Futuristic heat exchanger with enhanced efficiency tube inserts.

Supercharge Your Chiller: How New Tube Inserts Can Boost Efficiency and Cut Costs

Beau Callahan in Tech & Innovation September 2025 • 4 min read.

"Unlock hidden potential in your absorption chiller with innovative heat transfer enhancements."

For years, engineers have sought ways to improve the efficiency of heat exchangers. The goal? To shrink their size, cut their costs, and boost their overall performance. This pursuit has led to a fascinating array of techniques, broadly categorized as either active or passive methods. Among these, passive techniques—those that don't require external power—have gained considerable traction due to their simplicity and cost-effectiveness.

One particularly promising passive technique involves the insertion of various devices, often called 'tube inserts,' into the flow path of heat exchangers. These inserts, which can range from coiled wires to twisted tapes, work by inducing swirling flow and disrupting the boundary layer, ultimately enhancing heat transfer. While the concept isn't new, ongoing research continues to uncover novel designs and optimize existing ones.

Now, a recent study has explored the impact of new, uniquely designed tube inserts on the performance of single-effect absorption chillers. This technology is promising since it looks at applying passive techniques to chillers to look for real world efficiency.

How Do Tube Inserts Enhance Heat Transfer?

Futuristic heat exchanger with enhanced efficiency tube inserts.

Tube inserts primarily work by creating a swirling flow pattern within the heat exchanger tube. This swirling action promotes better mixing of the fluid, ensuring that the core fluid and the fluid near the wall—which tends to be cooler or less effectively heated—are constantly intermingling. This enhanced mixing leads to a more uniform temperature distribution and a higher overall heat transfer rate.

The study focused on four distinct types of tube inserts:

Wire Coils (S1, S2): Simple coiled wires of varying pitch.
Modified Wire Coils (GS1, GS2, GS5): Wire coils with alterations to their geometry.
Twisted Tape (TW): A classic design involving a twisted strip of metal.
Butterfly Inserts (BT): A novel design featuring butterfly-shaped elements.

Researchers conducted experiments using these inserts in the evaporator of a single-effect absorption chiller, meticulously measuring heat transfer rates and pressure drops across a range of fluid flow rates. The results were compelling: in nearly every scenario, the use of tube inserts led to a significant boost in heat transfer compared to a plain tube without any inserts. However, this enhancement came at the cost of increased pressure drop, a factor that must be carefully considered.

The Future of Chiller Efficiency

This research offers a compelling glimpse into the potential of tube inserts to significantly enhance the efficiency of absorption chillers. While the increased pressure drop is a factor that must be carefully managed, the substantial gains in heat transfer suggest that these technologies could play a crucial role in reducing energy consumption and lowering operating costs in a wide range of applications. Further research and development will undoubtedly focus on optimizing insert designs to maximize heat transfer while minimizing pressure drop, paving the way for even more efficient and sustainable cooling solutions in the future.

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Everything You Need To Know

What are tube inserts, and how do they improve the performance of absorption chillers?

Tube inserts are devices placed within the flow path of heat exchangers, such as those found in single-effect absorption chillers. They enhance heat transfer by creating a swirling flow pattern. This swirling action promotes better mixing of the fluid, leading to a more uniform temperature distribution and a higher overall heat transfer rate within the chiller. The study highlighted the effectiveness of various inserts, including Wire Coils (S1, S2), Modified Wire Coils (GS1, GS2, GS5), Twisted Tape (TW), and Butterfly Inserts (BT), in boosting heat transfer compared to a plain tube, potentially leading to significant energy savings and cost reductions in chiller operations.

What is the difference between active and passive techniques for improving heat exchanger efficiency?

Engineers use various methods to enhance heat exchanger efficiency, broadly categorized as active and passive techniques. Active techniques require external power to function, while passive techniques do not. The focus of the study was on passive techniques, specifically the use of tube inserts. These inserts, like Wire Coils, Modified Wire Coils, Twisted Tape, and Butterfly Inserts, improve heat transfer by modifying the fluid flow without needing any external power source, making them simple and cost-effective solutions for absorption chillers.

What are the main types of tube inserts discussed in the study, and how do they differ?

The study examined four distinct types of tube inserts within the evaporator of a single-effect absorption chiller: Wire Coils (S1, S2), which are simple coiled wires; Modified Wire Coils (GS1, GS2, GS5), which feature alterations to their geometry; Twisted Tape (TW), a classic twisted strip of metal; and Butterfly Inserts (BT), a novel design with butterfly-shaped elements. These inserts vary in design but all aim to enhance heat transfer by inducing a swirling flow pattern, thereby promoting better mixing of the fluid within the heat exchanger.

What are the trade-offs associated with using tube inserts in absorption chillers?

While tube inserts significantly boost heat transfer, leading to potentially reduced energy consumption, they also come with a trade-off: an increase in pressure drop. The research showed that although the inserts, such as Wire Coils, Modified Wire Coils, Twisted Tape, and Butterfly Inserts, enhanced heat transfer rates in the single-effect absorption chiller, they also caused a rise in pressure drop across the system. This means that while the chiller becomes more efficient at transferring heat, the pump must work harder to maintain the necessary flow rate, which could affect overall system efficiency and needs to be carefully managed during design and implementation.

How can future research optimize tube insert designs for absorption chillers?

Future research will likely focus on optimizing tube insert designs to balance heat transfer enhancement with minimizing pressure drop. The study has shown that tube inserts, including Wire Coils, Modified Wire Coils, Twisted Tape, and Butterfly Inserts, can significantly improve the efficiency of single-effect absorption chillers. To maximize the benefits, researchers will need to fine-tune the designs of these inserts to achieve the highest possible heat transfer rates while minimizing the increase in pressure drop. This optimization could involve experimenting with different materials, geometries, and configurations of the inserts to create even more efficient and sustainable cooling solutions.