Environmental Engineering Reference
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of the velocity gradient
a
(= 4
V
/
d
), which is represented with the constant velocity
2
1
T
3
1:Test section
2:Nozzle(d=12mm)
3:Ceramics honeycomb
4:Ceramics pipe (Al
2
O
3
)
5:Insulator
6:Igniter
7:Heat-Up Burner
8:Flow control unit
9:Ceramics ball (Al
2
O
3
)
T
2
3
4
3
T
1
5
6
7
8
Fuel gas
Air
Pl
Pl
9
Blower unit
Air
FIGURE 2.127
General appearance of high temperature air generator.
V
and the test specimen diameter
d
. Further, it should be noted that the temperature
and concentration distributions in this region are both one dimensional.
The test used a ground bar of artificial graphite (5 mm in diameter, 40 mm in
length, with a concentration of 1.25 × 10
3
kg/m
3
, and 44% porosity) as the solid
carbon test piece. The reactivity of the material has been analyzed by a series of
studies.
66,67
Electric heating using an AC current (16 V, max. 1625 A) was used in
the test and it enabled us to obtain combustion rates under the condition of a uniform
surface temperature regardless of the endothermic reaction or exothermic reaction
that is incidental to chemical reactions. Surface temperature was measured with a
two-color thermometer.
2.5.4.2
Experimental Results
When obtaining combustion rates from surface regression speeds, the combustion
of solid carbon (graphite) is greatly influenced by such factors as velocity gradient,
surface temperature, oxidizing agent temperature, and oxygen concentration. This
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