The Initial Values node sets the initial values of the dependent variables solved for in the Reaction Engineering interface.

For CSTR, constant mass and Semi reactor types, in which the reactor volume changes with reaction, an Initial system volume Vr0 can be set.

For nonisothermal conditions (that is, the Energy Balance is set to Include), enter an Initial temperature T0 for the system. For the Plug flow reactor a corresponding Inlet temperature T0,in is entered.

In the Volumetric Species Initial Values table, the Species column automatically includes all the species in the model. Enter the corresponding values or expression for each species initially in the Concentration (mol/m^3) column.

For the Plug flow reactor an Inlet molar flow rate table is instead shown. Enter the values or expressions representing the inlet conditions of each species in the Molar flow rate (mol/s) column.

The Surface Species Initial Values table is displayed when surface species are present in the reactor, that is, when the Type is set to Surface species for at least one species in the reactor. In the Surface concentration (mol/m^2) column, enter the corresponding values or expression for each species initially on the reactive surface area (Ar) within the reactor. The values in the Site occupancy number column are by default set to 1, edit the value if a surface species takes up more than one active site on the reactive surface.

The total surface concentration is restricted by the molar amount of available sites on the reactive surface area. This is defined by the Density of sites Γs (mol/m2) entry. Make sure that the sum of the entered initial surface concentrations do not surpass the value selected here. Note that the total amount of sites occupied of a surface species cads,i is the Surface concentration (mol/m^2) multiplied with the Site occupancy number σs,i. The restriction of the total surface concentration is defined as:

When one or more equilibrium reactions are present, a section which allows the user to enable Mass-preserving initialization is shown. When enabled, the solver will first solve for the values of the species participating in any equilibrium reaction, while disregarding any kinetic reactions. The solution to the equilibrium subproblem is then used as a consistent starting point for the time stepping. The functionality solves a log-transformed version of the problem, which in turn puts a requirement that a finite concentration is present for each building block (atom kinds, charge, and/or a combination thereof). If Settings is changed from Automatic to Manual, the user may change the maximum number of iterations and the absolute tolerance.