Thermal performance of combined annular and longitudinal fins-on-tube units in natural convection

Date

2025-05-15

Author

Salamatbakhsh, Elyas
Bayer, Özgür

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To enhance heat transfer in natural convection, annular and longitudinal fins have extensive usage in the industry and have been vastly studied in the literature. The current study investigates horizontal tubes with novel combined annular and longitudinal fin design which aims to enhance mixing and heat transfer by deflecting the airflow. Five test pieces are manufactured and the effects of annular fin spacing and longitudinal fin inclination angle on thermal performance are investigated at base-to-ambient temperature difference between 20 and 100°C. With experimental data validating the numerical simulations, the performance of the proposed design in single and array configurations is numerically investigated. For the single configuration, the addition of the longitudinal fin has a negligible effect on the best fin spacing for maximum heat transfer. The highest heat transfer is achieved when the annular fin spacing is 7.14 mm and the longitudinal fin inclination angle is 90° and the heat transfer consistently decreases as the longitudinal fin is displaced from the vertical position. In the array configuration, the maximum heat transfer is achieved when all longitudinal fins in the array are parallel with an inclination angle of 60°. In an array with 2 rows, the units with a fin spacing of 7.14 mm, longitudinal fin inclination angles of 60°, with the best longitudinal and transverse distances between the tubes achieve a 50% higher Nusselt number compared to the design without longitudinal fins, and this enhancement rises to 67% in a 5-row configuration.

Subject Keywords

Annular and longitudinal fins, CFD, Heat exchanger, Heat transfer, Natural convection

URI

https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85216928280&origin=inward
https://hdl.handle.net/11511/113653

Collections

Department of Mechanical Engineering, Article