Title page for ETD etd-08082001-110455


Type of Document Master's Thesis
Author Oyarzabal, Borja
URN etd-08082001-110455
Title Application of a decomposition strategy to the optimal synthesis/design of a fuel cell sub-system
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
von Spakovsky, Michael R. Committee Chair
Ellis, Michael W. Committee Member
Nelson, Douglas J. Committee Member
Keywords
  • decomposition
  • fuel cell
  • optimization
Date of Defense 2001-08-06
Availability unrestricted
Abstract
The application of a decomposition methodology to the synthesis/design

optimization of a stationary cogeneration fuel cell sub-system for residential/commercial

applications is the focus of this work. To accomplish this, a number of different

configurations for the fuel cell sub-system are presented and discussed. The most

promising candidate configuration, which combines features of different configurations

found in the literature, is chosen for detailed thermodynamic, geometric, and economic

modeling both at design and off-design. The case is then made for the usefulness and

need of decomposition in large-scale optimization. The types of decomposition strategies

considered are time and physical decomposition. Specific solution approaches to the

latter, namely Local-Global Optimization (LGO) and Iterative Local-Global Optimization

(ILGO) are outlined in the thesis. Time decomposition and physical decomposition using

the LGO approach are applied to the fuel cell sub-system. These techniques prove to be

useful tools for simplifying the overall synthesis/design optimization problem of the fuel

cell sub-system.

Finally, the results of the decomposed synthesis/design optimization of the fuel cell subsystem

indicate that this sub-system is more economical for a relatively large cluster of

residences (i.e. 50). To achieve a unit cost of power production of less than 10 cents/kWh

on an exergy basis requires the manufacture of more than 1500 fuel cell sub-system units

per year. In addition, based on the off-design optimization results, the fuel cell subsystem

is unable by itself to satisfy the winter heat demands. Thus, the case is made for

integrating the fuel cell sub-system with another sub-system, namely, a heat pump.

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