Study 3: Single Channel Model, Effect of ANR
We have now investigated the influence of both inlet temperature and ammonia to NOx ratio on the SCR monolith system. Now, solve for both of the catalysts in series. Begin by turning off the functionality to only plot when requested.
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In the Model Builder window, click Results.
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In the Settings window for Results, locate the Update of Results section.
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Clear the Only plot when requested checkbox.
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In the Home toolbar, click  Add Study to open the Add Study window.
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Go to the Add Study window.
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Find the Studies subsection. In the Select Study tree, select Preset Studies for Selected Physics Interfaces > Stationary Plug Flow.
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Click the Add Study button in the window toolbar.
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In the Home toolbar, click  Add Study to close the Add Study window.
Stationary Plug Flow, SCR
1
In the Settings window for Stationary Plug Flow, type Stationary Plug Flow, SCR in the Label text field.
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Locate the Study Settings section. In the Output volumes text field, type 0 V_SCR.
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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).
Stationary Plug Flow, ASC
1
Right-click Study 3 > Step 1: Stationary Plug Flow, SCR and choose Duplicate.
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In the Settings window for Stationary Plug Flow, type Stationary Plug Flow, ASC in the Label text field.
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Locate the Study Settings section. In the Output volumes text field, type V_SCR V_SCR+V_ASC.
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Locate the Physics and Variables Selection section. In the Solve for column of the table, under Component 1, clear the checkbox for Selective Catalytic Reduction Catalyst (SCR) .
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In the Solve for column of the table, under Component 1, select the checkbox for Ammonia Slip Catalyst (ASC).
To connect the two beds we need to create the dataset for the study.
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In the Model Builder window, click Study 3.
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In the Settings window for Study, type Study 3: Single Channel Model, Influence of ANR, Case 2 in the Label text field.
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Locate the Study Settings section. Select the Store solution for all intermediate study steps checkbox.
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Clear the Generate default plots checkbox.
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In the Study toolbar, click  Get Initial Value.
We can now connect the two Reaction Engineering interfaces with each other, so that the second catalyst uses the output from the first catalyst as input.
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In the Model Builder window, click Step 2: Stationary Plug Flow, ASC.
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In the Settings window for Stationary Plug Flow, click to expand the Values of Dependent Variables section.
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Find the Initial values of variables solved for subsection. From the Settings list, choose User controlled.
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From the Method list, choose Initial expression.
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From the Selection list, choose Last.
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Find the Values of variables not solved for subsection. From the Settings list, choose User controlled.
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From the Selection list, choose Last.
Solver Configurations
Use initial value based scales for the dependent variables.
1
In the Model Builder window, expand the Study 3: Single Channel Model, Influence of ANR, Case 2 > Solver Configurations node.
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In the Model Builder window, expand the Study 3: Single Channel Model, Influence of ANR, Case 2 > Solver Configurations > Solution 3 (sol3) node, then click Dependent Variables 1.
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In the Settings window for Dependent Variables, locate the Scaling section.
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From the Method list, choose Initial-value based.
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In the Model Builder window, click Dependent Variables 2.
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In the Settings window for Dependent Variables, locate the Scaling section.
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From the Method list, choose Initial-value based.
Add a Parametric Sweep feature to solve for three different ammonia to NOx ratios.
Parametric Sweep
1
In the Study toolbar, click  Parametric Sweep.
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In the Settings window for Parametric Sweep, locate the Study Settings section.
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Click  Add.
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In the table, enter the following settings:
Parameter name
Parameter value list
Parameter unit
ANR (Ammonia to NOx ratio in gas entering the reactor)
1 1.3 1.6
 
5
In the Study toolbar, click  Compute.