This model calculates medium properties for an ideal gas of a single substance, or for an ideal gas consisting of several substances where the mass fractions are fixed. Independent variables are temperature T and pressure p. Only density is a function of T and p. All other quantities are solely a function of T. The properties are valid in the range:
200 K ≤ T ≤ 6000 K
The following quantities are always computed:
| Variable | Unit | Description |
| h | J/kg | specific enthalpy h = h(T) |
| u | J/kg | specific internal energy u = u(T) |
| d | kg/m^3 | density d = d(p,T) |
For the other variables, see the functions in Modelica.Media.IdealGases.Common.SingleGasNasa. Note, dynamic viscosity and thermal conductivity are only provided for gases that use a data record from Modelica.Media.IdealGases.FluidData. Currently these are the following gases:
Ar C2H2_vinylidene C2H4 C2H5OH C2H6 C3H6_propylene C3H7OH C3H8 C4H8_1_butene C4H9OH C4H10_n_butane C5H10_1_pentene C5H12_n_pentane C6H6 C6H12_1_hexene C6H14_n_heptane C7H14_1_heptene C8H10_ethylbenz CH3OH CH4 CL2 CO CO2 F2 H2 H2O He N2 N2O NH3 NO O2 SO2 SO3
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 200K and 6000K. A few of the data sets for
monatomic gases have a discontinuous 1st derivative at 1000K, but
this never caused problems so far.
This model has been copied from the ThermoFluid library and adapted to the Modelica.Media package.
| Name | Description |
|---|---|
| ThermodynamicState | Thermodynamic state variables for ideal gases |
| BaseProperties | Base properties of ideal gas medium |
| 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 |
| specificHeatCapacityCp | Return specific heat capacity at constant pressure |
| specificHeatCapacityCv | Compute specific heat capacity at constant volume from temperature and gas data |
| 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 |
| 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 |
| dynamicViscosity | Dynamic viscosity |
| thermalConductivity | Thermal conductivity of gas |
| molarMass | Return the molar mass of the medium |
| T_h | Compute temperature from specific enthalpy |
| T_ps | Compute temperature from pressure and specific entropy |
| dynamicViscosityLowPressure | Dynamic viscosity of low pressure gases |
| thermalConductivityEstimate | Thermal conductivity of polyatomic gases(Eucken and Modified Eucken correlation) |