Package with moist air model that decouples pressure and temperature and that has no liquid water
Information
This is a medium model that is identical to
Buildings.Media.GasesPTDecoupled.MoistAir, except that
the water vapor is not condensing to the liquid phase if
Xi[Water] > X_sat. Instead, all water is assumed in vapor phase.
This new formulation often leads to smaller systems of nonlinear equations
because it allows to invert the function T_phX analytically.
Extends from Modelica.Media.Interfaces.PartialCondensingGases (Base class for mixtures of condensing and non-condensing gases).
Package Content
| 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=Buildings.Media.PerfectGases.Common.SingleGasData.Air | |
| steam=Buildings.Media.PerfectGases.Common.SingleGasData.H2O | |
 BaseProperties
| |
 Xsaturation
| Steam water mass fraction of saturation boundary in kg_water/kg_moistair |
 setState_pTX
| Thermodynamic state as function of p, T and composition X |
| setState_phX
| Thermodynamic state as function of p, h and composition X |
| setState_dTX
| Thermodynamic state as function of d, T and composition X |
| gasConstant
| Gas constant (computation neglects liquid fraction) |
| saturationPressureLiquid
| Saturation curve valid for 273.16 <= T <= 373.16. Outside of these limits a (less accurate) result is returned |
| sublimationPressureIce
| Saturation curve valid for 223.16 <= T <= 273.16. Outside of these limits a (less accurate) result is returned |
| saturationPressure
| Saturation curve valid for 223.16 <= T <= 373.16 (and slightly outside with less accuracy) |
| pressure
| Gas pressure |
| temperature
| Gas temperature |
| density
| Gas density |
| specificEntropy
| Specific entropy (liquid part neglected, mixing entropy included) |
| enthalpyOfVaporization
| Enthalpy of vaporization of water |
| HeatCapacityOfWater
| Specific heat capacity of water (liquid only) which is constant |
| enthalpyOfLiquid
| Enthalpy of liquid (per unit mass of liquid) which is linear in the temperature |
| der_enthalpyOfLiquid
| Temperature derivative of enthalpy of liquid per unit mass of liquid |
| enthalpyOfCondensingGas
| Enthalpy of steam per unit mass of steam |
| der_enthalpyOfCondensingGas
| Derivative of enthalpy of steam per unit mass of steam |
| enthalpyOfGas
| Enthalpy of gas mixture per unit mass of gas mixture |
| enthalpyOfDryAir
| Enthalpy of dry air per unit mass of dry air |
| der_enthalpyOfDryAir
| Derivative of enthalpy of dry air per unit mass of dry air |
| specificHeatCapacityCp
| Specific heat capacity of gas mixture at constant pressure |
| specificHeatCapacityCv
| Specific heat capacity of gas mixture at constant volume |
| dynamicViscosity
| dynamic viscosity of dry air |
| thermalConductivity
| Thermal conductivity of dry air as a polynomial in the temperature |
| specificEnthalpy
| Specific enthalpy |
| specificInternalEnergy
| Specific internal energy |
| specificGibbsEnergy
| Specific Gibbs energy |
| specificHelmholtzEnergy
| Specific Helmholtz energy |
| h_pTX
| Compute specific enthalpy from pressure, temperature and mass fraction |
| T_phX
| Compute temperature from specific enthalpy and mass fraction |
| Inherited |
|---|
| enthalpyOfNonCondensingGas
| Return enthalpy of the non-condensing species |
 ThermodynamicState
| thermodynamic state variables |
| FluidConstants
| extended fluid constants |
| fluidConstants | constant data for the fluid |
 moleToMassFractions
| Return mass fractions X from mole fractions |
| massToMoleFractions
| Return mole fractions from mass fractions X |
| setSmoothState
| Return thermodynamic state so that it smoothly approximates: if x > 0 then state_a else state_b |
| ThermoStates | Enumeration type for independent variables |
