Abstract
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.
Original language | English |
---|---|
Qualification | Doctor Degree |
Awarding Institution |
|
Supervisors/Advisors |
|
Award date | 25 Nov 2011 |
Place of Publication | Espoo |
Publisher | |
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) |
Keywords
- PEMFC
- fuel cell
- modelling