Assessment of Tier 4 Final Aftertreatment Strategies Bosch Emission Systems GmbH and Co KG

Format:

Conference/Event

Author/Creator:

Ohrnberger, Ohrnberger, author.

Contributor:

Becker, Carsten

Doehring, Christoph

Conference Name:

SAE 2012 Commercial Vehicle Engineering Congress (2012-10-02 : Rosemont, Illinois, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2012

Summary:

Non-road machineries cover a large variety of platformsrequiring aftertreatment strategies which are different from thoseutilized in on-road platforms. The right choice of anaftertreatment strategy is complex due to the consideration ofengine power rating, duty cycle, durability and regulatoryrequirements as well as fuel economy concerns and total operatingcosts.Some powertrain systems utilize merely a DOC-SCR aftertreatmentsystem, with or without EGR, depending upon engine-out versustargeted tailpipe NOx emission. This strategynecessitates integrating a urea (DEF/AdBlue®) injection system.When combined with moderate EGR, the requirements on NOxconversion efficiency can be reduced below 90%. Without EGR, aconversion efficiency about 95% is required.Some other platforms intend to use a DOC-DPF system, along witha "high PM" approach on the NOx/PM trade-off.While this strategy avoids utilizing a urea dosing system, it alsoadversely influences the engine fuel economy and typicallyprohibits NO₂-assisted soot oxidation in the DPF due to lowengine-out NOx. Hence this strategy requires an activeDPF regeneration (using in-cylinder fuel post injection, in-situfuel dosing in exhaust gas, burner technology or alike), it furtheradversely impacts the fuel economy.An aftertreatment strategy, somewhere "in-between" thetwo preceding ones, utilizes a complete system setup which consistsof DOC, DPF and SCR. This offers the opportunity for greaterflexibility in reducing engine emissions across a large variety ofduty cycles and also for use in unique environments (such as intunnel construction requiring PM emission at a near-zero level).These systems are particularly favorable if a passive DPFregeneration strategy is possible. For this purpose, certainplatforms such as tractors and crawlers have suitable exhaust gastemperature, along with sufficient NO₂ from the DOC.Costs for these in many cases larger aftertreatment systems arekept as low as possible by the use of a modular approach to systemdesign.This paper will discuss pros and cons of various non-roadaftertreatment strategies

Notes:

Vendor supplied data

Publisher Number:

2012-01-1953

Access Restriction:

Restricted for use by site license