| mediumName="unusablePartialMedium" | Name of the medium |
| substanceNames={mediumName} | 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 | = 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=fill(1/nX, nX) | Default mass fractions of medium |
| p_default=101325 | Default value for pressure of medium (for initialization) |
| T_default=Modelica.SIunits.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) |
| 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 |
| setState_psX
| Return thermodynamic state as function of p, s and composition X or Xi |
| prandtlNumber
| Return the Prandtl number |
 heatCapacity_cp
| alias for deprecated name |
| heatCapacity_cv
| alias for deprecated name |
| isentropicExponent
| Return isentropic exponent |
| isentropicEnthalpy
| Return isentropic enthalpy |
| velocityOfSound
| Return velocity of sound |
| isobaricExpansionCoefficient
| Return overall the isobaric expansion coefficient beta |
| beta
| alias for isobaricExpansionCoefficient for user convenience |
| isothermalCompressibility
| Return overall the isothermal compressibility factor |
| kappa
| alias of isothermalCompressibility for user convenience |
| density_derp_h
| Return density derivative wrt pressure at const specific enthalpy |
| density_derh_p
| Return density derivative wrt specific enthalpy at constant pressure |
| density_derp_T
| Return density derivative wrt pressure at const temperature |
| density_derT_p
| Return density derivative wrt temperature at constant pressure |
| density_derX
| Return density derivative wrt mass fraction |
| molarMass
| Return the molar mass of the medium |
| specificEnthalpy_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 |
| 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 |
| MassFlowRate
| Type for mass 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 resect to pressure with medium specific attributes |
| DerDensityByEnthalpy
| Type for partial derivative of density with resect to enthalpy with medium specific attributes |
| DerEnthalpyByPressure
| Type for partial derivative of enthalpy with resect to pressure with medium specific attributes |
| DerDensityByTemperature
| Type for partial derivative of density with resect to temperature with medium specific attributes |
 Choices
| Types, constants to define menu choices |
Types and constants
constant Integer Water=1
"Index of water (in substanceNames, massFractions X, etc.)";
constant Integer Air=2
"Index of air (in substanceNames, massFractions X, etc.)";
constant Real k_mair = steam.MM/dryair.MM "ratio of molar weights";
constant Buildings.Media.PerfectGases.Common.DataRecord dryair=
Buildings.Media.PerfectGases.Common.SingleGasData.Air;
constant Buildings.Media.PerfectGases.Common.DataRecord steam=
Buildings.Media.PerfectGases.Common.SingleGasData.H2O;
Parameters
| Type | Name | Default | Description |
|---|
| Boolean | standardOrderComponents | true | if true, and reducedX = true, the last element of X will be computed from the other ones |
| Advanced |
| Boolean | preferredMediumStates | false | = true if StateSelect.prefer shall be used for the independent property variables of the medium |
Modelica definition
redeclare replaceable model extends BaseProperties(
T(stateSelect=if preferredMediumStates then StateSelect.prefer else StateSelect.default),
p(stateSelect=if preferredMediumStates then StateSelect.prefer else StateSelect.default),
Xi(stateSelect=if preferredMediumStates then StateSelect.prefer else StateSelect.default))
/* p, T, X = X[Water] are used as preferred states, since only then all
other quantities can be computed in a recursive sequence.
If other variables are selected as states, static state selection
is no longer possible and non-linear algebraic equations occur.
