.TILMedia.UsersGuide.PropertyCalculation

Property Calculation

Information

The calculation of thermo-physical properties with the TILMedia Modelica interface is divided in five groups:

Gas - Ideal gases and mixtures with one component that can condense - gas vapor
Liquid - Incompressible single phase fluids and mixtures
VLEFluid - Real fluid or fluid mixture, which can be liquid, vaporous, super-critical or may have a vapor-liquid equilibrium (VLE)
Solid - Single phase solids
SLEMedium - can be solid, liquid or may have a solid-liquid equilibrium (SLE)

There are different options to calculate thermo-physical properties:

object-oriented [recommended] - An external object is created and all properties are calculated at once (e.g. TestGas, TestLiquid, TestVLEFluid).
function based [for single evaluations only] - Only one property is calculated. Useful for parameter expressions such as start values. For efficient calculation of time-varying variable use objects or object functions.
objects with functions [for conditional/additional properties] - The classes without inputs (Gas, Liquid and VLEFluid) can be used to calculate conditional or additional properties efficiently.
object functions [for additional properties] - Using the pointer to an existing external object additional properties can be computed efficiently.

The use of functions, objects with functions and object functions is shown in the example: TestVLEFluidObjectFunctions. Equivalent to the shown VLEFluid calculations are the use of Gas, Liquid and corresponding functions are possible.
The object-oriented calculation is recommended. The Fluid properties are calculated with independent variables that are declared as input. Depending on which variables are known, different classes are available with a corresponding ending:

_ph pressure and enthalpy
_ps pressure and entropy
_pT pressure and temperature
_dT density and temperature

The mass fraction vector is needed additionally, if the fluid is a mixture. For more information see the models itself and the testers.

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