Modelica.Media.Examples.TwoPhaseWater

Extension of the StandardWater package

Information

Example: TwoPhaseWater

The TwoPhaseWater package demonstrates how to extend the parsimonious BaseProperties with a minimal set of properties from the standard water package with most properties that are needed in two-phase situations. The model also demonstrates how to compute additional properties for the medium model. In this scenario, that builds a new medium model with many more properties than the default, the standard BaseProperties is used as a basis. For additional properties, a user has to:

Declare a new variable of the wanted type, e.g., "DynamicViscosity eta".
Compute that variable by calling the function form the package, e.g., eta = dynamicViscosity(state). Note that the instance of ThermodynamicState is used as an input to the function. This instance "state" is declared in PartialMedium and thus available in every medium model. A user does not have to know what actual variables are required to compute the dynamic viscosity, because the state instance is guaranteed to contain what is needed.
Attention: Many properties are not well defined in the two phase region and the functions might return undesired values if called there. It is the user's responsibility to take care of such situations. The example uses one of several possible models to compute an averaged viscosity for two-phase flows.

In two phase models, properties are often needed on the phase boundary just outside the two phase dome, right on the border.. To compute the thermodynamic state there, two auxiliary functions are provided: setDewState(sat) and setBubbleState(sat). They take an instance of SaturationProperties as input. By default they are in one-phase, but with the optional phase argument set to 2, the output is forced to be just inside the phase boundary. This is only needed when derivatives like cv are computed with are different on both sides of the boundaries. The usual steps to compute properties on the phase boundary are:

Declare an instance of ThermodynamicState, e.g., "ThermodynamicState dew".
Compute the state, using an instance of SaturationProperties, e.g., dew = setDewState(sat)
Compute properties on the phase boundary to your full desire, e.g., "cp_d = specificHeatCapacityCp(dew)".

The sample model TestTwoPhaseStates test the extended properties

The same procedure can be used to compute properties at other state points, e.g., when an isentropic reference state is computed.

Extends from Modelica.Media.Water.StandardWater (Water using the IF97 standard, explicit in p and h. Recommended for most applications).

