Mixture Property
A Mixture Property is used to compute a property function that depends on the concentration of the species in a thermodynamic system. Some examples of the available property functions are density, enthalpy, heat capacity, and surface tension.
Apart from the composition, the mixture property functions are also dependent on temperature and pressure. The first-order derivatives with respect to temperature and pressure are automatically defined. The second-order derivatives with respect to temperature and pressure are available for property functions of density and molar volume.
Right-click the relevant Thermodynamic System node (see FigureĀ 6-8), Predefined System node, or the relevant External Thermodynamic System node, and select Mixture Property to start the Mixture Property Wizard.
The Mixture Property Wizard contains the following steps:
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Select Properties
The settings in this step corresponds to those for Select Properties in the Species Property Wizard. Click the Next button () to proceed to the next step.
Select Phase
Use this list to specify the phase, among the ones available in the system, for the selected mixture property.
Some properties require that the system consists of two phases, for example surface tension. A two-phase system may consist of a combination of liquid-vapor or liquid-liquid phases.
Select Species
First select the Species composition base unit to be used for function arguments. Select Mole fraction or Mass fraction.
Select the species to be included in the list. Use the Add All button () to add all species in the thermodynamic system. It is also possible to select a subset of the available species. In that case use the Add Selected button () to add species. The Selected species table is updated as you add species.
Click the Next button () to proceed to the next step in the wizard.
Mixture Property Overview
The final step of the wizard displays an overview of the functions that the wizard has added. Click the Finish button () to exit the wizard and add the properties to the current thermodynamic system.
Settings
Selecting a desired Mixture Property node to display its settings window.
The Mixture Node Under a System
When creating mixture properties, the resulting functions are collected under the Mixture node. You can create new functions from an existing Mixture node. Right-click the node and select Mixture Property from the context menu to start the Mixture Property Wizard.
Figure 6-20: Mixture properties can be created by right-clicking a Mixture node under a thermodynamic system.