Over the past decade significant research and development
activities have been invested in alternative fuels in order to
reduce our dependency on fossil fuel sources and reduce CO₂ and
local emissions from traffic. One result of these R&D efforts
is paraffinic diesel fuels, which can be used with existing vehicle
fleets and infrastructures. Paraffinic diesels also have other
benefits compared to conventional diesels, for example, a very high
cetane number and the lack of sulfur and aromatic compounds. These
characteristics are beneficial in terms of exhaust gas emissions,
something which has been demonstrated in numerous studies.
The objective of this study was to develop low-emission
combustion technologies for paraffinic renewable diesel in a
compression ignition engine, and to study the possible benefits of
oxygenated paraffinic diesel. Hydrotreated vegetable oil (HVO),
which is a commercial example of paraffinic, renewable diesel, was
used with and without oxygenate in comparison with conventional
diesel. Exhaust emissions were measured in three steady state
conditions. The adjusted engine parameters, such as inlet valve
closure and injection timing, injection pressure and amount of
exhaust gas recirculation (EGR) were optimized for HVO. The results
demonstrate that significant reductions of particulate matter
(48-61%), polyaromatic hydrocarbon (75-87%) and NOx
(31-54%) emissions can be achieved simultaneously by using HVO with
adjusted engine parameters.