Buildings.Media.Interfaces.PartialSimpleMedium

Information

  rho(p) = rho(p0) * ( 1 + kappa_const * (p-p0))

Extends from Modelica.Media.Interfaces.PartialPureSubstance (base class for pure substances of one chemical substance).

Package Content

Name	Description
cp_const	Constant specific heat capacity at constant pressure
cv_const	Constant specific heat capacity at constant volume
d_const	Constant density
eta_const	Constant dynamic viscosity
lambda_const	Constant thermal conductivity
a_const	Constant velocity of sound
T_min	Minimum temperature valid for medium model
T_max	Maximum temperature valid for medium model
T0=reference_T	Zero enthalpy temperature
MM_const	Molar mass
fluidConstants	fluid constants
ThermodynamicState	Thermodynamic state
kappa_const=0	Compressibility factor at constant temperature
p0=3E5	Reference pressure for compressibility and default medium pressure
constantDensity=(kappa_const <= 1E-20)	Flag, true if density is modeled as a constant
BaseProperties
setState_pTX	Return thermodynamic state from p, T, and X or Xi
setState_phX	Return thermodynamic state from p, h, and X or Xi
setState_psX	Return thermodynamic state from p, s, and X or Xi
setState_dTX	Return thermodynamic state from d, T, and X or Xi
setSmoothState	Return thermodynamic state so that it smoothly approximates: if x > 0 then state_a else state_b
dynamicViscosity	Return dynamic viscosity
thermalConductivity	Return thermal conductivity
pressure	Return pressure
temperature	Return temperature
density	Return density
specificEnthalpy	Return specific enthalpy
specificHeatCapacityCp	Return specific heat capacity at constant pressure
specificHeatCapacityCv	Return specific heat capacity at constant volume
isentropicExponent	Return isentropic exponent
velocityOfSound	Return velocity of sound
specificEnthalpy_pTX	Return specific enthalpy from p, T, and X or Xi
temperature_phX	Return temperature from p, h, and X or Xi
density_phX	Return density from p, h, and X or Xi
Inherited
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
density_ph	Return density from p and h
temperature_ph	Return temperature from p and h
pressure_dT	Return pressure from d and T
specificEnthalpy_dT	Return specific enthalpy from d and T
specificEnthalpy_ps	Return specific enthalpy from p and s
temperature_ps	Return temperature from p and s
density_ps	Return density from p and s
specificEnthalpy_pT	Return specific enthalpy from p and T
density_pT	Return density from p and T
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
specificInternalEnergy	Return specific internal energy
specificEntropy	Return specific entropy
specificGibbsEnergy	Return specific Gibbs energy
specificHelmholtzEnergy	Return specific Helmholtz energy
heatCapacity_cp	alias for deprecated name
heatCapacity_cv	alias for deprecated name
isentropicEnthalpy	Return isentropic enthalpy
isobaricExpansionCoefficient	Return overall the isobaric expansion coefficient beta
beta	alias for isobaricExpansionCoefficient for user convenience
isothermalCompressibility	Return overall the isothermal compressibility factor
kappa	alias of isothermalCompressibility for user convenience
density_derp_h	Return density derivative w.r.t. pressure at const specific enthalpy
density_derh_p	Return density derivative w.r.t. specific enthalpy at constant pressure
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
molarMass	Return the molar mass of the medium
specificEntropy_pTX	Return specific enthalpy from p, T, and X or Xi
density_pTX	Return density from p, T, 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
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

Types and constants

  constant SpecificHeatCapacity cp_const 
  "Constant specific heat capacity at constant pressure";

  constant SpecificHeatCapacity cv_const 
  "Constant specific heat capacity at constant volume";

  constant Density d_const "Constant density";

  constant DynamicViscosity eta_const "Constant dynamic viscosity";

  constant ThermalConductivity lambda_const "Constant thermal conductivity";

  constant VelocityOfSound a_const "Constant velocity of sound";

  constant Temperature T_min "Minimum temperature valid for medium model";

  constant Temperature T_max "Maximum temperature valid for medium model";

  constant Temperature T0=reference_T "Zero enthalpy temperature";

  constant MolarMass MM_const "Molar mass";

  constant FluidConstants[nS] fluidConstants "fluid constants";

  constant Real kappa_const(unit="1/Pa") = 0 
  "Compressibility factor at constant temperature";

  constant Modelica.SIunits.AbsolutePressure p0 = 3E5 
  "Reference pressure for compressibility and default medium pressure";

  constant Boolean constantDensity = (kappa_const <= 1E-20) 
  "Flag, true if density is modeled as a constant";

