Modelica.Media.Examples.TwoPhaseWater

extension of the StandardWater package

Information

Example: TwoPhaseWater

The TwoPhaseWater package demonstrates how to extend the parsimonius 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 ituations. 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 ususal 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

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(p,s)

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 and T

setState_phX Return thermodynamic state of water as function of p and h

setState_psX Return thermodynamic state of water as function of p and s

setState_pTX Return thermodynamic state of water as function of p and T

setSmoothState Return thermodynamic state so that it smoothly approximates: if x > 0 then state_a else state_b

smoothModel true if the (derived) model should not generate state events

onePhase true if the (derived) model should never be called with two-phase inputs

FluidLimits validity limits for fluid model

FluidConstants extended fluid constants

fluidConstants constant data for the fluid

SaturationProperties Saturation properties of two phase medium

FixedPhase phase of the fluid: 1 for 1-phase, 2 for two-phase, 0 for not known, e.g. interactive use

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

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 wrt pressure at const temperature

density_derT_p Return density derivative wrt temperature at constant pressure

density_derX Return density derivative wrt mass fraction

density_pTX Return density from p, T, and X or Xi

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

MassFlowRate Type for mass 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 resect to pressure with medium specific attributes

DerDensityByEnthalpy Type for partial derivative of density with resect to enthalpy with medium specific attributes

DerEnthalpyByPressure Type for partial derivative of enthalpy with resect to pressure with medium specific attributes

DerDensityByTemperature Type for partial derivative of density with resect to temperature with medium specific attributes

Choices Types, constants to define menu choices

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
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(p,s)
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 and T
setState_phX	Return thermodynamic state of water as function of p and h
setState_psX	Return thermodynamic state of water as function of p and s
setState_pTX	Return thermodynamic state of water as function of p and T
setSmoothState	Return thermodynamic state so that it smoothly approximates: if x > 0 then state_a else state_b
smoothModel	true if the (derived) model should not generate state events
onePhase	true if the (derived) model should never be called with two-phase inputs
FluidLimits	validity limits for fluid model
FluidConstants	extended fluid constants
fluidConstants	constant data for the fluid
SaturationProperties	Saturation properties of two phase medium
FixedPhase	phase of the fluid: 1 for 1-phase, 2 for two-phase, 0 for not known, e.g. interactive use
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
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 wrt pressure at const temperature
density_derT_p	Return density derivative wrt temperature at constant pressure
density_derX	Return density derivative wrt mass fraction
density_pTX	Return density from p, T, and X or Xi
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
MassFlowRate	Type for mass 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 resect to pressure with medium specific attributes
DerDensityByEnthalpy	Type for partial derivative of density with resect to enthalpy with medium specific attributes
DerEnthalpyByPressure	Type for partial derivative of enthalpy with resect to pressure with medium specific attributes
DerDensityByTemperature	Type for partial derivative of density with resect to temperature with medium specific attributes
Choices	Types, constants to define menu choices

Modelica.Media.Examples.TwoPhaseWater.BaseProperties

Make StandardWater.BaseProperties non replaceable in order that inheritance is possible in model ExtendedProperties

Information

Extends from (Base properties of water).

Parameters

Type Name Default Description

Initialization

Integer phase.start 1 2 for two-phase, 1 for one-phase, 0 if not known

Advanced

Boolean preferredMediumStates false = true if StateSelect.prefer shall be used for the independent property variables of the medium

Type	Name	Default	Description
Initialization
Integer	phase.start	1	2 for two-phase, 1 for one-phase, 0 if not known
Advanced
Boolean	preferredMediumStates	false	= true if StateSelect.prefer shall be used for the independent property variables of the medium

Modelica definition

redeclare model extends BaseProperties 
  "Make StandardWater.BaseProperties non replaceable in order that inheritance is possible in model ExtendedProperties"
end BaseProperties;

Modelica.Media.Examples.TwoPhaseWater.ExtendedProperties

plenty of two-phase properties

Information

Extends from BaseProperties (Make StandardWater.BaseProperties non replaceable in order that inheritance is possible in model ExtendedProperties).

