The Impact of Varying Width Twisted Tape Inserts

Heat transfer plays a vital role in industries like power generation, refrigeration, air conditioning, and chemical processing. The efficiency of this process directly impacts energy consumption, operational costs, and overall system performance. One innovative technique for improving heat transfer efficiency is the use of twisted tape inserts. In this post, we’ll explore how varying the width of twisted tape inserts can enhance heat transfer in turbulent flow systems, reduce material costs, and balance pressure drops.

What are Twisted Tape Inserts?

Twisted tape inserts are metal strips twisted along their length and inserted into heat exchanger tubes. These inserts generate turbulence in the fluid flow, enhancing the heat transfer process by mixing the fluid more effectively and increasing the contact time between the fluid and the heated or cooled surfaces.

The swirling motion created by the twisted tape increases flow turbulence, which helps the fluid mix more thoroughly and makes the heat transfer more efficient. But how do different tape widths and twist ratios affect this process?

Experimenting with Different Tape Widths

A study examined the effect of using varying width twisted tape inserts in a horizontal tube with an inside diameter of 27.5 mm. The experiment tested full-width tapes (26 mm wide) alongside reduced-width tapes of 22 mm, 18 mm, 14 mm, and 10 mm. Each width was also evaluated using three different twist ratios (the ratio of the tape’s pitch to its width): 3, 4, and 5. The objective was to see how these variables impacted both heat transfer and pressure drop, while also considering material savings.

Key Findings

1. Heat Transfer Enhancement

The study revealed that twisted tape inserts significantly improved heat transfer compared to a plain tube with a twist ratio of 3. Full-width (26 mm) tapes produced the highest heat transfer enhancement, Reduced-width tapes also showed notable improvements, with heat transfer increases ranging from:

  • 58% to 70% for 26 mm tapes,

  • 33% to 39% for 22 mm tapes,

  • 24% to 34% for 18 mm tapes,

  • 16% to 31% for 14 mm tapes,

  • 11% to 22% for 10 mm tapes.

The swirling motion induced by the twisted tapes was the primary factor driving these improvements. The narrower tapes, though slightly less effective than the full-width versions, still enhanced heat transfer significantly and offered other benefits.

2. Pressure Drop and Friction

While increasing turbulence improves heat transfer, it also tends to cause higher pressure drops, which can increase energy consumption. The study found that reduced width twisted tapes helped minimize these pressure drops while still delivering solid heat transfer performance. For example, the friction factor increased by 18% f

or full-width (26 mm) tapes, while the friction factor for the narrower 22 mm tapes only rose by 17.3%.

Even narrower tapes—18 mm, 14 mm, and 10 mm—showed further reductions in friction factor, which is advantageous when balancing energy costs and heat transfer performance. The narrower tapes offer a practical solution for industries looking to manage pressure drops without sacrificing heat transfer efficiency.

3. Material Savings

One of the most significant advantages of reduced width twisted tapes is material savings. A 15% - 61% reduction in material was achieved using the range of reduced widths instead of full-width 26 mm tapes, with small reduction in heat transfer Although the heat transfer performance slightly decreased, the overall balance between efficiency and cost may make these options appealing.

The study showed that with 10 mm wide tapes, companies could achieve material savings of up to 61%, while still realizing heat transfer enhancements 11% to 22% better than a plain tube.

Practical Implications

The findings from this study have practical implications for industries seeking to optimize their heat transfer systems. By choosing the appropriate width and twist ratio of twisted tape inserts, it’s possible to achieve significant performance gains while also saving on material and controlling pressure drops.

Benefits of Twisted Tape Inserts with Specific Widths:

  • Full-width (26 mm) tapes: Maximum heat transfer increase of 70%, but with higher pressure drop.

  • Reduced-width (22 mm) tapes: Up to 44% heat transfer increase with lower friction factor and 15% material savings.

  • 18 mm, 14 mm, and 10 mm tapes: Provide additional material savings and reduced pressure drops, with lower specific heat transfer gains over a plain tube.

Conclusion

Twisted tape inserts—whether full-width or reduced-width—are a simple yet highly effective way to enhance heat transfer in turbulent flow systems. By varying the width and twist ratio, industries can optimize their heat exchangers to improve efficiency, minimize pressure drops, and reduce material costs.

Follow the link below to see our offering of twisted tape turbulators

*Sarada, S. N., Sita Rama Raju, A. V., Radha, K. K., & Shyam Sunder, L. (2010). Enhancement of heat transfer using varying width twisted tape inserts. International Journal of Engineering, Science and Technology, 2(6), 107–118