The spiral finned tube is composed of a base tube and a spiral fin. The manufacturing process of the spiral finned tube is usually to wind the fin material around the base pipe and weld the two together by high frequency welding. Therefore, the contact resistance of the base pipe and the spiral fin is relatively small.
As one of the typical structures of the extended surface, the spiral finned tube has the following characteristics:
1. Increasing the heat exchange area outside the tube and improving the heat transfer efficiency The spiral finned tube expands the heat exchange area outside the light pipe, so the convective heat transfer surface is composed of the expanded surface and the surface of the light pipe. In the case of the same volume, The heat exchange area is several times that of the light pipe, thus significantly improving the heat exchange capacity outside the pipe and the heat transfer efficiency of the heat exchanger.
2, the compact spiral finned tube bundle increases the heat exchange area per unit volume, so compared with the light tube bundle, in the case of the same heat exchange, the number of tubes of the finned tube bundle is relatively small, which can reduce heat exchange The volume of the device makes the structure compact and the metal consumption is reduced.
3, enhanced heat transfer conditions spiral finned tube through its external curved structure channel caused by the separation of the flow boundary layer and periodic development, thinning the thickness of the boundary layer, and shortening the length of the laminar boundary layer, which will help destroy the boundary layer The laminar flow layer acts to enhance heat transfer.
4. Reduce the flow resistance of the fluid outside the tube and save the running cost. When the gas flow rate on the fin side is the same, the resistance of each row of spiral finned tube bundles is greater than the resistance of each row of light tubes, but the finned tube bundle is larger than the light tube bundle. The heat exchange area of the row is increased a lot, and in the case of the same heat exchange amount, the number of rows of the tube bundle can be reduced, so that the total resistance of the heated surface is reduced. At the same time, due to the large increase in the heat transfer capacity of the spiral finned tube, the fluid velocity on the fin side can be appropriately reduced under the condition of ensuring the heat exchange capacity, and the flow resistance is usually proportional to the square of the velocity, thereby reducing the fluid velocity. Reduce the resistance of the heated surface and save operating costs.
5, to reduce the wear of the heated surface in the boiler burning solid fuel, the ash-containing gas flow when the flow is subjected to the hot surface, the impact and cutting heat transfer surface will cause the wear surface wear, and the amount of wear is proportional to the cube of the fluid velocity . Due to the improved heat transfer capability of the spiral finned tube bundle, the velocity of the fluid outside the tube can be reduced, thereby greatly reducing the wear of the heated surface.
At the same time, the structural characteristics of the spiral finned tube enable the fluid flowing through the spiral finned tube to form a flow condition which is beneficial to reduce wear to a certain extent. Thereby, the abrasion caused by the impact and cutting of the solid ash on the heated surface is impaired. It is precisely because of the above series of advantages of the spiral finned tube bundle. The heat exchange device as a heat exchange element has the advantages of compact structure, low metal consumption and low operating cost, and is therefore widely used in boiler economizers, heat pipe air preheaters, convection evaporation heating surfaces, and metallurgical and chemical industries. Waste heat recovery equipment.