Study 1: SCR Operating Window, Fixed ANR
Step 1: Stationary Plug Flow
Enter the volumes to solve for, from zero to total reactor volume.
1
In the Model Builder window, under Study 1 click Step 1: Stationary Plug Flow.
2
In the Settings window for Stationary Plug Flow, locate the Study Settings section.
3
In the Output volumes text field, type 0 V_SCR.
4
Locate the Physics and Variables Selection section. In the Solve for column of the table, under Component 1, clear the checkbox for Ammonia Slip Catalyst (ASC).
5
Click to expand the Study Extensions section. Select the Auxiliary sweep checkbox.
6
Click  Add.
7
In the table, enter the following settings:
Parameter name
Parameter value list
Parameter unit
T_gas_in (Temperature of inlet exhaust gas)
range(523,25,825)
K
It is good practice to check the default scales for the dependent variables set up by the study. These are found under the Solver Configurations node. For this case, using scales based on the initial values improves the convergence rate and the solution accuracy.
Solution 1 (sol1)
1
In the Study toolbar, click  Show Default Solver.
2
In the Model Builder window, expand the Solution 1 (sol1) node, then click Dependent Variables 1.
3
In the Settings window for Dependent Variables, locate the Scaling section.
4
From the Method list, choose Initial-value based.
Rename the study into something descriptive, and compute.
5
In the Model Builder window, click Study 1.
6
In the Settings window for Study, type Study 1: SCR Temperature Operating Window, ANR = 1.3, Case 2 in the Label text field.
7
In the Study toolbar, click  Compute.