*/
MassFraction x_water "Mass of total water/mass of dry air";
Real phi "Relative humidity";
protected
constant SI.MolarMass[2] MMX = {steam.MM,dryair.MM}
"Molar masses of components";
// MassFraction X_liquid "Mass fraction of liquid water";
// MassFraction X_steam "Mass fraction of steam water";
MassFraction X_air "Mass fraction of air";
MassFraction X_sat
"Steam water mass fraction of saturation boundary in kg_water/kg_moistair";
MassFraction x_sat
"Steam water mass content of saturation boundary in kg_water/kg_dryair";
AbsolutePressure p_steam_sat "Partial saturation pressure of steam";
constant AbsolutePressure pStp = 101325 "Pressure for which dStp is defined";
constant Density dStp = 1.2 "Fluid density at pressure pStp";
equation
assert(T >= 200.0 and T <= 423.15, "
Temperature T is not in the allowed range
200.0 K <= (T ="
+ String(T) + " K) <= 423.15 K
required from medium model \"" + mediumName + "\".");
MM = 1/(Xi[Water]/MMX[Water]+(1.0-Xi[Water])/MMX[Air]);
p_steam_sat = min(saturationPressure(T),0.999*p);
X_sat = min(p_steam_sat * k_mair/max(100*Modelica.Constants.eps, p - p_steam_sat)*(1 - Xi[Water]), 1.0)
"Water content at saturation with respect to actual water content";
// X_liquid = max(Xi[Water] - X_sat, 0.0);
// X_steam = Xi[Water]-X_liquid;
X_air = 1-Xi[Water];
h = specificEnthalpy_pTX(p,T,Xi);
R = dryair.R*(1 - Xi[Water]) + steam.R*Xi[Water];
//
u = h - R*T;
// d = p/(R*T);
d/dStp = p/pStp;
/* Note, u and d are computed under the assumption that the volume of the liquid
water is neglible with respect to the volume of air and of steam
*/
state.p = p;
state.T = T;
state.X = X;
// this x_steam is water load / dry air!!!!!!!!!!!
x_sat = k_mair*p_steam_sat/max(100*Modelica.Constants.eps,p - p_steam_sat);
x_water = Xi[Water]/max(X_air,100*Modelica.Constants.eps);
phi = p/p_steam_sat*Xi[Water]/(Xi[Water] + k_mair*X_air);
end BaseProperties;
Steam water mass fraction of saturation boundary in kg_water/kg_moistair
Inputs
| Type | Name | Default | Description |
|---|
| ThermodynamicState | state | | Thermodynamic state record |
Outputs
| Type | Name | Description |
|---|
| MassFraction | X_sat | Steam mass fraction of sat. boundary [kg/kg] |
Modelica definition
function Xsaturation = Buildings.Media.PerfectGases.MoistAir.Xsaturation
"Steam water mass fraction of saturation boundary in kg_water/kg_moistair";
Thermodynamic state as function of p, T and composition X
Inputs
Outputs
| Type | Name | Description |
|---|
| ThermodynamicState | state | Thermodynamic state |
Modelica definition
redeclare function setState_pTX
"Thermodynamic state as function of p, T and composition X"
extends Buildings.Media.PerfectGases.MoistAir.setState_pTX;
end setState_pTX;
Thermodynamic state as function of p, h and composition X
Information
Function to set the state for given pressure, enthalpy and species concentration.
This function needed to be reimplemented in order for the medium model to use
the implementation of T_phX provided by this package as opposed to the
implementation provided by its parent package.
Extends from Modelica.Icons.Function (Icon for a function).
