Environmental Engineering Reference
In-Depth Information
0.12
a=40000s
-1
Two-dimensional Air Flow
T
=320K
Yo
=0.233
0.1
a=40000s
-1
0.08
T
=1280K
0.06
a=10000s
-1
T
=320K
0.04
0.02
0
1000
1500
2000
2500
Surface temperature, K
FIGURE 2.130
Influence of the surface temperature on the combustion rate of a solid carbon
in high temperature airflow. The parameters are airflow temperature and velocity gradient.
Data points are based on the test results, and the solid and dotted lines indicate the results of
calculation.
formed.
66
Other known facts are that the gas-phase reaction has a minimal effect on
the combustion rate before the formation of a CO flame
69
and that the formed CO
flame can be treated as a flame front after the formation of a CO flame. The analytical
expression
66
of the combustion rate (dimensional) in connection with the above is
shown below:
µ
ρ
j
2
a
∞
=
()
≈
(
)
∞
m
ρυ
ρ
ln
1
+
β
(2.34)
∞
s
K
where, β is mass transfer number and
K
is the complement number of material
transfer factor. Further, the mass transfer number β is expressed as shown below.
1.
When a CO flame is not present:
KA
KA
KA
KA
+
2
W
W
W
W
S
,
0
Sp
,
β≈
C
Y
C
Y
(2.35)
0
,
∞
p
,
∞
1
+
1
+
S
,
0
0
Sp
,
P
2.
When the CO flame can be treated as a flame front:
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