Environmental Engineering Reference
In-Depth Information
Fig. 4.1 General scheme of
a direct H
2
PEMFC system
(H
2
FCS) for vehicles
H2
storage
FCS
Air
supply
system
Fuel
supply
system
FC stack
Air
system
Thermal /Water system
Electric
energy
stack, to optimize the FCS efficiency and reliability and to fully exploit the
dynamic performance of PEMFC.
The design of the fuel feeding section has to be focused on the optimal feeding of
hydrogen to the anode compartment of the stack. Details about the behavior of the
main components involved in hydrogen feeding management are given in
Sect. 4.2
.
Different typologies of air supply systems are examined in
Sect. 4.3
, in par-
ticular their performance are analyzed in terms of pressure working and power
consumption.
Thermal management system is necessary because the reaction heat gradually
elevates the MEA temperatures. This aspect, related also to humidification issues,
requires the development of a sub-system able to control both stack temperature and
heat flux inside the overall system. The related discussion is presented in
Sect. 4.4
.
FCS water management is the key factor for an efficient and reliable operation
of a PEMFC stack. Membrane hydration control and water balance for a durable
operation of FCS are the main objectives of this sub-system, whose design and
control issues, strictly connected to thermal management but also to reactant sub-
system components, are discussed in
Sect. 4.5
. The possibility of interactions
between the wet and warm cathode outlet stream and the components of thermal
and water management sub-systems is also discussed.
The analysis of the above sub-systems refers to BOP components suitable for
fuel cell vehicle applications, and underlines the main aspects related to the
framework of interactions inside a whole FCS.
A discussion about a basic configuration for a H
2
FCS is carried out in the
Sect. 4.6
, where an integrated plant is studied analyzing the main issues to be faced
for optimizing overall efficiency and reliability. The effect of the main operative
parameters on the system working is discussed, analyzing the dynamic behavior
issues related to fast load changes and warm-up phases. A brief overview on costs
expected for stack and BOP components closes this chapter.
