IdealGasMixtureProps; IdealGasMixtureThermoProps; IdealGasMixtureTransportProps
IdealGasMixtureProps is an EES Library that can determine the thermodynamic and transport properties for a mixture of ideal gases. The library consists of three procedures. The IdealGasMixtureProps procedure returns all thermodynamic and transport properties for a mixture. Because the temperature range associated with the thermodynamic properties is often much larger than the range available for transport properties it is often convenient to only obtain either one set or the other. Therefore the library also contains the procedure IdealGasMixtureThermoProps to obtain only the thermodynamic properties and the procedure IdealGasMixtureTransportProps to obtain only the transport properties.
The calling protocol for the three procedures are:
Call IdealGasMixtureProps(F$,T,P,y[1..N]: MW, h, s, mu, k, cp, Pr)
Call IdealGasMixtureThermoProps(F$,T,P,y[1..N]: MW, h, s, cp)
Call IdealGasMixtureTransportProps(F$,T,P,y[1..N]: mu, k, Pr)
Inputs: (Same for all three procedures)
F$ a string constant or string variable that contains the names of 1 or more (up to 20) names of ideal gases that are contained in the EES property library. The names of the gases are separated with a + sign, e.g., 'CH4+C3H8'
T temperature in the units EES is configured to work in.
P pressure in the units EES is configured to work in. (Pressure is used only for calculation of specific entropy)
y[1..N] the mass or mole fractions of the gases represented by string F$. The sum of the values of f must add to 1.0. Supply mass fractions if EES is configured to work with specific properties on a mass basis. Otherwise, supply mole fractions.
Outputs:
MW molar mass of the mixture in kg/kmol or lbm/lbmol
h specific enthalpy of the mixture determined as the mole fraction-weighted average of the specific enthalpies gases in the mixture. The units of h will be returned on a per unit mass basis if EES is configured to provide properties on a mass basis. Otherwise the units of h will be returned on a molar basis.
s specific entropy of the mixture determined as the mole fraction-weighted average of the specific entropies of the gases in the mixture plus the entropy change of mixing the gases. The units of s will be returned on a per unit mass basis if EES is configured to provide properties on a mass basis. Otherwise the units of s will be returned on a molar basis.
mu viscosity of the gas mixture determined using the Wilke Approximation as described in Eq. 9-5.2 of Reid, Prausnitz, and Sherwood.
k thermal conductivity of the gas mixture determined using the Mason and Saxena modification, as described in Eq. 10-6.2. of Reid, Prausnitz, and Sherwood.
cp specific heat capacity of the mixture determined as the mole fraction-weighted average of the specific heat capacities of the gases in the mixture. The units of cp will be returned on a per unit mass basis if EES is configured to provide properties on a mass basis. Otherwise the units of cp will be returned on a molar basis.
Pr Prandtl number of the gas mixture.
Reference:
Reid, Prausnitz, and Sherwood, 3rd edition, McGraw-Hill, (1977).
Note:
IdealGasMixtureProps is not built into EES. Rather, it is an external Procedure that is loaded from the ..\USERLIB\EES_System\IdealGasmixtureProps.LIB. This file is provided in the EES installation.
Example:
$UnitSystem SI C kPa molar kJ
$Varinfo MW1 Units ='kg/kmol'
$VarInfo h1 Units='kJ/kmol'
$VarInfo s1 Units='kJ/kmol-K'
$VarInfo cp1 Units='kJ/kmol-K'
$VarInfo mu1 Units='Pa-s'
$VarInfo k1 Units='W/m-K'
$Varinfo MW2 Units ='kg/kmol'
$VarInfo h2 Units='kJ/kmol'
$VarInfo s2 Units='kJ/kmol-K'
$VarInfo cp2 Units='kJ/kmol-K'
$VarInfo mu2 Units='Pa-s'
$VarInfo k2 Units='W/m-K'
F$='CH4+C4H10'
T=20 [C]
P=101.3 [kPa]
N=2
y[1..N]=[0.697,0.303]
Call IdealGasMixtureProps(F$,T,P,y[1..N]: MW1, h1, s1, mu1, k1, cp1, Pr1)
Call IdealGasMixtureTransportProps(F$,T,P,y[1..N]: mu2, k2, Pr2)
Call IdealGasMixtureThermoProps(F$,T,P,y[1..N]: MW2, h2, s2, cp2)
{Solution
cp1=54.26 [kJ/kmol-K]
cp2=54.26 [kJ/kmol-K]
F$='CH4+C4H10'
h1=-90378 [kJ/kmol]
h2=-90378 [kJ/kmol]
k1=0.02503 [W/m-K]
k2=0.02503 [W/m-K]
mu1=0.000009313 [Pa-s]
mu2=0.000009313 [Pa-s]
MW1=28.79 [kg/kmol]
MW2=28.79 [kg/kmol]
N=2
P=101.3 [kPa]
Pr1=0.7012
Pr2=0.7012
s1=228 [kJ/kmol-K]
s2=228 [kJ/kmol-K]
T=20 [C]
}
See also: Thermophysical Functions