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@PHDTHESIS{Wilkner:1034133,
      author       = {Wilkner, Kai},
      title        = {{A}nalyse des {G}astransports in komplexen
                      {M}embransystemen durch {M}odellierung und multiskalige
                      {S}imulation},
      volume       = {644},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2024-06947},
      isbn         = {978-3-95806-784-4},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {VIII, 122},
      year         = {2024},
      note         = {Dissertation, RWTH Aachen University, 2024},
      abstract     = {Gas separation membranes made of ceramic oxygen ion and
                      electron conducting [MIEC] materials can be used for
                      energy-efficient oxygen production or in a membrane reactor
                      for the homogeneous supply of oxygen to a chemical reaction.
                      To increase efficiency, the membranes are often manufactured
                      in an asymmetrical design. They consist of a very thin
                      membrane and a porous support to provide mechanical
                      stability. This structure results in complex, interdependent
                      transport processes. The aim of this work is to describe all
                      relevant gas transport steps separately and with high
                      resolution using suitable models that are based on the most
                      fundamental physical properties possible. Membrane transport
                      is calculated either using the Wagner equation including
                      surface exchange in the form of the characteristic thickness
                      or using the model of Zhu et al. The transport in the
                      support is described using the binary friction model, which
                      takes into account binary diffusion, Knudsen diffusion and
                      viscous flow in the pores of the support. An iterative
                      numerical root finding algorithm enables the calculation of
                      the partial pressure at the interface between the membrane
                      and the support. This can then be used to calculate the
                      oxygen flux through the asymmetric membrane.
                      Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) is used in this work as the
                      individual transport steps can be easily analysed
                      experimentally due to the high permeability of this
                      material. The transport processes in the gas phases on both
                      sides of the membrane are described using computational
                      fluid dynamics (CFD) in the Ansys Fluent software. The use
                      of a 3D geometry which replicates the test cell used in the
                      experiments as accurately as possible enables the flow condi
                      -tions and partial pressures during the experiment to be
                      modelled precisely. The transport model for the membrane is
                      integrated into the CFD software by means of a user-defined
                      function (UDF). The agreement between experiment and
                      simulation is analysed by comparing the state variables at
                      the inlets and outlets, by this the transport model is
                      validated. The suitability and accuracy of the methods for
                      determining the material parameters used are discussed and
                      evaluated with regard to their range of applicability. This
                      work thus provides important information on the methodology
                      for determining the model parameters and shows the limits of
                      usability. By considering the influence of the individual
                      parameters within a sensitivity analysis, a dedicated
                      optimisation of the microstructure of asymmetric membranes
                      is facilitated. The integration of the operating parameters
                      and the mapping of the test cell as a 3D geometry contribute
                      to the optimisation of the experimental setup. In several
                      cases, the simulations achieve good agreement with the
                      experimental data. In cases where significant deviations
                      occur, the results show, for example, that only the
                      consideration of the partial pressure-dependent surface
                      exchange can provide agreement with all experimental
                      results. The modular design of the presented framework and
                      the use of fundamental physical quantities allow the
                      transferability to other materials.},
      cin          = {IMD-2},
      cid          = {I:(DE-Juel1)IMD-2-20101013},
      pnm          = {1232 - Power-based Fuels and Chemicals (POF4-123)},
      pid          = {G:(DE-HGF)POF4-1232},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      doi          = {10.34734/FZJ-2024-06947},
      url          = {https://juser.fz-juelich.de/record/1034133},
}