integration of solid oxide fuel cells and ... - Ea Energianalyse

5.4. Sensitivity Analysis
1. The x-value in each end of a curve shows how much the real input
is (at most) likely to deviate from the chosen parameter value.
2. The y-value in each end of a curves shows how much the COP
or electrical efficiency will change if the x-value is as far from the
standard parameter value as the interval allows.
3. The slope of each curve shows how much the COP or electrical
efficiency will change if the given input parameter changes 1%.
ηsys,el,net increase
Key Parameters: Electrical efficiency
10%
8%
6%
4%
2%
0%
-100% -50% 0% 50% 100%
-2%
-4%
-6%
-8%
-10%
Paramter increase
ASR
∆pTower,air,wet
∆TSOFC,av
ηWB,Tower
FR
FW
id
ηFAN
ηBLOWER
COPABS,fuel increase
Key Parameters: COP
10%
8%
6%
4%
2%
0%
-100% -50% 0% 50% 100%
-2%
-4%
-6%
-8%
-10%
Parameter increase
ASR
∆pTower,air,wet
∆TSOFC,av
ηWB,Tower
FR
FW
id
ηFAN
ηBLOWER
Figure 5.29: A range of different parameters are changed and the effect on η el,sys,net (A) and
COP ABS,f uel (B) is plotted. Note that the y-axis scale has been increased to 10% (from 5% in
the previous figures).
η sys,el ,net
The current density (blue curve in figure 5.29A) doesn’t change so much
in itself, but each percent change has a very big influence on the electrical
efficiency, so it becomes the overall most important parameter so it seems
to be a good idea to buy a little more cells per kW of fuel input (this will
decrease current density).
The ASR (black) also has a very big influence on the efficiency despite
a limited uncertainty on the input (x-) value. The pressure loss of
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