Document Type : Research Paper


1 mechanical department , university of technology

2 University of Technology-Iraq


This paper presents an experimental and numerical study to investigate the heat transfer enhancement in a horizontal circular tube using hybrid nanofluid (CuO, Al₂O₃/ distilled water) and fitted with twisted tape (typical twisted tape, with twist ratios (TR=9.2). Under fully developed turbulent flow and uniform heat flux conditions, the studied hybrid nanofluid concentrations are (=0.6, 1.22, and 1.8% by volume). The experimental test rig includes all the required instruments to study the heat transfer enhancement. All the tests were carried out with a Reynolds number range of 3560-8320 and uniform heat flux (13217.5 W/m². The twisted tape, manufactured from polylactic acid (PLA) by 3-dimensional printer technology, was inserted inside the tube. In this numerical study, the finite volume method (CFD) procedure was employed to pattern the forced convection turbulent flow through the tube. For hybrid nanofluid with twisted, the maximum enhancement in the maximum thermal performance factor was 2.18 for φ = 1.8%, while for a tube (water with twisted) under the same conditions, it was (2.04). A high Nusselt number was obtained with a concentration of 1.8% and an enhancement in the heat transfer of about 6.70%) than water.

Graphical Abstract


  • Hybrid nanofluid in a tube with a typical inserted twisted tape has been investigated experimentally and numerically.
  • The most important basic dimensionless parameters, including Reynolds number, Nusselt number, and Friction factor, have been studied.
  • The results proved that there is a noticeable improvement in heat transfer in the presence of a typical inserted twisted tape.


Main Subjects

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