With the use of our Euro IV common-rail fuel injection diesel
engine, the HC emissions of tested fuels are observed to be very
low at all engine load conditions. Fig. 11 shows the variation of
HC emissions of diesel, biodiesel and their blend fuels with respect
to engine speed at full load conditions. Even though there is no linear
correlation can be drawn between the biodiesel blend ratio and
HC emissions, generally, one still can see that the use of biodiesel
improves the combustion process and reduces the HC emissions.
The same trend is also observed at other engine load conditions,
and there is no detrimental effect found on the HC emissions with
the use of biodiesel.