Parameters

Type	Name	Default	Description
Initialization
Integer	phase.start	1	2 for two-phase, 1 for one-phase, 0 if not known
Advanced
Boolean	preferredMediumStates	false	= true if StateSelect.prefer shall be used for the independent property variables of the medium

Modelica definition

model ExtendedProperties "plenty of two-phase properties"
  extends BaseProperties;
  ThermodynamicState dew "dew line Properties";
  ThermodynamicState bubble "bubble line Properties";
  ThermodynamicState bubble2 "bubble line Properties, on the 2-phase side";
  DynamicViscosity eta "viscosity (McAdams mixture rules if in 2-phase)";
  DynamicViscosity eta_d "dew line viscosity";
  DynamicViscosity eta_b "bubble line viscosity";
  ThermalConductivity lambda_d "dew line thermal conductivity";
  ThermalConductivity lambda_b "bubble line thermal conductivity";
  SpecificHeatCapacity cp_d "dew line Specific heat capacity";
  SpecificHeatCapacity cp_b "bubble line Specific heat capacity";
  Real ddhp;
  Real ddhp_d;
  Real ddhp_b "derivatives";
  Real ddph;
  Real ddph_d;
  Real ddph_b "derivatives";
  Real ddhp_b2;
  Real ddph_b2 "derivatives";
  // no derivatives yet, ... sat should be temporary
  MassFraction x "steam mass fraction";
  Real dTp;
  Real dTp2;
  SpecificEntropy s_b;
  SpecificEntropy s_d;
equation 
  eta = if phase == 1 then dynamicViscosity(state) else 1/(x/eta_d + (1 - x)
    /eta_b);
  dew =  setDewState(sat);
  bubble =  setBubbleState(sat);
  bubble2 =  setBubbleState(sat,2);
  x = (h - bubble.h)/max(dew.h - bubble.h,1e-6);
  eta_d = dynamicViscosity(dew);
  eta_b = dynamicViscosity(bubble);
  lambda_d = thermalConductivity(dew);
  lambda_b = thermalConductivity(bubble);
  cp_d = specificHeatCapacityCp(dew);
  cp_b = specificHeatCapacityCp(bubble);
  s_d = specificEntropy(dew);
  s_b = specificEntropy(bubble);
  ddph = density_derp_h(state);
  ddph_d = density_derp_h(dew);
  ddph_b = density_derp_h(bubble);
  ddhp = density_derh_p(state);
  ddhp_d = density_derh_p(dew);
  ddhp_b = density_derh_p(bubble);
  ddhp_b2 = density_derh_p(bubble2);
  ddph_b2 = density_derp_h(bubble2);
  dTp = saturationTemperature_derp(p);
  dTp2 = (1/dew.d - 1/bubble.d)/max(s_d - s_b,1e-6);
end ExtendedProperties;

Modelica.Media.Examples.TwoPhaseWater.TestTwoPhaseStates

Test the above model

Information

For details see the documentation of the example package TwoPhaseWater

Extends from Modelica.Icons.Example (Icon for an example model).

Parameters

Type Name Default Description

Real dh 80000.0 80 kJ/second

Real dp 1.0e6 10 bars per second

Type	Name	Default	Description
Real	dh	80000.0	80 kJ/second
Real	dp	1.0e6	10 bars per second

Modelica definition

model TestTwoPhaseStates "Test the above model"
  extends Modelica.Icons.Example;
  ExtendedProperties medium(p(start = 700.0),
   h(start = 8.0e5));
  parameter Real dh = 80000.0 "80 kJ/second";
  parameter Real dp = 1.0e6 "10 bars per second";
equation 
  der(medium.p) = dp;
  der(medium.h) = dh;
end TestTwoPhaseStates;

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