Package Content

Name	Description
BaseProperties	Make StandardWater.BaseProperties non replaceable in order that inheritance is possible in model ExtendedProperties
ExtendedProperties	Plenty of two-phase properties
TestTwoPhaseStates	Test the above model
Inherited
ThermodynamicState	Thermodynamic state
Region=0	Region of IF97, if known, zero otherwise
ph_explicit	True if explicit in pressure and specific enthalpy
dT_explicit	True if explicit in density and temperature
pT_explicit	True if explicit in pressure and temperature
density_ph	Computes density as a function of pressure and specific enthalpy
temperature_ph	Computes temperature as a function of pressure and specific enthalpy
temperature_ps	Compute temperature from pressure and specific enthalpy
density_ps	Computes density as a function of pressure and specific enthalpy
pressure_dT	Computes pressure as a function of density and temperature
specificEnthalpy_dT	Computes specific enthalpy as a function of density and temperature
specificEnthalpy_pT	Computes specific enthalpy as a function of pressure and temperature
specificEnthalpy_ps	Computes specific enthalpy as a function of pressure and temperature
density_pT	Computes density as a function of pressure and temperature
setDewState	Set the thermodynamic state on the dew line
setBubbleState	Set the thermodynamic state on the bubble line
dynamicViscosity	Dynamic viscosity of water
thermalConductivity	Thermal conductivity of water
surfaceTension	Surface tension in two phase region of water
pressure	Return pressure of ideal gas
temperature	Return temperature of ideal gas
density	Return density of ideal gas
specificEnthalpy	Return specific enthalpy
specificInternalEnergy	Return specific internal energy
specificGibbsEnergy	Return specific Gibbs energy
specificHelmholtzEnergy	Return specific Helmholtz energy
specificEntropy	Specific entropy of water
specificHeatCapacityCp	Specific heat capacity at constant pressure of water
specificHeatCapacityCv	Specific heat capacity at constant volume of water
isentropicExponent	Return isentropic exponent
isothermalCompressibility	Isothermal compressibility of water
isobaricExpansionCoefficient	Isobaric expansion coefficient of water
velocityOfSound	Return velocity of sound as a function of the thermodynamic state record
isentropicEnthalpy	Compute h(s,p)
density_derh_p	Density derivative by specific enthalpy
density_derp_h	Density derivative by pressure
bubbleEnthalpy	Boiling curve specific enthalpy of water
dewEnthalpy	Dew curve specific enthalpy of water
bubbleEntropy	Boiling curve specific entropy of water
dewEntropy	Dew curve specific entropy of water
bubbleDensity	Boiling curve specific density of water
dewDensity	Dew curve specific density of water
saturationTemperature	Saturation temperature of water
saturationTemperature_derp	Derivative of saturation temperature w.r.t. pressure
saturationPressure	Saturation pressure of water
dBubbleDensity_dPressure	Bubble point density derivative
dDewDensity_dPressure	Dew point density derivative
dBubbleEnthalpy_dPressure	Bubble point specific enthalpy derivative
dDewEnthalpy_dPressure	Dew point specific enthalpy derivative
setState_dTX	Return thermodynamic state of water as function of d, T, and optional region
setState_phX	Return thermodynamic state of water as function of p, h, and optional region
setState_psX	Return thermodynamic state of water as function of p, s, and optional region
setState_pTX	Return thermodynamic state of water as function of p, T, and optional region
setSmoothState	Return thermodynamic state so that it smoothly approximates: if x > 0 then state_a else state_b
smoothModel=false	True if the (derived) model should not generate state events
onePhase=false	True if the (derived) model should never be called with two-phase inputs
fluidConstants	Constant data for the fluid
setSat_T	Return saturation property record from temperature
setSat_p	Return saturation property record from pressure
saturationPressure_sat	Return saturation temperature
saturationTemperature_sat	Return saturation temperature
saturationTemperature_derp_sat	Return derivative of saturation temperature w.r.t. pressure
molarMass	Return the molar mass of the medium
specificEnthalpy_pTX	Return specific enthalpy from pressure, temperature and mass fraction
temperature_phX	Return temperature from p, h, and X or Xi
density_phX	Return density from p, h, and X or Xi
temperature_psX	Return temperature from p, s, and X or Xi
density_psX	Return density from p, s, and X or Xi
specificEnthalpy_psX	Return specific enthalpy from p, s, and X or Xi
setState_pT	Return thermodynamic state from p and T
setState_ph	Return thermodynamic state from p and h
setState_ps	Return thermodynamic state from p and s
setState_dT	Return thermodynamic state from d and T
setState_px	Return thermodynamic state from pressure and vapour quality
setState_Tx	Return thermodynamic state from temperature and vapour quality
vapourQuality	Return vapour quality
ThermoStates	Enumeration type for independent variables
mediumName="unusablePartialMedium"	Name of the medium
