This medium package models moist air using a gas law in which pressure and temperature are independent, which often leads to significantly faster and more robust computations. Additionally, the density is constant to improve the simulation stability and speed.
This medium uses the gas law
ρ = ρstp,
where pstd is a constant reference density.
The medium model can be used for air duct simulations, where the
pressures and temperatures are close to the reference values.
Note that models in this package implement the equation for the
internal energy as
u = h - pstp ⁄ ρstp,
where u is the internal energy per unit mass, h is the enthalpy per unit mass, pstp is the static pressure and ρstp is the mass density at standard pressure and temperature. The reason for this implementation is that in general,
h = u + p v,
from which follows that
u = h - p v = h - p ⁄ ρ = h - pstp ⁄ ρstd,
because p ⁄ ρ = pstp ⁄ ρstp in this medium model.
The enthalpy is computed using the convention that h=0 if T=0 °C and no water vapor is present.
| Name | Description |
|---|---|
| ThermodynamicState | ThermodynamicState record for moist air |
| BaseProperties | Base properties |
| density | Gas density |
| dynamicViscosity | Return the dynamic viscosity of dry air |
| enthalpyOfCondensingGas | Enthalpy of steam per unit mass of steam |
| enthalpyOfGas | Enthalpy of gas mixture per unit mass of gas mixture |
| enthalpyOfLiquid | Enthalpy of liquid (per unit mass of liquid) which is linear in the temperature |
| enthalpyOfNonCondensingGas | Enthalpy of non-condensing gas per unit mass of steam |
| enthalpyOfVaporization | Enthalpy of vaporization of water |
| gasConstant | Return ideal gas constant as a function from thermodynamic state, only valid for phi<1 |
| pressure | Returns pressure of ideal gas as a function of the thermodynamic state record |
| isobaricExpansionCoefficient | Isobaric expansion coefficient beta |
| isothermalCompressibility | Isothermal compressibility factor |
| saturationPressure | Saturation curve valid for 223.16 <= T <= 373.16 (and slightly outside with less accuracy) |
| specificEntropy | Return the specific entropy, only valid for phi<1 |
| density_derp_T | Return the partial derivative of density with respect to pressure at constant temperature |
| density_derT_p | Return the partial derivative of density with respect to temperature at constant pressure |
| density_derX | Return the partial derivative of density with respect to mass fractions at constant pressure and temperature |
| specificHeatCapacityCp | Specific heat capacity of gas mixture at constant pressure |
| specificHeatCapacityCv | Specific heat capacity of gas mixture at constant volume |
| setState_dTX | Return thermodynamic state as function of density d, temperature T and composition X |
| setState_phX | Return thermodynamic state as function of pressure p, specific enthalpy h and composition X |
| setState_pTX | Return thermodynamic state as function of p, T and composition X or Xi |
| setState_psX | Return the thermodynamic state as function of p, s and composition X or Xi |
| specificEnthalpy | Compute specific enthalpy from pressure, temperature and mass fraction |
| specificEnthalpy_pTX | Specific enthalpy |
| specificGibbsEnergy | Specific Gibbs energy |
| specificHelmholtzEnergy | Specific Helmholtz energy |
| isentropicEnthalpy | Return the isentropic enthalpy |
| specificInternalEnergy | Specific internal energy |
| temperature | Return temperature of ideal gas as a function of the thermodynamic state record |
| molarMass | Return the molar mass |
| temperature_phX | Compute temperature from specific enthalpy and mass fraction |
| thermalConductivity | Thermal conductivity of dry air as a polynomial in the temperature |