Twisted tube

History

 

Twisted tube was initiated by technicians of the Soviet Union in 1980s, but it was Alards company in Sweden and Brown Fintube company in US who put into industrial practice and developed heat exchanger with it. Twisted tube is made from straight tube by rolling and twisting process in defined helical pitch, so its cross section is similar to oval shape and flow pass is in helical arrangement. During movement, fluid changes flow speed and direction periodically, this could improve radical mixing of material and destroy thermal boundary layer to enhance heat transfer.

 

Specification

 

In different cases, the value of B/A, St, St/d can be customized for optimization. When flow rate is relatively low inside twisted tube, B/A value can be reduced to increase flow speed. Normally, the best range of B/A falls into 0.5-0.7. For St/d, it is 6-12.

 

Material

 

Applicable materials for fabrication of twisted tape include carbon steel, stainless steel, titanium, nickel, copper, Monel alloy, etc.

 

Advantages

 

• Both fluids in shell and tube pass is in spiral movement, turbulent flow increases thermal efficiency, and makes it more difficult to form fouling on tubes. Compared with straight tube, twisted tube is nearly 40% better.
• Higher heat transfer surface without increase in size of heat exchanger.
• Twisted tube bundles adopts adjacent support. No need for baffles, less pressure drop. Flow-induced vibration is eliminated.
• Obvious advantages when temperature difference between two fluids is low.

 

Application

 

Heat exchanger made of twisted tube could be used for gas/liquid heat transfer, and gets widely used in industries like oil, gas, chemical, food, power, metallurgy, mining, etc.