SUBJECT: Ph.D. Dissertation Defense
   
BY: James Ford
   
TIME: Wednesday, June 27, 2012, 10:00 a.m.
   
PLACE: MRDC Building, 4211
   
TITLE: Thermodynamic Optimization of a Planar Solid Oxide Fuel Cell
   
COMMITTEE: Dr. Samuel Graham, Co-Chair (ME)
Dr. Comas Haynes, Co-Chair (GTRI)
Dr. Andrei Fedorov (ME)
Dr. J. Rhett Mayor (ME)
Dr. Meilin Liu (MSE)
Dr. A. Allan Burke (NUWC)
 

SUMMARY

Solid oxide fuel cells (SOFCs) are high temperature (600C-1000C) composite metallic/ceramic-cermet electrochemical devices. There is a need to effectively manage the heat transfer through the cell to mitigate material failure induced by thermal stresses while yet preserving performance. The present dissertation offers a novel thermodynamic optimization approach that utilizes dimensionless geometric parameters to design a SOFC. Through a modified entropy generation minimization approach, the architecture of a planar SOFC has been redesigned to optimally balance thermal gradients and cell performance. Cell performance has been defined using the 2nd law metric of exergetic efficiency. Two optimizations were conducted. The first optimization sought to minimize thermal gradients by minimizing entropy generation due to thermal gradients. Designs were wrought that reduced thermal gradients by 80% relative to the baseline design. The great utility of this optimization is that a reliability parameter was included in a 2nd law analysis. The second optimization sought to maximize exergetic efficiency through minimizing total entropy production while constraining thermal gradients. Designs were produced that had exergetic efficiency exceeding 91% while maximum thermal gradients were between 432 C/m and 2508 C/m. As the architecture was modified, the magnitude of sources of entropy generation changed. Ultimately, it was shown that the architecture of a SOFC can be modified through thermodynamic optimization to maximize performance while limiting thermal gradients. The present dissertation highlights a new design methodology and provides insights on the connection between thermal gradients, sources of entropy generation, exergy, and cell architecture.