Finned tube, in order to improve heat transfer efficiency, usually by the addition of heat exchange fins on the surface, increasing the surface area of heat transfer tubes (or inner surface), so as to improve heat transfer efficiency purposes, such a change heat pipe.
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The main performance requirements finned tube
Finned tube production technology status
Classification of finned tubes Expand
The main performance requirements finned tube
Finned tube production technology status
Classification of finned tubes Expand
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The main performance requirements finned tube
As a finned tube heat exchanger components, long-term work in high temperature flue gas conditions, such as the boiler heat exchanger finned tubes using harsh environment, high temperature and pressure and in a corrosive atmosphere, which requires the finned tube should have a very high performance indicators.
1), corrosion resistance (Anti-corrosion)
2), wear resistance (Anti-wear)
3), low contact resistance (lower contact resistance)
4), a high stability (Higher Stability)
5), anti-fouling ability
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Finned tube production technology status
Set fin
Packages are pre-finned craft punch processing a batch with a single fin, and then use the manual or mechanical means, at a certain distance high (fin spacing), interference by the fin package outer surface of the tube. It is the first application of an finned tube processing method. As set process is simple, less demanding technologies, equipment used inexpensive, and easy to repair, so many factories are still in use. This process is a labor-intensive process scheme, suitable for general small factory or town enterprise funds and technical conditions.
Artificially set called handmade suit. It is the use of tools will depend on the strength of man pushed one fin. Because this method is pressed into the fin is limited, the amount of interference of small packages, prone to loosening of the fins.
Set in the fin fins mechanical machine for the packages. Since the fins are pressed into the liquid by mechanical impact force or pressure, the pressure into force, therefore, use a larger amount of interference. Between the fins and tubes combination of high strength, not easy to loose. Mechanical transmission package machine production rate, but noisy, poor security, poor working conditions of workers. Although hydraulic drive these problems do not exist, but the equipment is more expensive, the use of the technical requirements for maintenance personnel is high, its productivity is lower.
Mosaic spiral fin
Mosaic finned tubes are processed in advance on the pipe a certain width and depth of the spiral groove, and the strip set in the lathe on the pipe. In the winding process, due to a certain preload, Le strip held tightly in the spiral groove, thereby ensuring the steel strip and a contact area between. To prevent rebound off the strip, the strip ends to be welded to the pipe. In order to facilitate mosaic, strip and spiral grooves should be a backlash between. If the backlash is too small, the formation of interference, is inlaid process difficult smoothly. In addition, the winding of the strip there is always a certain resilience, so that the result and the helical strip of the bottom surface not well bonded. Fin embedded on the device in general, the cost is not high, but the process is complex and low production efficiency.
Spiral finned tubes brazed
Spiral finned tube brazing process in two steps. First, the steel strip plane perpendicular to the axis of the tube spiral is wound around at the outer surface of the tube and welded to the pipe ends of the steel strip is fixed, and to eliminate the steel strip and the contact point of the gap, by brazing method The steel and steel pipe welded together.
Because this method is expensive, it is commonly used another method, the strip wrapped around the pipe coming into the zinc hot-dip galvanizing bath at an overall instead. Although the use of hot-dip galvanizing bath is not necessarily a whole can be well infiltrated fins and tiny gap between the pipe, but the outer surface of the fin and tube outer surface has formed a complete zinc coating. With the overall hot-dip galvanized spiral finned tubes, because by limiting the thickness of the zinc coating (galvanizing layer thickness, the zinc layer firmly poor, easy to fall off), combined with liquid zinc is impossible to entirely penetrate the gap, so the fins and The combination of steel was still not high. In addition, the heat transfer coefficient than steel zinc is small (about 78% of steel), the heat capacity is low. Zinc in acid and alkali sulfides vulnerable to corrosion, therefore, not suitable for galvanized spiral fin tube production air preheater (flue gas waste heat recovery boiler).
High-frequency welding spiral fin
High frequency welding spiral finned tube is currently the most widely used one spiral finned tubes, is now widely used in electric power, metallurgy, cement industry, waste heat recovery, and petrochemical industries. High-frequency welding spiral finned tube is wrapped in a steel pipe at the same time
, The use of high-frequency current of the skin effect and proximity effect, the outer surface of steel strip and heated until molten or plastic state, the strip is wound under a certain pressure to complete the welding. This high-frequency welding solid as a solid phase welding. It is with inlay, brazing (or the whole hot dip galvanized) and other methods, both in the quality of products (fins welded rate, up to 95%), or the degree of productivity and automation are more advanced .
Three roll rolling overall type spiral finned tubes
Three roll rolling spiral finned tube its overall production principle is: the light pipe lining a mandrel, the rotation drive roller blades, seamless head through rolling groove and the core cavity formed on its outer surface machining the fins. This method of production out of the finned tube and the outer tube fin from base is an organic whole, and thus there is no loss of contact resistance
Three roll rolling overall type spiral finned tubes
Loss problems, a higher heat transfer efficiency. Three roll rolling method and welding method, compared to the production line with the production of high efficiency, low consumption of raw materials and the production of finned tube heat exchanger rate advantages.
Currently three roll rolling Integral finned tube technology has been successfully applied to the fin as copper, aluminum or composite single finned tubes finned tube, low-finned tube or steel; steel finned tubes present overall common on the market for the lower finned tube, the overall high-fin tube of its material is aluminum, copper, etc., are generally cold forming.
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Classification of finned tubes
Many different types of finned tubes, but also emerging new varieties. Generally be classified according to the following aspects:
1, according to classification process
1), rolling and forming finned tube (extruded fin tube);
2), welded finned tubes (high frequency welded finned tubes, submerged arc welding finned tube);
3), roll forming finned tube;
4), suits forming finned tube;
5), casting finned tube;
6), the tension wound finned tubes;
7), veneer tube.
Press the fin shape classification
1), square finned tube (Square finned tube);
2), the circular finned tube;
3), spiral finned tube (spiral finned tube);
4), the vertical fin tube (Longitudinal Finned Tube)
5), the corrugated fin tube;
6), serrated spiral finned tubes (Helical Serrated Finned Tubes);
7), needle finned tube;
8), the overall plate finned tube (plate-fin);
9), the inner fin tube (inner finned tube). And so on.
3, according to whether the material finned tubes finned tube material with the same group can be divided into:
1), a single metal finned tube
2), bi-metal composite finned tube
Single metal finned tube according to material classification
1), copper finned tube;
2), aluminum finned tube;
3), carbon steel finned tube;
4), stainless steel finned tube;
5), iron (steel) finned tube; etc.
By Application
1), air conditioning finned tube;
2), air-cooled with finned tubes;
3), Boilers: water wall, economizer, air preheater, respectively, using finned tubes;
4), industrial waste heat recovery with finned tubes;
5), other special purpose finned tubes; etc.
Key Words: Finned Tube, Fin Tubes, Tubos Aletados, Square finned tube
