Air: Moist air model (190 ... 647 K)

This package provides a full thermodynamic model of moist air including the fog region and temperatures below zero degC. The governing assumptions in this model are:

- the perfect gas law applies
- water volume other than that of steam is neglected

All extensive properties are expressed in terms of the total mass in order to comply with other media in this library. However, for moist air it is rather common to express the absolute humidity in terms of mass of dry air only, which has advantages when working with charts. In addition, care must be taken, when working with mass fractions with respect to total mass, that all properties refer to the same water content when being used in mathematical operations (which is always the case if based on dry air only). Therefore two absolute humidities are computed in the **BaseProperties** model: **X** denotes the absolute humidity in terms of the total mass while **x** denotes the absolute humidity per unit mass of dry air. In addition, the relative humidity **phi** is also computed.

At the triple point temperature of water of 0.01 °C or 273.16 K and a relative humidity greater than 1 fog may be present as liquid and as ice resulting in a specific enthalpy somewhere between those of the two isotherms for solid and liquid fog, respectively. For numerical reasons a coexisting mixture of 50% solid and 50% liquid fog is assumed in the fog region at the triple point in this model.

From the assumptions mentioned above it follows that the **pressure** should be in the region around **atmospheric** conditions or below (a few bars may still be fine though). Additionally a very high water content at low temperatures would yield incorrect densities, because the volume of the liquid or solid phase would not be negligible anymore. The model does not provide information on limits for water drop size in the fog region or transport information for the actual condensation or evaporation process in combination with surfaces. All excess water which is not in its vapour state is assumed to be still present in the air regarding its energy but not in terms of its spatial extent.

The thermodynamic model may be used for **temperatures** ranging from **190 ... 647 K**. This holds for all functions unless otherwise stated in their description. However, although the model works at temperatures above the saturation temperature it is questionable to use the term "relative humidity" in this region. Please note, that although several functions compute pure water properties, they are designed to be used within the moist air medium model where properties are dominated by air and steam in their vapor states, and not for pure liquid water applications.

Several additional functions that are not needed to describe the thermodynamic system, but are required to model transport processes, like heat and mass transfer, may be called. They usually neglect the moisture influence unless otherwise stated.

The model's main area of application is all processes that involve moist air cooling under near atmospheric pressure with possible moisture condensation. This is the case in all domestic and industrial air conditioning applications. Another large domain of moist air applications covers all processes that deal with dehydration of bulk material using air as a transport medium. Engineering tasks involving moist air are often performed (or at least visualized) by using charts that contain all relevant thermodynamic data for a moist air system. These so called psychrometric charts can be generated from the medium properties in this package. The model PsychrometricData may be used for this purpose in order to obtain data for figures like those below (the plotting itself is not part of the model though).

**Legend:** blue - constant specific enthalpy, red - constant temperature, black - constant relative humidity

Extends from Interfaces.PartialCondensingGases (Base class for mixtures of condensing and non-condensing gases).

Name | Description |
---|---|

Water=1 | Index of water (in substanceNames, massFractions X, etc.) |

Air=2 | Index of air (in substanceNames, massFractions X, etc.) |

k_mair=steam.MM/dryair.MM | Ratio of molar weights |

dryair=IdealGases.Common.SingleGasesData.Air | |

steam=IdealGases.Common.SingleGasesData.H2O | |

MMX={steam.MM,dryair.MM} | Molar masses of components |

ThermodynamicState | ThermodynamicState record for moist air |

BaseProperties | Moist air base properties record |

setState_pTX | Return thermodynamic state as function of pressure p, temperature T and composition X |

setState_phX | Return thermodynamic state as function of pressure p, specific enthalpy h and composition X |

setState_dTX | Return thermodynamic state as function of density d, temperature T and composition X |

