Choosing the Right Twisted Tape Turbulator for Heat Transfer Enhancement
In heat exchanger design, performance is often a balancing act. You want higher heat transfer rates to make the most of your energy, but you also want to avoid a steep penalty in pressure drop. Passive heat transfer methods that require no extra power offer a sweet spot, and one of the most popular options is the twisted tape turbulator.
But not all twisted tapes are created equal. Subtle changes in geometry can change how a turbulator performs. A comparative study from Ege University put different designs to the test under the same conditions, giving us a clear picture of their strengths, weaknesses, and ideal applications.
In this article, we’ll focus on four designs:
Twin counter twisted tapes
Twin co-twisted tapes
Coiled wire inserts
Standard twisted tape turbulators
Twin Counter Twisted Tapes (CTs)
Twin counter twisted tapes feature two tapes inside the tube, twisting in opposite directions to create counter-rotating swirl flows. This design delivered the highest heat transfer rates at higher Reynolds numbers. The opposing swirls create intense mixing, continually bringing fresh fluid into contact with the tube wall.
This is the most flow-resistant option of all those tested. If you operate a high-flow-rate system where maximum heat transfer is the top priority, such as a compact heat exchanger in a space-limited application, CTs can be the best choice, provided your system can handle the extra pumping power required.
Twin Co Twisted Tapes (CoTs)
Twin co twisted tapes have both tapes twisting in the same direction, creating co rotating swirls. They improve heat transfer compared to a plain tube, but not to the same degree as CTs. However, they do have a slightly lower friction factor, meaning less flow resistance.
CoTs are a good fit when you need more performance than a single twisted tape offers but can’t afford the high pressure drop that comes with CTs.
Coiled Wire Inserts
Coiled wire inserts are spiraled wires placed inside the tube, often positioned close to the wall. In testing, they offered the smallest improvement in heat transfer, but also caused the least disruption to flow.
They’re ideal when you want a modest performance boost without significantly increasing pressure drop, making them a good choice for situations where pumping capacity is limited.
Standard Twisted Tapes Turbulators
A standard twisted tape turbulator provides excellent thermal-hydraulic performance and a strong balance between heat transfer improvement and pressure drop. In the study, a clearance ratio of 0.0357 achieved the best overall efficiency.
This is the most versatile option, ideal when you need meaningful heat transfer gains but still want to keep system resistance in check.
Conclusions
The best turbulator for your heat exchanger depends on how much pressure drop your system can tolerate and how much heat transfer improvement you need.
Maximum performance: Twin counter twisted tapes (CTs)
Best balance of performance and resistance: Standard twisted tape turbulators
Lowest disruption: Coiled wire inserts
By understanding the trade-offs, you can select the right turbulator for your application and get the performance you need without overloading your system.
*Gürlek, Gökhan, and Özbalta, Necdet. Investigation of Heat Transfer Augmentation in a Tube with Different Modified Twisted Tape Inserts Under the Same Conditions. Journal of Naval Science and Engineering, Vol. 9, No. 2, 2013, pp. 50–65.