为什么锅炉使用翅片管?

Finned tubes are used in applications involving the transfer of heat from a hot fluid to a colder fluid through a tube wall.


Finned Tube Heat Exchangers

The rate at which such heat transfer can occur depends on three factors:

In the case of a bare (un-finned) 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.

“The whole concept of finned tubes is to increase the outside surface area of the tube.”
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.

通过增加管的外表面区域,总传热速率增加,从而减少了给定应用所需的总管数。这降低了整体设备尺寸和项目的成本。在许多情况下,一个翅片管取代了六个或更多个裸管,其成本低于1/3,并且体积。

翅片管热交换器是一种热交换器设计,其目的是使用板和翅片室以在流体之间传递热量。它被重复分类为紧凑的热交换器,以强调其相对高的传热表面积到体积比。

Advantages :

Fins can have a variety of shapes. For example, they can be pin fins protruding from a surface (as just described), or annular fins around a tube used to enhance heat flow into or out of the fluid flowing through the tube. The figure below illustrates such a fin.

If fins are attached to a wall with a metallurgical or adhesive joint, a significant thermal contact resistance may exist at the interface. This can be accounted for by a fin correction factor, discussed in a later section on the overall heat transfer coefficient.

接下来,我们将分析平行流动热交换器,用于稳态流动。稳态流是稳定操作条件和温度的有效假设。

Recommended finned tubes

Expansion joints are used in all kinds of different sectors and in a huge range of different industrial contexts. Essentially, wherever there is a need to control pipework movement expansion joints are required.

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