Environmental Engineering Reference
In-Depth Information
c
FUEL CELL
STACK
TT
Cooling Water In
De-ionized
Water Inlet
SV
M
TT
Cooling
Water
Out
PT
WL
FR
TD
FD
FT
Cooling Water
Tank
WF
TC
CV
Shell Water outlet
AL
WL
HE
BV
EV
BV
Shell Water Inlet
WP
WF
AL
BV
Alarm
PT
Pressure Transducer
Ball Valve
SV
Safety Valve
CV
Check Valve
TC
Thermocouple
EV
Electric valve
TD
Temperature Display
FD
Flow Rate Display
TT
Temperature Transducer
FR
Flow Rate Regulator
WF
Water Filter
FT
Flow Rate Transducer
WL
Water Level Indicator
HE
Heat Exchanger
WP
Water Pump
M
Manometer
Fig. 7.1
(continued)
hydrogen pressure is set higher than 30 kPa with respect to inlet air pressure. A water
condenser is located at the stack outlets before venting to verify the water balance in
the system. A cooling system, shown in Fig. 7.1 c, is adopted to control the
temperature in the range 290-346 K and is composed by a de-ionized water circuit
equipped with a pump and sensors to measure pressure, temperatures, and flow rate.
In order to guarantee a sufficient uniform temperature through the cells, a difference
of temperature not higher than 5 K is accepted between inlet and outlet cooling
water temperatures. This is achieved by imposing the cooling water flow rate at the
value required by the maximum stack power (4 m 3 h -1 ) and using a spiral heat
exchanger fed with external water to control the cooling water temperature.
Two tanks of 50 l are used as water containers, respectively, for the humidi-
fication and cooling circuits. On-off, three way and tuning valves permit pressures
and gas flow rates to be regulated.
The stack characterization is carried out by connecting it to a variable resistive
load able to control the discharge current electronically, making possible the
evaluation of different operative conditions with different values of constant
current (Table 7.1 ).
A dedicated acquisition system able to monitor and register the voltages of the
individual cells during the different runs is adopted. Moreover a d-space board is
used for the acquisition and control of all signals associated with the FCS system
components (valves, sensors, and transducers).
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