Thermodynamics
To access the functionality for thermodynamic calculations, right-click the Global Definitions node in the Model Builder tree and select Thermodynamics (). Using the Reaction Engineering or Chemistry interfaces, Thermodynamics is also available on the Reaction Engineering or Chemistry toolbar.
Figure 2-1: The Thermodynamics feature available under Global Definitions.
Thermodynamic properties given as parameters or functions are collected in a so called thermodynamic system. Each thermodynamic system includes a set of available species and phases, as well as different models used for the thermodynamic property calculations, for example an equation of state such as Peng-Robinson.
Select Thermodynamic System in the context menu to add a thermodynamic system that uses the database included in the Liquid & Gas Properties Module.
As an alternative, selecting External Thermodynamic System can make use of an installed thermodynamics software to make the corresponding calculations.
The option Predefined System, allows you to set up one of the following systems; Dry air, Moist air, or Water-steam.
It is also possible to import previously created and stored thermodynamic systems by selecting Import Thermodynamic System (see Exporting and Importing Thermodynamic Systems).
In addition to creating thermodynamic systems, you can also define User-Defined Species in Thermodynamics. Use User-Defined Species to add new species that are not available in COMSOL database. You can also edit available species in the database.
Figure 2-2: Adding Thermodynamic Systems to the Thermodynamics node. Note that external package providers have been installed.
When a thermodynamic system has been added, thermodynamic and transport properties are defined by functions. These can be used to describe properties for pure species, mixtures, and for gas-liquid (or liquid-liquid) systems at equilibrium.