Truck & Off-Highway Engineering - December 2024 - 5

TECHNICAL INNOVATIONS
Donaldson offers a range of technologies that help keep fuel cells running properly.
need more, so that's why we go for one
big air cleaner and two outlets. One air
cleaner can feed two fuel-cell stacks. To
get to the correct power you can have
two air cleaners, too, so on top you
have the radial sealed, more conventional
filter with a carbon pack also inside.
It does the same thing with a twostage
air cleaner, it's a round radial
sealed air cleaner. We have also added
a pre-cleaner with a two-stage air
cleaner and a carbon pack inside and
this is for those that give us one outlet. "
Since the carbon pack treats gaseous
pollutants, it needs to be monitored
to ensure that the outlet air is
clean enough. The unit provides a
warning for when the carbon pack
needs to be replaced.
In terms of the layout, it's a matter of
how the customer wants to package it,
Billiau said. They can opt for one filter
per stack or a larger air cleaner that can
feed two stacks. A sensor in each outlet
for the dual-outlet model ensures a balanced
airflow to the stacks.
Beyond fuel-cell filtration
Donaldson also displayed at IAA
Transportation its range of humidifiers,
water separators and coolant ion exchangers
for fuel cells, as well as venting
TRUCK & OFF-HIGHWAY ENGINEERING
solutions for battery packs and fuel
cells. The humidifiers ensure a high and
stable level of humidity in the air supply
by transferring humidity from the exhaust
gas to the inlet air stream prior to
entering the fuel cell. This provides optimal
operating conditions for the ionomer,
according to Donaldson.
The water separators ensure the intake
air filters stay as dry as possible.
Certain applications also require the
discharge of liquid water from the tailpipe
to be controlled.
The coolant ion exchangers help remove
other contaminants that can
come from within a PEM fuel cell itself.
Ions from materials in the bipolar
plates, radiators and other coolant circuit
components can leach into the
coolant. The exchangers work by capturing
the ions on a special resin, ensuring
the coolant remains non-conductive
and maintains a low dielectric
constant. A screen is integrated into
the same housing to prevent larger
particles from blocking the channels in
the bipolar plates.
Donaldson's Dual-Stage Jet, which
launched earlier in 2024 at The Battery
Show in Stuttgart, Germany, is its latest
battery-venting solution. The company
claims the technology offers the
High-pressure (<420 bar) and low-pressure
(<25 bar) filters help protect fuel cells from
contaminants that can affect performance
and lifetime.
industry's fastest degassing capabilities,
at rates of approximately 100 L/s at 100
mbar. The medium-pressure solution
features an intelligent poppet and cap
design that can be jettisoned to produce
a large opening for gas to escape
in case of an emergency. During normal
operation, pressure equalization is said
to be consistent with minimum airflow
of 97 L/hour at 10 mbar.
Though fuel cells operate within a
sealed housing, they incorporate a membrane
vent to allow the enclosure to
breathe. Donaldson offers a high-pressure
Dual-Stage Burst solution that enables
a pressure relief of 25 L/s at 300
mbar after a series of pins pierce its
Tetratex ePTFE membrane. Continuous
pressure equalization during normal operating
conditions sees minimum airflow
of 17.8 L/hour at 10 mbar.
John Kendall, with reporting by Ryan Gehm
December 2024 5
BOTH IMAGES: DONALDSON
Truck & Off-Highway Engineering - December 2024

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