Environmental Engineering Reference
In-Depth Information
Table 3.6 Absorptance
α
, Transmittance
τ
and Reflectance
ρ
for Different
Absorber Materials
Visible
Infrared
α
ε
τ
ρ
α
ε
τ
ρ
Material
=
=
Non-selective absorber
0.97
0
0.03
0.97
0
0.03
Black chrome
0.87
0
0.13
0.09
0
0.91
Black nickel
0.88
0
0.12
0.07
0
0.93
TiNOX (TiN + TiO +
TiO 2 )
0.95
0
0.05
0.05
0
0.95
inclination to allow the vapour to rise and the fluid to flow back. A cross-
section illustrating the operating principle of the evacuated tube collector is
shown in Figure 3.12. The photo in Figure 3.13 shows a detail of an evacuated
tube collector.
There are also evacuated tube collectors with a heat pipe that passes
through the end of the glass tube. The heat transfer medium of the solar cycle
can flow directly through the heat pipe of these collectors. Then, a heat
exchanger is no longer needed and the collector need not be mounted with a
minimum angle of inclination.
View from top
Condenser,
heat exchanger
Glass tube with
high vacuum
Heat pipe
Heat pipe fluid
Solar cycle
heat carrier
Selectively coasted
absorber sheet
2. Heat pipe fluid transfers heat
to solar cycle and condenses
1. Solar radiation vaporizes the heat pipe fluid.
The vapour rises along the heat pipe
View from side
3. Heat pipe fluid flows down and
is heated again by the sun
Figure 3.12 Assembly and Function of the Evacuated Tube Collector with
Heat Pipe
 
Search WWH ::




Custom Search