Contents


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.