Optimal Design and Operation of Solid Oxide Fuel Cell Systems for Small-scale Stationary Applications
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Date
2002Author
Braun, Robert J.
Publisher
University of Wisconsin-Madison
Metadata
Show full item recordAbstract
The advent of maturing fuel cell technologies presents an opportunity to achieve significant
improvements in energy conversion efficiencies at many scales; thereby, simultaneously
extending our finite resources and reducing "harmful" energy-related emissions to levels well
below that of near-future regulatory standards. However, before realization of the advantages
of fuel cells can take place, systems-level design issues regarding their application must be
addressed. Using modeling and simulation, the present work offers optimal system design
and operation strategies for stationary solid oxide fuel cell systems applied to single-family
detached dwellings.
A one-dimensional, steady-state finite-difference model of a solid oxide fuel cell (SOFC) is
generated and verified against other mathematical SOFC models in the literature. Fuel cell
system balance-of-plant components and costs are also modeled and used to provide an
estimate of system capital and life cycle costs. The models are used to evaluate optimal cell-
stack power output, the impact of cell operating and design parameters, fuel type, thermal
energy recovery, system process design, and operating strategy on overall system energetic
and economic performance.
Optimal cell design voltage, fuel utilization, and operating temperature parameters are found
using minimization of the life cycle costs. System design evaluations reveal that hydrogen-
fueled SOFC systems demonstrate lower system efficiencies than methane-fueled systems.
The use of recycled cell exhaust gases in process design in the stack periphery are found to
produce the highest system electric and cogeneration efficiencies while achieving the lowest
capital costs.
Annual simulations reveal that efficiencies of 45% electric (LHV basis), 85% cogenerative,
and simple economic paybacks of 5-8 years are feasible for 1-2 kW SOFC systems in
residential-scale applications. Design guidelines that offer additional suggestions related to
fuel cell-stack sizing and operating strategy (base-load or load-following and cogeneration or
electric-only) are also presented.
Subject
Thesis (Ph.D.)--University of Wisconsin--Madison, 2002.
Dissertations Academic Mechanical Engineering.
University of Wisconsin--Madison. College of Engineering.
Permanent Link
http://digital.library.wisc.edu/1793/7636Description
Under the supervision of Professors Sanford Klein and Douglas Reindl; 308pp.
Citation
Braun, R. (2002). Optimal Design and Operation of Solid Oxide Fuel Cell Systems for Small-scale Stationary Applications . Doctoral Dissertation, University of Wisconsin-Madison.