Finned tube is the most commonly used heat exchange element when there is a significant difference in heat transfer coefficient between the inside and outside of the tube

Finned tube is the most commonly used heat exchange element when there is a significant difference in heat transfer coefficient between the inside and outside of the tube

By adding fins outside the tube to achieve a considerable expansion of surface area, the heat transfer differences inside and outside the tube are minimized, making it the most widely used method in air heat transfer.

The performance characteristics of finned tubes are mainly reflected in the following points:;

1; The minimum temperature reflected by contact pressure and thermal resistance; The main reasons are the type of fins and the requirements for processing quality.

2; Fin materials have significant differences in thermal conductivity among different materials. From a heat transfer perspective, it is advisable to choose materials with high thermal conductivity and low manufacturing costs as fin or base tube materials. The thermal conductivity of various common metals is as follows:;

⑴ Silver --429 W/(m/℃)

⑵ Copper -- -401 W/(m/℃)

⑶ Gold --317 W/(m/℃)

Aluminum -203.5 W/(m/℃)

Brass -64-85.5 W/(m/℃)

Tin --67 W/(m/℃)

Cast iron -62.8 W/(m/℃)

Nickel --58.2 W/(m/℃)

Steel -45.3 W/(m/℃)

(10) Lead --34.9 W/(m/℃)

(11); Stainless steel -17 W/(m/℃)

Three; Anti corrosion performance, using appropriate materials based on the medium inside and outside the pipe to improve the corrosion resistance of the fins. Different forms of fin structures also have a certain impact on corrosion resistance.

4; Temperature resistance, different fin materials have different melting points. Considering the characteristics of the medium temperature, suitable fin tube materials should be chosen to avoid using low melting point materials at high temperatures and high melting point materials at low temperatures.

Five; The heat transfer performance is not only affected by the material, but also by the comprehensive results of various aspects. The structural type, processing form, manufacturing requirements, etc. of the fins will have a significant impact on the heat transfer performance.

Six; The difficulty of cleaning is related to the type and manufacturing process of the fins, and fins with wrinkles and prone to lodging have high cleaning difficulty at the same pitch.

Seven; Cost performance. The ratio of the comprehensive performance indicators of finned tubes to the manufacturing cost price.

Eight; Wing to wing ratio. The ratio of the maximum heat exchange area that can be processed by a finned tube to the surface area of the bare tube before processing.

There are several commonly used types of finned tubes:;

1; A bimetallic finned tube with steel or stainless steel tubes as the base tube, which is compounded with aluminum tubes on a specialized machine tool and processed into fins.

2; Copper strip; Plastic metal materials such as aluminum strips have L-shaped fins that rely on mechanical force to evenly wrap around base pipes such as steel pipes, stainless steel pipes, and copper pipes.

3; A single metal finned tube with steel strips and stainless steel strips as fins, wrapped in an inverted Y-shape on the base tube, and folded at the bottom of the fins.

4; High frequency current welding is used while winding to integrate the base tube and fins, which is high-temperature resistant and has low contact thermal resistance

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