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, and - 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
breakdown of the instantaneous DPF filtration efficiency during the
regeneration procedure - this is an effect of stronger artifact 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.