Flame Characteristics of Vaporized Renewable Fuels and Their Blends with Petroleum Fuels - Novel Combustion Concepts for Sustainable Energy Development - page 299

5 Results and Discussion

5.1 Flame Visualization

The fl flame photographs (exposure time of 1/25 s) are presented in Fig. 3 . The Jet A

fl flames were longer than the corresponding P100 fl flames at all equivalence ratios.

The highest =3,

corresponding to the maximum sooting height. In the near-burner region, a blue
region corresponding to the homogenous gas-phase reaction zone was observed.
The size of this region decreased as the equivalence ratio was increased due to the
reduction in the amount of air injected. Also, the size of the blue region was longer
for the P100

fl flame length was recorded for both Jet A and P100 fl ames at Φ

flames at all equivalence ratios due to the increased oxygen content in
the fuel (Table 1 ).

fl

5.2 Global Emission Indices

The global CO and NO emission indices of the Jet A and P100 ames are presented

in Figs. 4 and 5 , respectively. The CO emission index increased with equivalence
ratio (a dramatic increase was observed at the equivalence ratio of 7) due to the
reduction in the amount of injected air. The CO emission index of the P100

fl

fl ames

was smaller than that of the Jet A flames due to the presence of oxygen in the fuel.

The NO emission index decreased with equivalence ratio due to a reduction in the
fl

fl

flame temperature (as will be seen subsequently). The NO emission index of the
P100 fl flames was lower than that of the Jet A fl flames, with the difference becoming

smaller at the equivalence ratio of 7. The in- fl ame temperature and gas concen-

tration pro les will help understand the reasons for this behavior.

Fig. 3 Flame images at equivalence ratios of 2, 3, and 7 (exposure time of 1/25 s)