Truck & Off-Highway Engineering - April 2022 - 21

PROPULSION FEATURE
FEV believes hydrogenfueled
ICEs and FCEVs can be
implemented into the current
production infrastructure of
commercial trucks within the
next five years.
levels, as well as management of ignition hotspots.
FEV believes these concerns can be properly addressed. The company
states that it could bring a PFI (port fuel injection) H2
General Motors' Generation 2 Hydrotec power cubes can be
utilized for stationary power generation including charging
stations for BEVs.
efficiency) and have a high probability of uncontrolled
combustion. " PFI is very easy to implement
[for H2
] compared to PFI CNG. DFI H2
system to
market as early as 2023 and would be able to launch a DFI (direct
fuel injection) system by 2025. FEV claims a 5% increase in efficiency
from its PFI system to a DFI system.
World-class combustion efficiency
Bradlee Stroia, chief technology officer for Stanadyne, further
championed hydrogen's potential as an effective solution for carbon-free
ICE fueling. " It's important to understand the benefits of
hydrogen as an internal combustion fuel, " Stroia said. " It has challenges,
but it can enable not just decarbonization but also worldclass
combustion efficiency. "
According to Stanadyne, hydrogen has three times the energy
density as diesel fuel, which provides the opportunity for very high
combustion thermal efficiency. Hydrogen's flammability range also
allows for the reduction of " non-carbon " or NOX
emissions from the
combustion process. " Hydrogen has a wide flammability range, much
wider than most traditional fuels that we use in engines, " Stroia said.
" You can capitalize on that by adjusting your combustion parameters
to run stratified lean to get NOX
very low. "
Most applications will still require some type of NOX
aftertreatment,
but much less than is needed on a diesel equivalent. Stroia also
highlighted that H2
ICEs retain the current manufacturing and supply
base, including current fueling infrastructure (distribution, delivery,
filling stations) with the potential for faster market adoption and infrastructure
conversion than BEVs or FCEVs.
Stroia also covered the pros and cons of various H2
tems for ICEs. While PFI systems (7-20 bar/100-300 psi) are relatively
easy to implement and low complexity, they suffer from up
to 30% air displacement, result in the lowest BTE (brake thermal
TRUCK & OFF-HIGHWAY ENGINEERING
has advantages
because you're able to manage things after
the valves are closed such as uncontrolled combustion
and preignition, " Stroia said.
Mid-pressure DI systems (20-40 bar/300-600 psi)
offer an intermediate amount of complexity and lower
uncontrolled combustion but result in higher cylinder
temperatures and may require a compressor for operation.
High-pressure DFI systems (150-300
bar/2,000-4,300 psi) offer the greatest combustion
control and are capable if diesel levels of efficiency
courtesy of stratified and lean combustion. However,
they are by far the most complex system to implement.
It also generates the most combustion temperature
and may also require a compressor to implement.
" From an injection standpoint, it's hard to inject a
liquid fuel at very high thermal efficiency because you
have to get a lot of fuel into the cylinder in a short period
of time, " Stroia said. " But since hydrogen is a gas,
you optimize the thermal efficiency and reach even
higher efficiency than diesel. "
Fuel cell kits for existing platforms
injection sysChris
Rovik, executive program manager for Toyota,
outlined his company's developments on hydrogen
combustion and heavy-duty FCEVs. " Toyota announced
Project Portal in 2017. This product uses two
hydrogen fuel-cell stacks from our Mirai light vehicle.
We refined that into a Class 8 heavy-duty truck powertrain
kit. This kit is designed around existing OEM
truck platforms, " Rovik explained. " This allowed
quicker implementation rather than designing a new
April 2022 21
FROM LEFT: FEV; GENERAL MOTORS
Truck & Off-Highway Engineering - April 2022

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