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

Xsaturation | Return absolute humidity per unit mass of moist air at saturation as a function of the thermodynamic state record |

xsaturation | Return absolute humidity per unit mass of dry air at saturation as a function of the thermodynamic state record |

xsaturation_pT | Return absolute humidity per unit mass of dry air at saturation as a function of pressure p and temperature T |

massFraction_pTphi | Return steam mass fraction as a function of relative humidity phi and temperature T |

relativeHumidity_pTX | Return relative humidity as a function of pressure p, temperature T and composition X |

relativeHumidity | Return relative humidity as a function of the thermodynamic state record |

gasConstant | Return ideal gas constant as a function from thermodynamic state, only valid for phi<1 |

gasConstant_X | Return ideal gas constant as a function from composition X |

saturationPressureLiquid | Return saturation pressure of water as a function of temperature T in the range of 273.16 to 647.096 K |

saturationPressureLiquid_der | Derivative function for 'saturationPressureLiquid' |

sublimationPressureIce | Return sublimation pressure of water as a function of temperature T between 190 and 273.16 K |

sublimationPressureIce_der | Derivative function for 'sublimationPressureIce' |

saturationPressure | Return saturation pressure of water as a function of temperature T between 190 and 647.096 K |

saturationPressure_der | Derivative function for 'saturationPressure' |

saturationTemperature | Return saturation temperature of water as a function of (partial) pressure p |

enthalpyOfVaporization | Return enthalpy of vaporization of water as a function of temperature T, 273.16 to 647.096 K |

HeatCapacityOfWater | Return specific heat capacity of water (liquid only) as a function of temperature T |

enthalpyOfLiquid | Return enthalpy of liquid water as a function of temperature T(use enthalpyOfWater instead) |

enthalpyOfGas | Return specific enthalpy of gas (air and steam) as a function of temperature T and composition X |

enthalpyOfCondensingGas | Return specific enthalpy of steam as a function of temperature T |

enthalpyOfNonCondensingGas | Return specific enthalpy of dry air as a function of temperature T |

enthalpyOfWater | Computes specific enthalpy of water (solid/liquid) near atmospheric pressure from temperature T |

enthalpyOfWater_der | Derivative function of enthalpyOfWater |

pressure | Returns pressure of ideal gas as a function of the thermodynamic state record |

temperature | Return temperature of ideal gas as a function of the thermodynamic state record |

T_phX | Return temperature as a function of pressure p, specific enthalpy h and composition X |

density | Returns density of ideal gas as a function of the thermodynamic state record |

specificEnthalpy | Return specific enthalpy of moist air as a function of the thermodynamic state record |

h_pTX | Return specific enthalpy of moist air as a function of pressure p, temperature T and composition X |

h_pTX_der | Derivative function of h_pTX |

isentropicExponent | Return isentropic exponent (only for gas fraction!) |

isentropicEnthalpyApproximation | Approximate calculation of h_is from upstream properties, downstream pressure, gas part only |

specificInternalEnergy | Return specific internal energy of moist air as a function of the thermodynamic state record |

specificInternalEnergy_pTX | Return specific internal energy of moist air as a function of pressure p, temperature T and composition X |

specificInternalEnergy_pTX_der | Derivative function for specificInternalEnergy_pTX |

specificEntropy | Return specific entropy from thermodynamic state record, only valid for phi<1 |

specificGibbsEnergy | Return specific Gibbs energy as a function of the thermodynamic state record, only valid for phi<1 |

specificHelmholtzEnergy | Return specific Helmholtz energy as a function of the thermodynamic state record, only valid for phi<1 |

specificHeatCapacityCp | Return specific heat capacity at constant pressure as a function of the thermodynamic state record |

specificHeatCapacityCv | Return specific heat capacity at constant volume as a function of the thermodynamic state record |

dynamicViscosity | Return dynamic viscosity as a function of the thermodynamic state record, valid from 123.15 K to 1273.15 K |

thermalConductivity | Return thermal conductivity as a function of the thermodynamic state record, valid from 123.15 K to 1273.15 K |

velocityOfSound | |

isobaricExpansionCoefficient | |

isothermalCompressibility | |

density_derp_h | |

density_derh_p | |

density_derp_T | |

density_derT_p | |

density_derX | |

molarMass | |

T_psX | Return temperature as a function of pressure p, specific entropy s and composition X |

setState_psX | |

s_pTX | Return specific entropy of moist air as a function of pressure p, temperature T and composition X (only valid for phi<1) |

s_pTX_der | Return specific entropy of moist air as a function of pressure p, temperature T and composition X (only valid for phi<1) |

isentropicEnthalpy | Isentropic enthalpy (only valid for phi<1) |

Utilities | Utility functions |

Inherited | |

fluidConstants={IdealGases.Common.FluidData.H2O,IdealGases.Common.FluidData.N2} | Constant data for the fluid |

moleToMassFractions | Return mass fractions X from mole fractions |

massToMoleFractions | Return mole fractions from mass fractions X |

ThermoStates=Modelica.Media.Interfaces.Choices.IndependentVariables.pTX | Enumeration type for independent variables |

mediumName="Moist air" | Name of the medium |

substanceNames={"water","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=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={0.01,0.99} | 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 |

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 |

ThermodynamicState record for moist air

Extends from (Thermodynamic state variables).

