Confidence Interval for Polarization Curve
45
40
35
30
g
S25
0 20
15
10
5
0
0 5 10 15 20 25 30 35 40 45 50
Stack Current (amps)
Figure 5-2. Confidence interval of polarization curves based on six tests.
Baseline Constant Load Data
Although polarization curves give excellent information about the different
parameters that affect fuel cell performance it is easier to see the contaminants effect on
performance by testing the contaminants under a constant load. The three loads selected
were 20, 30 and 40 amps. These three loads best reflect the linear portion of the
polarization, the part of the curve that is most affected by changing operating conditions.
Figures 5-3 and 5-4 show the stack voltage and the stack power for constant loads of 20
and 40 amps, the data for 30 amps is similar to these two graphs and hence not shown.
Data was collected every 10 seconds for 45 minutes.