IDEAS home Printed from https://ideas.repec.org/a/gam/jeners/v18y2025i2p293-d1564500.html
   My bibliography  Save this article

Heat Transfer in U-Tubes: Simulating the Performance of Delta Winglet Pairs in Laminar and Turbulent Flows

Author

Listed:
  • Fotis Naoumis

    (Department of Mechanical Engineering and Aeronautics, University of Patras, 26504 Patras, Greece)

  • Harris Linardos

    (Department of Mechanical Engineering and Aeronautics, University of Patras, 26504 Patras, Greece)

  • Giouli Mihalakakou

    (Department of Mechanical Engineering and Aeronautics, University of Patras, 26504 Patras, Greece)

  • John A. Paravantis

    (Department of International and European Studies, University of Piraeus, 18534 Piraeus, Greece)

  • Vassilis Kostopoulos

    (Department of Mechanical Engineering and Aeronautics, University of Patras, 26504 Patras, Greece)

Abstract

As the environmental crisis intensifies, the demand for energy-efficient systems has never been greater. Vortex generators have emerged as an effective method for enhancing heat transfer within tubes. While extensive research has been conducted on their application in straight tubes, studies focusing on their performance in curved tubes remain limited. This simulation study examined three different arrangements of triangular vortex generators in a common flow-down configuration within a U-turn tube to optimize heat transfer. The analysis conducted under constant wall temperature conditions across a range of Reynolds numbers spans both laminar and turbulent flow regimes to evaluate the broader impacts of vortex generators on flow and thermal fields. The efficiency of each arrangement was evaluated based on the Nusselt number and friction factor. Results show a remarkable increase in the Nusselt number, reaching up to 115% for the configuration with the highest number of vortex generators. However, this enhancement was accompanied by a significant increase in the friction factor, rising by up to 383% at higher Reynolds numbers. Overall, vortex generators demonstrated their highest effectiveness in curved tubes during the laminar-to-turbulent flow transition. In fully turbulent flow, the friction factor increased disproportionately to the modest gains in heat transfer. Despite these limitations, the use of vortex generators in curved tubes offers promising efficiency improvements and merits further exploration.

Suggested Citation

  • Fotis Naoumis & Harris Linardos & Giouli Mihalakakou & John A. Paravantis & Vassilis Kostopoulos, 2025. "Heat Transfer in U-Tubes: Simulating the Performance of Delta Winglet Pairs in Laminar and Turbulent Flows," Energies, MDPI, vol. 18(2), pages 1-18, January.
  • Handle: RePEc:gam:jeners:v:18:y:2025:i:2:p:293-:d:1564500
    as

    Download full text from publisher

    File URL: https://www.mdpi.com/1996-1073/18/2/293/pdf
    Download Restriction: no

    File URL: https://www.mdpi.com/1996-1073/18/2/293/
    Download Restriction: no
    ---><---

    Corrections

    All material on this site has been provided by the respective publishers and authors. You can help correct errors and omissions. When requesting a correction, please mention this item's handle: RePEc:gam:jeners:v:18:y:2025:i:2:p:293-:d:1564500. See general information about how to correct material in RePEc.

    If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.

    We have no bibliographic references for this item. You can help adding them by using this form .

    If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your RePEc Author Service profile, as there may be some citations waiting for confirmation.

    For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: MDPI Indexing Manager (email available below). General contact details of provider: https://www.mdpi.com .

    Please note that corrections may take a couple of weeks to filter through the various RePEc services.

    IDEAS is a RePEc service. RePEc uses bibliographic data supplied by the respective publishers.