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Heidi Van Parys, Thomas Nierhaus, Pedro Maciel, Steven Van Damme

Mutech. Novel Multiscale approach to Transport phenomena in Electrochemical Processes Integrating the research of different partners SBO 04 0094 2 9 May 2008. Heidi Van Parys, Thomas Nierhaus, Pedro Maciel, Steven Van Damme. Outline. S.  Introduction of the team  Test reactors

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Heidi Van Parys, Thomas Nierhaus, Pedro Maciel, Steven Van Damme

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  1. Mutech Novel Multiscale approach to Transport phenomena in Electrochemical ProcessesIntegrating the research of different partnersSBO 04 0094 29 May 2008 Heidi Van Parys, Thomas Nierhaus, Pedro Maciel, Steven Van Damme

  2. Outline S •  Introduction of the team •  Test reactors •  Software approach •  Flow solvers • Single phase flow •  Two phase flow •  Extending the team

  3.  Introduction of the team S • Heidi Van Parys • IRDE Experiments • Thomas Nierhaus • Morpheus and PLaS • Pedro Maciel • COOLFluiD • Steven Van Damme • MITReM library

  4.  Test reactors S • Parallel flow reactor (PFR)

  5.  Test reactors S • Inverted rotating disc electrode (IRDE)

  6.  Software approach  Software approach S Flow solver Morpheus or COOLFluiD Momentum exchange Bubble solver PLaS Gas volume fraction Bubble size distribution Bubble velocity Bubble position Flow field Post processing Electrochemical solver MITReM library Gas molar production rate

  7.  Software approach  Software approach P • Governing equations • Fluid flow • Continuous representation • Incompressible Navier-Stokes • Closure relation for momentum transfer (bubbles)

  8.  Software approach  Software approach S • Governing equations • Electrochemistry • Bruggeman model • Bubble production model

  9.  Software approach  Software approach T • Governing equations • Bubble equation motion (Euler-Lagrange) • Mass-point approximation • Sphericity assumption • Drag, lift, virtual mass & buoyancy forces • Momentum-back coupling on the flow

  10.  Flow solvers T • Morpheus • Navier-Stokes solver with plug-in extensions • Two-phase flow (PLaS interface) • Electrochemistry (MITReM interface) • Widely portable (Linux, Windows, Mac...) • Parallel computations (MPI) • Limited dependence on external packages • Parallel linear solvers (SAMGp, Trilinos, SuperLU) • Meshing tool (Metis) • Tecplot • MPI distribution (LAM, MPICH, OpenMPI)

  11.  Flow solvers T • Morpheus • Fast and robust time integration scheme • Crank-Nicholson with convective velocity extrapolation • Large time steps with a single linear solve • Unstructured tetrahedral (3D) grids • Space discretization by Finite Elements • Galerkin FEM with stabilization terms • At least 2nd order accuracy in time and space Titel van de presentatie 23/08/2014 | pag. 11

  12.  Flow solvers P • COOLFluiD • Multi-physics solver • Fluid flow • RDS spacial discretization • Incompressible Navier-Stokes (Single-phase, Steady-state) • RANS turbulence modeling (k-e / k-w) • Link to electrochemistry code • MITReM library (Electrolyte & electrostatic models) • Convection + diffusion + migration + reactions • Link to particle tracking code • PLaS library

  13.  Single phase flow S • MITReM Model • Electrochemistry

  14.  Single phase flow S • PFR with MITReM • κ = 1.74 S/m • Polarization curves O2 reaction H2 reaction

  15.  Single phase flow S • PFR with MITReM • Current response

  16.  Single phase flow S • PFR with MITReM • Current density profile at 2V

  17.  Single phase flow S • PFR with MITReM • cH profile at 2V 0.100 m/s 0.010 m/s 0.001 m/s

  18.  Single phase flow S • PFR with MITReM • If the total current and even the current density distribution is the same, the dissolved gas concentration can be very different depending on the hydrodynamics. • J  same bubble production. • cH very different bubble production.  See Flora for experimental observations

  19.  Single phase flow  Single phase flow P • PFR flow field • COOLFluiD • Laminar (Re~100) • Vinlet ~ 1e-2 m/s • Computational grid • ~100.000 nodes • Electrochemistry layer (1e-6m) • PFR flow field • COOLFluiD flow Titel van de presentatie 23/08/2014 | pag. 19

