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Chapter 12
Radiation Heat Transfer
1228
The base, top, and side surfaces of a furnace of cylindrical shape are black, and are maintained at
uniform temperatures. The net rate of radiation heat transfer to or from the top surface is to be determined.
Assumptions
1
Steady operating conditions exist
2
The
surfaces are black.
3
Convection heat transfer is not
considered.
Properties
The emissivity of all surfaces are
ε
= 1 since they are black.
T
1
= 700 K
ε
1
= 1
r
1
= 2 m
T
2
= 1200 K
ε
2
= 1
r
2
= 2 m
T
3
= 500 K
ε
3
= 1
h
=2 m
Analysis
We consider the top surface to be surface 1, the base
surface to be surface 2 and the side surfaces to be surface 3.
The cylindrical furnace can be considered to be threesurface
enclosure. We assume that steadystate conditions exist. Since
all surfaces are black, the radiosities are equal to the emissive
power of surfaces, and the net rate of radiation heat transfer
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 Fall '10
 Dr.DanielArenas
 Thermodynamics, Mass, Heat, Radiation

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