LESS IS MORE FOR POWERCORE

FILTRATION
Donaldson Co. has developed the second generation of its PowerCore air filter technology for engine
air intake applications. One of the key attributes of the PowerCore G2 technology is that it is designed
to provide enhanced filtration efficiency and life at a significantly more compact size. This is evidenced
when comparing a conventional cellulose filter (left), an original PowerCore
filter (center) and a PowerCore G2 filter (right). The PowerCore
G2 filter is 60% smaller than the conventional filter and 30%
smaller than the previous
PowerCore unit.
LESS IS MORE FOR POWERCORE
Second generation of Donaldson’s PowerCore air filter system
engineered for higher performance in a smaller package
Editor’s Note: Much of the information
for this article is from the technical
bulletin “Methods for Diesel Engine Air
Intake and Filtration System Size Reductions,”
by Dan Adamek, director –
Engine Air Filtration Development,
Donaldson Co.
It has been well documented that
since the dawning of engine
emissions regulations, underhood
and engine compartment real
estate has become more precious.
Add to that an ever-increasing
emphasis on aerodynamics in onhighway
trucks and the streamlining
of hoods and engine cowlings in offhighway
equipment — done mostly
for improving sight lines and enhancing
productivity and safety — and the
result is that any component technology
that resides in proximity to an
engine has to do more in the same or,
more likely, less physical space.
And do it all while providing minimal
changes in overall life-cycle costs and
service intervals.
For suppliers of engine air filtration
systems, this has led to continued
development and refinement of filter
technologies to meet the new design
challenges. A case in point is Donaldson
Engine Systems & Parts, which
has released the next generation of its
PowerCore air intake filter technology.
Since its debut, the PowerCore
technology has found wide application
in a range of engine-powered
vehicles and equipment, including
Class 8 trucks and construction and
ag machinery. In all, Donaldson said
more than 5 million units have been
put into service.
The new PowerCore G2 products
are engineered to have a 30% smaller
footprint with the same straightthrough
airflow and high-density filtration
system as the original PowerCore.
The new units, which incorporate a
metal-free, cartridge-style design, can
provide an array of performance advantages,
including smaller size,
lower pressure drop and longer filter
life or a combination of the three depending
on customer underhood
space and performance requirements,
the company said.
Along with additional space restrictions,
many new diesel engine designs
are also placing greater
emphasis on
An example of an axial flow air intake system using
a PowerCore intake system. The axial flow arrangement
allows the air to pass straight through the filter, reducing potential pressure losses.
DIESEL PROGRESS NORTH AMERICAN EDITION November 2008

FILTRATION
A schematic representation of how airflow moves through a PowerCore air filter.
lower restrictions in the air intake system,
as higher restrictions can increase
the emissions levels being
measured in the engine exhaust.
Air intake system pressure losses
have historically been a key design
consideration, as they can have a
negative impact on both performance
and fuel economy. While it
might seem minor — air intake
restriction is estimated to have less
than a 1% impact on fuel economy
— the annual additional fuel usage
with a sub-optimal air filter can easily
exceed the original purchase price
of the filter, Donaldson said. And with
diesel fuel nearing $4 a gallon in
many parts of the U.S., truck and
equipment operators who burn thousands
of gallons of fuel yearly are
looking for any relief they can get,
however incremental.
Fuel savings also translate into
reduced CO 2 emissions. While greenhouse
gas emissions are not yet the
focus of most existing diesel regulations,
there seems little doubt that the
case is being built for new federal
standards. In the meantime, there are
regions where taxation is based on
vehicles’ emissions.
When looking to reduce life-cycle
costs related to air filters, efforts
often take the form of either increasing
the air filter’s life at equal cost or
reducing the air filter cost at equivalent
life. In some cases, vehicle and
equipment manufacturers are looking
for ways to reconfigure the air
intake system layout to reduce cost.
In on-highway trucks, for example,
behind-the-cab air intake systems
have become the answer to underhood
space constraints. Size reductions
in the system can allow for alternate
configurations such as a frontal
intake system. This can shorten the
ductwork, thereby reducing costs,
and also utilize the engine compartment
to mitigate noise transmission
through the inlet.
The design of diesel engine air
intake systems requires the integration
of many technologies and the balancing
of many factors, such as filter
efficiency, filter life, restriction, size
The normalized total
media area for equalsized
air filters, comparing
the original
PowerCore technology
with PowerCore
G2. Performance may
vary depending on geometry
and operating
conditions, the company
noted.
Normalized Total
Media Area
140%
120%
100%
80%
60%
40%
20%
0%
and cost. In most cases, any aspect
can be improved, usually through
compromises in another property.
For example, size can be reduced
by reducing filter efficiency, reducing
filter life or increasing filter pressure
loss. Advancements in technology are
required to achieve simultaneous
improvement in multiple parameters.
These technology advancements can
take several forms, from simply improving
via design and materials expertise,
to the utilization of advanced
tools such as computation fluid
dynamics (CFD), to the development
of breakthrough configurations.
Other system requirements — such
as noise attenuation, elevated temperature
operation, chemical resistance,
durability under vibration and
shock, etc. — also need to be addressed
during the design process as
well. The ability to meet such a range
of diverse challenges is mostly determined
by the design and performance
of the air filter.
Engine wear rates have been calculated
to decrease by a factor of 10
when high-efficiency air filters are used
in place of standard efficiency filters.
Increased efficiency levels have been
achieved primarily through the optimization
of the fibrous structure of the
filter media. The use of nanofibers on
the media surface has allowed the
thickness and density of the media to
be reduced, thereby decreasing the
pressure losses through the media
and the amount of material used.
Like the original PowerCore filters,
the new PowerCore G2 filters utilize
PowerCore
PowerCore G2
November 2008
DIESEL PROGRESS NORTH AMERICAN EDITION

