15.3.1 User Inputs for Particle Surface Reactions

The setup procedure for particle surface reactions requires only a few inputs in addition to the procedure for volumetric reactions described in Sections  15.1.1- 15.1.6. These additional inputs are as follows:

• In the Species Model dialog box, enable the Particle Surface option under Reactions.

  Models Species Edit...

• When you specify the species involved in the particle surface reaction, be sure to identify the surface species, as described in Section  15.1.3.

  You will find all species (including the surface species) in the list of Fluent Fluid Materials. If, for example, you are modeling coal gasification, you will find solid carbon, C(s), in the materials list for the fluid material type.

• For each particle surface reaction, select Particle Surface as the Reaction Type in the Reactions dialog box, and specify the following parameters (in addition to those described in Section  15.1.3):

  Diffusion-Limited Species   When there is more than one gaseous reactant taking part in the particle surface reaction, the diffusion-limited specie is the specie for which the concentration gradient between the bulk and the particle surface is the largest. See this figure in the separate Theory Guide for an illustration of this concept. In most cases, there is a single gas-phase reactant and the diffusion-limited specie does not need to be defined.

  Catalyst Species   This option is available only when there are no solid species defined in the stoichiometry of the particle surface reaction. In such a case, you will need to specify the solid specie that acts as a catalyst for the reaction. The reaction will proceed only on the particles that contain this solid specie. See Section  15.3.3 for details on defining the particle surface species mass fractions.

  Diffusion Rate Constant   ( $C_{1,r}$ in this equation in the separate Theory Guide)

  Effectiveness Factor   ( $\eta_r$ in this equation in the separate Theory Guide)