Optimization and modelling of fuel cell electrodes with emphasis upon catalyst utilization ageing phenomena and ageing prevention

doi:10.1098/rsta.1996.0069

Cited by 5 publications

(3 citation statements)

References 21 publications

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“…The final group of models is those that incorporate possible failure mechanisms. − These failure mechanisms are time or condition dependent and are not the same as the effects examined in earlier sections, such as carbon monoxide poisoning, that was also valid for steady-state operation. The model by Darling and Meyers 330 examined platinum catalyst loss as the potential is cycled.…”

Section: Other Modelsmentioning

confidence: 99%

“…This is something that has also been observed in phosphoric-acid fuel cells , and can occur during start up and shut down. Similar to the case of the Darling and Meyers model, Wendt et al examined catalyst aging due to changing catalyst morphology and, to a lesser extent, accumulation of impurities. The models of Jiang and Chu 332 and Fowler et al examined slow voltage degradation over time for a cell stack and a single cell, respectively.…”

Section: Other Modelsmentioning

confidence: 99%

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Modeling Transport in Polymer-Electrolyte Fuel Cells

2004

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In this review, we have examined the different models for polymer-electrolyte fuel cells operating with hydrogen. The major focus has been on transport of the various species within the fuel cell. The different regions of the fuel cell were examined, and their modeling methodologies and equations were elucidated. In particular, the 1-D fuel-cell sandwich was discussed thoroughly because it is the most important part of the fuel-cell assembly. Models that included other effects such as temperature gradients and transport in other directions besides through the fuel-cell sandwich were also discussed. Models were not directly compared to each other; instead they were broken down into their constitutive parts. The reason for this is that validation of the models is usually accomplished by comparison of simulation to experimental polarization data (e.g., Figure 3). However, other data can also be used such as the net flux of water through the membrane. In fitting these data, the models vary not only in their complexity and treatments but also in their number and kind of fitting parameters. This is one reason it is hard to justify one approach over another by just looking at the modeling results. In general, it seems reasonable that the more complex models, which are based on physical arguments and do not contain many fitting parameters, are perhaps closest to reality. Of course, this assumes that they fit the experimental data and observations. This last point has been overlooked in the validation of many models. For example, a model may fit the data very well for certain operating conditions, but if it does not at least predict the correct trend when one of those conditions is changed, then the model is shown to be valid only within a certain operating range. This review has highlighted the important effects that should be modeled. These include two-phase flow of liquid water and gas in the fuel-cell sandwich, a robust membrane model that accounts for the different membrane transport modes, nonisothermal effects, especially in the directions perpendicular to the sandwich, and multidimensional effects such as changing gas composition along the channel, among others. For any model, a balance must be struck between the complexity required to describe the physical reality and the additional costs of such complexity. In other words, while more complex models more accurately describe the physics of the transport processes, they are more computationally costly and may have so many unknown parameters that their results are not as meaningful. Hopefully, this review has shown and broken down for the reader the vast complexities of transport within polymer-electrolyte fuel cells and the various ways they have been and can be modeled.

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Section: Other Modelsmentioning

confidence: 99%

Section: Other Modelsmentioning

confidence: 99%

Modeling Transport in Polymer-Electrolyte Fuel Cells

2004

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“…In terms of modeling, some effort has been done on the dissolution mechanism of platinum [217,233] and on platinum migration using dilute solution equations as mentioned in the preceding section [216]. Also mentioned there are issues associated with cation exchanged membranes causing water management problems and changes in transport properties and perhaps membrane microstructure [208].…”

Section: Membrane Durability and Transient Modelingmentioning

confidence: 99%