Use the Additional Source node () to add an additional rate expression (SI unit: mol/m3) and/or an additional volumetric production rate (SI unit: m3/s) to the mass balance of certain species.

Add the node from the Reaction Engineering toolbar or right-click Reaction Engineering and add it from the context menu.

An additional Additional volumetric production rate can be added for some of the available reactor types, namely CSTR, constant mass/generic, CSTR, constant volume, or Semi.

Here, values or expressions describing additional rates can be entered for selected Species in the column denoted Additional rate expression (mol/m^3*s) within the Volumetric species table.

Here, values or expressions describing additional surface species rates can be entered for selected Surface species in the column denoted Additional rate expression (mol/m^2*s) within the Surface species table.