Low-Emission, Fuel-Flexible Combustion of Liquid Fuels - Novel Combustion Concepts for Sustainable Energy Development - page 463

Fig. 11 SMD measured in
different glycerol flames

50

45

40

35

30

25

20

G68
G45
G45-29

15

10

5

0

-40 -20 0 20 40

Transverse position [mm]

for G68, G45, and G45-29, respectively. Clearly, the fl flow-weighted SMD for all

three flames is similar and again highlights the effectiveness of the FB technique to

atomize an extremely high-viscosity liquid for a range of operating conditions.

fl

6 Biofuel Combustion

In this section, experimental results are presented for FB injector produced ames

of biodiesel and straight VO as the two types of biofuels along with diesel (as
baseline) and 70

fl

30 diesel-VO blend. Experiments are conducted in an atmospheric
pressure burner for

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fixed heat release rate and total air fl ow rate (Simmons et al.

2008 ). The total air fl ow rate is split between the atomizing air and primary com-

bustion air ow rates. The air-to-fuel mass ratio through the injector is varied to

document the injector

fl

fl fluid dynamics effects on emissions. Figures 12 and 13 show

fl ow rates, AA = 10 and 15 %,

respectively. In Fig. 12 , for AA = 10 %, diesel, 70

flame images taken for all fuels at atomizing air fl

30 diesel-VO blend, and
biodiesel flames all have a blue premixed region overlapped with a yellow diffusion
fl

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flame in the downstream region. The images revealed that the VO has a very
distinct blue premixed fl flame. Figure 13 , for AA = 15 %, showed that all fuels result

in a blue premixed fl flame. The only visually conspicuous difference is that the

straight VO fl flame is narrower and longer than the fl flames for the other fuels. At both

atomizing air flames with no particulate matter

depositing on the combustor wall or escaping in the combustion products.
Figure 14 shows the radial pro

fl ow rates, all fuels exhibited stable fl

les of CO and NO X concentrations measured at the
combustor exit plane for AA = 10 % and 15 %. Figure 14 a shows that the CO
emissions for AA = 10 % are similar for all fuels, around 10

15 ppm, with slightly

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