Phase objects are used in the IDAES Process Modeling Framework to identify the thermodynamic phases of interest in a property package and to contain information describing the behavior of that phase (for example the equation of state which describes that phase). Additional information on the Phase Class is provided in the technical specifications.
The IDAES Process Modeling Framework currently supports the following types of phases, along with a generic Phase object:
In a number of unit operations, different phases behave in different ways. For example, in a Flash operation, the vapor phase exits through the top outlet whilst liquid phase(s) (and any solids) exit through the bottom outlet. In order to determine how a given phase should behave in these situations, each Phase object implements the following three methods:
These methods return a boolean (True or False) indicating whether the unit operation should treat the phase as being of the specified type in order to decide on how it should behave. Each type of phase returns True for its type and False for all other types (e.g. LiquidPhase returns True for is_liquid_phase() and False for is_solid_phase() and is_vapor_phase().
The generic Phase object determines what to return for each method based on the user-provided name for the instance of the Phase object as shown below:
- is_liquid_phase() returns True if the Phase name contains the string Liq, otherwise it returns False.
- is_solid_phase() returns True if the Phase name contains the string Sol, otherwise it returns False.
- is_vapor_phase() returns True if the Phase name contains the string Vap, otherwise it returns False.
Users should avoid using the generic Phase object, as this is primarily intended as a base class for the specific phase classes and for backwards compatibility.