Solar Vacuum Tube

1) Hihgh Performance 2) All size available 3) Automatic production line 4) Long life time

Evacuated tubes are the absorber of the solar water heater. They absorb solar energy converting it into heat for use in water heating. Evacuated tubes have already been used for years in Germany, Canada, China and the UK. There are several types of evacuated tubes in use in the solar industry. Sunwe collectors use the most common "twin-glass tube". This type of tube is chosen for its reliability, performance and low manufacturing cost. Each evacuated 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 (aln/ss-aln/cu) which features excellent solar radiation absorption and minimal reflection properties. The top of the two 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 gasses forms a vacuum, which is an important factor in the performance of the evacuated tubes. 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 evacuated 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 absorbs any co, CO2, n2, o2, H2O and h2 out-gassed from the evacuated tube during storage and operation, thus helping to maintaining the vacuum. The barium layer also provides a clear visual indicator of the vacuum status. The silver colored barium layer will turn white if the vacuum is ever lost. This makes it easy to determine whether or not a tube is in good condition. See picture left side.

Model			47x1500		47x1800		58x1800		58x2000
Diameter			47mm		47mm		58mm		58mm
Length			1500mm		1800mm		1800mm		2000mm
Coating			ALN/SS-ALN/CU		ALN/SS-ALN/CU		ALN/SS-ALN/CU		ALN/SS-ALN/CU
Vacuum			< 5*10 -3		< 5*10 -3		< 5*10 -3		< 5*10 -3
Thickness			1.6mm		1.6mm		1.6mm		1.6mm
Thermal expansion			3.3x10 -6 o C		3.3x10 -6 o C		3.3x10 -6 o C		3.3x10 -6 o C
Material			Borosilicate G 3.3		Borosilicate G 3.3		Borosilicate G 3.3		Borosilicate G 3.3
Stagnation Temperature			> 200 o C		> 200 o C		> 200 o C		> 200 o C
Heat Loss			< 0.8W/ ( m2oC )		< 0.8W/ ( m2oC )		< 0.8W/ ( m2oC )		< 0.8W/ ( m2oC )
Bearing Hail			D25mm		D25mm		D25mm		D25mm
Life Span			15years		15years		15years		15years

Solar Vacuum Tube