What is it about?
Heat exchangers are widely used in energy systems, industrial processes and thermal management applications. Improving their ability to transfer heat can make these systems more effective, but design changes that enhance heat transfer may also increase the resistance to fluid flow. This study experimentally investigates a method that combines magnetic fields, iron oxide (Fe₃O₄) nanoparticles and a specially designed corrugated tube to improve heat transfer. The researchers examined water-based ferrofluids flowing under laminar conditions through two types of tubes: a conventional plain tube and an eight-start spirally corrugated tube. The effects of nanoparticle concentration and a localized transverse magnetic field were evaluated. Under the most intensified operating condition, using a 3.0% Fe₃O₄ mass fraction and a magnetic field strength of 200 mT, the combined enhancement strategy increased the Nusselt number by up to 73.69% in the plain tube and 151.30% in the corrugated tube. The study also considered the additional flow resistance associated with heat transfer enhancement. The maximum performance evaluation criteria (PEC) values reached 1.69 for the plain tube and 1.74 for the corrugated tube. These findings demonstrate the potential of combining magnetic control and corrugated tube geometry to improve the thermo-hydraulic performance of heat exchangers.
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Why is it important?
Enhancing heat transfer without imposing an excessive frictional penalty is a major challenge in heat exchanger design. This study explores a combined approach using magnetically controlled Fe₃O₄ ferrofluid and an eight-start spirally corrugated tube. Its experimental results show that the combined strategy can substantially increase heat transfer, with a maximum Nusselt number enhancement of 151.30% in the corrugated tube under the most intensified operating condition. Importantly, the performance evaluation criteria also account for the trade-off between heat transfer improvement and flow resistance. The results provide experimental insight into how magnetic fields, nanoparticle concentration and tube geometry can work together to improve thermo-hydraulic performance. This approach may inform the development of more effective heat exchangers for thermal engineering applications.
Perspectives
From my perspective, one of the most interesting aspects of this research is the combination of magnetic field control and modified tube geometry to enhance heat transfer. Improving heat transfer alone is not sufficient when designing practical heat exchangers; the accompanying frictional penalty must also be considered. I believe that evaluating both effects through thermo-hydraulic performance criteria provides a more meaningful understanding of the system. The experimental findings highlight the potential of ferrofluids and magnetic control as complementary approaches to heat transfer enhancement. I hope this work encourages further investigations into magnetically responsive fluids, advanced heat exchanger geometries and their practical applications in energy systems.
Assoc Prof Selcuk Selimli
Karabuk Universitesi
Read the Original
This page is a summary of: Magnetically controlled ferrofluid flow in an eight-start corrugated tube: experimental assessment of coupled heat transfer enhancement and frictional penalty, Experimental Heat Transfer, April 2026, Taylor & Francis,
DOI: 10.1080/08916152.2026.2649735.
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