Properties of dry air calculated using the equation of state by Lemmon et. al.
Information
This model calculates medium properties
for air in the liquid, gas and two phase regions.
Three variable pairs can be the independent variables of the model:
- Pressure p and specific enthalpy h are the most natural choice for general applications. This is the recommended choice for most general purpose applications.
- Pressure p and temperature T are the most natural choice for applications where air is always in the same phase (liquid or gas).
- Density d and temperature T are explicit variables of the Helmholtz function in the near-critical region and can be the best choice for applications with super-critical or near-critical states.
The following quantities are always computed:
| Variable |
Unit |
Description |
| T |
K |
temperature |
| u |
J/kg |
specific internal energy |
| d |
kg/m^3 |
density |
| p |
Pa |
pressure |
| h |
J/kg |
specific enthalpy |
In some cases additional medium properties are needed.
A component that needs these optional properties has to call
one of the functions listed in
Modelica.Media.UsersGuide.MediumUsage.OptionalProperties and in
Modelica.Media.UsersGuide.MediumUsage.TwoPhase.
Many further properties can be computed. Using the well-known Bridgman's Tables, all first partial derivatives of the standard thermodynamic variables can be computed easily.
Extends from Modelica.Media.Interfaces.PartialPureSubstance (Base class for pure substances of one chemical substance).
Package Content
| Name |
Description |
| 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 |
 ThermodynamicState
|
Thermodynamic state |
 BaseProperties
|
Base properties of air |
 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 |
| dynamicViscosity
|
Return dynamic viscosity as a function of the thermodynamic state record |
| thermalConductivity
|
Thermal conductivity of air |
| 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 air |
| specificHeatCapacityCp
|
Specific heat capacity at constant pressure of air |
| specificHeatCapacityCv
|
Specific heat capacity at constant volume of air |
| isentropicExponent
|
Return isentropic exponent |
| isothermalCompressibility
|
Isothermal compressibility of air |
| isobaricExpansionCoefficient
|
Isobaric expansion coefficient of air |
| velocityOfSound
|
Return velocity of sound as a function of the thermodynamic state record |
| density_derh_p
|
Density derivative by specific enthalpy |
| density_derp_h
|
Density derivative by pressure |
| setState_dTX
|
Return thermodynamic state of air as function of d and T |
| setState_phX
|
Return thermodynamic state of air as function of p and h |
| setState_psX
|
Return thermodynamic state of air as function of p and s |
| setState_pTX
|
Return thermodynamic state of air as function of p and T |
| setSmoothState
|
Return thermodynamic state so that it smoothly approximates: if x > 0 then state_a else state_b |
| isentropicEnthalpy
|
|
| molarMass
|
Return the molar mass of the medium |
| 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 |
| ThermoStates |
Enumeration type for independent variables |
| mediumName="Air" |
Name of the medium |
| substanceNames={"air"} |
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=false |
= 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=true |
= 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.Units.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) |
| C_default=fill(0, nC) |
Default value for trace substances 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 |
| specificEnthalpy_pTX
|
Return specific enthalpy from p, T, and X or Xi |
| specificEntropy_pTX
|
Return specific enthalpy from p, T, and X or Xi |
| density_pTX
|
Return density 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 |
| 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 |
Thermodynamic state
Information
Extends from (Minimal variable set that is available as input argument to every medium function).
Base properties of air
Information
Extends from .
Parameters
| Name | Description |
|---|
| Advanced |
| preferredMediumStates | = true if StateSelect.prefer shall be used for the independent property variables of the medium |
Computes density as a function of pressure and specific enthalpy
Information
Extends from Modelica.Icons.Function (Icon for functions).
Inputs
Outputs
| Name | Description |
|---|
| d | Density [kg/m3] |
Computes temperature as a function of pressure and specific enthalpy
Information
Extends from Modelica.Icons.Function (Icon for functions).
Inputs
Outputs
| Name | Description |
|---|
| T | Temperature [K] |
Compute temperature from pressure and specific enthalpy
Information
Extends from Modelica.Icons.Function (Icon for functions).
Inputs
Outputs
| Name | Description |
|---|
| T | Temperature [K] |
Computes density as a function of pressure and specific enthalpy
Information
Extends from Modelica.Icons.Function (Icon for functions).
Inputs
Outputs
| Name | Description |
|---|
| d | Density [kg/m3] |
Computes pressure as a function of density and temperature
Information
Extends from Modelica.Icons.Function (Icon for functions).
Inputs
Outputs
| Name | Description |
|---|
| p | Pressure [Pa] |
Computes specific enthalpy as a function of density and temperature
Information
Extends from Modelica.Icons.Function (Icon for functions).
Inputs
Outputs
| Name | Description |
|---|
| h | Specific enthalpy [J/kg] |
Computes specific enthalpy as a function of pressure and temperature
Information
Extends from Modelica.Icons.Function (Icon for functions).
Inputs
Outputs
| Name | Description |
|---|
| h | Specific enthalpy [J/kg] |
Computes specific enthalpy as a function of pressure and temperature
Information
Extends from Modelica.Icons.Function (Icon for functions).
Inputs
Outputs
| Name | Description |
|---|
| h | Specific enthalpy [J/kg] |
Computes density as a function of pressure and temperature
Information
Extends from Modelica.Icons.Function (Icon for functions).
