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)

    Fingerprint

    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

    @phdthesis{4d1b82c974e5444182687d30e95d3778,
    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",

    }

    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

    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 -