Copper and aluminum composite U-shaped finned tube

Copper finned-tube heat exchangers are widely used in residential, commercial, and industrial refrigeration and air-conditioning systems. Their excellent thermal‑transfer performance is essential for maintaining the high efficiency of these systems. Typically, copper finned tubes exhibit high heat‑transfer efficiency during the initial stages of operation; however, after a period of use, their cooling and heating capacities decline, indicating a deterioration in the long-term heat‑transfer performance of the finned‑tube heat exchanger.

Copper finned‑tube heat exchangers are widely used in residential, commercial, and industrial refrigeration and air‑conditioning systems. Their excellent heat‑transfer performance is essential for maintaining the high efficiency of these systems. Typically, copper finned tubes exhibit high heat‑transfer efficiency during the initial stages of operation; however, after a period of use, their cooling and heating capacity declines, indicating a deterioration in the long‑term heat‑transfer characteristics of the finned‑tube heat exchanger. 
According to the investigation, the annual operating time of household air conditioners was determined to be 842.9 hours, with an estimated number of intermittent cycles per year of 1,214. The test specimens were heat exchangers featuring aluminum fins with copper fin tubes and copper‑finned tubes; both the aluminum and copper fins are hydrophilic. To simulate four years of typical residential air‑conditioner operation, each heat exchanger underwent 4,800 intermittent cycling tests. Intermittent operation was achieved by immersing the heat exchanger in a cold water bath for one minute, reducing the surface temperature of the copper‑finned tubes to 5°C to emulate cooling‑mode conditions, followed by placing the heat exchanger in a warm‑air chamber for three minutes, raising the tube surface temperature to 27°C to simulate the off‑state. To examine how the number of cycles affects the heat transfer and pressure‑drop performance of finned‑tube heat exchangers, every 300 cycles, the heat transfer and pressure‑drop characteristics were evaluated at different air velocities. An experimental test rig was designed to measure air‑side heat transfer performance. The rig comprises three main subsystems: a water circuit, an air‑side circuit, and a data‑acquisition system. Each experiment collected heat transfer data for the finned‑tube heat exchanger at four distinct air velocities. A total of 136 experiments were conducted. 
A commonly used copper finned-tube welding process includes bridge welding and full‑penetration welding. In concrete applications, as time passes, fouling may accumulate inside the finned tubes. During bridge welding, where two tubes are stacked, the drainage openings at the weld joint are relatively small, making blockages more likely. By contrast, in assembly welding, the tubes are welded immediately, which reduces the risk of clogging. Using this type of equipment can achieve a one‑pass forming effect. 
The thickness of the plate directly affects the service life of copper finned tubes; typically, it should be 1.3 mm. However, to pass off inferior products as superior, some manufacturers use plates even thinner than specified. A simple way to identify this is to skip the standard small‑scale measurements and instead rely on a straightforward, visual assessment of the thickness. 
Currently, the architectural coatings commonly used for internal corrosion protection of copper finned tubes fall into two categories: one is organic‑chemical coating, specifically zinc‑based chromate formulations. These coatings exhibit excellent adhesion to electric underfloor heating systems and finned tubes even at extremely low temperatures, making them resistant to peeling. However, their application demands strict adherence to rigorous procedures, with key process parameters meticulously controlled at every stage. Professional expertise and innovative design ensure superior coating quality.

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