
507Simulation Model for Analysis and Design of Fuel Cells
Mass Continuity:
(11.75a)
or
∂
+
∂
+
∂
=
u
x
v
y
w
z
0
(11.75b)
Momentum:
ρρµ
VVgP V⋅
=− +
2
(11.76a)
and in scalar form as
x-component:
ρρµu
u
x
v
u
y
w
u
z
g
P
x
u
x
u
y
x
∂
∂
+
∂
∂
+
∂
∂
=−
∂
∂
+
∂
∂
+
∂
∂
2
2
2
22
2
2
+
∂
∂
u
z
(11.76b)
y-component:
ρρµu
v
x
v
v
y
w
v
z
g
P
y
v
x
v
y
y
∂
∂
+
∂
∂
+
∂
∂
=−
∂
∂
+
∂
∂
+
∂
∂
2
2
2
22
2
2
+
∂
∂
v
z
(11.76c)
z-component:
µu
w
x
v
w
y
w
w
z
g
P
z
w
x
w
y
x
∂
∂
+
∂
∂
+
∂
∂
=−
∂
∂
+
∂
∂
+
∂
∂
2
2
2
22
2
2
+
∂
∂
w
z
(11.76d )
11.6.2.1.2 Mass Transport
Mass concentration distribution in a gas channel is given considering diffu-
sion and convection mass transfers given as
ρ
VC
⋅
=⋅
eff
(11.77a)
or
ρ u
C
x
v
C
y
w
C
z
D
C
x
C
y
ii
ij
ii
∂
∂
+
∂
∂
+
∂
∂
=
∂
∂
+
∂
∂