Moist air base properties record

This model computes thermodynamic properties of moist air from three independent (thermodynamic or/and numerical) state variables. Preferred numerical states are temperature T, pressure p and the reduced composition vector Xi, which contains the water mass fraction only. As an EOS the **ideal gas law** is used and associated restrictions apply. The model can also be used in the **fog region**, when moisture is present in its liquid state. However, it is assumed that the liquid water volume is negligible compared to that of the gas phase. Computation of thermal properties is based on property data of dry air and water (source: VDI-Wärmeatlas), respectively. Besides the standard thermodynamic variables **absolute and relative humidity**, x_water and phi, respectively, are given by the model. Upper case X denotes absolute humidity with respect to mass of moist air while absolute humidity with respect to mass of dry air only is denoted by a lower case x throughout the model. See package description for further information.

Extends from (Base properties (p, d, T, h, u, R_s, MM and, if applicable, X and Xi) of a medium).

Name | Description |
---|---|

standardOrderComponents | If true, and reducedX = true, the last element of X will be computed from the other ones |

Advanced | |

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

Return thermodynamic state as function of pressure p, temperature T and composition X

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

Name | Description |
---|---|

p | Pressure [Pa] |

T | Temperature [K] |

X[:] | Mass fractions [kg/kg] |

Name | Description |
---|---|

state | Thermodynamic state |

Return thermodynamic state as function of pressure p, specific enthalpy h and composition X

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

Name | Description |
---|---|

p | Pressure [Pa] |

h | Specific enthalpy [J/kg] |

X[:] | Mass fractions [kg/kg] |

Name | Description |
---|---|

state | Thermodynamic state |

Return thermodynamic state as function of density d, temperature T and composition X

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

Name | Description |
---|---|

d | Density [kg/m3] |

T | Temperature [K] |

X[:] | Mass fractions [kg/kg] |

Name | Description |
---|---|

state | Thermodynamic state |

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

Extends from (Return thermodynamic state so that it smoothly approximates: if x > 0 then state_a else state_b).

Name | Description |
---|---|

x | m_flow or dp |

state_a | Thermodynamic state if x > 0 |

state_b | Thermodynamic state if x < 0 |

x_small | Smooth transition in the region -x_small < x < x_small |

Name | Description |
---|---|

state | Smooth thermodynamic state for all x (continuous and differentiable) |

Return absolute humidity per unit mass of moist air at saturation as a function of the thermodynamic state record

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

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

X_sat | Steam mass fraction of sat. boundary [kg/kg] |

Return absolute humidity per unit mass of dry air at saturation as a function of the thermodynamic state record

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

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

x_sat | Absolute humidity per unit mass of dry air [kg/kg] |

Return absolute humidity per unit mass of dry air at saturation as a function of pressure p and temperature T

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

Name | Description |
---|---|

p | Pressure [Pa] |

T | Temperature [K] |

Name | Description |
---|---|

x_sat | Absolute humidity per unit mass of dry air [kg/kg] |

Return steam mass fraction as a function of relative humidity phi and temperature T

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

Name | Description |
---|---|

p | Pressure [Pa] |

T | Temperature [K] |

phi | Relative humidity (0 ... 1.0) |

Name | Description |
---|---|

X_steam | Absolute humidity, steam mass fraction [kg/kg] |

Return relative humidity as a function of pressure p, temperature T and composition X

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

Name | Description |
---|---|

p | Pressure [Pa] |

T | Temperature [K] |

X[:] | Composition [1] |

Name | Description |
---|---|

phi | Relative humidity |

Return relative humidity as a function of the thermodynamic state record

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

Name | Description |
---|---|

state | Thermodynamic state |

Name | Description |
---|---|

phi | Relative humidity |

Return ideal gas constant as a function from thermodynamic state, only valid for phi<1

Extends from (Return the gas constant of the mixture (also for liquids)).

