Environmental Engineering Reference
In-Depth Information
Chapter 6
Case Study A: Fuel Cell Power Train
for Mopeds
6.1 Description of the 3.5 kW Fuel Cell Power Train
The experimental results discussed in this case study are obtained on a fuel cell
power train installed on a laboratory test bench. It is constituted by a 3.5 kW
electric drive connected in hybrid configuration to a 2 kW PEM fuel cell system
(FCS) and an electrical energy storage system (lead batteries). The main technical
specifications of the FCS are reported in Table
6.1
, whereas its scheme is shown in
Fig.
6.1
[
1
,
2
].
The system is based on a PEM fuel cell stack (2.5 kW maximum power) equipped
with all the auxiliary components required for the stack operation, such as air supply
unit, fuel supply unit, cooling system, humidification system, and a management
unit. Hydrogen is supplied by 200 bar cylinders connected to a laboratory gas
decompression unit. A side channel compressor (see
Sect. 4.3
), operating in the
range 25-40 kPa, is used to feed air to the cathode side, the cooling system is
realized by a de-ionized water circuit equipped with sensors to measure temperature
and flow rate. The diameter of the hydrogen purge valve guarantees a minimum
absolute value of pressure at anode inlet, in particular not lower than 130 kPa while
in order to control the stoichiometric ratio (R), air flow rate is regulated through the
speed regulation of the electric motor directly connected to the air compressor and
then measured by a variable-area flow meter.
Two pressure transducers are located upstream of the stack to monitor anode
and cathode pressure during the experimental runs. A spiral heat exchanger, using
external water at room temperature as second fluid, is used to control the
temperature of the cooling water. The FCS humidification strategy is based on
the deionized water injection method (see
Sect. 4.5
), activating the injection when
the outlet air temperature is higher than 60C.
The fuel cell system is equipped with several sensors able to measure the air
and water flow rates, the temperatures of cathode outlet stream and of water in
cooling circuit, the hydrogen pressure, stack current and voltage, and individual
