Evacuated Vacuum Tube Collector Solar Water

Evacuated Vacuum Tube Collector Solar Water Heating System
Each solar tube consists of two glass tubes made from extremely strong
borolisicate glass. The outer tube is transparent allowing light rays
to pass through with minimal refection. The inner tube is coated with a
special coating (AI-N/A1) which features excellent solar radiation
absorption and minimal reflection properties. The top of the tubes are
fused together and the air contained in the space between the two
layers of glass is pumped out while exposing the tube to high
temperatures. This "evacuation" of the gases forms a vacuum, which is
an important factor in the performance of the solar tubes
Why a Vaccum ? As you would know if you have used a glass lined thermos
flask, a vacuum is an excellent insulator. This is important because
once the solar tubes absorbs the radiation from the sun and converts to
heat, it will not loose it ! The vacuum help to achieve this. The
insulation properties are so good that while the inside of the tube may
be 150C the outer tube is cold to touch. This means that solar tube
water heaters can perform well even in winter and rainy seasons.
In order to maintain the vacuum between the two glass layers, a barium
getter is used (the same as in television tubes). During manufacture of
the solar tube this getter is exposed to high temperatures which causes
the bottom of the evacuated tube to be coated with a pure layer of
barium. This barium layer actively any CO, CO2, N2, O2, H2O
out-gassed from the solar tube during storage and operations, thus
helping to maintaining the vaccum. Evacuated tube collectors still
provide excellent results on cloudy days, this is because the tubes are
able to absorb the energy from infrared rays which can passes through
clouds.How Vaccum tube solar technology efficient than traditional solar water heaters.

As the Vaccum tube is round, the sun rays are always striking the tubes surface at right angles, thus maintaining reflection.
If the collector surface is flat than the amount of solar radiation
which strikes the collector surface will be maximum only at the noon
time is when the sun is at straight line to the collector. In the
morning or afternoon the sun rays strike the collectors surface at an
angle and thus the amount of solar radiation that the collector is
exposed will be comparatively less with that of evacuated tube.
Evacuated tubes, however, are round and thus the amount of solar
radiation striking the collector is relatively constant from mid
morning to mid afternoon, furthermore, the sun is always striking the
tubes of an angle which is perpendicular to their surface thus reducing
reflection.Technical Specification











Tube Material

Special Borosilicate Glass



Outer Tube Diameter

47 mm



Inner Tube Diameter

37 mm with Selective absorption coating layer



Storage Tank

SS304 Grade



Outer Cladding

SS / AL / PC



Support Structure

M.S. Powder Coated



Insulation Meterial

Puf



Tube Length

1500 mm



Temperature Rage

50 to 80C



Warranty

1 Year except on glass



Heater

Provision for Heater Coil Provided