Environmental Engineering Reference
In-Depth Information
Fig. 7.6 Powers provided or
absorbed by the different
components of the FCS ver-
sus stack current at
T = 346 K and
P air = 250 kPa
Fig. 7.7 Effect of air pres-
sure on characteristic curves
of the 20 kW PEM stack at
346 K
360 A, which corresponds to maximum load), and the constant and negligible
consumption of 110 W is due to the cooling water pump.
The effect of the main operative parameters on both stack performance and
electric consumptions of the auxiliary devices is shown in Figs. 7.7 , 7.8 , 7.9 , and
7.10 , whose results can be utilized to select the working conditions suitable for
automotive application. The effect of the reactant pressure on the fuel cell per-
formance is shown in Fig. 7.7 , where the stack voltage is reported versus current
for three values of the air pressure obtained with the centralized compression plant
at the temperature of 346 K, minimizing the air flow rate for each load and setting
the humidification temperature equal to stack temperature for each current value.
Decreasing the pressure from 250 to 130 kPa, the stack performance is not
significantly reduced. In fact, the maximum effect is observed at 300 A when the
stack voltage decreases from 56 V at 250 kPa to 52 V at 130 kPa (see Sect. 3.3 ).
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