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DPF's Regeneration Procedures and Emissions with RME Blend Fuels

The fatty acid methyl esters (FAME's) - in Europe mostly RME (Rapeseed methyl ester) - are used in several countries as alternative biogene Diesel fuels in various blending ratios with fossil fuels (Bxx). Questions often arise about the influences of these biocomponents on the modern exhaust aftertreatment systems and especially on the regeneration of Diesel particle filters (DPF).

In the present work different regeneration procedures of DPF systems were investigated with biofuels B0, B20 & B100.

The tested regeneration procedures were:

passive regenerations: DOC + CSF; CSF alone,

active regenerations: standstill burner; fuel injections & DOC.

During each regeneration on-line measurements of regulated and unregulated emission components (nanoparticles & FTIR) were conducted.

It can be stated that the increased portion of RME in fuel provokes longer time periods to charge the filter with soot. This is due to the lower PM-emissions of the engine, as well as to the higher reactivity and higher SOF-portion of the particle mass from RME.

With the passive regeneration system with stronger catalytic activity (DOC + CSF) there is a stronger NO2-production with B100 and due to the NO2-supported oxidation of PM the balance point temperature is approx. 20?C lower, than with B0. For the active regenerations the time histories of emissions and temperatures are closely connected with the chosen regeneration strategy - switching, timing and intensity (of burner, or fuel aerosol generator).

A higher portion of biocomponent usually causes a stronger break-down of the instantaneous DPF filtration efficiency during the regeneration procedure - this is an effect of stronger artefact of spontaneous condensation after DPF.

In summary there is no negative short term effect of bio-blend-fuels on the investigated regeneration procedures. Some recommendations for a successful long term operation, basing on other works and literature are given at the end of the paper.

Andreas Mayer, TTM

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