Name | Description |
---|---|

state | Thermodynamic state |

Name | Description |
---|---|

R_s | Mixture gas constant [J/(kg.K)] |

Return ideal gas constant as a function from composition X

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

Name | Description |
---|---|

X[:] | Gas phase composition [1] |

Name | Description |
---|---|

R_s | Ideal gas constant [J/(kg.K)] |

Return saturation pressure of water as a function of temperature T in the range of 273.16 to 647.096 K

Saturation pressure of water above the triple point temperature is computed from temperature.

Source: A Saul, W Wagner: "International equations for the saturation properties of ordinary water substance", equation 2.1

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

Name | Description |
---|---|

Tsat | Saturation temperature [K] |

Name | Description |
---|---|

psat | Saturation pressure [Pa] |

Derivative function for 'saturationPressureLiquid'

Saturation pressure of water above the triple point temperature is computed from temperature.

Source: A Saul, W Wagner: "International equations for the saturation properties of ordinary water substance", equation 2.1

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

Name | Description |
---|---|

Tsat | Saturation temperature [K] |

dTsat | Saturation temperature derivative [K/s] |

Name | Description |
---|---|

psat_der | Saturation pressure derivative [Pa/s] |

Return sublimation pressure of water as a function of temperature T between 190 and 273.16 K

Sublimation pressure of water below the triple point temperature is computed from temperature.

Source: W Wagner, A Saul, A Pruss: "International equations for the pressure along the melting and along the sublimation curve of ordinary water substance", equation 3.5

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

Name | Description |
---|---|

Tsat | Sublimation temperature [K] |

Name | Description |
---|---|

psat | Sublimation pressure [Pa] |

Derivative function for 'sublimationPressureIce'

Sublimation pressure of water below the triple point temperature is computed from temperature.

Source: W Wagner, A Saul, A Pruss: "International equations for the pressure along the melting and along the sublimation curve of ordinary water substance", equation 3.5

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

Name | Description |
---|---|

Tsat | Sublimation temperature [K] |

dTsat | Sublimation temperature derivative [K/s] |

Name | Description |
---|---|

psat_der | Sublimation pressure derivative [Pa/s] |

Return saturation pressure of water as a function of temperature T between 190 and 647.096 K

Extends from (Return saturation pressure of condensing fluid).

Name | Description |
---|---|

Tsat | Saturation temperature [K] |

Name | Description |
---|---|

psat | Saturation pressure [Pa] |

Derivative function for 'saturationPressure'

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

Name | Description |
---|---|

Tsat | Saturation temperature [K] |

dTsat | Time derivative of saturation temperature [K/s] |

Name | Description |
---|---|

psat_der | Saturation pressure [Pa/s] |

Return saturation temperature of water as a function of (partial) pressure p

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

Name | Description |
---|---|

p | Pressure [Pa] |

T_min | Lower boundary of solution [K] |

T_max | Upper boundary of solution [K] |

Name | Description |
---|---|

T | Saturation temperature [K] |

Return enthalpy of vaporization of water as a function of temperature T, 273.16 to 647.096 K

Enthalpy of vaporization of water is computed from temperature in the region of 273.16 to 647.096 K.

Source: W Wagner, A Pruss: "International equations for the saturation properties of ordinary water substance. Revised according to the international temperature scale of 1990" (1993).

Extends from (Return vaporization enthalpy of condensing fluid).

Name | Description |
---|---|

T | Temperature [K] |

Name | Description |
---|---|

r0 | Vaporization enthalpy [J/kg] |

Return specific heat capacity of water (liquid only) as a function of temperature T

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

Name | Description |
---|---|

T | Temperature [K] |

Name | Description |
---|---|

cp_fl | Specific heat capacity of liquid [J/(kg.K)] |

Return enthalpy of liquid water as a function of temperature T(use enthalpyOfWater instead)

Extends from (Return liquid enthalpy of condensing fluid).

Name | Description |
---|---|

T | Temperature [K] |

Name | Description |
---|---|

h | Liquid enthalpy [J/kg] |

Return specific enthalpy of gas (air and steam) as a function of temperature T and composition X

Extends from (Return enthalpy of non-condensing gas mixture).

Name | Description |
---|---|

T | Temperature [K] |

X[:] | Vector of mass fractions [kg/kg] |

Name | Description |
---|---|

h | Specific enthalpy [J/kg] |

Return specific enthalpy of steam as a function of temperature T

Extends from (Return enthalpy of condensing gas (most often steam)).

