
302 Fuel Cells
This voltage loss owing to charge transport is referred to as ohmic loss,
η
ohmic
, in a fuel cell. In order to determine the expression for the ohmic
loss, let us consider charge transport in a plane conductor lm as shown in
Figure7.6.
The charge transport across a conductor of cross-sectional area, A, and
thickness, L, is given by Ohm’s law and Equation 7.6b as
=−σ
c
d
Φ
. (7.56)
Integrating Equation 7.56 across a charge conductor of thickness L and
cross-sectional area A, we get total voltage drop across the electrolyte or the
ohmic loss owing to charge transport as
IA
=
−
σ
c
L0
. (7.57)
a
i
φ
L
R
ohm
0
FIGURE 7.6
Charge transpor