Structure of all-glass vacuum tube
The structure of all-glass vacuum tube is composed of inner glass tube, solar selective absorption coating, vacuum interlayer, cover glass tube, support (spring clip), getter and other parts.
1. The inner glass tube is used as a water flow pipe;
2. Copper oxide, black nickel, black chrome, black zinc, black copper and other solar selective absorption coatings are uniformly coated on the outer surface of the inner glass tube by using vacuum deposition, sputtering technology, electrochemical treatment and other processes. To absorb solar radiation energy;
3. Seal the inner glass tube coated with selective coating into the cover glass, and then evacuate the inner and outer glass tubes to form a vacuum interlayer with a vacuum of 0.05Pa to reduce the heat caused by air convection and conduction Loss, which is similar to the principle of thermos;
4. The all-glass vacuum heat collecting tube adopts a single-end opening design, which is sealed by an inner and outer tube at one end, and the other end of the inner tube is a closed hemispherical round head. The spring clip is used to support the round head on the cover glass tube The inner end of the tube makes the inner glass tube absorb solar radiation and the temperature rises, the glass round head forms the free end of thermal expansion, thereby buffering the thermal stress caused by the open end of the vacuum collector tube when the water heater is working;
5. After the vacuum tube is heated, the trace gas (mainly water vapor) originally adsorbed on the wall of the tube will be released, which affects the degree of vacuum. The getter and the getter film are used to absorb these released gases. Maintain a high vacuum in the collector tube.