Name | Description |
---|---|

T | Temperature [K] |

Name | Description |
---|---|

h | Specific enthalpy [J/kg] |

Return specific enthalpy of dry air as a function of temperature T

Extends from (Return enthalpy of the non-condensing species).

Name | Description |
---|---|

T | Temperature [K] |

Name | Description |
---|---|

h | Specific enthalpy [J/kg] |

Computes specific enthalpy of water (solid/liquid) near atmospheric pressure from temperature T

- heat capacity of liquid water:4200 J/kg
- heat capacity of solid water: 2050 J/kg
- enthalpy of fusion (liquid=>solid): 333000 J/kg

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

Name | Description |
---|---|

T | Temperature [K] |

Name | Description |
---|---|

h | Specific enthalpy of water [J/kg] |

Derivative function of enthalpyOfWater

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

Name | Description |
---|---|

T | Temperature [K] |

dT | Time derivative of temperature [K/s] |

Name | Description |
---|---|

dh | Time derivative of specific enthalpy [J/(kg.s)] |

Returns pressure of ideal gas as a function of the thermodynamic state record

Extends from (Return pressure).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

p | Pressure [Pa] |

Return temperature of ideal gas as a function of the thermodynamic state record

Extends from (Return temperature).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

T | Temperature [K] |

Return temperature as a function of pressure p, specific enthalpy h and composition X

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

Name | Description |
---|---|

p | Pressure [Pa] |

h | Specific enthalpy [J/kg] |

X[:] | Mass fractions of composition [kg/kg] |

Name | Description |
---|---|

T | Temperature [K] |

Returns density of ideal gas as a function of the thermodynamic state record

Extends from (Return density).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

d | Density [kg/m3] |

Return specific enthalpy of moist air as a function of the thermodynamic state record

Extends from (Return specific enthalpy).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

h | Specific enthalpy [J/kg] |

Return specific enthalpy of moist air as a function of pressure p, temperature T and composition X

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

Name | Description |
---|---|

p | Pressure [Pa] |

T | Temperature [K] |

X[:] | Mass fractions of moist air [1] |

Name | Description |
---|---|

h | Specific enthalpy at p, T, X [J/kg] |

Derivative function of h_pTX

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

Name | Description |
---|---|

p | Pressure [Pa] |

T | Temperature [K] |

X[:] | Mass fractions of moist air [1] |

dp | Pressure derivative [Pa/s] |

dT | Temperature derivative [K/s] |

dX[:] | Composition derivative [1/s] |

Name | Description |
---|---|

h_der | Time derivative of specific enthalpy [J/(kg.s)] |

Return isentropic exponent (only for gas fraction!)

Extends from (Return isentropic exponent).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

gamma | Isentropic exponent [1] |

Approximate calculation of h_is from upstream properties, downstream pressure, gas part only

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

Name | Description |
---|---|

p2 | Downstream pressure [Pa] |

state | Thermodynamic state at upstream location |

Name | Description |
---|---|

h_is | Isentropic enthalpy [J/kg] |

Return specific internal energy of moist air as a function of the thermodynamic state record

Extends from Modelica.Icons.Function (Icon for functions), (Return specific internal energy).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

u | Specific internal energy [J/kg] |

Return specific internal energy of moist air as a function of pressure p, temperature T and composition X

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

Name | Description |
---|---|

p | Pressure [Pa] |

T | Temperature [K] |

X[:] | Mass fractions of moist air [1] |

Name | Description |
---|---|

u | Specific internal energy [J/kg] |

Derivative function for specificInternalEnergy_pTX

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

Name | Description |
---|---|

p | Pressure [Pa] |

T | Temperature [K] |

X[:] | Mass fractions of moist air [1] |

dp | Pressure derivative [Pa/s] |

dT | Temperature derivative [K/s] |

dX[:] | Mass fraction derivatives [1/s] |

Name | Description |
---|---|

u_der | Specific internal energy derivative [J/(kg.s)] |

Return specific entropy from thermodynamic state record, only valid for phi<1

Extends from (Return specific entropy).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

s | Specific entropy [J/(kg.K)] |

Return specific Gibbs energy as a function of the thermodynamic state record, only valid for phi<1

Extends from Modelica.Icons.Function (Icon for functions), (Return specific Gibbs energy).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

g | Specific Gibbs energy [J/kg] |

Return specific Helmholtz energy as a function of the thermodynamic state record, only valid for phi<1

