Environmental Engineering Reference
In-Depth Information
Load
Hydrogen
purge
DC/DC
Membrane
humidifier
Pressure
regulator
Hydrogen tank
Air
exhaust
Heat exchanger
humidifier
H
2
O
Back pressure
regulator
Fuel Cell
Air
compressor
M
Heat
exchanger
Reservoir
Fan
Water
pump
Start-up
battery
M
Fig. 4.9
Example of a low pressure H
2
FCS integrated plant
content of the exhaust cathodic stream, and in minor quantities of the anode outlet
stream. The recovered water could be used as feed of humidifiers installed in the
entrances of the stack for oxidant or for both reducing and oxidant streams,
concurring to the operation of stack in water neutral conditions, improving reli-
ability of the power generator.
4.6.1 FCS Efficiency
The behavior of fuel cells in terms of individual and overall voltage as function of
current density represents the basic performance from which an overall efficiency
evaluation has to start. The impact of the parasitic consumption of auxiliary
components involved in the system management strategies on the net power
produced by the fuel cell stack represents the second important step to be carefully
evaluated.
The main ancillary components that concur to reduce the gross stack power are
reported in Fig.
4.10
. The auxiliaries are actuated electrically, and the total DC
power produced by stack is partially consumed by the motors that move the
compressors and pumps, and by the electricity necessary to supply the radiator fan
and the controller.
The power consumption of ancillary components results particularly significant
in the low power ranges [
44
], and among them the air compressor provides the
