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H. Pflaum, B. Geringer, P. Hofmann, W. Weissel:
"Potential of Hydrogenated Vegetable Oil (HVO) in a Modern Diesel Engine";
Talk: 2010 Small Engine Technology Conference, Linz (invited); 2010-09-28 - 2010-09-30; in: "2010 Small Engine Technology", D. Nehmer et al. (ed.); SAE International, (2010), Paper ID SAE Technical Paper 2010-32-0081, 11 pages.

Future legislations claim further reduction of all restricted
emissions as well as the limitation of soot emissions in diesel
engines. Special alternative diesel fuels that do not contain
aromatic compounds, therefore, promise great potential for
further reduction of HC, CO and particulate emissions.
During a research project carried out at the Institute for
Powertrains and Automotive Technology at the Vienna
University of Technology, the potential of alternative diesel
fuels was investigated using a state-of-the-art diesel engine
with common rail direct injection. The testing took part using
an engine test rig as well as on the chassis dynamometer test
bench to demonstrate the emission levels in real life
conditions. As real biofuel, pure HVO (Hydrogenated
Vegetable Oil) was investigated and additionally in different
blends with fossil diesel fuel.
The results on the engine test bench show that HVO can
reduce the NO x -particulate trade-off up to 50% compared to
conventional diesel, whereas this is not the case at all load
points. Especially in low-load conditions, the high cetane
number of the alternative fuel leads to a decreased ignition
delay and thereby reduces the potential to lower particulate
emissions.
Besides the reduction of particulate emissions, the fact that
HVO does not contain any aromatic compounds also helps to
reduce unburned HC and CO emissions. For both, a reduction
of up to 50% could be achieved compared to fossil diesel,
whereas the magnitude of the decrease depends on the
temperatures occurring during the combustion. Due to the
fact that today's diesel engines often have low exhaust gas
temperatures, the cold start phase is very important. During
the time before the light off of the oxidation catalyst has
taken place, low unburned raw emissions can mean a big
advantage in real life conditions.