Date of Award

12-1-2004

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemical Engineering

Abstract

An electrochemical-thermal model has been developed to simulate the performance of a solid oxide fuel cell under different operating conditions and geometrical factors. The model was specifically created for a novel manifold design that produces a more uniform thermal distribution inside the cell. Temperature, current, gas distribution and fuel utilization were calculated with the model in the different regions of interest. In addition, the model developed in this research was used to investigate the optimal operating conditions under different gasifier compositions. Accordingly, the model was successfully used to identify the principal operating conditions and geometrical factors that affected the performance of the fuel cell (i.e., gasifier compositions, operating temperature, fuel/oxidant flow rates, and geometrical parameters). The modeling results showed that the novel design was successful in reducing the steep temperature gradients inside the cell but at lower fuel utilization than a conventional co-flow design. However, the model was also used to determine the optimal flow rates at which the fuel utilization of the novel design was quantitatively equivalent to that of conventional cell. Finally, the model was used to investigate the factors that affected the performance of an experimental cell developed at the EERC. Active surface area and contact resistance were identified as principal limiting factors in the performance of the cell for our specific experiments. Based on these assumptions a new experimental cell was constructed. The experimental results of the new design gave a six-fold increase in performance with respect to the original design.

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