No, there are selective coatings on vacuum tube collectors. The water is heated through the collector, then the density of the cold water is greater than the density of the hot water to be circulated. In detail, the front of the vacuum tube is heated from the side facing solar energy. The water temperature is high, while the temperature at the back is low. According to the rise of hot water and fall of cold water, the water in the water tank is heated again and again in a continuous cycle.
The water cannot be released and will not freeze, because the vacuum tube of the solar water heater has a two-layer structure, and the vacuum structure between the layers does not have no thermal conductivity. absorbed during the day will be stored in the water, and the water can maintain a certain temperature without freezing, so solar water heaters are generally not prone to freezing and cracking in winter.
Detailed informationRelated:
Structural structure
All glass vacuum tube The structure consists of an inner glass tube, a selective solar absorption coating, a vacuum interlayer, a protective glass tube, a bracket (spring clip), a getter and other parts.
1. The inner glass tube is used as a water flow pipe;
2. Selective solar absorption coatings such as copper oxide, black nickel, black chrome, black zinc and black. copper is The outer surface of the inner glass tube is evenly coated using vacuum deposition, spraying technology, electrochemical treatment and other processes to absorb solar radiation energy
3. glass tube. The glass tube is sealed in the protective glass, then a vacuum is established between the inner and outer glass tubes to form an intermediate layer sous vacuum with a vacuum degree of 0.05 Pa in order to reduce heat loss due to convection and air conduction, which is similar to the principle of a thermos bottle
Baidu Encyclopedia-Solar Vacuum Tube