  20.  Single phase flow T • IRDE flow field • Morpheus simulations • Flow fields for different rpm • 250rpm • 500rpm • 1000rpm • Computational grid • 41.500 nodes • 145.500 tetrahedral elements • Electrochemistry layer (1e-6m) • Fluid boundary layer (2e-4m) Titel van de presentatie 23/08/2014 | pag. 20

  21.  Single phase flow T • IRDE flow field • Rotation-induced vetical downflow velocity 250rpm 500rpm Titel van de presentatie 23/08/2014 | pag. 21

  22.  Single phase flow T • IRDE flow field • Rotation-induced vertical downflow velocity 250rpm 500rpm Titel van de presentatie 23/08/2014 | pag. 22

  23.  Two phase flow T • PFR with bubbles • SFELES/PLaS simulations • Flow speeds in the PFR 0.004 m/s – 10 m/s • Reynolds number range 20 – 50.000 • Laminar & turbulent flow regimes

  24.  Two phase flow T • PFR with bubbles • Fully turbulent model channel (Re=2600) • Advection & buoyancy play macroscopic role • TBL interaction plays mesoscopic role Bubbles align with vortices in TBL (Centripetal force) Bubbles move faster in high-speed streaks (Drag) Titel van de presentatie 23/08/2014 | pag. 24

  25.  Two phase flow P • PFR with bubbles and MITReM • Fully coupled simulations • Laminar flow conditions • Steady-state flow (COOLFluiD) • Unsteady flow (Morpheus) • Real geometry (0.864m * 0.1m * 0.01m) Titel van de presentatie 23/08/2014 | pag. 25

  26.  Two phase flow  Two phase flow P P • PFR with MITReM and dissolved H • ∆V=0.2V • Cathode at bottom • Anode on top (downstream) • Laminar (Re=100) • Vinlet ~ 1e-2 m/s • Computational grid • ~100.000 nodes • Electrochemistry layer (1e-6m) • Parallel Titel van de presentatie 23/08/2014 | pag. 26

  27.  Two phase flow PFR with MITReM and dissolved H  Two phase flow P P Titel van de presentatie 23/08/2014 | pag. 27

  28.  Two phase flow PFR with MITReM and H bubbles  Two phase flow P P • ∆V=2.0V • ~Laminar? Vin 1m/s... Current density Movie! Titel van de presentatie 23/08/2014 | pag. 28

  29.  Two phase flow PFR with MITReM and H bubbles  Two phase flow P P • ∆V=2.0V • ~Laminar? Vin 1m/s... Dissolved H Movie! Titel van de presentatie 23/08/2014 | pag. 29

  30.  Two phase flow T • IRDE with bubbles • Experimental data for 250rpm Test case: H2-bubbles 0.1M Na2SO4 / pH = 2.5 2H+ + 2 e- H2 Potential: -2V/ NHE Titel van de presentatie 23/08/2014 | pag. 30

  31.  Two phase flow T • IRDE with bubbles • Quantitative evaluation of two-phase flow Bubble size distribution for 0rpm Experiment Mean: 144.52 μm Std: 75.55 μm Simulation input Mean: 122.94 μm Std: 57.15 μm Titel van de presentatie 23/08/2014 | pag. 31

  32.  Two phase flow T • IRDE with bubbles • Quantitative evaluation of two-phase flow Bubble size distribution for 250rpm Experiment Mean: 152.52 μm Std: 80.01 μm Simulation Mean: 131.94 μm Std: 45.55 μm Titel van de presentatie 23/08/2014 | pag. 32

  33.  Two phase flow T • IRDE with bubbles • Quantitative evaluation of two-phase flow Bubble size distribution for 250rpm Experiment Mean: 63.77 μm Std: 29.16 μm Simulation Mean: 70.62 μm Std: 22.14 μm Titel van de presentatie 23/08/2014 | pag. 33

  34.  Two phase flow T • IRDE with bubbles • Morpheus/PLaS simulations • Diameter spectrum from experiments at 0rpm 250rpm 500rpm 1000rpm Titel van de presentatie 23/08/2014 | pag. 34

  35.  Extending the team S • Additional future collaborations • Flora Tomasoni • Measurements in the PFR • Post-processing of electrochemical solver output (J, c, ...) to bubble solver input (d, v, ...) • Pawel Skuza • Micro-scale simulations of bubble evolution from electrodes • Correlations for macro-scale (MITReM)

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