The evacuated tube solar collector is a solar collector that uses a glass tube and has a vacuum space between the tube wall and the heat sink. The evacuated tube solar collector also contains all-glass evacuated tube collectors and glass-metal structure evacuated tube collectors. According to the structure of vacuum solar collectors, it can be classified into three categories, namely, all-glass evacuated tube solar collectors, U-tube evacuated tube solar collectors, and heat pipe evacuated tube solar collectors.
1. All-glass evacuated tube solar collector
The manifold collector in the all-glass evacuated tube solar collector is composed of evacuated collector tubes, headers, tailstocks, brackets and other components, and the all-glass evacuated collector is used as the collector component, and then the joint The header connects multiple vacuum tubes together to form a whole. If water is in the glass tube, the solar radiation will pass through the cover glass tube of the vacuum collector and then be absorbed by the inner glass tube coated with a selective absorption coating. The water in the tube can be directly heated. Generally, the header collector is mainly used for non-pressure-bearing systems.
Because the inner tube of the collector tube of the header collector is in direct contact with water, and metal materials such as copper and stainless steel are not used, the cost performance is still quite high, and the glass tube has strong corrosion resistance, so the all-glass vacuum tube collection Heater replacement and maintenance are also relatively convenient and easy, so this collector is suitable for domestic hot water and solar hot water projects. However, the collector is sealed with a silicone ring, which makes it unable to operate under pressure. If a vacuum tube ruptures during operation under pressure, the entire system may be paralyzed. In cities with high water hardness, it is easier to build up scale in the collector tubes and headers, so it needs to be cleaned regularly.
2. All-glass vacuum tube U-tube collector
The all-glass evacuated tube U-tube collector uses all-glass evacuated collector tubes as the heat-collecting element, inserts metal U-tubes, and double-layer glass for vacuum insulation. The heat absorber is an inner glass plated with a selective absorption coating. The heat transfer working medium in the metal U-shaped tube is then heated by the heat transfer component. It is an improved type of header collector. It makes the all-glass vacuum heat collection tube fully operable in a pressure-bearing system. Improved reliability. Even if some of the glass vacuum heat collection tubes are broken, the internal metal heat transfer working fluid channel will not leak, so that it can still operate normally.
The heat absorbing body of the glass-metal structure vacuum solar collector tube and the vacuum solar collector tube with no phase change in the heat transfer medium. Similarly, this kind of collector tube is a collector made of collector elements. The glass-metal sealing vacuum is a sealed structure. It is a single-layer glass vacuum tube. The metal absorption strip is used as the heat absorption plate. The U-shaped tube is used as the metal flow channel of the heat absorption body. The heat transfer medium will not be phased. There are two sealing methods, melt sealing and heat compression sealing.
3. All-glass evacuated tube heat pipe collector
The all-glass evacuated tube heat pipe collector uses all-glass evacuated heat-collecting tubes as the heat-collecting element, and it is also double-glazed for vacuum insulation. The heat sink is an inner glass tube plated with a selective absorption coating, and then passes through the heat transfer component. The evaporation section of the metal heat pipe is heated and the heat is transferred from the metal heat pipe to the condensation section of the metal heat pipe, and then the water or heat transfer working fluid in the header is heated. It can be used in pressure-bearing systems as well as non-pressure-bearing systems, and its performance is relatively reliable. Borrowing from the previous paragraph, even if some of the glass vacuum collector tubes are broken, the internal metal heat transfer working fluid channel will not leak, so that it can still operate normally.
The heat pipe type vacuum tube means that the heat transfer element of the vacuum tube heat collection tube is a heat pipe. Similarly, the heat pipe type vacuum tube heat collector is a heat collector composed of heat pipe vacuum tubes. The glass-metal sealing vacuum is a sealed structure. It is a single-layer glass vacuum tube. The metal absorption strip serves as a heat-absorbing plate. The heat-absorbing body contains a metal heat pipe. The phase change working fluid inside the heat pipe passes through a phase change, and then removes the heat from The evaporating section of the heat pipe is transferred to the heating and heat transfer working medium of the condensing section, and there are two sealing methods for glass and metal, fusion sealing and heat compression sealing.