Thermal and Rheological Analysis of Elliptical Ducts and non-Newtonian Nanofluids in Heat Exchanger Applications

Articles in Press

Document Type : Full Length Research Article

Authors

1 Laboratory of Physical Engineering of Hydrocarbons, Faculty of Hydrocarbons and Chemistry, University M'hamed Bougara of Boumerdes, 35000, Boumerdes, Algeria

2 Laboratory of Energy and Mechanical Engineering (LEMI), Faculty of Technology, University M’Hamed Bougara of Boumerdes, 35000, Boumerdes, Algeria

3 c Laboratory of Mechanical and Materials Development, LDMM, University of Djelfa, Djelfa 17000, Algeria

Abstract

This study numerically investigates the thermal and rheological performance of a double-pipe heat exchanger (DPHE) with an inner elliptical duct (with an aspect ratio of 0.25) using non-Newtonian nanofluids comprising multi-walled carbon nanotubes (MWCNTs) dispersed in water, stabilized with 0.2 wt.% cationic chitosan. Employing the finite volume method, we demonstrate that elliptical ducts significantly enhance heat transfer compared to circular tubes, increasing the number of transfer units (NTU) by up to 25% and effectiveness by 17%. The incorporation of MWCNTs further improves heat transfer by enhancing thermal conductivity, achieving up to 30% increase in NTU and 20% in effectiveness. Despite higher pressure losses in elliptical ducts, the shear-thinning behavior of the nanofluids mitigates these losses at higher flow rates, reducing pumping power requirements. These findings highlight the potential of combining elliptical ducts and non-Newtonian nanofluids to optimize DPHE efficiency, offering significant implications for energy-efficient heat exchanger designs in industrial applications.

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Main Subjects

Journal of Heat and Mass Transfer Research

Articles in Press, Accepted Manuscript
Available Online from 16 August 2025

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History

  • Receive Date: 18 April 2025
  • Revise Date: 19 July 2025
  • Accept Date: 16 August 2025

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