2/09/2014 | pag. 1 novel multiscale approach to transport phenomena in electrochemical processes...
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11/04/23 | pag. 1
Novel Multiscale approach to Transport phenomena in Electrochemical Processes
Integrating the research of different partners
SBO 04 0094 29 May 2008
Heidi Van Parys, Thomas Nierhaus, Pedro Maciel, Steven Van Damme
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Vakgroep elektrotechniek
MutechTitel van de presentatie11/04/23 | pag. 2
Outline
Introduction of the team
Test reactors
Software approach
Flow solvers Single phase flow
Two phase flow
Extending the team
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Introduction of the team
Heidi Van Parys– IRDE Experiments
Thomas Nierhaus– Morpheus and PLaS
Pedro Maciel– COOLFluiD
Steven Van Damme– MITReM library
Titel van de presentatie11/04/23 | pag. 3
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MutechTitel van de presentatie11/04/23 | pag. 4
Test reactors
Parallel flow reactor (PFR)
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MutechTitel van de presentatie11/04/23 | pag. 5
Test reactors
Inverted rotating disc electrode (IRDE)
Water jacket
water jacket
RDE electrode
O-ring
Platinum grid
Reference electrode
30mm
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MutechTitel van de presentatie11/04/23 | pag. 6
Software approach Software approach
Flow solverMorpheus or COOLFluiD
Electrochemical solverMITReM library
Bubble solverPLaS
Post processing
Flow field
Gas molar production rate
Bubble size distributionBubble velocityBubble position
Momentum exchange
Gas volume fraction
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Software approach
Governing equations– Fluid flow
• Continuous representation• Incompressible Navier-Stokes• Closure relation for momentum transfer (bubbles)
Titel van de presentatie11/04/23 | pag. 7
Software approach
Φ
cρcτ
cρ
p
cρ
uutu
u
111
0
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Software approach
Governing equations– Electrochemistry
• Bruggeman model
• Bubble production model
Titel van de presentatie11/04/23 | pag. 8
Software approach
0
0
ii i i i i
i ii
z Fv c D c D c U
RTz c
1
1
i i
i i
c c
D D
g gg t S
g
jRTV dSdt
p n F
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Software approach
Governing equations– Bubble equation motion (Euler-Lagrange)
• Mass-point approximation• Sphericity assumption• Drag, lift, virtual mass & buoyancy forces• Momentum-back coupling on the flow
Titel van de presentatie11/04/23 | pag. 9
Software approach
guvuLC
Dt
uDvubt
v
t
x
2))()((23)(2
v
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MutechTitel van de presentatie11/04/23 | pag. 10
Flow solvers
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)
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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
Flow solvers
Titel van de presentatie11/04/23 | pag. 11
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MutechTitel van de presentatie11/04/23 | pag. 12
Flow solvers
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
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MutechTitel van de presentatie11/04/23 | pag. 13
Single phase flow
MITReM Model– Electrochemistry
Component D (10−9 m2/s) c (mol/m3)
H+ 9.311 5.8
Na+ 0.773 200
SO42− 0.618 102.9
H 2 0
Electrode reaction kox kred αox αred
H H+ + e− 0 4e-6 m/s 0 0.5
2H2O O2 + 4H+ + 4e− 1e-12 mol/m2s 0 0.058 0
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MutechTitel van de presentatie11/04/23 | pag. 14
Single phase flow
PFR with MITReM– κ = 1.74 S/m– Polarization curves
050
100150200250300350400450500
1.0 1.5 2.0 2.5
J (A
/m2 )
V-U (V)
experiment
simulation
-250
-200
-150
-100
-50
0
-1.5 -1.0 -0.5 0.0 0.5 1.0
J (A
/m2 )
V-U (V)
experiment
simulation
H2 reaction O2 reaction
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MutechTitel van de presentatie11/04/23 | pag. 15
Single phase flow
PFR with MITReM– Current response
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0.0
-3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0
I cath
ode
(A)
Vcathode - Vanode (V)
@ 0.001 m/s
@ 0.010 m/s
@ 0.100 m/s
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MutechTitel van de presentatie11/04/23 | pag. 16
Single phase flow
PFR with MITReM– Current density profile at 2V
0.0
0.5
1.0
1.5
2.0
2.5
0.38 0.40 0.42 0.44 0.46 0.48
Log
J (A
/m2 )
x (m)
@ 0.001 m/s
@ 0.010 m/s
@ 0.100 m/s
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MutechTitel van de presentatie11/04/23 | pag. 17
Single phase flow
PFR with MITReM– cH profile at 2V
0.001 m/s 0.010 m/s 0.100 m/s