FILTRATION
350%
Normalized Dust
Holding Capacity
300%
250%
200%
150%
100%
50%
The normalized ISO fine dust capacity for
equal-sized air filters. Again, performance
may vary depending on geometry and
operating conditions, the company said.
0%
Conventional
Cylindrical
PowerCore
PowerCore
G2
Donaldson’s Ultra-Web Nanofiber Filtration
technology. Ultra-Web has been
used for more than 25 years in a range
of heavy-duty industrial air filtration
applications, and the company said it
has sold more than 1 billion sq.ft. of the
media since its initial development.
Donaldson said the Ultra-Web nanofibers
show high initial efficiency compared
to conventional cellulose media,
which only achieves its targeted efficiency
level after it has built up a sufficient
dust cake on its surface.
The build-up of contaminants on the
filter media causes pressure losses to
increase over time, until it reaches a
magnitude that is determined to be the
maximum allowable by the engine.
The ability of an air filter to load slowly
provides for extended change intervals
and is also important because the
longer an engine operates at low
restriction, the lower the average fuel
consumption that can be achieved.
For many years, cylindrical filters
were the technology of choice, and
the development in the 1980s of radial
seal designs enabled the transition
from metal air cleaner housings to
polymeric housings, thereby greatly
reducing product costs and improving
product quality.
When introduced in the following
decade, Donaldson’s PowerCore
technology incorporated an axial flow
configuration that allowed the airflow
to pass straight through the filter without
the 90° change in direction seen
in cylindrical filters, decreasing potential
pressure losses within the air
intake system.
Axial flow filters have been widely
adopted by OEMs, and the new
PowerCore G2 products are designed
to provide even greater levels of performance
and efficiency, Donaldson
said. The internal configuration of the
PowerCore G2 filter has been optimized
by reconfiguration of every
geometric feature within the filter to
reduce pressure losses and increase
filter life, the company said.
One challenge in air filter design —
and particularly in axial-style filters —
is the effort to minimize the media
area that is unutilized or underutilized
due to masking. PowerCore G2 is
engineered to reduce media masking
when compared to previous axial flow
air filters, Donaldson said. Because
increases in effective media area decrease
the velocity though media, it
has the dual effect of decreasing the
pressure loss across the media and
reducing the loading per unit area.
This leads to a significant increase in
filter life from relatively small increases
in effective media area, the company
noted.
Additionally, Donaldson said that
the PowerCore G2 has been designed
to allow for increased total media area
to be packaged into a filter through a
proprietary media-forming process,
which leads to increased filter life
when combined with the correct filter
channel configurations.
Channel pressure losses can be
lowered through increasing the air filter’s
channel size, the company noted.
This also decreases the amount of
media, however, so the application requirements
need to be factored into
the choice of channel size, Donaldson
said. Additionally, increases in channel
space can also be obtained by utilizing
thin filter media. Nanofiber laminates
allow for thinner media because particulate
efficiency increases as media
fiber size decreases.
Donaldson said that PowerCore G2
configurations have been optimized in
their development through use of advanced
modeling tools that allowed
comparison of the performance of millions
of unique axial flow filter configurations.
Prototypes of these selected configurations
have been tested and validated
against the theoretical models.
The PowerCore G2 technology is
available in panel, round and obround
shaped air intake systems that can be
customized to meet a wide spectrum
of performance, size, shape and space
constraints, the company said. dp
REPRINTED FROM NOVEMBER 2008 DIESEL PROGRESS North American Edition
Copyright Diesel & Gas Turbine Publications
Printed in U.S.A.