
225Heat and Mass Transfer in Fuel Cells
where φ represents ow variables such as velocity and pressure and ∀ rep-
resents the volume.
For simplicity, the modied Navier–Stokes equation is written without the
volume average symbol as
ρρµ
µ
κ
ε
∂
∂
+⋅
()
=−
V
t
VV gP
2
. (6.22)
The modied Navier–Stokes equation reduces to Brinkman’s equation
when the inertia force term is dropped and it reduces to Darcy’s law when
both inertia and viscous force terms are dropped.
A selection of appropriate momentum equation for the porous GDL and
CL will depend on the operating conditions and the design of GDL and CL
regions for a fuel cell.
6.1.5 Inlet and Bound ...