D_12_gas
D_12_gas(G1$, G2$, T, P) calculates the binary diffusion coefficient for gases using the Chapmann-Enskog relation presented in Poling et al., Properties of Gases and Liquids, 5th edition, McGraw-Hill, (2000)
Inputs:
G1$ and G2$ are strings containing the names of any gases in EES data base
T and P are the temperature and pressure in the unit system indicated by the EES Unit System dialog.
Output:
D_12_gas is returned in units of [m^2/s] for SI units or [ft^2/s] for English units.
Example:
"Calculate the diffusion coefficient for water vapor in air at 25°C"
$unitSystem SI C kPa mass
T=25 [C]
P=101.3 [kPa]
G1$='water'
G2$='Air'
D=D_12_gas(G1$,G2$,T,P)
D is 2.083e-5 m^2/s. Note that the values returned from this routine are approximate and that D_12=D_21.