Emissions and Performance Implications of Biodiesel Use in an SCR-equipped Caterpillar C6.6 Caterpillar Incorporated

Format:

Conference/Event

Author/Creator:

McWilliam, McWilliam, author.

Contributor:

Zimmermann, Anton

Conference Name:

SAE 2010 Powertrains Fuels & Lubricants Meeting (2010-10-25 : San Diego, California, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2010

Summary:

Tier 4 Final legislation commences from 2008 - 2015, dependingon engine power. At the same time the use of biodiesel is beingincentivized or mandated in many countries. This is driving up theproportion of biodiesel available to the diesel engine fleet and soit is important to understand its impact on possible Tier 4 Finalengine and aftertreatment systems. One of the solutions beingexplored to meet Tier 4 Final emissions regulations is selectivecatalytic reduction (SCR) using urea and an appropriatecatalyst.Previous researchers have highlighted the potential forbiodiesel to have a much greater impact on percentage increase intailpipe NOx on engines equipped with Urea SCRaftertreatment than has historically been the case for engine-outNOx increase. Increases of as much as 80% have beenpresented, but without knowledge of the engine-out or absoluteNOx emission data, it has not been possible to draw anyconclusions from some of these publications.As a result, a Cat 6.6l, common rail, DI engine fitted with aurea SCR, vanadium-based catalyst system and DOC was operated onB20, B100 and ULSD. The engine was equipped with NOxsensors at engine-out and SCR-out. The engine was also fitted withpiezo cylinder pressure sensors and standard temperature andpressure sensors. The test cell had Horiba MEXA 7000 series benchesat both engine- and SCR-out and CDS6 Siemens laser analyzer atSCR-out to monitor ammonia slip.The engine was run on each fuel over the European non-roadtransient cycle (NRTC). Each set of tests on a biodiesel blend wasbook-ended with a ULSD test to track any engine degradation, whichwas not observed.It was found that B20 caused engine-out NOx toincrease by less than 1% while the SCR-out NOx increasedby 12.5% for an absolute increase of 3 ppm. For B100 the increasein NOx at engine-out was 4.8%, which is at the low-endof expectations based on historical trends. The SCR-outNOx increase was 105.7%, for an increase in absoluteterms of 25 ppm.Also related to the SCR operation, it was found that theconversion efficiency of the vanadium SCR system dropped by lessthan 1% point when operating on B20 but dropped by 6% points whenoperating on B100. This can be explained by the difference inNO₂:NOx ratio which changes due to the differentchemical structure of biodiesel resulting in changes toNOx speciation during combustion and across the DOC aswell as changes in exhaust gas temperature

Notes:

Vendor supplied data

Publisher Number:

2010-01-2157

Access Restriction:

Restricted for use by site license