Chapter 12
Radiation Heat Transfer
1270
The temperature, pressure, and composition of combustion gases flowing inside long tubes are
given. The rate of heat transfer from combustion gases to tube wall is to be determined.
Assumptions
All the gases in the mixture are ideal gases.
Analysis
The volumetric analysis of a gas mixture gives the mole fractions
y
i
of the components, which are
equivalent to pressure fractions for an ideal gas mixture. Therefore, the partial pressures of CO
2
and H
2
O
are
atm
09
.
0
atm)
1
(
09
.
0
atm
06
.
0
atm)
1
(
06
.
0
2
2
H
CO
=
=
=
=
=
=
P
y
P
P
y
P
O
w
c
T
s
=
600 K
D
= 15 cm
Combustion
gases, 1 atm
T
g
=
1500 K
The mean beam length for an infinite cicrcular
cylinder is, from Table 124,
L
= 0.95(0.15 m) = 0.1425 m
Then,
atm
ft
0.042
atm
m
0128
.
0
m)
5
atm)(0.142
09
.
0
(
atm
ft
.028
0
atm
m
00855
.
0
m)
5
atm)(0.142
06
.
0
(
⋅
=
⋅
=
=
⋅
=
⋅
=
=
L
P
L
P
w
c
The emissivities of CO
2
and H
2
O corresponding to these values at the gas temperature of
T
g
= 1500 K and
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 Fall '10
 Dr.DanielArenas
 Thermodynamics, Mass, Heat, Radiation, ε w

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