Problem Statement
This problem requires that a species DMc
be added to DM
and DP.
The FEMLAB mixed steady-state expression for these conservation principles
in the flow field is
DM:
DP:
DMc:
where D denotes the diffusion coefficient
(m2/s) for species mass transport, c is the
concentration (mol/m3) and h
(kg/m×s)
is dynamic viscosity. Inside the catalyst pellet, the steady state mass
conservation principle is
DMc:
where Deff
is the effective diffusion coefficient (m2/s), related to the
porosity and tortuosity of the pellet, and k is the rate constant
for the assumed second order reaction (m3/mol×s)
creating the species mass. The non-D Reynolds and Schmidt numbers are defined in FEMLAB terminology as
where w
is the diameter of the pellet and vo is the inflow velocity.
The corresponding non-D forms for the conservation principles are
DM:
DP:
DMc:
DMc:
In FEMLAB nomenclature, the BCs for the symmetric half-domain
flowfield simulation are shown in Figure 1a, while the BCs for the mass
transport are given in Figure 1b. For the flowfield, the word symmetry
specifies
Figure 1. Pellet problem BCs, a) flowfield, b)
mass transport. Setting-up the problem in FEMLAB This problem requires you to select two modes, the
Incompressible Navier-Stokes and the convection and conduction mode from
the Chemical Engineering module. It is required to set the axis and grid
based on the given geometry as shown in the following table
The base case data specification is:
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