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WOLFRAM SYSTEM MODELER

MixtureGasNasa

Medium model of a mixture of ideal gases based on NASA source

Package Contents

	ThermodynamicState Thermodynamic state variables
	BaseProperties Base properties (p, d, T, h, u, R_s, MM, X, and Xi of NASA mixture gas
	setState_pTX Return thermodynamic state as function of p, T and composition X
	setState_phX Return thermodynamic state as function of p, h and composition X
	setState_psX Return thermodynamic state as function of p, s and composition X
	setState_dTX Return thermodynamic state as function of d, T and composition X
	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
	density Return density of ideal gas
	specificEnthalpy Return specific enthalpy
	specificInternalEnergy Return specific internal energy
	specificEntropy Return specific entropy
	specificGibbsEnergy Return specific Gibbs energy
	specificHelmholtzEnergy Return specific Helmholtz energy
	h_TX Return specific enthalpy
	h_TX_der Return specific enthalpy derivative
	gasConstant Return gasConstant
	specificHeatCapacityCp Return specific heat capacity at constant pressure
	specificHeatCapacityCv Return specific heat capacity at constant volume from temperature and gas data
	MixEntropy Return mixing entropy of ideal gases / R
	s_TX Return temperature dependent part of the entropy, expects full entropy vector
	isentropicExponent Return isentropic exponent
	velocityOfSound Return velocity of sound
	isentropicEnthalpyApproximation Approximate method of calculating h_is from upstream properties and downstream pressure
	isentropicEnthalpy Return isentropic enthalpy
	gasMixtureViscosity Return viscosities of gas mixtures at low pressures (Wilke method)
	dynamicViscosity Return mixture dynamic viscosity
	mixtureViscosityChung Return the viscosity of gas mixtures without access to component viscosities (Chung, et. al. rules)
	lowPressureThermalConductivity Return thermal conductivities of low-pressure gas mixtures (Mason and Saxena Modification)
	thermalConductivity Return thermal conductivity for low pressure gas mixtures
	isobaricExpansionCoefficient Return isobaric expansion coefficient beta
	isothermalCompressibility Return isothermal compressibility factor
	density_derp_T Return density derivative by pressure at constant temperature
	density_derT_p Return density derivative by temperature at constant pressure
	density_derX Return density derivative by mass fraction
	molarMass Return molar mass of mixture
	T_hX Return temperature from specific enthalpy and mass fraction
	T_psX Return temperature from pressure, specific entropy and mass fraction
	specificEntropyOfpTX Protected Return specific entropy from pressure, temperature and mass fractions

Package Constants (27)

ThermoStates	Value: Modelica.Media.Interfaces.Choices.IndependentVariables.pTX Type: IndependentVariables Description: Enumeration type for independent variables
mediumName	Value: "unusablePartialMedium" Type: String Description: Name of the medium
substanceNames	Value: data[:].name Type: String[:] Description: Names of the mixture substances. Set substanceNames={mediumName} if only one substance.
extraPropertiesNames	Value: fill("", 0) Type: String[:] Description: Names of the additional (extra) transported properties. Set extraPropertiesNames=fill("",0) if unused
singleState	Value: false Type: Boolean Description: = true, if u and d are not a function of pressure
reducedX	Value: false Type: Boolean Description: = true if medium contains the equation sum(X) = 1.0; set reducedX=true if only one substance (see docu for details)
fixedX	Value: false Type: Boolean Description: = true if medium contains the equation X = reference_X
reference_p	Value: 101325 Type: AbsolutePressure (Pa) Description: Reference pressure of Medium: default 1 atmosphere
reference_T	Value: 298.15 Type: Temperature (K) Description: Reference temperature of Medium: default 25 deg Celsius
reference_X	Value: fill(1 / nX, nX) Type: MassFraction[nX] (kg/kg) Description: Default mass fractions of medium
p_default	Value: 101325 Type: AbsolutePressure (Pa) Description: Default value for pressure of medium (for initialization)
T_default	Value: Modelica.Units.Conversions.from_degC(20) Type: Temperature (K) Description: Default value for temperature of medium (for initialization)
h_default	Value: specificEnthalpy_pTX(p_default, T_default, X_default) Type: SpecificEnthalpy (J/kg) Description: Default value for specific enthalpy of medium (for initialization)
X_default	Value: reference_X Type: MassFraction[nX] (kg/kg) Description: Default value for mass fractions of medium (for initialization)
C_default	Value: fill(0, nC) Type: ExtraProperty[nC] Description: Default value for trace substances of medium (for initialization)
nS	Value: size(substanceNames, 1) Type: Integer Description: Number of substances
nX	Value: nS Type: Integer Description: Number of mass fractions
nXi	Value: if fixedX then 0 else if reducedX then nS - 1 else nS Type: Integer Description: Number of structurally independent mass fractions (see docu for details)
nC	Value: size(extraPropertiesNames, 1) Type: Integer Description: Number of extra (outside of standard mass-balance) transported properties
C_nominal	Value: 1.0e-6 * ones(nC) Type: Real[nC] Description: Default for the nominal values for the extra properties
fluidConstants	Value: redeclare replaceable record FluidConstants = Modelica.Media.Interfaces.Types.IdealGas.FluidConstants Type: FluidConstants[nS] Description: Constant data for the fluid
data	Value: Type: DataRecord[:] Description: Data records of ideal gas substances
excludeEnthalpyOfFormation	Value: true Type: Boolean Description: If true, enthalpy of formation Hf is not included in specific enthalpy h
referenceChoice	Value: ReferenceEnthalpy.ZeroAt0K Type: ReferenceEnthalpy Description: Choice of reference enthalpy
h_offset	Value: 0.0 Type: SpecificEnthalpy (J/kg) Description: User defined offset for reference enthalpy, if referenceChoice = UserDefined
MMX	Value: data[:].MM Type: MolarMass[nX] (kg/mol) Description: Molar masses of components
methodForThermalConductivity	Value: 1 Type: Integer

Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

This model calculates the medium properties for single component ideal gases.

Sources for model and literature:
Original Data: Computer program for calculation of complex chemical equilibrium compositions and applications. Part 1: Analysis Document ID: 19950013764 N (95N20180) File Series: NASA Technical Reports Report Number: NASA-RP-1311 E-8017 NAS 1.61:1311 Authors: Gordon, Sanford (NASA Lewis Research Center) Mcbride, Bonnie J. (NASA Lewis Research Center) Published: Oct 01, 1994.

Known limits of validity:
The data is valid for temperatures between 200 K and 6000 K. A few of the data sets for monatomic gases have a discontinuous 1st derivative at 1000 K, but this never caused problems so far.

This model has been copied from the ThermoFluid library. It has been developed by Hubertus Tummescheit.

Wolfram Language

In[1]:=

SystemModel["Modelica.Media.IdealGases.Common.MixtureGasNasa"]

Out[1]:=

Extended by (5)

	SimpleNaturalGas Modelica.Media.IdealGases.MixtureGases Simple natural gas mix with 6 components
	FlueGasSixComponents Modelica.Media.IdealGases.MixtureGases Simplest flue gas for over-and understochiometric combustion of hydrocarbons
	FlueGasLambdaOnePlus Modelica.Media.IdealGases.MixtureGases Simple flue gas for overstochiometric O2-fuel ratios
	AirSteam Modelica.Media.IdealGases.MixtureGases Air and steam mixture (no condensation!, pseudo-mixture)
	CombustionAir Modelica.Media.IdealGases.MixtureGases Air as mixture of N2 and O2