Diffusion coefficients for binary gas systems at low pressure
Estimated using the empirical correlation of Wilke and Lee (1955).
Notes
This calculator uses the Wilke and Lee empirical correlation to estimate the diffusion coefficients of binary gas systems at low pressure.
\[D_\mathrm{12} \: \mathrm{[cm^2 \: s^{-1}]} = \frac{[3.03 - (0.98 / M_\mathrm{12}^{1/2})] (10^{-3}) T^{3/2}}{P M_\mathrm{12}^{1/2} \sigma_\mathrm{12}^{2} \Omega_\mathrm{D}}\]
\[M_\mathrm{12} = \frac{2}{1/M_1 + 1/M_2}\]
where \(D_\mathrm{12}\) is the binary diffusion coefficient in cm2/s, \(T\) is the temperature in K, \(P\) is pressure in bar, \(M_\mathrm{A}\) and \(M_\mathrm{B}\) are the molecular weights of components 1 and 2 in g/mol, \(\sigma_\mathrm{12}\) is the scale parameter, and \(\Omega_\mathrm{D}\) is a function with tabulated parameters.
Values of the diffusion coefficient estimated using Wilke and Lee correlation generally agree with experimental values to within 5 to 10 %, although discrepancies of more than 20 % are possible.
References
B.E. Poling, J.M. Prausnitz, J.P. O'Connell. Properties of Gases and Liquids, 5th Edition, McGraw-Hill, 2001.