Page 87 - High Temperature Solid Oxide Fuel Cells Fundamentals, Design and Applications

64 High Temperature Solid Oxide Fuel Cells: Fundamentals, Design and Applications

1 n*
ileal = - . h . -
2 0,21'
The outlet flow of the cathode can be calculated by

n*
1
hCaO =-.A .---. 1 .
2 0,21 2 nH2,U.
The molar oxygen flow at the inlet is
1
j102,J = - h . n* (43)
*
2
and the molar oxygen flow at the outlet is

(44)

Equations (43) and (44) can be written as a function of Uf
1 )
+n*. (A
2
ncao =-.fi*. (Lh) 0,21 up2 (45)
n*
0,21
and

Now we can express yi as a function of the fuel utilisation Uf

gH2.0 = 1 - ufH2

yH20,O = up2
and

Using Eqs. (24), (27) and (34) we get for the equilibriumconstant K

We can use Eqs. (50) and (27) to calculate the ideal Nernst voltage VN as a
function of the fuel utilisation U' Using Eq. (33) we see that the current I is
proportional to the fuel utilisation Uf