Environmental Engineering Reference
In-Depth Information
Fig. 11 Variation of average
primary soot particle size with
premixing air
30
Average Primary Particle Size (nm)
28
26
24
22
20
18
16
14
12
10
8
6
01
23 56789 0 1
4
Φ
p
hooting, combustion instabilities can also be addressed. The premixed mixtures were
rich for all the cases studied here. A probable area for further study can be lean PPC,
where the premixed mixtures employed are already lean. Measurements of radical
species can also be done, along with measurement of temperatures at various radial
and axial locations along the burner. This can give an idea about the heat release rate,
the temperature
field, reaction mechanisms and mechanisms of formation of soot, etc.
The use of various sophisticated instruments like Particle Image Velocimetry (PIV)
and Planar Laser Induced Fluorescence (PLIF) might prove to be helpful in providing
information about
les of temperatures,
radical concentrations and various gases like NO. Moreover, similar studies can be
undertaken at extremely low levels of premixing, wherein the mixture cannot ignite
without the addition of secondary air. This would prove to be advantageous when
dealing with the safety aspects of premixed and PPC.
fl
ow
fields,
fl
flow velocities, the planar pro
4 Conclusions
From the above study conducted on partially premixed, LPG/air
fl
ames,
it
is
observed that
U
p) is found to be
between 1.5 and 2. At such high premixing levels, the emissions of CO, UHCs, NO
and soot are seen to be considerably reduced. Trade-off between CO, UHCs and
NO was not there in this range of
this optimum premixing equivalence ratio (
U
p. Another observation is that the soot primary
particle size is comparatively higher for partially premixed cases, than for a pure
diffusion
flame. This also is advantageous, as larger-sized pollutant particles are
prevented from entering the human body through its self-defence mechanisms.
Hence, the health hazards posed to travellers and people working or staying in the
vicinity of airports are reduced. But again, though the particle size of soot is more at
moderate to high levels of premixing as compared to that at lower premixing levels;
fl
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