Extends from Modelica.Icons.Function (Icon for functions), (Return specific Helmholtz energy).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

f | Specific Helmholtz energy [J/kg] |

Return specific heat capacity at constant pressure as a function of the thermodynamic state record

Extends from (Return specific heat capacity at constant pressure).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

cp | Specific heat capacity at constant pressure [J/(kg.K)] |

Return specific heat capacity at constant volume as a function of the thermodynamic state record

Extends from (Return specific heat capacity at constant volume).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

cv | Specific heat capacity at constant volume [J/(kg.K)] |

Return dynamic viscosity as a function of the thermodynamic state record, valid from 123.15 K to 1273.15 K

Dynamic viscosity is computed from temperature using a simple polynomial for dry air. Range of validity is from 123.15 K to 1273.15 K. The influence of pressure and moisture is neglected.

Source: VDI Waermeatlas, 8th edition.

Extends from (Return dynamic viscosity).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

eta | Dynamic viscosity [Pa.s] |

Return thermal conductivity as a function of the thermodynamic state record, valid from 123.15 K to 1273.15 K

Thermal conductivity is computed from temperature using a simple polynomial for dry air. Range of validity is from 123.15 K to 1273.15 K. The influence of pressure and moisture is neglected.

Source: VDI Waermeatlas, 8th edition.

Extends from (Return thermal conductivity).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

lambda | Thermal conductivity [W/(m.K)] |

Extends from (Return velocity of sound).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

a | Velocity of sound [m/s] |

Extends from (Return overall the isobaric expansion coefficient beta).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

beta | Isobaric expansion coefficient [1/K] |

Extends from (Return overall the isothermal compressibility factor).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

kappa | Isothermal compressibility [1/Pa] |

Extends from (Return density derivative w.r.t. pressure at const specific enthalpy).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

ddph | Density derivative w.r.t. pressure [s2/m2] |

Extends from (Return density derivative w.r.t. specific enthalpy at constant pressure).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

ddhp | Density derivative w.r.t. specific enthalpy [kg.s2/m5] |

Extends from (Return density derivative w.r.t. pressure at const temperature).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

ddpT | Density derivative w.r.t. pressure [s2/m2] |

Extends from (Return density derivative w.r.t. temperature at constant pressure).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

ddTp | Density derivative w.r.t. temperature [kg/(m3.K)] |

Extends from (Return density derivative w.r.t. mass fraction).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

dddX[nX] | Derivative of density w.r.t. mass fraction [kg/m3] |

Extends from (Return the molar mass of the medium).

Name | Description |
---|---|

state | Thermodynamic state record |

Name | Description |
---|---|

MM | Mixture molar mass [kg/mol] |

Return temperature as a function of pressure p, specific entropy s and composition X

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

Name | Description |
---|---|

p | Pressure [Pa] |

s | Specific entropy [J/(kg.K)] |

X[:] | Mass fractions of composition [kg/kg] |

Name | Description |
---|---|

T | Temperature [K] |

Extends from (Return thermodynamic state as function of p, s and composition X or Xi).

Name | Description |
---|---|

p | Pressure [Pa] |

s | Specific entropy [J/(kg.K)] |

X[:] | Mass fractions [kg/kg] |

Name | Description |
---|---|

state | Thermodynamic state record |

Return specific entropy of moist air as a function of pressure p, temperature T and composition X (only valid for phi<1)

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

Name | Description |
---|---|

p | Pressure [Pa] |

T | Temperature [K] |

X[:] | Mass fractions of moist air [1] |

Name | Description |
---|---|

s | Specific entropy at p, T, X [J/(kg.K)] |

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

Name | Description |
---|---|

p | Pressure [Pa] |

T | Temperature [K] |

X[:] | Mass fractions of moist air [1] |

dp | Derivative of pressure [Pa/s] |

dT | Derivative of temperature [K/s] |

dX[nX] | Derivative of mass fractions [1/s] |

Name | Description |
---|---|

ds | Specific entropy at p, T, X [J/(kg.K.s)] |

Isentropic enthalpy (only valid for phi<1)

Extends from Modelica.Icons.Function (Icon for functions), (Return isentropic enthalpy).

Name | Description |
---|---|

p_downstream | Downstream pressure [Pa] |

refState | Reference state for entropy |

Name | Description |
---|---|

h_is | Isentropic enthalpy [J/kg] |