Fig. 6 shows that unburned HC emissions decrease with respect
to load. And, at full load, there is no significant difference between
emissions. Below 50% load, although methanol-blended fuels do
not indicate any change in HC emissions as compared to diesel,
ethanol-blended fuels show a significant increase in HC emissions.
This figure also indicates that increasing ethanol concentration inbiodieseleethanolediesel blend increases HC emissions. HC emission
is a product of incomplete combustion. Perhaps methanol
concentrations up to 20% increase oxygen content of the mixture,
which leads to better combustion and lower HC emissions. On the
other hand, more methanol addition is expected to show a cooling
effect, which causes incomplete combustion and higher HC. The
results show that ethanol concentration should be much lower
than 10% in order to have the positive effect of higher oxygen
content rather than the cooling effect of ethanol.