
512 Fuel Cells
At the electrode–membrane interface, a heat ux discontinuity
condition is given as
n · (q
1
− q
2
) = Q
gen
, (11.97)
where
q
i
= −k
i
∇T
i
+ ρ
i
C
pi
T
i
u
i
. (11.98)
Channel Inlet conditions:
Uniform temperature, T
i
= T
o
, and concentration, C
i
= C
o
, are used
at the channel inlets.
Inlet condition:
A uniform gas velocity condition is used at the inlet to the gas ow
channel, given as
u = U
in
.
(11.99)
The inlet velocities for reactant gases are calculated based on the
total consumption rate given in terms of the total current density
and stoichiometric ratio.
uU
I
nF
A
A
RT
==
in
mea
ξ
, (11.100)
where ξ = stoichiometric ratio, A
mea