Equation to estimate the viscosity of gas mixtures at low pressures.
It is a simplification of an extension of the rigorous kinetic theory
of Chapman and Enskog to determine the viscosity of multicomponent
mixtures, at low pressures and with a factor to correct for molecule
shape and polarity.
The input argument Kappa is a special correction for highly polar substances such as
alcohols and acids.
Values of kappa for a few such materials:
Compound | Kappa | Compound | Kappa |
---|---|---|---|
Methanol | 0.215 | n-Pentanol | 0.122 |
Ethanol | 0.175 | n-Hexanol | 0.114 |
n-Propanol | 0.143 | n-Heptanol | 0.109 |
i-Propanol | 0.143 | Acetic Acid | 0.0916 |
n-Butanol | 0.132 | Water | 0.076 |
i-Butanol | 0.132 |
Chung, et al. (1984) suggest that for other alcohols not shown in the
table:
kappa = 0.0682 + 4.704*[(number of -OH
groups)]/[molecular weight]
S.I. units relation for the debyes:
1 debye = 3.162e-25 (J.m^3)^(1/2)
[1] THE PROPERTIES OF GASES AND LIQUIDS, Fifth Edition,
Bruce E. Poling, John M.
Prausnitz, John P. O'Connell.
[2] Chung, T.-H., M. Ajlan, L. L. Lee, and K. E. Starling: Ind. Eng.
Chem. Res., 27: 671 (1988).
[3] Chung, T.-H., L. L. Lee, and K. E. Starling; Ing. Eng. Chem.
Fundam., 23: 3 ()1984).
function mixtureViscosityChung extends Modelica.Icons.Function; input Temperature T "Temperature"; input Temperature[nX] Tc "Critical temperatures"; input MolarVolume[nX] Vcrit "Critical volumes (m3/mol)"; input Real[nX] w "Acentric factors"; input Real[nX] mu "Dipole moments (debyes)"; input MolarMass[nX] MolecularWeights "Molecular weights (kg/mol)"; input MoleFraction[nX] y "Molar Fractions"; input Real[nX] kappa = zeros(nX) "Association Factors"; output DynamicViscosity etaMixture "Mixture viscosity (Pa.s)"; end mixtureViscosityChung;