
260 Fuel Cells
The empirical correlations for the binary diffusion coefcient are derived
based on kinetic theory and using experimental data. A widely used correla-
tion is given as (Fuller et al., 1966)
D
T
MM
Pv v
ab
=
+
()
+
()
∑∑
0 00100
11
175
13 13
.
.
2
/
, (6.111)
where M
a
and M
b
are the molecular weights of species a and b, respectively,
and the quantity v
represents the summation of atomic-diffusion
volumes for each species of the binary mixture. A list of data for atomic-
diffusion volume for some common gas species is given in Table 6.5 (Cussler,
1984; Sherwood et al., 1975).
Another frequently used equation for binary gas dif ...