Transport Properties (Pellets)
Use this node to specify transport properties of the fluid mixture inside porous pellets.
Domain Selection
The domain selection inherits all valid domains from its parent feature. For the invalid domains, not applicable is shown.
Fluid and matrix properties
Select Fluid density — Ideal gas, or User defined to enter an expression for the density ρ of the fluid inside pellets. If a density variable is defined in Chemistry with the Define variables for porous pellets selected (in the Pellet Chemistry section), the density can be selected from the list.
Select Dynamic viscosity — User defined for the fluid inside pellets. Enter a number or expression for the viscosity μ. If a viscosity variable is defined in Chemistry with the Define variables for porous pellets selected (in the Pellet Chemistry section), the viscosity can be selected from this list.
Select Permeability — From material or User defined for the fluid inside pellets. If User defined is selected, enter a permeability expression for κ. The default value is 1·10-12 m2.
Diffusion
To account for the effect of porosity in the binary diffusivities, select an Effective diffusivity model — Millington and Quirk model, Bruggeman model, Tortuosity model, or No correction. Using one of the first three models, the effective transport factor, fe, is defined from the porosity and the fluid tortuosity factor in the manner of:
(3-129)
For No correction, the effective transport factor is set to one.
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For the Millington and Quirk model, the effective transport factor is .
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For the Bruggeman model, the effective transport factor is .
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For the Tortuosity model, specify the tortuosity factor τpe.
The species diffusivities are automatically adjusted for porous media transport using the effective transport factor.
Select Binary diffusion input type — Table (the default), or Matrix to input the binary diffusion coefficients.
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Table. In the Maxwell-Stefan diffusivities table, the first (Species 1) and second (Species 2) columns are the species names for a binary diffusion coefficient. Select a diffusivity from the Diffusivity column. If User defined is selected, enter a binary diffusion coefficient expression in the Diffusion coefficient (m2/s) column (this column is editable with the User defined selected, otherwise read only).
If there are diffusivity variables defined in the Chemistry interface (with Define variables for porous pellets selected in the Pellet Chemistry section), these diffusivities can be selected from the Diffusivity column.
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Matrix. In the Maxwell-Stefan diffusivity matrix, enter the diffusivity expressions in the upper part of the matrix. The default values are 1·10-5 m2/s.
Enter the thermal diffusion coefficient for different species under the Thermal diffusion coefficient list.