerter Kathodenschichten der oxidkeramischen Brennstoffzelle

Wedershoven, C. (Corresponding author)FZJ*

2010
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-89336-666-8

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Schriften des Forschungszentrums Jülich : Energie & Umwelt / Energy & Environment 83, VI, 137 S. (2010) = RWTH Aachen, Diss., 2010

This record in other databases:

Please use a persistent id in citations: http://hdl.handle.net/2128/3813

Abstract: The aim of this work was to determine the transport properties of thin cathode layers, which are part of the composite layer of a fabricated anode-supported solid oxide fuel cell (SOFC). The transport properties of the anode and cathode have a significant influence on the electrochemical performance of a fuel cell stack and therefore represent an important parameter when designing fuel cell stacks. In order to determine the transport parameters of the cathode layers in a fabricated SOFC, it is necessary to permeate the thin cathode layer deposited on the gas-tight electrolyte with a defined gas transport. These thin cathode layers cannot be fabricated as mechanically stable single layers and cannot therefore be investigated in the diffusion and permeation experiments usually used to determine transport parameters. The setup of these experiments – particularly the sample holder - was therefore altered in this work. The result of this altered setup was a three-dimensional flow configuration. Compared to the conventional setup, it was no longer possible to describe the gas transport in the experiments with an analytical one-dimensional solution. A numerical solution process had to be used to evaluate the measurements. The new setup permitted a sufficiently symmetrical gas distribution and thus allowed the description of the transport to be reduced to a two-dimensional description, which significantly reduced the computational effort required to evaluate the measurements. For pressure-induced transport, a parametrized coherent expression of transport could be derived. This expression is equivalent to the analytical description of the transport in conventional measurement setups, with the exception of parameters that describe the geometry of the gas diffusion. In this case, a numerical process is not necessary for the evaluation. Using the transport parameters of mechanically stable anode substrates, which can be measured both in the old and the new setups, the old and the new setups were compared with each other. Deviations of the transport parameters of between 4 and 11% were determined. Following this, the transport parameters of the cathode layers in the Jülich SOFC were determined using the new setup. The thickness of the cathode layers investigated was 65-70 $\mu$m. The transport properties were compared with the transport properties of mechanically stable cathode substrates, which were used to calculate mass transfer in stack simulations. The transport rates of oxygen in the original cathode layers were 3 to 6 times greater than in the cathode substrates. Information on the original transport parameters of the SOFC cathode layers allows the calculation of a more accurate simulation of the transport, and thus increases the robustness of model calculations of fuel cell stacks.

Keyword(s): SOFC

Classification: