1、In daily life, people who have used glass should know that when cold water is poured into a glass that has just filled boiling water, or boiling water is poured into a glass that has just filled boiling water, the glass will burst. The same is true for vacuum tube solar collectors. For some reasons, such as the temperature difference between the outlet water of the forced circulation solar hot water system is too large, and the noon water with strong sunshine will cause theRaw material glass tube cracking tube
2 improper installation
Due to improper selection of pumps, high lift, or the use of tap water network pressure, resulting in excessive pressure on glass tubes, resulting in solar vacuum tube burst. In addition, when the water tank is lower than the collector, sometimes the negative pressure phenomenon of the system will be caused, and it is also very easy to burst the tube. When the temperature of the vacuum tube is low at night in winter, the water in the vacuum tube freezes because of the temperature drop, and the vacuum tube bursts. In addition, the incorrect installation position of the exhaust valve of the system results in the blockage of exhaust and gas resistance. After the system is watered, the maximum stress of the nozzle will approach the applicable stress, which may cause the explosion of the tube. The incorrect installation angle of the system and the failure of the solar collector to be installed on the same plane will result in the stress between the vacuum tube and the header. When the stress limit is reached, the tube will be easily exploded.
The temperature in the solar vacuum tube is easy to reach 890 degrees, which is easy to produce scale. It is attached to the surface of the header and vacuum tube. The thermal conductivity of the scale is small and the scale layer is thicker. The heat exchange between the heat absorber of the vacuum tube and the heat conducting fluid in the tube is blocked. The temperature difference between the inside and outside of the scale is formed. When the solar radiation is good, the outer temperature of the scale is higher. Large temperature difference in the inner layer results in scaling cracks, and the cold liquid in the tube enters the inner wall of glass along the crack, which is easy to cause explosion of the tube.
Among the above problems, scaling causes the most difficult problem to solve. Whether softening the water source ahead of time or regularly removing the scales from the system, the cost is quite high and the effect is not satisfactory for individual users. If the municipal tap water with water quality up to the standard can be used, the hardness of groundwater should be avoided as far as possible. The source of water.