Computational analysis of heat transfer augmentation and thermodynamic irreversibility of hybrid nanofluids in a tube fitted with classical and elliptical-cut twisted tape inserts

Khfagi, A. M., Hunt, G. , Paul, M. C. and Karimi, N. (2022) Computational analysis of heat transfer augmentation and thermodynamic irreversibility of hybrid nanofluids in a tube fitted with classical and elliptical-cut twisted tape inserts. Journal of Thermal Analysis and Calorimetry, 147(21), pp. 12093-12110. (doi: 10.1007/s10973-022-11418-0)

Abstract

This work investigates heat transfer and entropy generation of a turbulent flow of an Al2O3–Cu/water hybrid nanofluid in a plain tube (PT) with classical (TPT) and elliptical‑cut twisted tape (TECT) inserts. The heat transfer and pressure drop are investigated numerically at Re (7000–15,000), mass concentration (1–4%), and the inlet temperature of the fluid (300 K). Further, the total entropy generation and Bejan number are examined at Re = 7000 and a mass concentration of 4%. The obtained results indicate that heat transfer can be intensified when inserting classical and elliptical‑cut twisted tape. In addition, an increase in the thermal conductivity of the fluid may cause a slight increase in the heat transfer coefficient. Moreover, heat transfer and thermal performance factors increase when the mass concentration of nanoparticles increases. The Nusselt numbers for TECT and TPT are 1.7 and 1.57 times higher than those for PT, respectively. The Nusselt number and thermal performance factor of hybrid nanofluid are greatest at roughly 195 and 1.9, respectively, showing 3.9% and 7.73% improvement compared to CuO/water nanofluid at Re = 7000. The analysis of the generation of entropy is expressed as a function of thermal and frictional contributions. The results indicate the existence of a minimum entropy generation for each type of tubes for Al2O3–Cu/water hybrid nanofluid. Total entropy generation analysis demonstrates that thermal entropy generation dominates at high heat flux. Moreover, increasing the nanoparticles decreases the generation of total entropy, which is ascribed to the thermal conductivity increment. In addition, the rate of total entropy generation declines as the vortex flow increases.

• Item Type: Articles
• Additional Information: The first author would like to thank the Libyan Ministry of Higher Education and Scientific Studies for financing his PhD research at the University of Glasgow.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Paul, Professor Manosh and Hunt, Dr Graeme and Karimi, Dr Nader and KHFAGI, Amir Mohamed Ibrahim
• Authors: Khfagi, A. M., Hunt, G., Paul, M. C., and Karimi, N.
• College/School: College of Science and Engineering > School of Engineering; College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: Journal of Thermal Analysis and Calorimetry
• Publisher: Springer
• ISSN: 1388-6150
• ISSN (Online): 1588-2926
• Published Online: 21 June 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Journal of Thermal Analysis and Calorimetry 147(21): 12093-12110
• Publisher Policy: Reproduced under a Creative Commons License