A heat exchanger is the main equipment in a heat exchange device that uses cold and hot media to cool or heat air. It is applied in various industries such as industrial and mining, light industry, papermaking, textiles, pharmaceuticals, and food for hot air heating, air conditioning, cooling, dehumidification, drying, and other projects. The commonly used air heat exchangers include steel tube wrapped steel strip heat exchangers and copper tube series aluminum foil heat exchangers.

The steel pipe wrapped steel strip heat exchanger is a thin steel strip with a width of 10mm that is vertically wrapped around the outer diameter of a seamless steel pipe. The single tube structure is shown in Figure 1, and the spiral spacing of the winding is t=3.2mm~7mm. Due to the gap between the steel strip and the steel pipe, hot-dip galvanizing (i.e. hot-dip galvanizing) is generally used to fill the gap and carry out anti-corrosion treatment to eliminate the gap. This process is difficult to ensure that the gap between the steel pipe and the steel strip is completely eliminated, or the contact is not tight, resulting in a certain contact thermal resistance. The contact surface between the steel strip and the heat dissipation pipe is almost in linear contact, and the contact area is small, resulting in low heat conduction and poor heat dissipation conditions. Although the wrapped steel strip is coated with zinc, it will rust after working in a humid and hot environment for a long time, and the contact gap that was originally immersed in zinc will come out again. Severe rusting of the wrapped steel strip will cause it to fall off, not only reducing its heat transfer performance, but also shortening its service life.

Copper tube series aluminum foil heat exchanger, also known as surface cooler, is a type of heat exchanger that uses aluminum foil punched and flanged on copper tubes, and then uses a dedicated tube expansion machine to enlarge the copper tubes. The aluminum fins are in close contact with the copper tubes, and the heat transfer performance and air flow performance are good. At present, this type of heat exchanger is widely used in air conditioning, and due to the use of copper pipes, the material cost is high. The material cost of steel pipe wrapped steel strip heat exchanger is low, but the use effect is poor, the service life is short, and the energy waste is large; Copper tube series aluminum foil heat exchanger has good performance, but the material cost is high. In order to seek a heat exchanger with low material cost and good performance, we replaced copper pipes with steel pipes and tightened aluminum foil strips instead of winding structures. We conducted theoretical calculation analysis and product trial production and application.

Many steel tube wrapped steel strip heat exchangers corrode after 5 years of use, and rust forms on the surface of the fins; The longer winding tape began to peel off, exposing the heat dissipation pipes inside. The service life of aluminum foil is over 10 years, and some aluminum foil surfaces have been oxidized. We can see that aluminum foil that has been used for more than 10 years still has a bright surface after washing away dust with water.