The NO emissions were 608 ppm and 558 ppm when engine fueled
with 10% and 20% water emulsion ratios, with 21% oxygen concentration,
and the NO emission was 654 ppm when engine fueled
with 30% water emulsion ratio, with 21%e23% oxygen concentration.
The NO emission was lower than the original at the combination
of the above five water emulsification ratios and intake
oxygen concentrations. It can be seen from Fig. 4b that the NO
emission of the original enginewas 1130 ppm under 100% load. And
the mixing fuel with 30% water emulsion ratio has the best inhibition
effect on NO emission. When engine fueled with 30% water
emulsion, the NO emission wasn’t higher than that of the original
(the maximum NOwas 1059 ppm) even when the intake air oxygen
concentration increased from 21% to 24%. When fueled with fuel of
20% water emulsion and oxygen concentration changed from 21%
to 22%, as well as fueled with fuel of 10% water emulsion and 21%
O2, the NO emission was lower than the original. Therefore, there
are seven kinds of combinations of water emulsification ratios and
intake oxygen concentrations. From the comparison between these
two different operating conditions, it can be found that under the
high-load condition of (100% load), the in-cylinder gas flow was
more intense with the increase of fuel supply, and more moisture
would enter combustion chamber. Therefore, the water emulsified
diesel actually plays a more effective control of NO when intake
oxygen concentration increases.