Shrinking Core Reactions
Use this node to define reactions occurring on the surface of the solid pellet core.
The pellet core can consist or one of more solid phase species. Core consumption occurs when the solid species are consumed by surface reactions on the core outer surface (facing the porous layer). Core consuming reactions can also involve bulk species. In this case the bulk species are removed or produced at the core surface.
Domain Selection
The node inherits all valid domains from its parent feature. For invalid domains, not applicable is shown.
Pellet
Select All to apply the core consumption reactions for all available pellets types. Or, select one of the pellet types in the list.
core consuming reactions
If there is one solid species only, the core shrinking rate depends on the consumed rate of this species. If there are more than one solid species, the core shrinking rate depends on the weighted mass consumed rate of all species, assuming that the same consumed rate is held for all species along the core axial direction.
In the Core species reaction rate table, select the reaction rate (SI unit: mol/(m2·s)) for solid species under the column Surface reaction rate. Select the Define variables for porous pellets check box in the Pellet Chemistry section to couple the reaction rate to the chemistry. With User defined selected from the column Surface reaction rate, enter a reaction-rate expression in the column Surface rate expression (mol/(m^2*s)).
For bulk species that take part in the core consuming reactions, or other surface reactions on the core surface, the reaction rate is some kind of molar flux between core surface and reacted layer.
Select bulk species reaction rate (or molar flux, SI unit: mol/(m2·s)) for bulk species i from the Jpe, i list. The reaction rate can be picked up from the chemistry by selecting the Define variables for porous pellets check box. Enter a reaction-rate expression when User defined is selected from the list.
Heat Source
Specify the Heat source (QsRc) evolved from core surface reactions. When multiple pellets types are present, all respective heat source are included.
The heat sources are most conveniently picked up from a surface reaction in a Chemistry interface (with the Define variables for porous pellets selected in the Pellet Chemistry section). In that case, the heat source expression can be selected from the list. Otherwise, you can enter an expression in the text field.
The heat source can be applied in a Heat Transfer in Packed Beds interface by using a Heat Source node added to the Pellets feature.
The total heat source (including heat from Porous Layer Reactions nodes) can be applied in a Heat Transfer in Porous Media interface by using a Heat Source feature.