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Solar Vacuum Tube

Update:2014-11-27 15:16:05      Click:
  • Brand:   真空波纹管
  • Model:   
  • Online ordering
Product introduction
SVT is constituted by inner tube and a coaxial outer glass tube of solar-selective absorbing coating. One end of the inner tube is sealed in a dome shape and supported by the spring holder with a getter at the sealed-off end of the outer tube. The other end of the inner tube is frit sealed with the outer glass forming a cyclic open end. SVT can be divided into seven parts.
1) inner tube: water flows in it and it is coated with solar selective absorbing coating, the vacuum space between the inner and outer tube protect the vacuum absorbing coating and play the role of insulation, the material inner and outer tube used is borosilicate glass 3.3 who has the lowest coefficient of expansion in various materials.
2) Solar selective absorbing coating: with a high solar absorption ratio and low emissive coatings ratio, the coating absorbs solar radiation, reduces thermal radiation and converts solar energy to heat.
3) Vacuum space: vacuum space between the outer tube and the inner tube has a low pressure inside so that the gas heat conduction and convection can be neglected, therefore the insulation effect is improved (Note: High vacuum insulation is the world's most efficient insulation measures).
4) Spring holder: its main function is to avoid the contact with the inner tube and the outer tube and support the inner tube at the round end.
5) Getter: by using evapotranspiration technology, getter material relying on the getter effect to absorb the gas in the process of evapotranspiration and after the precipitation. ( main ingredient:Ba、Ca、Mg)
6) Getter film: Getter film is a silver film with suction effect; it is precipitated at the round wall of outer tube after the evapotranspiration when being heated by high-frequency electric. Through the reaction with residual gas in the vacuum space, the getter turns into solid material. Therefore, it improves and maintains the vacuum degree of the vacuum space so that the life of SVT is prolonged. (Note: the getter be used in our product is the same as kinescope), the getter is shining silver mirror when it work effectively, on the contrary, the getter will turn to translucent milky white when it invalid to work.
Main Production Technology of SVT.
   1 Coating technology not only affects the performance but also the service life of the SVT, high and low degree of vacuum and thickness of the film will affect the life of SVT.
    The degree of vacuum will affect the degree of adhesion of the coating film; the case of high vacuum and fewer impurities, the adhesion of coating film is strong. Film thickness will affect the life of the SVT, the film will gradually decompose and become thinner at high temperature for a long time use, thus if the layer is too thin, the SVT will lose the absorbing effect after several years of use for the reduction of absorbing layer. 
    2 venting is to exhaust the vacuum space between the inner tube and the outer tube by the vacuum. This is useful to increase insulation effect of SVT. Our exhausting is under an automatic control of holding temperature at 420 ℃ ± 5 ℃, holding time is 60 minutes, the vacuum degree requirement of venting machine is a display value  p≤3.0 × 10-3Pa of a composite vacuum gauge.
The exhaust technology directly affects the absorption and thermal insulation properties of SVT. A low degree of vacuum will cause slow-warming, low-temperature even the scrapping of SVT caused by disappearance of mirror.
    Our exhausting time is no less than 60 minutes under an automatic control of holding temperature at 420 ℃ ± 5 ℃, Target are made  of aluminum, copper and stainless steel, the structure is Cu-SS/Al/N-AL/N
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