H2Tech - Q1 2022 - 35

SPECIAL FOCUS: ADVANCES IN HYDROGEN TECHNOLOGY
Choose the most effective components
for H2
fuel cell vehicles
C. HAYES, Swagelok, Cleveland, Ohio
As part of the industry-wide drive to
develop high-efficiency, low-emissions
vehicles, manufacturers are investing significant
revenue in H2
related infrastructure. H2
and oxygen (O2
emissions.
)
mobility and its
fuel cell technology
has proven particularly promising,
particularly in regard to heavy-duty
vehicle applications. These fuel cells operate
by combining H2
gas to form an electrical current. The current
drives a motor, providing the necessary
power and torque to move a vehicle
while producing no CO2
tential of H2
The quick evolution and evident po-based
technologies have
produced a rapidly growing market.
Barriers to adoption still exist, but both
government and industry leaders are
working to eliminate these obstacles
while putting research and development
funds toward creating H2
transportation
infrastructure. In Europe, for example,
multiple countries have agreed to participate
in the Joint Initiative for H2
Vehicles
across Europe (JIVE), which is
designed to bring H2
-powered buses into
the mainstream. The program is expected
to put nearly 300 such buses on the
streets of 22 European cities (FIG. 1) by
the early 2020s. JIVE also aims to help
manufacturers lower the cost of building
H2
-powered buses, making them
more cost competitive with natural gas
and diesel-powered vehicles. The key to
reducing manufacturing costs is the use
of more efficient and effective components.
Choosing the right components
is essential to reliable infrastructure and
vehicle operation.
Material selection. Though corrosion
prevention is important wherever tube
fittings are involved, H2
uniquely challenging. H2
into metal; this diffusion can change the
containment is
gas can diffuse
Performance under pressure. Though
leak prevention is important in all fluid
systems, it is critical in the componentry
of H2
vehicles and infrastructure. H2
storage
occurs under high pressure-there is
a direct correlation between H2
storage
pressure and the expected range of the
Joint initiative for hydrogen vehicles across europe (JIVE)
Lower bus cost, 30%
Double bus fleet size
metal's mechanical properties, reducing
its ductility, impact strength, fracture
toughness and resistance to failure by fatigue
(FIG. 2). This results in the phenomenon
known as H2
embrittlement. Metal
that has been compromised in this way is
more likely to fail when subjected to significant
static or cyclic tensile strength.
H2
embrittlement occurs when H2
atoms,
which are smaller than those of any
other element, lodge in the cubic lattice
network of the metal. This weakens the
metal's molecular bonds and compromises
its integrity. In certain applications,
H2
embrittlement can cause lesser
grades of stainless steel to behave like
cast iron: extremely brittle and susceptible
to cracking. To prevent weakening
of tubing and other components used for
H2
gas fueling systems, designers of H2
atoms, such as
FIG. 2. This H2
embrittled diaphragma
shows
evidence of intergranular corrosion that could
lead to its failure.
infrastructure must specify materials that
resist the infusion of H2
austenitic stainless steels (e.g., 316/316L
stainless steel and 6-moly) that contain
between 10% and 30% nickel.
vehicle that H2
range vehicle fleets often use H2
is intended to fuel. Shortstored
at
350 bar because they frequently return to
a central location for refueling. By contrast,
long-range fleets require the use of
H2
stored at 700 bar because manufacturers
are aiming for a range of ~400 mi
(~644 km) without refueling.
It is crucial to work with manufacturers
that have completed a product certification
process to remain in compliFIG.
1. Europe's JIVE project aims to promote
the manufacture and use of H2
-powered buses.
FIG. 3. A twin ferrule tube fitting. The
hardened back ferrule (light gray) provides
direct and axial support.
H2Tech | Q1 2022 35
H2Tech - Q1 2022

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