Brian Wetton | University of British Columbia (original) (raw)
Papers by Brian Wetton
ASME 2006 Fourth International Conference on Fuel Cell Science, Engineering and Technology, Parts A and B, 2006
A computational model is developed for a PEM unit cell capable of describing the reactions that o... more A computational model is developed for a PEM unit cell capable of describing the reactions that occur in the cell in understoich conditions. Such conditions can occur as a result of reactant supply system failure (blockage, leaks, system control, etc.). The model applies to ...
Journal of Computational Physics, 2015
We investigate the spectral stability of the travelling wave solution for the coupled motion of a... more We investigate the spectral stability of the travelling wave solution for the coupled motion of a free surface and grain boundary that arises in materials science. In this problem a grain boundary, which separates two materials that are identical except for their crystalline orientation, evolves according to mean curvature. At a triple junction, this boundary meets the free surfaces of the two crystals, which move according to surface diffusion. The model is known to possess a unique travelling wave solution. We study the linearization about the wave, which necessarily includes a free boundary at the location of the triple junction. This makes the analysis more complex than that of standard travelling waves, and we discuss how existing theory applies in this context. Furthermore, we compute numerically the associated point spectrum by restricting the problem to a finite computational domain with appropriate physical boundary conditions. Numerical results strongly suggest that the two-dimensional wave is stable with respect to both two-and three-dimensional perturbations.
International Journal of Non-Linear Mechanics, 2004
In this paper, the steady unidirectional ow of a rivulet, driven by interfacial shear and gravity... more In this paper, the steady unidirectional ow of a rivulet, driven by interfacial shear and gravity, is considered. When the aspect ratio of the rivulet is small the pressure, velocity, ux and cross-sectional shape are determined in the form of asymptotic power series. The problem is also solved numerically without the small aspect ratio assumption. The analytical and numerical results are compared to test the range of validity of the asymptotics. Both sets of results are also compared with existing experimental data. Finally, the rivulet energy is considered to determine whether it is energetically favourable for a rivulet to split. ? (T.G. Myers).
2nd International Conference on Fuel Cell Science, Engineering and Technology, 2004
ABSTRACT
Physics Procedia, 2012
ABSTRACT
Journal of the Electrochemical Society, 2014
Models were derived for the scavenging effect of product liquid water on airborne proton exchange... more Models were derived for the scavenging effect of product liquid water on airborne proton exchange membrane fuel cell (PEMFC) contaminants. A time scale analysis of contaminant mass transfer processes, product water accumulation in the gas diffusion electrode, and dissociation reactions indicated that the contaminant saturates the product liquid water simplifying model derivation. The baseline model only accounts for contaminant solubility. A multi-scale extension to this model was derived for the presence of contaminant dissociation reactions within the product liquid water using SO 2 as a model contaminant. The extended model demonstrates the large impact of dissociation reactions at low SO 2 concentrations. For both models, explicit expressions for the average gas phase contaminant concentration within the fuel cell were also derived and can be used as a surrogate for the effective contaminant concentration to correlate the fuel cell performance loss and facilitate the definition of tolerance limits and filtering equipment. The model was validated using a non-operating PEMFC. The water was transferred from the anode to the cathode by thermo-osmosis. Model contaminants, methanol and SO 2 , were injected with an inert carrier gas to avoid reactions. The model proved to be acceptable with parameters approximately equal to published values.
3rd International Conference on Fuel Cell Science, Engineering and Technology, 2005
... Members Mathematics Modelling Academic Group: Faculty: Keith Promislow (MSU), John Stockie (S... more ... Members Mathematics Modelling Academic Group: Faculty: Keith Promislow (MSU), John Stockie (SFU), Brian Wetton (UBC) PDFs: Sandra Barsky (UBC), Paul Chang (UBC), Akeel Shah (SFU) Ballard Scientists: Jean St-Pierre, Gwang-Soo Kim, Jurgen Stumper. Page 4. ...
Journal of Engineering Mathematics, 2014
ABSTRACT
Heat Transfer, Volume 2, 2004
ABSTRACT
The authors develop a model of steady state thermal transfer in proton exchange membrane fuel cel... more The authors develop a model of steady state thermal transfer in proton exchange membrane fuel cell stacks. The model is appropriate for straight coolant channel unit cell designs and considers quantities averaged over the cross-channel direction, ignoring the impact of the gas and coolant channel geometries. At steady state and under the as- sumption that the membrane and electrodes are innitesimally thin, a simple description can be made of the temperature distribution in the cells. The model provides estimates on two important quantities: the local temperature dierence between coolant and membrane, and the spread of heat from an anomalously hot cell to its neighbours in a stack environment. The former question is easy to address after the model is presented. The latter requires small argument Laplace Transform asymptotics that correspond to a large scaled heat transfer coecient to the coolant channels. Results of computational approximation of the model are also shown and compared to the asymptotics.
It is well-known that during start-up, a PEM fuel cell experiences a transient that can lead to c... more It is well-known that during start-up, a PEM fuel cell experiences a transient that can lead to carbon oxidation in the cathode catalyst. During the transient, a hydrogen rich area near the anode inlet drives the cell voltage high. In open circuit operation, a positive current in this region is matched by a negative current in the hydrogen depleted region at the anode outlet. This negative current includes carbon oxidation at the cathode. Capacitance effects have been shown to be significant in such start- up situations. In this work, a simple model is presented that describes the start-up phenomena described above including capacitance effects. Numerical simulations of the model are performed. Qualitative agreement with current density and electrochemical potential measurements for the transient are obtained. Sensitivity studies of estimates of carbon corrosion are performed: to the Hydrogen introduction time and to cell number in a stack setting in which the introduction of Hydrogen is staggered between cells, roughly simulating inlet header effects.
