Colloquium
3:00 p.m., Friday (September 26, 2003)
Math Annex 1100
Brian Wetton
UBC
Computational Models of Electrically Coupled Hydrogen Fuel Cells
We present a minimal model for proton exchange membrane unit
cells with straight channels in steady state conditions capable of
predicting: current density profiles, local and total water crossover,
effects of inlet humidity, and voltage sensitivities. The model is capable
of describing co-flow and counter-flow operation. In the model, channel
flows are represented by average molar fluxes. The membrane is represented
in some detail, with proton concentration determined by a local chemical
equilibrium, and nonlinear water and proton diffusivities. Cathode
electrochemical losses are considered based on standard Tafel
relationships. The model contains only three main fit parameters: exchange
current density, a parameter representing oxygen transport losses from the
channels to the catalyst sites, and a parameter representing limitations
on water transport from the catalyst to the channels. Techniques for
effectively fitting these parameters to experimental data are outlined.
Extensive comparison to data from the Ballard Mk9 hardware has been
conducted.
Refreshments will be served at 2:45 p.m. in the Faculty Lounge,
Math Annex (Room 1115).
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