Inputs
Outputs
| Name | Description |
|---|
| d | Density [kg/m3] |
Return dynamic viscosity as a function of the thermodynamic state record
Information
Extends from (Return dynamic viscosity).
Inputs
Outputs
| Name | Description |
|---|
| eta | Dynamic viscosity [Pa.s] |
Thermal conductivity of air
Information
Extends from (Return thermal conductivity).
Inputs
Outputs
| Name | Description |
|---|
| lambda | Thermal conductivity [W/(m.K)] |
Return pressure of ideal gas
Information
Extends from (Return pressure).
Inputs
Outputs
| Name | Description |
|---|
| p | Pressure [Pa] |
Return temperature of ideal gas
Information
Extends from (Return temperature).
Inputs
Outputs
| Name | Description |
|---|
| T | Temperature [K] |
Return density of ideal gas
Information
Extends from (Return density).
Inputs
Outputs
| Name | Description |
|---|
| d | Density [kg/m3] |
Return specific enthalpy
Information
Extends from (Return specific enthalpy).
Inputs
Outputs
| Name | Description |
|---|
| h | Specific enthalpy [J/kg] |
Return specific internal energy
Information
Extends from (Return specific internal energy).
Inputs
Outputs
| Name | Description |
|---|
| u | Specific internal energy [J/kg] |
Return specific Gibbs energy
Information
Extends from (Return specific Gibbs energy).
Inputs
Outputs
| Name | Description |
|---|
| g | Specific Gibbs energy [J/kg] |
Return specific Helmholtz energy
Information
Extends from (Return specific Helmholtz energy).
Inputs
Outputs
| Name | Description |
|---|
| f | Specific Helmholtz energy [J/kg] |
Specific entropy of air
Information
Extends from (Return specific entropy).
Inputs
Outputs
| Name | Description |
|---|
| s | Specific entropy [J/(kg.K)] |
Specific heat capacity at constant pressure of air
Information
Extends from (Return specific heat capacity at constant pressure).
Inputs
Outputs
| Name | Description |
|---|
| cp | Specific heat capacity at constant pressure [J/(kg.K)] |
Specific heat capacity at constant volume of air
Information
Extends from (Return specific heat capacity at constant volume).
Inputs
Outputs
| Name | Description |
|---|
| cv | Specific heat capacity at constant volume [J/(kg.K)] |
Return isentropic exponent
Information
Extends from (Return isentropic exponent).
Inputs
Outputs
| Name | Description |
|---|
| gamma | Isentropic exponent [1] |
Isothermal compressibility of air
Information
Extends from (Return overall the isothermal compressibility factor).
Inputs
Outputs
| Name | Description |
|---|
| kappa | Isothermal compressibility [1/Pa] |
Isobaric expansion coefficient of air
Information
Extends from (Return overall the isobaric expansion coefficient beta).
Inputs
Outputs
| Name | Description |
|---|
| beta | Isobaric expansion coefficient [1/K] |
Return velocity of sound as a function of the thermodynamic state record
Information
Extends from (Return velocity of sound).
Inputs
Outputs
| Name | Description |
|---|
| a | Velocity of sound [m/s] |
Density derivative by specific enthalpy
Information
Extends from (Return density derivative w.r.t. specific enthalpy at constant pressure).
Inputs
Outputs
| Name | Description |
|---|
| ddhp | Density derivative w.r.t. specific enthalpy [kg.s2/m5] |
Density derivative by pressure
Information
Extends from (Return density derivative w.r.t. pressure at const specific enthalpy).
Inputs
Outputs
| Name | Description |
|---|
| ddph | Density derivative w.r.t. pressure [s2/m2] |
Return thermodynamic state of air as function of d and T
Information
Extends from (Return thermodynamic state as function of d, T and composition X or Xi).
Inputs
Outputs
| Name | Description |
|---|
| state | Thermodynamic state record |
Return thermodynamic state of air as function of p and h
Information
Extends from (Return thermodynamic state as function of p, h and composition X or Xi).
Inputs
Outputs
| Name | Description |
|---|
| state | Thermodynamic state record |
Return thermodynamic state of air as function of p and s
Information
Extends from (Return thermodynamic state as function of p, s and composition X or Xi).
Inputs
Outputs
| Name | Description |
|---|
| state | Thermodynamic state record |
Return thermodynamic state of air as function of p and T
Information
Extends from (Return thermodynamic state as function of p, T and composition X or Xi).
Inputs
Outputs
| Name | Description |
|---|
| state | Thermodynamic state record |
Return thermodynamic state so that it smoothly approximates: if x > 0 then state_a else state_b
Information
Extends from (Return thermodynamic state so that it smoothly approximates: if x > 0 then state_a else state_b).
Inputs
Outputs
| Name | Description |
|---|
| state | Smooth thermodynamic state for all x (continuous and differentiable) |
Information
Extends from (Return isentropic enthalpy).
Inputs
Outputs
| Name | Description |
|---|
| h_is | Isentropic enthalpy [J/kg] |
Return the molar mass of the medium
Information
Extends from (Return the molar mass of the medium).
Inputs
Outputs
| Name | Description |
|---|
| MM | Mixture molar mass [kg/mol] |
Automatically generated Thu Oct 1 16:08:03 2020.
Modelica.Media.Air.ReferenceAir.Air_Base.ThermodynamicState
Modelica.Media.Air.ReferenceAir.Air_Base.BaseProperties
Modelica.Media.Air.ReferenceAir.Air_Base.density_ph