Twisted tube
   Twisted tube is a kind of enhanced heat transfer tubes that firstly presented by Swedish Alards Company, and then improved by the USAâ Koch Heat Transfer Company, LP.
Fig. Structure of twisted tube | Fig. Twisted tube with carbon steel, stainless steel, copper |
Structure and manufacture of twisted tube   The structure feature of twisted tube is that every cross section is an oval, when when assembled into heat exchangers they exchanger they can be mixed bundles (that is, the mix of twisted tubes and bare tubes), and also can be a pure twisted tube bundle.   The manufacturing process of twisted tube includes:"partial pressure" and "distortion". The tubeâs cross section is nearly an ellipse, of which the ratio of long axis and short axis is designed according to the flow velocity in tubes passes and shell passes of heat transfer tubes. When the flow rate in tube pass is low, the ratio of the long axis and short axis shall be increased, or the flow surface shall be reduced in order to increase the flow rate.
Enhanced heat transfer principles of twisted tube   The unique structure of twisted tube can make the flow in tube pass and shell pass in the spiral motion at the same time, by this way it enhanced the turbulent intensity. The heat transfer coefficient of the twisted tube is 40% higher than the normal one, but the pressure drop is almost the same.
Advantages of heat transfer with twisted tube
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Fig.  Stereogram of the twisted tube (Stainless steel) | Fig.  Stereogram of the twisted tube (Carbon steel) | Fig. Stereogram of the twisted tube (Cooper) |
   Seamless steel twisted tubes used for producing heat exchangers are complete ones without joints. Common materials used in steel tubes shows in bellow chartã
Fig. Twisted tubes produced by our company | Fig. Twisted tubes produced by our company | Fig. Twisted tubes produced by our company |