Parameters
Start by importing a set of global parameters that will be used when setting up this model. The parameter files contain process conditions for different engine loads, kinetic parameters, and catalyst dimensions.
Note: The location of a file is based on the installation. For example, if the installation is on your hard drive, the file path might be similar to C:\Program Files\COMSOL\COMSOL64\Multiphysics\applications\.
Parameters: Engine Load Cases
1
In the Home toolbar, click Parameters  and choose Parameter 1 .
Note: On Linux and macOS, the Home toolbar refers to the specific set of controls near the top of the Desktop.
2
In the Settings window under Parameters, click the Load from File button .
3
Browse to the file monolith_kinetics_engine_load_cases_parameters.txt in the application library folder on your computer, Chemical_Reaction_Engineering_Module\Tutorials. Double-click to add or click Open. The parameters from the txt-file are added to the table. The loaded file contains mass flow rates, nitrogen monoxide concentration, and temperature of the exhaust gas entering the reactor. Low engine load gives a lower mass flow rate, lower temperature, and less nitrogen oxides, than a high engine load.
4
Rename the parameter node by editing the label text field. Rename it to Parameters: Engine Load Cases.
Use the global feature Parameter Case to specify the load cases. By using this feature, it is even easier to set up a Parametric Sweep later. A Parametric Sweep feature is used when solving the same system with different parameter values.
Cases
1
In the Home toolbar, click  Parameters and choose Add > Parameters.
2
In the Settings window for Parameters, type Cases in the Label text field.
3
Locate the Parameters section. In the table, enter the following settings:
Name
Expression
Value
Description
m
m2
0.11 kg/s
Mass flow rate (case 2 is default)
y
y2
8E-4
NO molar fraction (case 2 is default)
T
T2
623 K
Inlet temperature (case 2 is default)
4
In the Home toolbar, click  Parameter Case.
5
In the Settings window for Case, type Low Load in the Label text field.
6
Locate the Parameters section. In the table, enter the following settings:
Name
Expression
Description
m
m1
Mass flow rate (case 2 is default)
y
y1
NO molar fraction (case 2 is default)
T
T1
Inlet temperature (case 2 is default)
7
In the Home toolbar, click  Parameter Case.
8
In the Settings window for Case, type Intermediate Load in the Label text field.
9
In the Home toolbar, click  Parameter Case.
10
In the Settings window for Case, type High Load in the Label text field.
11
Locate the Parameters section. In the table, enter the following settings:
Name
Expression
Description
m
m3
Mass flow rate (case 2 is default)
y
y3
NO molar fraction (case 2 is default)
T
T3
Inlet temperature (case 2 is default)
Load some more parameter files.
Parameters: Temperature and Monolith Parameters
1
In the Home toolbar, click  Parameters and choose Add > Parameters.
2
In the Settings window for Parameters, type Parameters: Temperature and Monolith Parameters in the Label text field.
3
Locate the Parameters section. Click  Load from File.
4
Browse to the model’s Application Libraries folder and double-click the file monolith_kinetics_temperature_monolith_parameters.txt.
Parameters: Flow and Composition
1
In the Home toolbar, click  Parameters and choose Add > Parameters.
2
In the Settings window for Parameters, type Parameters: Flow and Composition in the Label text field.
3
Locate the Parameters section. Click  Load from File.
4
Browse to the model’s Application Libraries folder and double-click the file monolith_kinetics_flow_composition_parameters.txt.
Parameters: Reaction Kinetics
1
In the Home toolbar, click  Parameters and choose Add > Parameters.
2
In the Settings window for Parameters, type Parameters: Reaction Kinetics in the Label text field.
3
Locate the Parameters section. Click  Load from File.
4
Browse to the model’s Application Libraries folder and double-click the file monolith_kinetics_kinetic_parameters.txt.
Load some variable files. These are, compared to parameters, not constant in value. We will add expressions for reaction rate constants, that vary with composition and temperature. For your convenience, we load the expressions from file, but you can also type them in directly in the table.