Yazar "Chowdhury M.Z." seçeneğine göre listele

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    Numerical Investigation of Convergent and Divergent Parallel Flow Fields for PEMFCs
    (John Wiley and Sons Ltd, 2018) Timurkutluk B.; Chowdhury M.Z.
    In this study, the classical parallel flow field pattern is modified by a convergent and divergent design concept for proton exchange membrane fuel cells (PEMFCs). The modification is achieved by varying the channel depth with different constant inclination gradients from the inlet to the outlet, along with the bipolar plate width which creates either a convergent or divergent flow field depending on the position of the inlet and outlet selected. The numerical model is solved to predict the cell performance including the mass transport, water vapor concentration and, pressure and current density distribution for the flow fields. The numerical results reveal that the modified convergent parallel flow fields have a better mass transport and water removal characteristics than those in the conventional one, whereas mal-distribution of species and excessive water concentration occur in the conventional and divergent parallel flow fields. Introducing convergent parallel flow field design concept not only minimizes these issues but the cell power density is also improved by a maximum of 16%, which can show a new window in PEMFC flow field design concept. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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    Numerical optimization of channel to land width ratio for PEM fuel cell
    (Elsevier Ltd, 2018) Chowdhury M.Z.; Genc O.; Toros S.
    Flow field plays a vital role in proton exchange membrane (PEM) fuel cell where channel geometry being the primary factor. Most of the channel geometry analyses were limited to few number of case studies, whereas in this study total 73 case studies were analyzed for the optimization of channel and land width. A three dimensional isothermal single phase flow mathematical model is developed and further validated with experimental study to optimize the channel and land width through parametric sweep function for a staggering 73 number of case studies. The optimization analyses are carried out for a straight channel geometry considering a fixed operating voltage of 0.4 V and channel depth of 1.0 mm. Due to the large number of case studies, the analyzed performance parameters i.e. current density and pressure drop are easily understandable for the change in different channel and land width. The numerical results predicted that the pressure drop is more dependent on channel width compare to the land width and anode pressure drop is less significant than cathode pressure drop. However, both channel and land width have an equal importance on the cell current density. Considering channel pressure drop and current density, the optimization analyses showed that the channel to land width of 1.0 mm/1.0 mm would be best suitable for PEMFC channel geometry. © 2017 Hydrogen Energy Publications LLC
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    Transport phenomena of convergent and divergent serpentine flow fields for PEMFC
    (Elsevier Ltd, 2018) Chowdhury M.Z.; Timurkutluk B.
    Reactive species and water transport are crucial for the proton exchange membrane fuel cell operation and performance, and for this, effective flow field design can facilitate the desired transport characteristics of species. From this motivation, the conventional single serpentine flow field pattern is modified by convergent and divergent design concepts and the complex transport phenomena of the newly developed flow field designs are investigated by a numerical approach. For the numerical analyses, an experimentally validated mathematical model is developed to predict the current density, oxygen mass transport, water concentration and pressure distribution. The different configurations of modified convergent and divergent serpentine flow fields are then numerically solved and the results are compared with the conventional serpentine flow field pattern. The transport of reactive species and water concentration are analyzed from the different perspectives including cathode domains and surfaces with a quantitative formulation of the transport species. The numerical results reveals that the modified convergent serpentine flow fields yield to a uniform current density due to the lower mass fraction of water concentration over the reaction zone facilitating better oxygen mass transport and also higher channel pressure distribution along the flow field comparing the conventional and divergent type serpentine flow fields. © 2018 Elsevier Ltd