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Forced convection in a double tube heat exchanger using nanofluids with constant and variable thermophysical properties

Mohammad Hussein Bahmani (Department of Mechanical Engineering, University of Kashan, Kashan, Iran)
Omid Ali Akbari (Young Researchers and Elite Club, Khomeinishahr Branch, Islamic Azad University, Khomeinishahr, Iran)
Majid Zarringhalam (Young Researchers and Elite Club, South Tehran Branch, Islamic Azad University, Tehran, Iran)
Gholamreza Ahmadi Sheikh Shabani (Young Researchers and Elite Club, Khomeinishahr Branch, Islamic Azad University, Khomeinishahr, Iran)
Marjan Goodarzi (Sustainable Management of Natural Resources and Environment Research Group, Faculty of Environment and Labour Safety, Ton Duc Thang University, Ho Chi Minh City, Vietnam)

International Journal of Numerical Methods for Heat & Fluid Flow

ISSN: 0961-5539

Article publication date: 29 July 2019

Issue publication date: 22 May 2020

Abstract

Purpose

This paper aims to study forced convection in a double tube heat exchanger using nanofluids with constant and variable thermophysical properties.

Design/methodology/approach

The cold fluid was distilled water flowing in the annulus and the hot fluid was aluminum oxide/water nanofluid which flows in the inner tube. Thermal conductivity and viscosity were taken as variable thermophysical properties, and the results were compared against runs with constant values. Finite volume method was used for solving the governing equations. For distilled water, Re = 500 was used, while for nanofluid, nanoparticles volume fraction equal to 2.5-10 per cent and Re = 100-1,500 were used.

Findings

Heat transfer rate can be enhanced by increasing the volume fraction of nanoparticles and Reynolds number. Thermal efficiency is better with constant thermophysical characteristics and the average Nusselt number is better for variable characteristics.

Originality/value

Heat exchanger efficiency is evaluated by using distilled water and nanofluid bulk temperature, thermal efficiency and average and local Nusselt numbers for both variable and constant thermophysical characteristics.

Keywords

Acknowledgements

Conflicts of interest: The authors declare that there is no conflict of interest regarding the publication of this paper.

Citation

Bahmani, M.H., Akbari, O.A., Zarringhalam, M., Ahmadi Sheikh Shabani, G. and Goodarzi, M. (2020), "Forced convection in a double tube heat exchanger using nanofluids with constant and variable thermophysical properties", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 30 No. 6, pp. 3247-3265. https://doi.org/10.1108/HFF-01-2019-0017

Publisher

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Emerald Publishing Limited

Copyright © 2019, Emerald Publishing Limited