Selecting Physics Models

You define separate solid continua for the anode and cathode current collectors, the solid oxide electrolyte membrane (which separates the anode and cathode), and the tubes. Then you define separate fluid continua for the air and fuel domains.

It is necessary to maintain a continuous supply of fuel at the anode and air (oxygen) at the cathode. A solid continuum is set up for the aluminium tubes which supply the fuel and air.
  1. Rename the Continua > Physics 1 node to Tubes.
  2. For the physics continuum, Continua > Tubes, select the following models in order:
    Group Box Model
    Enabled Models Three Dimensional (selected automatically)
    Solution Interpolation (selected automatically)
    Time Steady
    Material Solid
    Optional Models Segregated Solid Energy
    Gradients (selected automatically)
    Equation of State Constant Density
  3. Click Close.
The solid oxide electrolyte membrane separator is modeled as a solid shell region that separates the anode and cathode reactions.
  1. Create a physics continuum. Rename the resulting Physics 1 node to Mem. For this continuum, select the following models in order:
    Group Box Model
    Space Three Dimensional
    Time Steady
    Material Solid
    Optional Models Segregated Solid Energy
    Gradients (selected automatically)
    Equation of State Constant Density
    Optional Models Electrochemistry
    Enabled Models Electrochemical Reactions (selected automatically)
    Electromagnetism (selected automatically)
    Shell Electrodynamic Potential (selected automatically)
    Optional Models Ohmic Heating
    Electrochemical Reaction Heating
    Solid Ion Shell
  2. Click Close.
  3. Select the Mem > Models > Solid > Al node and rename it MEM.
The anode is a porous solid ceramic material on the surface of which the electrochemical reactions take place.
  1. Create a physics continuum named CCanode, and for it select the following models in order:
    Group Box Model
    Space Three Dimensional
    Time Steady
    Material Solid
    Optional Models Segregated Solid Energy
    Gradients (selected automatically)
    Equation of State Constant Density
    Optional Models Electromagnetism
    Electromagnetism Electrodynamic Potential
    Optional Models Ohmic Heating
  2. Click Close.
  3. Select the CCanode > Models > Solid > Al node and rename it Anode.
Air is modeled as a multi-component gas mixture of oxygen and nitrogen. The Air continuum supplies oxygen to the porous cathode surface.
  1. Create a physics continuum named Air, and for it select the following models in order:
    Group Box Model
    Space Three Dimensional
    Time Steady
    Material Multi-Component Gas
    Reaction Regime Non-reacting
    Flow Segregated Flow
    Gradients (selected automatically)
    Segregated Species (selected automatically)
    Equation of State Constant Density
    Viscous Regime Laminar
    Optional Models Segregated Fluid Temperature
    Electrochemistry
    Electrochemistry Electrochemical Reactions
    Optional Models Porous Media
    Porous Media Energy Porous Media Thermal Equilibrium
    Optional Models Porous Media Drag
    Optional Models Electrochemical Reaction Heating
  2. Click Close.
Fuel is modeled as a multi-component gas mixture of hydrogen and water vapour. The Fuel continuum supplies hydrogen to the porous anode surface.
  1. Make a copy of the Air node and rename it Fuel.
The mass fraction gradient is high at the flow boundaries into the fuel and air continua. Since the flow boundary diffusion affects the mass flux of the components, it is necessary to turn off the flow boundary diffusion.
  1. Multi-select the following models in the Air and Fuel continua:
    • Air > Segregated Flow
    • Air > Segregated Fluid Temperature
    • Air > Segregated Species
    • Fuel > Segregated Flow
    • Fuel > Segregated Fluid Temperature
    • Fuel > Segregated Species
  2. Deactivate Flow Boundary Diffusion.
    The open-boundary fluxes m˙ are now calculated as:
    Figure 1. EQUATION_DISPLAY
    m˙=ρiv⁢ A=Yiρ⁢ v⁢ A
    (5282)
    • ρi is the density of species i
    • v is the velocity
    • A is the surface area of the boundary
    • Yi is the mass fraction of species i
  3. Save the simulation.