Environmental Engineering Reference
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Fig. 15 Effect of ALR on CO
and NO X emissions for 50/50
mixture, HRR = 7 kW
Fig. 16 Effect of total heat
release on CO emissions for
50/50 mixture
With increasing HRR, the resulting
flame images became increasingly brighter,
presumably because of the higher concentrations of radicals in the reaction zone.
Next, Fig. 16 shows radial pro
fl
les of CO emissions at the combustor exit plane for
the three heat release rates. Results show high CO concentrations of around
3,000 ppm near the combustor wall. Two factors account for this observation: (1)
quenching of reactions because of heat loss through the wall and (2) larger droplets
migrating and burning in diffusion mode near the wall. The CO concentrations
decrease to 40
60 ppm toward the center of the combustor.
Although HRR = 11.7 kW case shows the lowest CO emissions over part of the
plot, all cases give similar CO values overall. Figure 17 shows the NO X emissions
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