The effects of using neat FAME (Fatty Acid Methyl Ester) in a
modern small displacement passenger car diesel engine have been
evaluated in this paper.
In particular the effects on engine performance at full load
with standard (i.e., without any special tuning) ECU calibration
were analyzed, highlighting some issues in the low end torque due
to the lower exhaust gas temperatures at the turbine inlet, which
caused a remarkable decrease of the available boost, with a
substantial decrease of the engine torque output, far beyond the
expected engine derating due to the lower LHV of the fuel. However,
further tests carried out after ECU recalibration, showed that the
same torque levels measured under diesel operation can be obtained
with neat biodiesel too, thus highlighting the potential for
maintaining the same level of performance.
Moreover, the effects of FAME on brake specific fuel consumption
and on engine-out exhaust emissions (CO₂, CO, HC, NOx and PM) were
also evaluated at 7 different part load operating conditions,
representative of the New European Driving Cycle.
Both standard and specifically adjusted engine calibrations were
evaluated for part load operating conditions, highlighting a 13%
average rise of fuel consumption, on a mass basis, at same fuel
conversion efficiency and CO₂ emissions. A remarkable increase of
CO and HC emissions at low load could be noticed, along with an
almost negligible increase in NOx emissions when using a
specifically adjusted engine calibration, and a considerable smoke
emission reduction.
