Cause Analysis and Solution of Vacuum Tube Explosion of Solar Water Heating System
We all know that the vacuum tube of the solar water heating system often has a burst tube phenomenon, so what causes the vacuum tube to burst? To understand this problem, it is necessary to fully understand the quality control standards of the vacuum tube production process:
There are many reasons for the failure of a vacuum tube, and basically it will cause the explosion of the vacuum tube. So, will a qualified vacuum tube be so easy to explode? In fact, the vacuum tubes currently on the market are basically qualified as long as they are from regular manufacturers, but the problem of explosion tubes still occurs from time to time. Since there is no problem with the quality of the vacuum tubes, why do they still explode? The reasons are usually as follows:
1. Hot and cold shock: In daily life, people who have used glass water glasses should know that pouring cold water into a glass that has just been filled with boiling water, or pouring boiling water into a glass that has just been filled with cold water, the glass will burst. . The same is true for vacuum tube solar collectors. For some reasons, for example, the temperature difference between the inlet and outlet of the forced circulation solar hot water system is too large, and the water at noon when the sunlight is strong will cause the solar vacuum tube to burst.
2. Improper installation: Due to improper selection of the pump, the head is too high, or the pressure of the tap water pipe network is used, the glass tube is subjected to excessive pressure and the solar vacuum tube bursts. In addition, when the water tank is lower than the heat collector, sometimes it will cause the negative pressure of the system, and it is also very easy to explode the tube. Improper thermal insulation of the pipeline or insufficient vacuum degree of the vacuum tube, and the thermal insulation performance does not meet the standard. When the temperature is low at night in winter, the water in the vacuum tube freezes due to the temperature drop, and the vacuum tube is broken. In addition, the incorrect installation position of the exhaust valve of the system results in poor exhaust and air resistance. After the system is filled with water, the maximum stress of its nozzle will be close to the applicable stress, which may cause the explosion of the tube; the installation angle of the system is incorrect, solar energy The heat collector is not installed on the same plane, resulting in stress between the vacuum tube and the header. When the stress limit is reached, the tube is also easy to explode.
3. Scale: The temperature in the solar vacuum tube easily reaches 80 or 90 degrees, and it is easy to produce scale. It adheres to the surface of the header and the vacuum tube. The thermal conductivity of the scale is small. The thickened scale layer makes the vacuum tube heat sink and the tube. The heat transfer of the heat transfer fluid is blocked, and a certain temperature difference is formed between the inside and outside of the scale. When the solar radiation is good, the temperature of the outer layer of the scale is higher, which forms a larger temperature difference with the inner layer, causing scale cracks and cold liquid in the pipe. Into the inner wall of the glass along the crack, it is easy to cause the explosion tube.
The scale of the above explosion tube problem causes the problem of solar vacuum tube explosion tube * It is difficult to solve, whether it is softening the water source in advance, or regularly descaling the system, the cost is very high for individual users, and the effect is not satisfactory. If you can use municipal tap water that meets the water quality conditions, try not to use groundwater and other hard water sources.
As for the bad consequences of the solar vacuum tube explosion caused by improper installation, it is usually serious, and of course it is also easy to avoid, as long as the correct design scheme is selected, an excellent construction team, and reliable product quality and responsible suppliers. The problem of explosive tubes caused by improper installation can be completely avoided.