Abstract
| Original language | English |
|---|---|
| Qualification | Doctor Degree |
| Awarding Institution |
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| Supervisors/Advisors |
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| Award date | 25 Nov 2011 |
| Place of Publication | VTT |
| Print ISBNs | 978-951-38-7754-5 |
| Electronic ISBNs | 978-951-38-7755-2 |
| Publication status | Published - 2011 |
| MoE publication type | G5 Doctoral dissertation (article) |
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Keywords
- PEMFC
- fuel cell
- modelling
Cite this
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Modelling approaches to mass transfer and compression effects in polymer electrolyte fuel cells : Dissertation. / Karvonen, Suvi.
VTT, 2011. 150 p.Research output: Thesis › Dissertation › Collection of Articles
TY - THES
T1 - Modelling approaches to mass transfer and compression effects in polymer electrolyte fuel cells
T2 - Dissertation
AU - Karvonen, Suvi
PY - 2011
Y1 - 2011
N2 - The subject of the thesis is modelling polymer electrolyte membrane fuel cells (PEMFCs) locally and on a cell scale. The modelling was done using software based on the finite element method and focused on mass transfer issues and compression pressure distribution and its effects on local phenomena. Mass transfer, more specifically the flow distribution in the flow field system, was studied on the cathode. The velocity distribution was improved by changing the geometry of the channel system. This improvement was also observed experimentally. Mass transport problems of free-breathing fuel cells were also studied. These cells rely on free convection to provide reactants and remove reaction products. In this thesis, the aim was to develop an accurate model that is also computationally light. The compression distribution in a stack was modelled based on an existing stack design. The results showed poor internal pressure distribution, with most of the cell experiencing insufficient compression. The modelling was then used to find a better end plate structure and suitable torques for the nut and bolt assemblies. The results were validated experimentally. The effect of compression was studied on a local scale on which compression variations caused by the channel structure had been seen to affect the gas diffusion layer properties and contact resistances between components. According to the modelling results, there are strong local transversal electric currents in the cell. This phenomenon can affect the cell performance and lifetime negatively.
AB - The subject of the thesis is modelling polymer electrolyte membrane fuel cells (PEMFCs) locally and on a cell scale. The modelling was done using software based on the finite element method and focused on mass transfer issues and compression pressure distribution and its effects on local phenomena. Mass transfer, more specifically the flow distribution in the flow field system, was studied on the cathode. The velocity distribution was improved by changing the geometry of the channel system. This improvement was also observed experimentally. Mass transport problems of free-breathing fuel cells were also studied. These cells rely on free convection to provide reactants and remove reaction products. In this thesis, the aim was to develop an accurate model that is also computationally light. The compression distribution in a stack was modelled based on an existing stack design. The results showed poor internal pressure distribution, with most of the cell experiencing insufficient compression. The modelling was then used to find a better end plate structure and suitable torques for the nut and bolt assemblies. The results were validated experimentally. The effect of compression was studied on a local scale on which compression variations caused by the channel structure had been seen to affect the gas diffusion layer properties and contact resistances between components. According to the modelling results, there are strong local transversal electric currents in the cell. This phenomenon can affect the cell performance and lifetime negatively.
KW - PEMFC
KW - fuel cell
KW - modelling
M3 - Dissertation
SN - 978-951-38-7754-5
T3 - VTT Publications
CY - VTT
ER -