Inputs
Outputs
| Type | Name | Description |
|---|
| ThermodynamicState | state | |
Modelica definition
redeclare function setState_phX
"Thermodynamic state as function of p, h and composition X"
extends Modelica.Icons.Function;
input AbsolutePressure p "Pressure";
input SpecificEnthalpy h "Specific enthalpy";
input MassFraction X[:] "Mass fractions";
output ThermodynamicState state;
algorithm
state := if size(X,1) == nX then ThermodynamicState(p=p,T=T_phX(p,h,X),X=X) else
ThermodynamicState(p=p,T=T_phX(p,h,X), X=cat(1,X,{1-sum(X)}));
end setState_phX;
Thermodynamic state as function of d, T and composition X
Inputs
Outputs
| Type | Name | Description |
|---|
| ThermodynamicState | state | Thermodynamic state |
Modelica definition
redeclare function setState_dTX
"Thermodynamic state as function of d, T and composition X"
extends Buildings.Media.PerfectGases.MoistAir.setState_dTX;
end setState_dTX;
Gas constant (computation neglects liquid fraction)
Inputs
| Type | Name | Default | Description |
|---|
| ThermodynamicState | state | | thermodynamic state |
Outputs
Modelica definition
redeclare function gasConstant
"Gas constant (computation neglects liquid fraction)"
extends Buildings.Media.PerfectGases.MoistAir.gasConstant;
end gasConstant;
Saturation curve valid for 273.16 <= T <= 373.16. Outside of these limits a (less accurate) result is returned
Inputs
| Type | Name | Default | Description |
|---|
| Temperature | Tsat | | saturation temperature [K] |
Outputs
Modelica definition
function saturationPressureLiquid =
Buildings.Media.PerfectGases.MoistAir.saturationPressureLiquid
"Saturation curve valid for 273.16 <= T <= 373.16. Outside of these limits a (less accurate) result is returned";
Saturation curve valid for 223.16 <= T <= 273.16. Outside of these limits a (less accurate) result is returned
Inputs
| Type | Name | Default | Description |
|---|
| Temperature | Tsat | | sublimation temperature [K] |
Outputs
Modelica definition
function sublimationPressureIce =
Buildings.Media.PerfectGases.MoistAir.sublimationPressureIce
"Saturation curve valid for 223.16 <= T <= 273.16. Outside of these limits a (less accurate) result is returned";
Saturation curve valid for 223.16 <= T <= 373.16 (and slightly outside with less accuracy)
Inputs
| Type | Name | Default | Description |
|---|
| Temperature | Tsat | | saturation temperature [K] |
Outputs
Modelica definition
redeclare function extends saturationPressure
"Saturation curve valid for 223.16 <= T <= 373.16 (and slightly outside with less accuracy)"
algorithm
psat := Buildings.Utilities.Math.Functions.spliceFunction(
saturationPressureLiquid(Tsat),sublimationPressureIce(Tsat),Tsat-273.16,1.0);
end saturationPressure;
Gas pressure
Inputs
Outputs
Modelica definition
redeclare function pressure "Gas pressure"
extends Buildings.Media.PerfectGases.MoistAir.pressure;
end pressure;
Gas temperature
Inputs
Outputs
Modelica definition
redeclare function temperature "Gas temperature"
extends Buildings.Media.PerfectGases.MoistAir.temperature;
end temperature;
Gas density
Inputs
| Type | Name | Default | Description |
|---|
| ThermodynamicState | state | | |
Outputs
| Type | Name | Description |
|---|
| Density | d | Density [kg/m3] |
Modelica definition
redeclare function density "Gas density"
extends Modelica.Icons.Function;
input ThermodynamicState state;
output Density d "Density";
algorithm
d :=state.p*1.2/101325;
end density;
Specific entropy (liquid part neglected, mixing entropy included)
Inputs
Outputs
Modelica definition
redeclare function specificEntropy
"Specific entropy (liquid part neglected, mixing entropy included)"
extends Buildings.Media.PerfectGases.MoistAir.specificEntropy;
end specificEntropy;
Enthalpy of vaporization of water
Inputs
| Type | Name | Default | Description |
