Modelling approaches to mass transfer and compression effects in polymer electrolyte fuel cells: Dissertation

Research output: ThesisDissertationCollection of Articles

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 languageEnglish
QualificationDoctor Degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Lund, Peter D., Supervisor, External person
Award date25 Nov 2011
Place of PublicationVTT
Print ISBNs978-951-38-7754-5
Electronic ISBNs978-951-38-7755-2
Publication statusPublished - 2011
MoE publication typeG5 Doctoral dissertation (article)

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Fuel cells
Compaction
Mass transfer
Electrolytes
Pressure distribution
Polymers
Nuts (fasteners)
Diffusion in gases
Electric currents
Proton exchange membrane fuel cells (PEMFC)
Contact resistance
Bolts
Velocity distribution
Reaction products
Natural convection
Flow fields
Cathodes
Torque
Finite element method
Geometry

Keywords

  • PEMFC
  • fuel cell
  • modelling

Cite this

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title = "Modelling approaches to mass transfer and compression effects in polymer electrolyte fuel cells: Dissertation",
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.",
keywords = "PEMFC, fuel cell, modelling",
author = "Suvi Karvonen",
year = "2011",
language = "English",
isbn = "978-951-38-7754-5",
series = "VTT Publications",
publisher = "VTT Technical Research Centre of Finland",
number = "772",
school = "Aalto University",

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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: ThesisDissertationCollection 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

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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

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