Buildings.Media.Interfaces.PartialSimpleMedium.ThermodynamicState

Information

Modelica definition

redeclare record extends ThermodynamicState "Thermodynamic state"
  AbsolutePressure p "Absolute pressure of medium";
  Temperature T "Temperature of medium";
end ThermodynamicState;

Buildings.Media.Interfaces.PartialSimpleMedium.BaseProperties

Information

This is the most simple incompressible medium model, where specific enthalpy h and specific internal energy u are only a function of temperature T and all other provided medium quantities are assumed to be constant.

Extends from .

Parameters

Type	Name	Default	Description
Advanced
Boolean	preferredMediumStates	false	= true if StateSelect.prefer shall be used for the independent property variables of the medium

Modelica definition

redeclare replaceable model extends BaseProperties
equation 
      assert(T >= T_min and T <= T_max, "
Temperature T (= " + String(T) + " K) is not
in the allowed range (" + String(T_min) + " K <= T <= " + String(T_max)
         + " K)
required from medium model \"" + mediumName + "\".
");

      // h = cp_const*(T-T0);
  h = specificEnthalpy_pTX(p,T,X);
  u = cv_const*(T-T0);
  // original equation d = d_const;
  d = if constantDensity then d_const else d_const * (1+kappa_const*(p-p0));
 // d = d_const * (1+kT*(T-T0)/T0); "this gives large coupled equations"
  R = 0;
  MM = MM_const;
  state.T = T;
  state.p = p;
end BaseProperties;

Buildings.Media.Interfaces.PartialSimpleMedium.setState_pTX

Information

Inputs

Type	Name	Default	Description
AbsolutePressure	p		Pressure [Pa]
Temperature	T		Temperature [K]
MassFraction	X[:]	reference_X	Mass fractions [kg/kg]

Outputs

Type	Name	Description
ThermodynamicState	state	thermodynamic state record

Modelica definition

redeclare function setState_pTX 
  "Return thermodynamic state from p, T, and X or Xi"
  extends Modelica.Icons.Function;
  input AbsolutePressure p "Pressure";
  input Temperature T "Temperature";
  input MassFraction X[:]=reference_X "Mass fractions";
  output ThermodynamicState state "thermodynamic state record";
algorithm 
  state := ThermodynamicState(p=p,T=T);
end setState_pTX;

Buildings.Media.Interfaces.PartialSimpleMedium.setState_phX

Information

Inputs

Type	Name	Default	Description
AbsolutePressure	p		Pressure [Pa]
SpecificEnthalpy	h		Specific enthalpy [J/kg]
MassFraction	X[:]	reference_X	Mass fractions [kg/kg]

Outputs

Type	Name	Description
ThermodynamicState	state	thermodynamic state record

Modelica definition

redeclare function setState_phX 
  "Return thermodynamic state from p, h, and X or Xi"
  extends Modelica.Icons.Function;
  input AbsolutePressure p "Pressure";
  input SpecificEnthalpy h "Specific enthalpy";
  input MassFraction X[:]=reference_X "Mass fractions";
  output ThermodynamicState state "thermodynamic state record";
algorithm 
  state := ThermodynamicState(p=p,T=temperature_phX(p, h, X));
end setState_phX;

Buildings.Media.Interfaces.PartialSimpleMedium.setState_psX

Information

Inputs

Type	Name	Default	Description
AbsolutePressure	p		Pressure [Pa]
SpecificEntropy	s		Specific entropy [J/(kg.K)]
MassFraction	X[:]	reference_X	Mass fractions [kg/kg]

Outputs

Type	Name	Description
ThermodynamicState	state	thermodynamic state record

Modelica definition

redeclare replaceable function setState_psX 
  "Return thermodynamic state from p, s, and X or Xi"
  extends Modelica.Icons.Function;
  input AbsolutePressure p "Pressure";
  input SpecificEntropy s "Specific entropy";
  input MassFraction X[:]=reference_X "Mass fractions";
  output ThermodynamicState state "thermodynamic state record";
algorithm 
  state := ThermodynamicState(p=p,T=Modelica.Math.exp(s/cp_const + Modelica.Math.log(T0))) 
    "here the incompressible limit is used, with cp as heat capacity";
end setState_psX;