|---|
| Temperature | T | | temperature [K] |
Outputs
Modelica definition
redeclare function extends enthalpyOfVaporization
"Enthalpy of vaporization of water"
algorithm
r0 := 2501014.5;
end enthalpyOfVaporization;
Specific heat capacity of water (liquid only) which is constant
Inputs
Outputs
Modelica definition
function HeatCapacityOfWater
"Specific heat capacity of water (liquid only) which is constant"
extends Modelica.Icons.Function;
input Temperature T;
output SpecificHeatCapacity cp_fl;
algorithm
cp_fl := 4186;
end HeatCapacityOfWater;
Enthalpy of liquid (per unit mass of liquid) which is linear in the temperature
Inputs
| Type | Name | Default | Description |
|---|
| Temperature | T | | temperature [K] |
Outputs
Modelica definition
redeclare replaceable function extends enthalpyOfLiquid
"Enthalpy of liquid (per unit mass of liquid) which is linear in the temperature"
annotation(derivative=der_enthalpyOfLiquid);
algorithm
h := (T - 273.15)*4186;
end enthalpyOfLiquid;
Temperature derivative of enthalpy of liquid per unit mass of liquid
Inputs
Outputs
Modelica definition
replaceable function der_enthalpyOfLiquid
"Temperature derivative of enthalpy of liquid per unit mass of liquid"
extends Modelica.Icons.Function;
input Temperature T "temperature";
input Temperature der_T "temperature derivative";
output SpecificHeatCapacity der_h "derivative of liquid enthalpy";
algorithm
der_h := 4186;
end der_enthalpyOfLiquid;
Enthalpy of steam per unit mass of steam
Inputs
| Type | Name | Default | Description |
|---|
| Temperature | T | | temperature [K] |
Outputs
Modelica definition
redeclare function enthalpyOfCondensingGas
"Enthalpy of steam per unit mass of steam"
annotation(derivative=der_enthalpyOfCondensingGas);
extends Modelica.Icons.Function;
input Temperature T "temperature";
output SpecificEnthalpy h "steam enthalpy";
algorithm
h := (T-273.15) * steam.cp + Buildings.Media.GasesPTDecoupled.MoistAirNoLiquid.enthalpyOfVaporization(T);
end enthalpyOfCondensingGas;
Derivative of enthalpy of steam per unit mass of steam
Inputs
Outputs
Modelica definition
replaceable function der_enthalpyOfCondensingGas
"Derivative of enthalpy of steam per unit mass of steam"
extends Modelica.Icons.Function;
input Temperature T "temperature";
input Temperature der_T "temperature derivative";
output SpecificHeatCapacity der_h "derivative of steam enthalpy";
algorithm
der_h := steam.cp;
end der_enthalpyOfCondensingGas;
Enthalpy of gas mixture per unit mass of gas mixture
Inputs
Outputs
Modelica definition
redeclare replaceable function extends enthalpyOfGas
"Enthalpy of gas mixture per unit mass of gas mixture"
algorithm
h := Buildings.Media.GasesPTDecoupled.MoistAirNoLiquid.enthalpyOfCondensingGas(T)*X[Water]
+ Buildings.Media.GasesPTDecoupled.MoistAirNoLiquid.enthalpyOfDryAir(T)*(1.0-X[Water]);
end enthalpyOfGas;
Enthalpy of dry air per unit mass of dry air
Inputs
| Type | Name | Default | Description |
|---|
| Temperature | T | | temperature [K] |
Outputs
Modelica definition
replaceable function enthalpyOfDryAir
"Enthalpy of dry air per unit mass of dry air"
annotation(derivative=der_enthalpyOfDryAir);
extends Modelica.Icons.Function;
input Temperature T "temperature";
output SpecificEnthalpy h "dry air enthalpy";
algorithm
h := (T - 273.15)*dryair.cp;
end enthalpyOfDryAir;
Derivative of enthalpy of dry air per unit mass of dry air
Inputs
Outputs
Modelica definition
replaceable function der_enthalpyOfDryAir
"Derivative of enthalpy of dry air per unit mass of dry air"
extends Modelica.Icons.Function;
input Temperature T "temperature";
input Temperature der_T "temperature derivative";
output SpecificHeatCapacity der_h "derivative of dry air enthalpy";
algorithm
der_h := dryair.cp;
end der_enthalpyOfDryAir;
