The focus of this work is to investigate transport phenomena in recently
developed microscale fuel cell designs using computational fluid dynamics (CFD).
Two microscale fuel cell systems are considered in this work: the membraneless
microfluidic fuel cell and a planar array of integrated fuel cells.
A concise electrochemical model of the key reactions and appropriate
boundary conditions are presented in conjunction with the development of a threedimensional
CFD model of a membraneless microfluidic fuel cell that accounts for
the coupled flow, species transport and reaction kinetics. Numerical simulations show
that the fuel cell is diffusion limited, and the system performances of several
microchannel and electrode geometries are compared. A tapered-electrode design is
proposed, which results in a fuel utilization of over 50 %.
A computational heat transfer analysis of an array of distributed fuel cells on
the bottom wall of a horizontal enclosure is also presented. The fuel cells are
modelled as flush-mounted sources with prescribed heat flux boundary conditions.
The optimum heat transfer rates and the onset of thermal instability are found to be
governed by the length and spacing of the sources and the width-to-height aspect ratio
of the enclosure. The transition from a conduction-dominated to a convectiondominated
regime occurs over a range of Rayleigh numbers. Smaller source lengths
result in higher heat transfer rates due to dramatic changes in Rayleigh-Bénard cell
structures following transition.
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/1341 |
| Date | 04 February 2009 |
| Creators | Bazylak, Aimy Ming Jii |
| Contributors | Djilali, Ned |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | Available to the World Wide Web |
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