ASME 2006 Fourth International Conference on Fuel Cell Science, Engineering and Technology, Parts A and B, 2006
A computational model is developed for a PEM unit cell capable of describing the reactions that o... more A computational model is developed for a PEM unit cell capable of describing the reactions that occur in the cell in understoich conditions. Such conditions can occur as a result of reactant supply system failure (blockage, leaks, system control, etc.). The model applies to ...
Journal of Computational Physics, 2015
We investigate the spectral stability of the travelling wave solution for the coupled motion of a... more We investigate the spectral stability of the travelling wave solution for the coupled motion of a free surface and grain boundary that arises in materials science. In this problem a grain boundary, which separates two materials that are identical except for their crystalline orientation, evolves according to mean curvature. At a triple junction, this boundary meets the free surfaces of the two crystals, which move according to surface diffusion. The model is known to possess a unique travelling wave solution. We study the linearization about the wave, which necessarily includes a free boundary at the location of the triple junction. This makes the analysis more complex than that of standard travelling waves, and we discuss how existing theory applies in this context. Furthermore, we compute numerically the associated point spectrum by restricting the problem to a finite computational domain with appropriate physical boundary conditions. Numerical results strongly suggest that the two-dimensional wave is stable with respect to both two-and three-dimensional perturbations.
International Journal of Non-Linear Mechanics, 2004
In this paper, the steady unidirectional ow of a rivulet, driven by interfacial shear and gravity... more In this paper, the steady unidirectional ow of a rivulet, driven by interfacial shear and gravity, is considered. When the aspect ratio of the rivulet is small the pressure, velocity, ux and cross-sectional shape are determined in the form of asymptotic power series. The problem is also solved numerically without the small aspect ratio assumption. The analytical and numerical results are compared to test the range of validity of the asymptotics. Both sets of results are also compared with existing experimental data. Finally, the rivulet energy is considered to determine whether it is energetically favourable for a rivulet to split. ? (T.G. Myers).
2nd International Conference on Fuel Cell Science, Engineering and Technology, 2004
ABSTRACT
Physics Procedia, 2012
ABSTRACT
Journal of the Electrochemical Society, 2014
Models were derived for the scavenging effect of product liquid water on airborne proton exchange... more Models were derived for the scavenging effect of product liquid water on airborne proton exchange membrane fuel cell (PEMFC) contaminants. A time scale analysis of contaminant mass transfer processes, product water accumulation in the gas diffusion electrode, and dissociation reactions indicated that the contaminant saturates the product liquid water simplifying model derivation. The baseline model only accounts for contaminant solubility. A multi-scale extension to this model was derived for the presence of contaminant dissociation reactions within the product liquid water using SO 2 as a model contaminant. The extended model demonstrates the large impact of dissociation reactions at low SO 2 concentrations. For both models, explicit expressions for the average gas phase contaminant concentration within the fuel cell were also derived and can be used as a surrogate for the effective contaminant concentration to correlate the fuel cell performance loss and facilitate the definition of tolerance limits and filtering equipment. The model was validated using a non-operating PEMFC. The water was transferred from the anode to the cathode by thermo-osmosis. Model contaminants, methanol and SO 2 , were injected with an inert carrier gas to avoid reactions. The model proved to be acceptable with parameters approximately equal to published values.
3rd International Conference on Fuel Cell Science, Engineering and Technology, 2005
... Members Mathematics Modelling Academic Group: Faculty: Keith Promislow (MSU), John Stockie (S... more ... Members Mathematics Modelling Academic Group: Faculty: Keith Promislow (MSU), John Stockie (SFU), Brian Wetton (UBC) PDFs: Sandra Barsky (UBC), Paul Chang (UBC), Akeel Shah (SFU) Ballard Scientists: Jean St-Pierre, Gwang-Soo Kim, Jurgen Stumper. Page 4. ...
Journal of Engineering Mathematics, 2014
ABSTRACT
Heat Transfer, Volume 2, 2004
ABSTRACT
The authors develop a model of steady state thermal transfer in proton exchange membrane fuel cel... more The authors develop a model of steady state thermal transfer in proton exchange membrane fuel cell stacks. The model is appropriate for straight coolant channel unit cell designs and considers quantities averaged over the cross-channel direction, ignoring the impact of the gas and coolant channel geometries. At steady state and under the as- sumption that the membrane and electrodes are innitesimally thin, a simple description can be made of the temperature distribution in the cells. The model provides estimates on two important quantities: the local temperature dierence between coolant and membrane, and the spread of heat from an anomalously hot cell to its neighbours in a stack environment. The former question is easy to address after the model is presented. The latter requires small argument Laplace Transform asymptotics that correspond to a large scaled heat transfer coecient to the coolant channels. Results of computational approximation of the model are also shown and compared to the asymptotics.
It is well-known that during start-up, a PEM fuel cell experiences a transient that can lead to c... more It is well-known that during start-up, a PEM fuel cell experiences a transient that can lead to carbon oxidation in the cathode catalyst. During the transient, a hydrogen rich area near the anode inlet drives the cell voltage high. In open circuit operation, a positive current in this region is matched by a negative current in the hydrogen depleted region at the anode outlet. This negative current includes carbon oxidation at the cathode. Capacitance effects have been shown to be significant in such start- up situations. In this work, a simple model is presented that describes the start-up phenomena described above including capacitance effects. Numerical simulations of the model are performed. Qualitative agreement with current density and electrochemical potential measurements for the transient are obtained. Sensitivity studies of estimates of carbon corrosion are performed: to the Hydrogen introduction time and to cell number in a stack setting in which the introduction of Hydrogen is staggered between cells, roughly simulating inlet header effects.