Combustion Phenomena of High Temperature Air Combustion - High Temperature Air Combustion: From Energy Conservation to Pollution Reduction - page 150

First, total radiance predictions have been performed using Equation 2.31 and
considering gas phase, only. Comparison between measured and predicted radiance
profiles shows that the presence of particulate significantly enhances radiation.
Second, total radiance calculations have been performed using the measured
particulate concentration at the axial distance of 205 cm. No solid concentration
measurement has been performed between R D = -25 cm and R D = +25 cm. The
particulate concentration in this area has been supposed equal to the recirculation
zone particulate concentration.
For the sake of simplicity, it was considered that the particles radiate as soot
particles. The density of particulate was taken equal to 1800 kg/m 3 . The constant
C 0 typically lies between 4 and 10 for soot. The value 10 has been chosen arbitrarily
for the predictions.
Good agreement between measurements and calculations has been obtained (see
Figure 2.116 ) . The experimental values and prediction curve follow a similar trend.
However, the model does not capture the large variation of total radiance occurring
in the flame region between R D = +0.0 cm and R D = +20 cm. The lack of solid
concentration measurements between these two radial distances does not permit a
more accurate analysis.

120

Measurements at AD= 205 cm
Predictions of the EWBM:
GAS
GAS+PARTICLES
(assuming as soot C 0 =10)

100

80

60

40

20

0

− 100 − 80 − 60 − 40 − 20 0 20 40 0 0 0

Radial distance [cm]

FIGURE 2.116 Comparison between total radiance predictions and total radiance measure-
ments.

TABLE 2.10
Baseline Output Conditions
for the Parameters Study

Temperature, ˚C 1100

Oxygen, vol. % dry 2.9

NO x , ppm 216

Burnout, % 98