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
ISSN: 0961-5539
Article publication date: 15 August 2019
Issue publication date: 15 January 2020
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