Predefined System
A Predefined System uses the built-in database with native functionality to set up one of the following common systems; dry air, moist air, or water and steam.
To create a Predefined System, start the Thermodynamic System Wizard in one of the following ways:
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Right-click the Global Definitions node, select Thermodynamics and choose Predefined System.
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Using the Reaction Engineering interface, choose Predefined System from the Thermodynamics section of the Reaction Engineering toolbar.
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Correspondingly, using the Chemistry interface, choose Predefined System from the Thermodynamics section of the Chemistry toolbar.
The Thermodynamic System Wizard that opens is identical to the wizard used to create a Thermodynamic System, but with the important difference that all settings have been entered for the chosen predefined system. The wizard contains the following steps:
1
Select System
2
Select Species
3
Select Thermodynamic Model
Select System
In the Select System window, choose one of the predefined systems in the list. Choose among Dry air, Moist air and Water-steam. Click the Next button () to proceed to the next step in the wizard.
Figure 2-11: Thermodynamic System Wizard: Select Predefined System.
Select Species
If Dry or Moist air was chosen in the Select System step, the Selected species table is populated with the species relevant for the chosen system. For Dry air the species are: nitrogen, oxygen, argon, carbon dioxide, neon and helium. For Moist air the list also contains water. If instead Water-steam was chosen in the Select System step, the Next button in that step guides you directly to the Select Thermodynamic Model pane. No additions of species can be done in the wizard.
To add more species to the Dry air and Moist air systems, use the Species Type filter text field to search among the available species in the COMSOL database or the User-Defined Species. Species can be searched for by typing the name, CAS number, or the chemical formula. Select one or more species in the list and click the Add Selected button () to add species to the Selected species table. To remove species from the Selected species table, use either the Remove Selected button () or the Remove All button (), both located below the table. Click the Next button () to proceed to the next step in the wizard.
Figure 2-12: Thermodynamic System Wizard: Select Species.
Select Thermodynamic Model
This last step of the Thermodynamic System Wizard allows you to choose what thermodynamic model to use. For the system Dry air and Moist air, the Ideal Gas law is chosen by default. For Water-steam, the model Water (IAPWS) is used. For more information about this step in the Thermodynamic System Wizard, see Select Thermodynamic Model for Thermodynamic System.
Click the Finish button () to exit the Thermodynamic System Wizard and add the corresponding Predefined System under the Thermodynamics node. Note that the default node label reflects the chosen predefined system.
Settings
Selecting a Predefined System node shows its Settings window with a description of the package content and the available properties. For information about the content in the Settings window, see Settings for Thermodynamic System and Predefined System.
Modifying a Predefined System
Please see Modifying an Existing System for information about how to modify an existing thermodynamic system.