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2.2 CVSKC-10 Vacuum Tube Collector
The Firebird CVSKC-10 Vacuum Tube Collector offers one of the best
performance to area of any collector on the market and delivers higher
efficiency in less favourable weather conditions.
Each solar tube consists of two glass tubes made from extremely strong
borosilicate glass. The outer tube is transparent, allowing light rays to pass
through with minimal reflection. The inner tube is coated with a special
selective coating which features excellent solar radiation absorption and
minimal reflection properties. The tops of the two tubes are fused together
and the air is withdrawn “evacuated” from the space between the
two glass tubes to form a vacuum, which eliminates conductive and
convective heat loss. This means wind and low temperatures have
less of an effect on the function of evacuated tubes when compared to
flat plate solar collectors, due to the insulating properties of the
vacuum.
The CVSKC-10 Vacuum Tube Collector is a U-pipe direct flow tube
type often called a “Sydney” tube. The heat transfer fluid flows inside a
U shaped pipe within the inner tube (absorber) of each solar tube.
The selective coating on the inner tube converts
solar energy into heat energy and transfers heat
to the copper U-tube by means of a close fitting
aluminium plate. The heat transfer fluid (usually
glycol-water antifreeze mixture) in the U-tube is
heated and conducts the heat energy to the water
inside the storage tank through a plate exchanger
or internal spiral coils.
As the fluid takes its energy directly from the sun,
the heat collecting effectiveness is very high and
the efficiency remains at a constant high level
throughout the product life because the U-tube
does not degrade.
CPC mirror
In order to increase the efficiency of the Firebird vacuum
tube, a highly reflective weatherproof CPC mirror
(Compound Parabolic Concentrator) is placed behind the
evacuated tubes. This “tracks” the sun and ensures that
direct and diffuse sunlight strikes the absorber, even when
the angles of irradiation are unfavourable (such as easterly
early morning and westerly late afternoon light).
The CPC reflector makes a significant contribution to an
extremely high-energy yield, as the radiation that usually
passes through the gap between tubes is driven back onto
the 360˚ absorber area.
COLLECTOR SPECIFICATIONS