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MutechTitel van de presentatie11/04/23 | pag. 18
Single phase flow
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
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Single phase flow
PFR flow field– COOLFluiD
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Titel van de presentatie11/04/23 | pag. 19
Single phase flow
PFR flow field– COOLFluiD– Laminar (Re~100)
• Vinlet ~ 1e-2 m/s
– Computational grid• ~100.000 nodes• Electrochemistry layer
(1e-6m)
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Single phase flow
Titel van de presentatie11/04/23 | pag. 20
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)
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MutechTitel van de presentatie11/04/23 | pag. 21
Single phase flow
IRDE flow field– Rotation-induced vetical downflow velocity
250rpm 500rpm
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MutechTitel van de presentatie11/04/23 | pag. 22
Single phase flow
IRDE flow field– Rotation-induced vertical downflow velocity
250rpm 500rpm
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MutechTitel van de presentatie11/04/23 | pag. 23
Two phase flow
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
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MutechTitel van de presentatie11/04/23 | pag. 24
Two phase flow
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)
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Two phase flow
Titel van de presentatie11/04/23 | pag. 25
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)
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Two phase flow
Titel van de presentatie11/04/23 | pag. 26
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Two phase flow
– ∆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
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PFR with MITReM and dissolved H
Vakgroep elektrotechniek
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Two phase flow
Titel van de presentatie11/04/23 | pag. 27
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Two phase flow
PFR with MITReM and dissolved H
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Two phase flow
Titel van de presentatie11/04/23 | pag. 28
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Two phase flow
PFR with MITReM and H bubbles
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Movie!Current density
– ∆V=2.0V– ~Laminar? Vin 1m/s...
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Two phase flow
Titel van de presentatie11/04/23 | pag. 29
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Two phase flow
PFR with MITReM and H bubbles
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Movie!Dissolved H
– ∆V=2.0V– ~Laminar? Vin 1m/s...
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Two phase flow
Titel van de presentatie11/04/23 | pag. 30
IRDE with bubbles– Experimental data for 250rpm
Test case: H2-bubbles
0.1M Na2SO4 / pH = 2.5
2H+ + 2 e- H2
Potential: -2V/ NHE
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Two phase flow
Titel van de presentatie11/04/23 | pag. 31
IRDE with bubbles– Quantitative evaluation of two-phase flow
0 50 100 150 200 250 300 350 4000
10
20
30
40
50
60
70
80
90
100
Num
ber
of b
ubbl
es (
-)
Diameter (m)
ExperimentMean: 144.52 μm
Std: 75.55 μm
Bubble size distribution for 0rpm
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Simulation inputMean: 122.94 μm
Std: 57.15 μm
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Two phase flow
Titel van de presentatie11/04/23 | pag. 32
IRDE with bubbles– Quantitative evaluation of two-phase flow
0 100 200 300 400 5000
20
40
60
80
100
Num
ber
of b
ubbl
es (
-)
Diameter (m)
Bubble size distribution for 250rpm
ExperimentMean: 152.52 μm
Std: 80.01 μm
SimulationMean: 131.94 μm
Std: 45.55 μm
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Two phase flow
Titel van de presentatie11/04/23 | pag. 33
IRDE with bubbles– Quantitative evaluation of two-phase flow
50 100 150 200 250 3000
20
40
60
80
100
120
140
160
180
200
Num
ber
of b
ubbl
es (
-)
Diameter (m)
Bubble size distribution for 250rpm
ExperimentMean: 63.77 μmStd: 29.16 μm
SimulationMean: 70.62 μmStd: 22.14 μm
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Two phase flow
Titel van de presentatie11/04/23 | pag. 34
IRDE with bubbles– Morpheus/PLaS simulations– Diameter spectrum from experiments at 0rpm
250rpm 500rpm 1000rpm
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MutechTitel van de presentatie11/04/23 | pag. 35
Extending the team
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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