271
Radiation Exchange in a Nonparticipating Medium
1
1(3)
4(3)
4
2(3)
2
Specular surface
FIGURE 13.11
Radiation exchange among diffuse and specular surfaces.
13.5 Energy Balance in an Enclosure with Diffuse
and Specular Surface
N d is the diffuse reflection surface,
N − N d the specular reflection surface.
Assume all surfaces shown in Figure 13.12 are diffuse emitting, gray, and
isothermal; then
= ε i σT
4
+ (1 − ε i )G i
J i
i
where G i = G i
d + G s
i .
From the diffuse surface,
Nd
G
d
i =
J j E Ai−Aj
(13.25)
j=1
where
ρ
s
E Ai−Aj = F Ai−Aj +
k F Ai(k)−Aj
k
i
q
i
}
T i
E i
J i
G i
A i
A
j
N
ε i
ρ i G i
FIGURE 13.12
Radiation heat transfer between N surfaces (including diffuse and specular) in an enclosure.