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Three-dimensional modelling of natural convection and entropy generation in a vertical cylinder under heterogeneous heat flux using nanofluids

Iman Rashidi (Department of Mechanical Engineering, Quchan University of Technology, Quchan, Iran)
Lioua Kolsi (Department of Mechanical Engineering, University of Hail College of Engineering, Hail, Saudi Arabia and Laboratoire de Métrologie et des Systèmes Énergétiques, École Nationale d’Ingénieurs, University of Monastir, Monastir, Tunisia)
Goodarz Ahmadi (Department of Mechanical and Aeronautical Engineering, Clarkson University, Potsdam, New York, USA)
Omid Mahian (School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an, China and Department of Mechanical Engineering, Quchan University of Technology, Quchan, Iran)
Somchai Wongwises (Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Lab (FUTURE), Faculty of Engineering, Department of Mechanical Engineering, King Mongkut’s University of Technology Thonburi, Bangmod, Bangkok, Thailand)
E. Abu-Nada (Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates)

International Journal of Numerical Methods for Heat & Fluid Flow

ISSN: 0961-5539

Article publication date: 15 August 2019

Issue publication date: 15 January 2020

151

Abstract

Purpose

This study aims to investigate a three-dimensional computational modelling of free convection of Al2O3 water-based nanofluid in a cylindrical cavity under heterogeneous heat fluxes that can be used as a thermal storage tank.

Design/methodology/approach

Effects of different heat flux boundary conditions on heat transfer and entropy generation were examined and the optimal configuration was identified. The simulation results for nanoparticle (NP) volume fractions up to 4 per cent, and Rayleigh numbers of 104, 105 and 106 were presented.

Findings

The results showed that for low Ra (104) the heat transfer and entropy generation patterns were symmetric, whereas with increasing the Rayleigh number these patterns became asymmetric and more complex. Therefore, despite the symmetric boundary conditions imposed on the periphery of the enclosure (uniform in Ɵ), it was necessary to simulate the problem as three-dimensional instead of two-dimensional. The simulation results showed that by selecting the optimal values of heat flux distribution and NP volume fraction for these systems the energy consumption can be reduced, and consequently, the energy efficiency can be ameliorated.

Originality/value

The results of the present study can be used for the design of energy devices such as thermal storage tanks, as both first and second laws of thermodynamics have been considered. Using the optimal design will reduce energy consumption.

Keywords

Acknowledgements

The first author would like to acknowledge the financial support of the Quchan University of Technology under grant number 9,463.

Citation

Rashidi, I., Kolsi, L., Ahmadi, G., Mahian, O., Wongwises, S. and Abu-Nada, E. (2020), "Three-dimensional modelling of natural convection and entropy generation in a vertical cylinder under heterogeneous heat flux using nanofluids", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 30 No. 1, pp. 119-142. https://doi.org/10.1108/HFF-12-2018-0731

Publisher

:

Emerald Publishing Limited

Copyright © 2019, Emerald Publishing Limited

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