Specific heat capacity of gas mixture at constant pressure
Inputs
Outputs
Modelica definition
redeclare replaceable function extends specificHeatCapacityCp
"Specific heat capacity of gas mixture at constant pressure"
algorithm
cp := dryair.cp*(1-state.X[Water]) +steam.cp*state.X[Water];
end specificHeatCapacityCp;
Specific heat capacity of gas mixture at constant volume
Inputs
Outputs
Modelica definition
redeclare replaceable function extends specificHeatCapacityCv
"Specific heat capacity of gas mixture at constant volume"
algorithm
cv:= dryair.cv*(1-state.X[Water]) +steam.cv*state.X[Water];
end specificHeatCapacityCv;
dynamic viscosity of dry air
Inputs
Outputs
Modelica definition
redeclare function extends dynamicViscosity
"dynamic viscosity of dry air"
algorithm
eta := 1.85E-5;
end dynamicViscosity;
Thermal conductivity of dry air as a polynomial in the temperature
Inputs
Outputs
Modelica definition
redeclare function extends thermalConductivity
"Thermal conductivity of dry air as a polynomial in the temperature"
import Modelica.Media.Incompressible.TableBased.Polynomials_Temp;
algorithm
lambda := Polynomials_Temp.evaluate({(-4.8737307422969E-008), 7.67803133753502E-005, 0.0241814385504202},
Modelica.SIunits.Conversions.to_degC(state.T));
end thermalConductivity;
Specific enthalpy
Inputs
Outputs
Modelica definition
redeclare function extends specificEnthalpy "Specific enthalpy"
algorithm
h := Buildings.Media.GasesPTDecoupled.MoistAirNoLiquid.h_pTX(state.p, state.T, state.X);
end specificEnthalpy;
Specific internal energy
Inputs
Outputs
Modelica definition
redeclare function extends specificInternalEnergy
"Specific internal energy"
extends Modelica.Icons.Function;
algorithm
u := Buildings.Media.GasesPTDecoupled.MoistAirNoLiquid.h_pTX(state.p,state.T,state.X) - gasConstant(state)*state.T;
end specificInternalEnergy;
Specific Gibbs energy
Inputs
Outputs
Modelica definition
redeclare function extends specificGibbsEnergy
"Specific Gibbs energy"
extends Modelica.Icons.Function;
algorithm
g := Buildings.Media.GasesPTDecoupled.MoistAirNoLiquid.h_pTX(state.p,state.T,state.X) - state.T*specificEntropy(state);
end specificGibbsEnergy;
Specific Helmholtz energy
Inputs
Outputs
Modelica definition
redeclare function extends specificHelmholtzEnergy
"Specific Helmholtz energy"
extends Modelica.Icons.Function;
algorithm
f := Buildings.Media.GasesPTDecoupled.MoistAirNoLiquid.h_pTX(state.p,state.T,state.X)
- gasConstant(state)*state.T
- state.T*Buildings.Media.GasesPTDecoupled.MoistAirNoLiquid.specificEntropy(state);
end specificHelmholtzEnergy;
Compute specific enthalpy from pressure, temperature and mass fraction
Inputs
Outputs
Modelica definition
function h_pTX
"Compute specific enthalpy from pressure, temperature and mass fraction"
extends Modelica.Icons.Function;
input SI.Pressure p "Pressure";
input SI.Temperature T "Temperature";
input SI.MassFraction X[nX] "Mass fractions of moist air";
output SI.SpecificEnthalpy h "Specific enthalpy at p, T, X";
algorithm
h := (T - 273.15)*dryair.cp * (1 - X[Water]) + ((T-273.15) * steam.cp + 2501014.5) * X[Water];
end h_pTX;
Compute temperature from specific enthalpy and mass fraction
Inputs
Outputs
Modelica definition
function T_phX
"Compute temperature from specific enthalpy and mass fraction"
extends Modelica.Icons.Function;
input AbsolutePressure p "Pressure";
input SpecificEnthalpy h "specific enthalpy";
input MassFraction[:] X "mass fractions of composition";
output Temperature T "temperature";
algorithm
T := 273.15 + (h-2501014.5 * X[Water])/(dryair.cp * (1 - X[Water])+steam.cp*X[Water]);
end T_phX;
HTML-documentation generated by Dymola Fri May 15 10:15:33 2009.
Buildings.Media.GasesPTDecoupled.MoistAirNoLiquid.BaseProperties
Buildings.Media.GasesPTDecoupled.MoistAirNoLiquid.setState_pTX