Controlling Transient Behavior of Solid Oxide Fuel Cells Using an Invariant Property

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The research objective of this award is to address the important yet conflicting goals of improving load-following ability of SOFCs and simultaneously maintaining safe transient operation under aggressive power fluctuations. Deficient load-following is attributed to transport delays that render SOFCs susceptible to hydrogen starvation during transients. Hydrogen starvation will be addressed by limiting fuel utilization, a critical performance variable in SOFCs, within an optimal range. Transient control through direct measurement of fuel utilization is impractical due to elaborate and costly sensing requirement. In contrast, the proposed approach will achieve this objective by using an invariant property. Its invariance with respect to pressures, temperatures, and internal and external reforming reactions, admits simple control implementation. The research will reveal the underlying conditions for existence of this property and develop a formal approach for deriving it in a model independent manner. By integrating the property within robust control strategies for hybrid SOFC systems containing an energy storage element, it will improve the load-following ability of SOFCs while achieving the aforementioned transient control.If successful, this research will extend the usability of SOFCs from uniform power applications to rapid response scenarios. It will provide acceptable transient response with reduced sensing and limited knowledge of the system dynamics, which consists of numerous interconnected physical phenomena. The research will open the possibility of a generalized transient control approach for SOFCs that is applicable across variations in fuel types, reformer types, stack technologies, etc. It will lower the need for model identification and tuning efforts that are crucial in traditional approaches. The research will involve graduate and undergraduate students from multiple engineering disciplines through graduate research, co-op opportunities, etc. and will attempt to increase the involvement of women and minority students. Research results will be disseminated through university and department-wide outreach activities, and through publications and conference participation.