Talking of... - MTU Shop

MTU and Deutsche Bahn are to get together to test an engine in a Type 225 freight locomotive. The test findings are to be used to provide the EU with recommen-
dations regarding future emissions stages for rail applications.
sible to increase that figure to 50 percent. “In
that way we can further reduce nitrogen oxide
emission,” Bergmann states with certainty.
Injection at 2,200 bar for sootless
combustion
To keep the soot particulate emissions as low
as possible, the developers also increased the
injection pressure of the common-rail system.
The fuel now squirts into the combustion chambers
at 2,200 bar instead of “only” 1,800 bar.
That may sound like just another number but it
is actually a major milestone in fuel injection
technology. So that the system can operate at
such high pressures, the individual components
have to fit together with micrometer accuracy.
For the same reason, the engine designers
have also halved the weight of the pilot valve,
which controls injection by the injector. And
their efforts have been worthwhile. As a result
of the higher injection pressure, the fuel now
burns even more cleanly and almost no particulate
matter is produced. But to prevent even
those last few particles escaping into the atmos-
phere, they are trapped by a diesel particulate
filter. The filter also acts as an exhaust silencer
and so saves space by taking the place of the
silencer. As the soot levels produced by combustion
are already so low, the filter can be rege-
32 I MTU Report 02/11
nerated passively, in other words during normal
engine operation without the need for an additional
heat source. Only when it is exceptionally
cold or the locomotive is working at very low
speeds over a long period does the exhaust temperature
have to be raised to clean the filter.
Powerline simplifies retrofitting
But where is the filter in the locomotive? So far,
only the engine is evident inside the red locomotive
body. Is it so small as to be hardly noticeable?
“No,” laughs a railway worker who is just
fixing the engine subframe to the base plate inside
the locomotive with a ratchet, “we don’t fit
that until later; the engine has to be in properly
first.” Having offered enlightenment, he returns
immediately to the task in hand. Thanks to the
MTU Powerline automation system, it is a simple
matter integrating the engine in the 40-year-old
locomotive. The system’s standardized interfaces
enable straightforward connection of the engine
to the existing train control system. A DC-DC
convertor installed in the MTU switchgear cabinet
converts the 110-volt supply available in the
locomotive to the 24-volt rating required by the
electronic components. The CaPoS starting system
(Capacitor Power System) also allows the
use of much smaller batteries. It replaces the
starter battery set and, unlike the starter batte-
ries, is not filled with acid, but works on the basis
of capacitors.
Real conditions test for goods loco
The refitted locomotive is due on the track in
July. And it will be fully integrated in the absolutely
normal freight services: “There are no special
concessions, even if the loco is something
special. It has to show what it can do in everyday
operating conditions.“
A glimpse of the future for emissions
technology
From the results of this trial, a study will be produced
next year. Its purpose is to provide the
European Union with recommendations for what
a possible Stage 4 emission legislation phase
might look like. MTU pilot development manager
Dirk Bergmann is certain that, “The limits will be
tightened.” As far as soot particulates are concerned,
however, he sees little scope for further
reducing the mass emitted, because the levels
are already nearly undetectable on engines that
meet the requirements applicable from 2012.
“There is still some scope with the nitrogen oxides,
however,” he optimistically observes. He is reluctant
to talk about precise figures at this stage.
But he is more definite about the technological
possibilities for reducing nitrogen oxide emis-