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Assessing the flow characteristics of nanofluids during turbulent natural convection

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Title: Assessing the flow characteristics of nanofluids during turbulent natural convection
Authors: Kouloulias, K
Sergis, A
Hardalupas, I
Item Type: Journal Article
Abstract: High-performance cooling is of vital importance for the cutting-edge technology of today, from nanoelectronic mechanical systems to nuclear reactors. Advances in nanotechnology have allowed the development of a new category of coolants, termed nanofluids that have the potential to enhance the thermal performance of conventional heat transfer fluids. At the present time, nanofluids are a controversial research theme, since there is yet no conclusive answer to explain the underlying physical mechanisms of heat transfer. The current study investigates experimentally the heat and mass transfer behaviour of dilute Al2O3–H2O nanofluids under turbulent natural convection—Rayleigh number of the order of 109—in a cubic Rayleigh–Bénard cell with optical access. Traditional heat transfer measurements were combined with a velocimetry method to obtain a deeper understanding of the impact of nanoparticles on the heat transfer performance of the base fluid. Particle image velocimetry was employed to quantify the resulting mean velocity field and flow structures in dilute nanofluids under natural convection, at three parallel planes inside the cubic cell. All the results were compared with that for the base fluid, i.e. deionised water. It was observed that the presence of a minute amount of Al2O3 nanoparticles in deionised water, φv = 0.00026 vol.%, considerably modifies the mass transfer behaviour of the fluid in the bulk region of turbulent Rayleigh–Bénard convection. Simultaneously, the general heat transport, as expressed by the Nusselt number, remained unaffected within the experimental uncertainty.
Issue Date: 30-Mar-2019
Date of Acceptance: 2-Aug-2018
URI: http://hdl.handle.net/10044/1/62962
DOI: 10.1007/s10973-018-7631-y
ISSN: 1388-6150
Publisher: Akadémiai Kiadó
Start Page: 3181
End Page: 3189
Journal / Book Title: Journal of Thermal Analysis and Calorimetry: an international forum for thermal studies
Volume: 135
Issue: 6
Copyright Statement: © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Sponsor/Funder: Commission of the European Communities
Funder's Grant Number: 3000205116 (GA633053)
Keywords: Science & Technology
Physical Sciences
Chemistry, Analytical
Chemistry, Physical
Turbulent natural convection
Particle image velocimetry
Large-scale circulation
Physical Chemistry
0303 Macromolecular and Materials Chemistry
0306 Physical Chemistry (incl. Structural)
0399 Other Chemical Sciences
Publication Status: Published
Online Publication Date: 2018-08-14
Appears in Collections:Mechanical Engineering
Faculty of Natural Sciences
Faculty of Engineering