Finned Tubes

Shanghai ShengQiu has exported finned tubes successfully and the following table shows the details of these finned tubes:

Tube Size: 25MM x 2.5MM x 9000MM

Tube Material: SB163 N04400

Fin Material: AL99.5

Fin OD: 58MM

Fin Thickness: 0.4MM

Fins/Meter: 400PCS/Meter

Fin Pitch: 2.5MM

Fin Type: Embedded G

 

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Finned tubes are the main components of heat exchangers. They are a series of tubes where fins have been added on the outside to increase the contact area with the outside fluid, to exchange heat and between the fluid inside the tube and the fluid outside the tube. Finned tubes are elongated aluminium cladded carbon steel flat tubes with brazed aluminium fins.

 

Why use finned tubes?

Finned tubes are used in applications involving the transfer of heat from a hot fluid to a colder fluid through a tube wall. The rate at which such heat transfer can occur depends on three factors: (1) the temperature difference between the two fluids; (2) the heat transfer coefficient between each of the fluids and the tube wall; and (3) the surface area to which each fluid is exposed. In the case of a bare (unfinned) tubes, where the outside surface area is not significantly greater than the inside surface area, the fluid with the lowest heat transfer coefficient will dictate the overall heat transfer rate. When the heat transfer coefficient of the fluid inside the tube is several times larger than that of fluid outside the tube (for example steam inside and oil outside), the overall heat transfer rate can be greatly improved by increasing the outside surface of the tube. In mathematical terms, the product of heat transfer coefficient for the outside fluid multiplied by the outside surface area is made to more closely match the product of the inside fluid heat transfer coefficient multiplied by the inside surface area.

 

So the whole concept of finned tubes is to increase the outside surface area of the tube. As an example, a finned tube configuration of 2” (nominal, 2.375” actual) pipe with a ¾” high welded helical solid fin of 12 gauge thickness with 6 fins per inch has an outside surface area of 8.23 sq. ft. per linear foot; whereas the same bare pipe has an outside surface area of only .62 sq. ft. per linear foot. That is a 13X increase in outside surface area. See Design Information for extensive tables of surface areas and fin weights.

 

Typical Applications

Typical examples of applications where finned tubes are used include the following:

·         A wide variety of economizers and waste heat recovery units to utilize heat from boiler flue gas, gas turbine exhaust, incinerators, etc.

·         Glycol dehydration units

·         Fired heaters, such as LNG vaporizers, air pre-heaters, oil heaters, etc.

·         Asphalt tank heaters

·         Air coolers, such as compressor jacket water and lube oil coolers

·         Lumber drying kilns, and similar applications

·         Livestock enclosure and greenhouse heaters