substanceNames={mediumName}	Names of the mixture substances. Set substanceNames={mediumName} if only one substance.
extraPropertiesNames=fill("", 0)	Names of the additional (extra) transported properties. Set extraPropertiesNames=fill("",0) if unused
singleState	= true, if u and d are not a function of pressure
reducedX=true	= true if medium contains the equation sum(X) = 1.0; set reducedX=true if only one substance (see docu for details)
fixedX=false	= true if medium contains the equation X = reference_X
reference_p=101325	Reference pressure of Medium: default 1 atmosphere
reference_T=298.15	Reference temperature of Medium: default 25 deg Celsius
reference_X=fill(1/nX, nX)	Default mass fractions of medium
p_default=101325	Default value for pressure of medium (for initialization)
T_default=Modelica.SIunits.Conversions.from_degC(20)	Default value for temperature of medium (for initialization)
h_default=specificEnthalpy_pTX(p_default, T_default, X_default)	Default value for specific enthalpy of medium (for initialization)
X_default=reference_X	Default value for mass fractions of medium (for initialization)
nS=size(substanceNames, 1)	Number of substances
nX=nS	Number of mass fractions
nXi=if fixedX then 0 else if reducedX then nS - 1 else nS	Number of structurally independent mass fractions (see docu for details)
nC=size(extraPropertiesNames, 1)	Number of extra (outside of standard mass-balance) transported properties
C_nominal=1.0e-6*ones(nC)	Default for the nominal values for the extra properties
FluidConstants	Critical, triple, molecular and other standard data of fluid
prandtlNumber	Return the Prandtl number
heatCapacity_cp	Alias for deprecated name
heatCapacity_cv	Alias for deprecated name
beta	Alias for isobaricExpansionCoefficient for user convenience
kappa	Alias of isothermalCompressibility for user convenience
density_derp_T	Return density derivative w.r.t. pressure at const temperature
density_derT_p	Return density derivative w.r.t. temperature at constant pressure
density_derX	Return density derivative w.r.t. mass fraction
specificEntropy_pTX	Return specific enthalpy from p, T, and X or Xi
density_pTX	Return density from p, T, and X or Xi
MassFlowRate	Type for mass flow rate with medium specific attributes
AbsolutePressure	Type for absolute pressure with medium specific attributes
Density	Type for density with medium specific attributes
DynamicViscosity	Type for dynamic viscosity with medium specific attributes
EnthalpyFlowRate	Type for enthalpy flow rate with medium specific attributes
MassFraction	Type for mass fraction with medium specific attributes
MoleFraction	Type for mole fraction with medium specific attributes
MolarMass	Type for molar mass with medium specific attributes
MolarVolume	Type for molar volume with medium specific attributes
IsentropicExponent	Type for isentropic exponent with medium specific attributes
SpecificEnergy	Type for specific energy with medium specific attributes
SpecificInternalEnergy	Type for specific internal energy with medium specific attributes
SpecificEnthalpy	Type for specific enthalpy with medium specific attributes
SpecificEntropy	Type for specific entropy with medium specific attributes
SpecificHeatCapacity	Type for specific heat capacity with medium specific attributes
SurfaceTension	Type for surface tension with medium specific attributes
Temperature	Type for temperature with medium specific attributes
ThermalConductivity	Type for thermal conductivity with medium specific attributes
PrandtlNumber	Type for Prandtl number with medium specific attributes
VelocityOfSound	Type for velocity of sound with medium specific attributes
ExtraProperty	Type for unspecified, mass-specific property transported by flow
CumulativeExtraProperty	Type for conserved integral of unspecified, mass specific property
ExtraPropertyFlowRate	Type for flow rate of unspecified, mass-specific property
IsobaricExpansionCoefficient	Type for isobaric expansion coefficient with medium specific attributes
DipoleMoment	Type for dipole moment with medium specific attributes
DerDensityByPressure	Type for partial derivative of density with respect to pressure with medium specific attributes
DerDensityByEnthalpy	Type for partial derivative of density with respect to enthalpy with medium specific attributes
DerEnthalpyByPressure	Type for partial derivative of enthalpy with respect to pressure with medium specific attributes
DerDensityByTemperature	Type for partial derivative of density with respect to temperature with medium specific attributes
DerTemperatureByPressure	Type for partial derivative of temperature with respect to pressure with medium specific attributes
SaturationProperties	Saturation properties of two phase medium
FluidLimits	Validity limits for fluid model
FixedPhase	Phase of the fluid: 1 for 1-phase, 2 for two-phase, 0 for not known, e.g., interactive use
Basic	The most basic version of a record used in several degrees of detail
IdealGas	The ideal gas version of a record used in several degrees of detail
TwoPhase	The two phase fluid version of a record used in several degrees of detail