This preview shows page 1. Sign up to view the full content.
Chapter 12
Radiation Heat Transfer
1212
View factors from the very long grooves shown in the figure to the surroundings are to be
determined.
Assumptions
1
The surfaces are diffuse emitters and reflectors.
2
End effects are neglected.
Analysis
(
a
) We designate the circular dome surface by (1) and the imaginary flat top surface by (2).
Noting that (2) is flat,
(1)
(2)
D
0
22
=
F
1
1
:
rule
summation
21
22
21
=
⎯→
⎯
=
+
F
F
F
0.64
=
=
=
=
⎯
=
π
2
)
1
(
2
A
:
rule
y
reciprocit
21
1
2
12
21
2
12
1
D
D
F
A
A
F
F
A
F
(
b
) We designate the two identical surfaces of length
b
by (1) and (3), and the imaginary flat top surface by
(2). Noting that (2) is flat,
0
22
=
F
(3)
(1)
a
b
b
(2)
5
.
0
1
:
rule
summation
23
21
23
22
21
=
=
⎯
=
+
+
F
F
F
F
F
(symmetry)
1
1
:
rule
summation
)
3
1
(
2
)
3
1
(
2
22
=
⎯
=
+
+
→
+
→
F
F
F
2b
a
=
=
=
⎯
=
+
→
+
→
+
→
+
+
+
→
)
1
(
A
:
rule
y
reciprocit
)
3
1
(
2
)
3
1
(
2
)
3
1
(
2
)
3
1
(
)
3
1
(
)
3
1
(
2
2
A
A
F
F
F
A
F
surr
(
c
) We designate the bottom surface by (1), the side surfaces
by (2) and (3), and the imaginary top surface by (4). Surface 4
is flat and is completely surrounded by other surfaces.
Therefore,
and
.
F
This is the end of the preview. Sign up
to
access the rest of the document.
This note was uploaded on 01/24/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.
 Fall '10
 Dr.DanielArenas
 Thermodynamics, Mass, Heat, Radiation

Click to edit the document details