https://doi.org/10.1140/epjp/s13360-026-07604-w
Regular Article
Numerical study on heat transfer and flow characteristics of nanofluids in twisted elliptical tubes at low Reynolds numbers
College of Petrochemical Engineering, Lanzhou University of Technology, 730050, Lanzhou, China
a
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Received:
24
January
2026
Accepted:
21
March
2026
Published online:
7
April
2026
Abstract
Efficient heat transfer at low Reynolds numbers is a critical requirement in various engineering applications, making the development of passive enhancement techniques highly valuable. This study numerically investigates passive heat transfer enhancement using nanofluids in twisted elliptical tubes within the Reynolds number range of 600–2000. Under constant heat flux conditions, the results indicate that twisted tubes significantly enhance secondary flow and radial mixing, thereby increasing the Nusselt number compared to straight elliptical tubes. The Performance Evaluation Criterion (PEC) confirms an overall thermo-hydraulic improvement, with the optimal geometry (aspect ratio 1.78, pitch 100 mm) achieving a PEC of 1.49 at a Reynolds number of 2000. Among the tested nanofluids, the graphite nanofluid demonstrates superior performance under the mixture model. The synergistic application of twisted elliptical tubes and graphite nanofluids offers an effective passive strategy for designing efficient compact heat exchangers in low-velocity thermal systems.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2026
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
