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Emissions and Performance Implications of Biodiesel Use in an SCR-equipped Caterpillar C6.6
Technical Paper
2010-01-2157
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Tier 4 Final legislation commences from 2008 - 2015, depending
on engine power. At the same time the use of biodiesel is being
incentivized or mandated in many countries. This is driving up the
proportion of biodiesel available to the diesel engine fleet and so
it is important to understand its impact on possible Tier 4 Final
engine and aftertreatment systems. One of the solutions being
explored to meet Tier 4 Final emissions regulations is selective
catalytic reduction (SCR) using urea and an appropriate
catalyst.
Previous researchers have highlighted the potential for
biodiesel to have a much greater impact on percentage increase in
tailpipe NOx on engines equipped with Urea SCR
aftertreatment than has historically been the case for engine-out
NOx increase. Increases of as much as 80% have been
presented, but without knowledge of the engine-out or absolute
NOx emission data, it has not been possible to draw any
conclusions from some of these publications.
As a result, a Cat 6.6l, common rail, DI engine fitted with a
urea SCR, vanadium-based catalyst system and DOC was operated on
B20, B100 and ULSD. The engine was equipped with NOx
sensors at engine-out and SCR-out. The engine was also fitted with
piezo cylinder pressure sensors and standard temperature and
pressure sensors. The test cell had Horiba MEXA 7000 series benches
at both engine- and SCR-out and CDS6 Siemens laser analyzer at
SCR-out to monitor ammonia slip.
The engine was run on each fuel over the European non-road
transient cycle (NRTC). Each set of tests on a biodiesel blend was
book-ended with a ULSD test to track any engine degradation, which
was not observed.
It was found that B20 caused engine-out NOx to
increase by less than 1% while the SCR-out NOx increased
by 12.5% for an absolute increase of 3 ppm. For B100 the increase
in NOx at engine-out was 4.8%, which is at the low-end
of expectations based on historical trends. The SCR-out
NOx increase was 105.7%, for an increase in absolute
terms of 25 ppm.
Also related to the SCR operation, it was found that the
conversion efficiency of the vanadium SCR system dropped by less
than 1% point when operating on B20 but dropped by 6% points when
operating on B100. This can be explained by the difference in
NO₂:NOx ratio which changes due to the different
chemical structure of biodiesel resulting in changes to
NOx speciation during combustion and across the DOC as
well as changes in exhaust gas temperature.
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Citation
McWilliam, L. and Zimmermann, A., "Emissions and Performance Implications of Biodiesel Use in an SCR-equipped Caterpillar C6.6," SAE Technical Paper 2010-01-2157, 2010, https://doi.org/10.4271/2010-01-2157.Also In
References
- Signer, M. “Euro V and Future Euro VI Heavy Duty Diesel Engines and their Fuel/Biofuel Requirements” SAE Biofuels Paris 2008
- Williams, A. Pedersen, D. Ireland, J. McCormick, R.L. “Effect of Biodiesel Blends on Urea Selective Catalytic Reduction Catalyst Performance with a Medium-Duty Engine,” SAE Technical Paper 2008-01-2484 2008 10.4271/2008-01-2484
- Mueller, C.J. Boehman, A.L. Martin, G.C. “An Experimental Investigation of the Origin of Increased NO x Emissions When Fuelling a Heavy-Duty Compression-Ignition Engine with Soy Biodiesel,” SAE Int. J. Fuels Lubr. 2 1 789 816 2009
- Walde, T. “Development of Smart NO x Sensors” 5 th International CTI Forum Exhaust Systems 2007
- US Environment Protection Agency “A Comprehensive Analysis of Biodiesel Impacts on Exhaust Emissions” EPA420-P-02-001 37 2002
- Heywood, J.B. Internal Combustion Engine Fundamentals McGraw-Hill 572 578 1988
- Majewski, W.A. “Selective Catalytic Reduction”, Dieselnet, Revision 2005.05d 5 Jan 2010
- Madia, G. Koebel, M. Elsener, M. Wokaun, A. “The Effect of an Oxidation Precatalyst on the NOx Reduction by Ammonia SCR” Ind. Eng. Chem. Res. 41 3512 3517 2002