When it comes to improving the efficiency of heat exchangers, few technologies have stood the test of time like the twisted tape insert. This simple device has been enhancing heat transfer performance for more than a century. From its beginnings in steam boilers to its modern use in advanced energy systems.

The first known use of twisted tapes dates back to 1896, when Whitham conducted one of the earliest documented experiments using twisted inserts in a 74.6 kW boiler. with fuel savings of up to 18% under peak operation.

Over fifty years later, in the mid-20th century, Kirov reported on the concept with savings of 7–10%, depending on the twist ratio used. Around the same era, the first U.S. patent for a twisted tape was issued for improving gas-side heat transfer in waste heat recovery systems to J. Kemnal in 1930.

In the 1960s. As the nuclear power industry rapidly expanded, Researchers found that twisted tapes could dramatically enhance liquid-phase and two-phase flows as well. In particular, they help increase the critical heat flux (CHF) in boiling water by up to 100%, delaying the onset of dryout and improving safety margins.

By the 1970s, there were studies on laminar and viscous fluid flows, including non-Newtonian fluids like polymer solutions and process oils. In these applications, twisted tapes often performed even better than in turbulent flow, making them a valuable tool in chemical processing and other viscous media industries. Around the same time, they began their adoption into refrigeration and condenser systems.

As researchers explored ways to balance performance and pressure drop, numerous variations emerged:

• Short inlet inserts to generate swirl near the tube entrance

• Intermittent tapes spaced along the tube to renew swirl flow while reducing drag

• Perforated or bent-strip designs to fine-tune performance

• Compound systems combining twisted tapes with other enhancement methods

These refinements maintained or improved heat transfer while minimizing the energy cost of increased flow resistance.

With the rise of computer modeling in the late 20th century, researchers began simulating swirl-flow heat transfer. These studies confirmed what experiments had shown for decades; that twisted tapes work by continuously mixing the fluid near the tube wall, preventing thermal stagnation and improving overall performance.

Today, twisted tapes remain relevant across a wide range of industries:

• Process heat exchangers handling viscous or non-Newtonian fluids

• Refrigeration and cryogenic systems requiring precise temperature control

• Waste heat recovery systems for high-temperature gases

Despite their simplicity, twisted tapes continue to find new applications thanks to their low cost, manufacturability, and versatility.

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Manglik, Raj M., and Arthur E. Bergles. “Swirl Flow Heat Transfer and Pressure Drop with Twisted-Tape Inserts.” Advances in Heat Transfer, vol. 36, Elsevier Science, 2002, pp. 183–266.