Buildings.Media.GasesConstantDensity.SimpleAir

Package with dry air model that decouples pressure and temperature

Information

This medium model is similar to Modelica.Media.Air.SimpleAir, except that the gas density is constant.

The use of a constant density avoids having pressure as a state variable in mixing volumes. Hence, fast transients introduced by a change in pressure are avoided. The drawback is that the dimensionality of the coupled nonlinear equation system is typically larger for flow networks.

As in Modelica.Media.Air.SimpleAir, the specific enthalpy h and specific internal energy u are only a function of temperature T and all other provided medium quantities are constant.

Extends from Buildings.Media.Interfaces.PartialSimpleIdealGasMedium (Medium model of Ideal gas with constant cp and cv. All other quantities, e.g., transport properties, are constant.).

Package Content

Name	Description
fluidConstants=FluidConstants(iupacName={"simple air"}, casRegistryNumber={"not a real substance"}, chemicalFormula={"N2, O2"}, structureFormula={"N2, O2"}, molarMass=Modelica.Media.IdealGases.Common.SingleGasesData.N2.MM)	constant data for the fluid
pStp=101325	Pressure for which dStp is defined
dStp=1.2	Fluid density at pressure pStp
BaseProperties	Basic medium properties
setState_dTX	Return thermodynamic state from d, T, and X or Xi
density	return density of ideal gas
specificInternalEnergy	Return specific internal energy
specificEntropy	Return specific entropy
enthalpyOfCondensingGas	Enthalpy of steam per unit mass of steam
saturationPressure	Return saturation pressure of condensing fluid
Inherited
cp_const	Constant specific heat capacity at constant pressure
cv_const=cp_const - R_gas	Constant specific heat capacity at constant volume
R_gas	medium specific gas constant
MM_const	Molar mass
eta_const	Constant dynamic viscosity
lambda_const	Constant thermal conductivity
T_min	Minimum temperature valid for medium model
T_max	Maximum temperature valid for medium model
T0=reference_T	Zero enthalpy temperature
ThermodynamicState	Thermodynamic state of ideal gas
FluidConstants	fluid constants
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
setSmoothState	Return thermodynamic state so that it smoothly approximates: if x > 0 then state_a else state_b
pressure	Return pressure of ideal gas
temperature	Return temperature of ideal gas
specificEnthalpy	Return specific enthalpy
specificGibbsEnergy	Return specific Gibbs energy
specificHelmholtzEnergy	Return specific Helmholtz energy
dynamicViscosity	Return dynamic viscosity
thermalConductivity	Return thermal conductivity
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
isentropicEnthalpy	Return isentropic enthalpy
isobaricExpansionCoefficient	Returns overall the isobaric expansion coefficient beta
isothermalCompressibility	Returns overall the isothermal compressibility factor
density_derp_T	Returns the partial derivative of density with respect to pressure at constant temperature
density_derT_p	Returns the partial derivative of density with respect to temperature at constant pressure
density_derX	Returns the partial derivative of density with respect to mass fractions at constant pressure and temperature
molarMass	Returns the molar mass of the medium
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
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_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
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
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

Types and constants

  constant FluidConstants[nS] fluidConstants=
    FluidConstants(iupacName={"simple air"},
                   casRegistryNumber={"not a real substance"},
                   chemicalFormula={"N2, O2"},
                   structureFormula={"N2, O2"},
                   molarMass=Modelica.Media.IdealGases.Common.SingleGasesData.N2.MM) 
  "constant data for the fluid";

   constant AbsolutePressure pStp = 101325 "Pressure for which dStp is defined";

   constant Density dStp = 1.2 "Fluid density at pressure pStp";

Buildings.Media.GasesConstantDensity.SimpleAir.BaseProperties

Basic medium properties

Parameters

Modelica definition

Buildings.Media.GasesConstantDensity.SimpleAir.setState_dTX

Return thermodynamic state from d, T, and X or Xi

Information

Extends from Modelica.Icons.Function (Icon for functions).

Inputs

Outputs

Modelica definition

Buildings.Media.GasesConstantDensity.SimpleAir.density

return density of ideal gas

Information

Extends from Modelica.Icons.Function (Icon for functions).

Inputs

Outputs

Modelica definition

Buildings.Media.GasesConstantDensity.SimpleAir.specificInternalEnergy

Return specific internal energy

Information

Extends from Modelica.Icons.Function (Icon for functions).

Inputs

Outputs

Modelica definition

Buildings.Media.GasesConstantDensity.SimpleAir.specificEntropy

Return specific entropy

Information

Extends from Modelica.Icons.Function (Icon for functions).

Inputs

Outputs

Modelica definition

Buildings.Media.GasesConstantDensity.SimpleAir.enthalpyOfCondensingGas

Enthalpy of steam per unit mass of steam

Information

Extends from Modelica.Icons.Function (Icon for functions).

Inputs

Outputs

Modelica definition

Buildings.Media.GasesConstantDensity.SimpleAir.saturationPressure

Return saturation pressure of condensing fluid

Information

Extends from Modelica.Icons.Function (Icon for functions).

Inputs

Outputs

Modelica definition

Buildings.Media.GasesConstantDensity.SimpleAir.BaseProperties.InputAbsolutePressure

Pressure as input signal connector

Modelica definition

Buildings.Media.GasesConstantDensity.SimpleAir.BaseProperties.InputMassFraction

Mass fraction as input signal connector

Modelica definition

Buildings.Media.GasesConstantDensity.SimpleAir.BaseProperties.InputSpecificEnthalpy

Specific enthalpy as input signal connector

Modelica definition