Buildings.Media.Interfaces.PartialSimpleMedium.setState_dTX

Information

Inputs

Type	Name	Default	Description
Density	d		density [kg/m3]
Temperature	T		Temperature [K]
MassFraction	X[:]	reference_X	Mass fractions [kg/kg]

Outputs

Type	Name	Description
ThermodynamicState	state	thermodynamic state record

Modelica definition

redeclare function setState_dTX 
  "Return thermodynamic state from d, T, and X or Xi"
  extends Modelica.Icons.Function;
  input Density d "density";
  input Temperature T "Temperature";
  input MassFraction X[:]=reference_X "Mass fractions";
  output ThermodynamicState state "thermodynamic state record";
algorithm 
  assert(false,"pressure can not be computed from temperature and density for an incompressible fluid!");
end setState_dTX;

Buildings.Media.Interfaces.PartialSimpleMedium.setSmoothState

Information

Inputs

Type	Name	Default	Description
Real	x		m_flow or dp
ThermodynamicState	state_a		Thermodynamic state if x > 0
ThermodynamicState	state_b		Thermodynamic state if x < 0
Real	x_small		Smooth transition in the region -x_small < x < x_small

Outputs

Type	Name	Description
ThermodynamicState	state	Smooth thermodynamic state for all x (continuous and differentiable)

Modelica definition

redeclare function extends setSmoothState 
  "Return thermodynamic state so that it smoothly approximates: if x > 0 then state_a else state_b"
algorithm 
  state := ThermodynamicState(p=Modelica.Media.Common.smoothStep(
      x,
      state_a.p,
      state_b.p,
      x_small), T=Modelica.Media.Common.smoothStep(
      x,
      state_a.T,
      state_b.T,
      x_small));
end setSmoothState;

Buildings.Media.Interfaces.PartialSimpleMedium.dynamicViscosity

Information

Inputs

Type	Name	Default	Description
ThermodynamicState	state		thermodynamic state record

Outputs

Type	Name	Description
DynamicViscosity	eta	Dynamic viscosity [Pa.s]

Modelica definition

redeclare function extends dynamicViscosity 
  "Return dynamic viscosity"

algorithm 
  eta := eta_const;
end dynamicViscosity;

Buildings.Media.Interfaces.PartialSimpleMedium.thermalConductivity

Information

Inputs

Type	Name	Default	Description
ThermodynamicState	state		thermodynamic state record

Outputs

Type	Name	Description
ThermalConductivity	lambda	Thermal conductivity [W/(m.K)]

Modelica definition

redeclare function extends thermalConductivity 
  "Return thermal conductivity"

algorithm 
  lambda := lambda_const;
end thermalConductivity;

Buildings.Media.Interfaces.PartialSimpleMedium.pressure

Information

Inputs

Type	Name	Default	Description
ThermodynamicState	state		thermodynamic state record

Outputs

Type	Name	Description
AbsolutePressure	p	Pressure [Pa]

Modelica definition

redeclare function extends pressure "Return pressure"

algorithm 
  p := state.p;
end pressure;

Buildings.Media.Interfaces.PartialSimpleMedium.temperature

Information

Inputs

Type	Name	Default	Description
ThermodynamicState	state		thermodynamic state record

Outputs

Type	Name	Description
Temperature	T	Temperature [K]

Modelica definition

redeclare function extends temperature "Return temperature"

algorithm 
  T := state.T;
end temperature;

Buildings.Media.Interfaces.PartialSimpleMedium.density

Information

Inputs

Type	Name	Default	Description
ThermodynamicState	state		thermodynamic state record

Outputs

Type	Name	Description
Density	d	Density [kg/m3]

Modelica definition

redeclare function extends density "Return density"

algorithm 
  d := if constantDensity then d_const else d_const * (1+kappa_const*(state.p-p0));
end density;

Buildings.Media.Interfaces.PartialSimpleMedium.specificEnthalpy

Information

Inputs

Type	Name	Default	Description
ThermodynamicState	state		thermodynamic state record

Outputs

Type	Name	Description
SpecificEnthalpy	h	Specific enthalpy [J/kg]

Modelica definition

redeclare function extends specificEnthalpy 
  "Return specific enthalpy"

algorithm 
  h := cp_const*(state.T-T0);
end specificEnthalpy;

