A Next Generation Cordierite Diesel Particle Filter
with Significantly Reduced Pressure Drop
Thorsten Boger, Suhao He, Thomas Collins, Achim Heibel, Douglas Beall and Christophe Remy
Corning Inc.
ABSTRACT
Diesel particle filters (DPF) have become a standard after
treatment component for all current and future on-road diesel
engines used in the US. In Europe the introduction of EUVI is
expected to also result in the broad implementation of DPF’s.
The anticipated general trend in engine technology towards
higher engine out NOx/PM ratios results in a somewhat
changing set of boundary conditions for the DPF predominantly
enabling passive regeneration of the DPF. This enables the
design of a novel filter concept optimized for low pressure
drop, low thermal mass for optimized regeneration and fast
heat-up of a downstream SCR system, therefore reducing CO
2
implications for the DPF operation. In this paper we will
discuss results from a next generation cordierite DPF designed
to address these future needs. The new materials are based on
a thinwall design with optimized material and microstructure,
resulting in an almost linear pressure drop response with soot
loading in the bare and catalyzed state. A significant reduction
in soot loaded pressure drop for uncoated and coated filters is
demonstrated of the new filter design vs. current EPA 2010
filter technologies. The optimized microstructure also enables
high filtration efficiency for mass and number. Results from
a wide range of regeneration experiments will be used to
discuss the thermal operating window of the new material
and the thermal response during normal operation and active
regeneration. A uniform temperature distribution and the fast
thermal response of the low mass filter minimize implications
on fuel consumption.
INTRODUCTION
Diesel particulate filters have been used for several decades in
retrofit and certain particulate emissions focused applications.
With the introduction of EPA 2007 regulations, diesel particulate
filters became the standard choice of technology for meeting
emissions requirements for on-road vehicles in the US and
Canada. These systems were implemented with a combination
of active and passive regeneration, where the lack of DeNOx
aftertreatment resulted in a reduced range for optimum
passive regeneration operation. To comply with the strict NOx
emissions limits (0.2 g/(hp·hr)) in EPA 2010 many systems
implemented SCR based DeNOx technology (Figure 1).
This also enabled engine makers to take advantage of lower
fuel consumption by calibrating for lower engine out PM and
higher NOx emissions and furthermore widened the window
for passive regeneration operation. A similar direction is
anticipated for systems complying with EUVI regulations, as
the regulated tailpipe NOx emissions levels are significantly
higher allowing higher engine-out NOx emissions at similar
DeNOx efficiencies.
With higher engine-out NOx/PM ratios the filter requirements
change as the hydrodynamic, filtration and thermal aspects
gain importance with predominantly passive regeneration
operation focused systems. It is anticipated that next generation
DPF designs need to be as fuel consumption neutral as possible
by providing ultra low restriction and supporting engine
thermal management needs in cold start and regeneration
operations.
Copyright © 2011 SAE International
doi: 10.4271/2011-01-0813
2011-01-0813
Published
04/12/2011
Future directions to reduce fuel consumption to meet anticipated
CO
2
or GHG emissions limits and also reduce operating cost
for the end user, especially given the potential for higher fuel
prices, support this direction.
PRODUCT CONCEPT
As outlined in the previous section, new designs and products
are based on the assumption of a need for 1) reduced pressure
drop with improved deep bed filtration impact related to the
soot loaded pressure drop, 2) reduced thermal mass for
optimized regeneration and fast heat-up of a downstream SCR
system, and 3) decreased soot mass limit requirements due
to the expected trend towards engines operating at higher