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    Vacuum tubes

    Working Principle
    Tri-target solar vacuum tube, connecting with water tank or manifold, when it works, cold water flows down into the vacuum tube, and there it is heated with solar energy absorbed by the coating outside of inner vacuum tube, the solar will be absorbed efficiently by the coating with little loss of heat because of the vacuum between the inner and outer glass tubes, and when cold water becomes hot, hot water will rise up to water tank or manifold because of the larger proportion to cold water, cold water again flows into solar vacuum tube for another heating process.

    1. Detailed information


    Tri-element tubes consist of two glass tubes which are fused together at one end. The inner tube is coated with a selective coating with 12 layers of spattering deposition technology that absorbs solar energy well. The coating is ALN/AIN-SS/CU by gradual change techniques, which has better heating efficiency.

    The air is withdrawn ("evacuated") from the space between the two glass tubes to form a vacuum, which eliminates conductive and convective heat loss. Therefore, evacuated tubes could achieve up to 380 degree from theoretical condition, and act as the key component of solar water heater



    Technical Data Of Three-target Vacuum Tube:

    Tube structureAll-glass double-tube co-axial structure
    Glass material High borosilicate 3.3 glass
    Outer tube sizeΦ=47±0.7mm &=1.6±0.15mm, Φ=58±0.7mm &=1.6±0.15mm,
    Φ=70±0.7mm &=2.0±0.15mm
    Inner tube sizeΦ=37±0.7mm &=1.6±0.15mm, Φ=47±0.7mm &=1.6±0.15mm,
    Φ=58±0.7mm &=2.0±0.15mm
    Tube length800mm, 1200mm, 1500mm, 1600mm, 1800mm,
    1900mm, 2000mm, 2100mm, etc.
    Absorber coatingCoating material Cu/SS-ALN(H)/SS-ALN(L)/ALN
    Sediment methodThree target magnetron sputtering plating
    Absorptivity as=0.93 ~ 0.96 (AM1.5)
    Emission ratio Eh=0.04 ~ 0.06 (80±5 oC)
    Vacuum degree P≤5.0X10-3 Pa
    Stagnation temperature260 ~ 300 oC
    Average heat loss ULT=0.4 ~ 0.6 W/(m2* oC)
    Pressure-endure 1.0 Mpa
    Hail Resistance Φ25 mm