Buildings.Media.Interfaces.PartialSimpleMedium.specificHeatCapacityCp

Information

Inputs

Type	Name	Default	Description
ThermodynamicState	state		thermodynamic state record

Outputs

Type	Name	Description
SpecificHeatCapacity	cp	Specific heat capacity at constant pressure [J/(kg.K)]

Modelica definition

redeclare function extends specificHeatCapacityCp 
  "Return specific heat capacity at constant pressure"

algorithm 
  cp := cp_const;
end specificHeatCapacityCp;

Buildings.Media.Interfaces.PartialSimpleMedium.specificHeatCapacityCv

Information

Inputs

Type	Name	Default	Description
ThermodynamicState	state		thermodynamic state record

Outputs

Type	Name	Description
SpecificHeatCapacity	cv	Specific heat capacity at constant volume [J/(kg.K)]

Modelica definition

redeclare function extends specificHeatCapacityCv 
  "Return specific heat capacity at constant volume"

algorithm 
  cv := cv_const;
end specificHeatCapacityCv;

Buildings.Media.Interfaces.PartialSimpleMedium.isentropicExponent

Information

Inputs

Type	Name	Default	Description
ThermodynamicState	state		thermodynamic state record

Outputs

Type	Name	Description
IsentropicExponent	gamma	Isentropic exponent [1]

Modelica definition

redeclare function extends isentropicExponent 
  "Return isentropic exponent"

algorithm 
  gamma := cp_const/cv_const;
end isentropicExponent;

Buildings.Media.Interfaces.PartialSimpleMedium.velocityOfSound

Information

Inputs

Type	Name	Default	Description
ThermodynamicState	state		thermodynamic state record

Outputs

Type	Name	Description
VelocityOfSound	a	Velocity of sound [m/s]

Modelica definition

redeclare function extends velocityOfSound 
  "Return velocity of sound "

algorithm 
  a := a_const;
end velocityOfSound;

Buildings.Media.Interfaces.PartialSimpleMedium.specificEnthalpy_pTX

Information

Inputs

Type	Name	Default	Description
AbsolutePressure	p		Pressure [Pa]
Temperature	T		Temperature [K]
MassFraction	X[nX]		Mass fractions [kg/kg]

Outputs

Type	Name	Description
SpecificEnthalpy	h	Specific enthalpy [J/kg]

Modelica definition

redeclare function specificEnthalpy_pTX 
  "Return specific enthalpy from p, T, and X or Xi"
  extends Modelica.Icons.Function;
  input AbsolutePressure p "Pressure";
  input Temperature T "Temperature";
  input MassFraction X[nX] "Mass fractions";
  output SpecificEnthalpy h "Specific enthalpy";
algorithm 
  h := cp_const*(T-T0);
end specificEnthalpy_pTX;

Buildings.Media.Interfaces.PartialSimpleMedium.temperature_phX

Information

Inputs

Type	Name	Default	Description
AbsolutePressure	p		Pressure [Pa]
SpecificEnthalpy	h		Specific enthalpy [J/kg]
MassFraction	X[nX]		Mass fractions [kg/kg]

Outputs

Type	Name	Description
Temperature	T	Temperature [K]

Modelica definition

redeclare function temperature_phX 
  "Return temperature from p, h, and X or Xi"
  extends Modelica.Icons.Function;
  input AbsolutePressure p "Pressure";
  input SpecificEnthalpy h "Specific enthalpy";
  input MassFraction X[nX] "Mass fractions";
  output Temperature T "Temperature";
algorithm 
  T := T0 + h/cp_const;
end temperature_phX;

Buildings.Media.Interfaces.PartialSimpleMedium.density_phX

Information

Inputs

Type	Name	Default	Description
AbsolutePressure	p		Pressure [Pa]
SpecificEnthalpy	h		Specific enthalpy [J/kg]
MassFraction	X[nX]		Mass fractions [kg/kg]

Outputs

Type	Name	Description
Density	d	density [kg/m3]

Modelica definition

redeclare function density_phX 
  "Return density from p, h, and X or Xi"
  extends Modelica.Icons.Function;
  input AbsolutePressure p "Pressure";
  input SpecificEnthalpy h "Specific enthalpy";
  input MassFraction X[nX] "Mass fractions";
  output Density d "density";
algorithm 
  d := density(setState_phX(p,h,X));
end density_phX;