Entropy generation and thermohydraulics of mixed convection of hybrid-nanofluid in a vertical tube fitted with elliptical cut twisted tape inserts - A computational study

Khfagi, A. M., Hunt, G. , Paul, M. C. and Karimi, N. (2023) Entropy generation and thermohydraulics of mixed convection of hybrid-nanofluid in a vertical tube fitted with elliptical cut twisted tape inserts - A computational study. Energy Sources Part A: Recovery, Utilization, and Environmental Effects, 45(2), pp. 3369-3391. (doi: 10.1080/15567036.2023.2194855)

Abstract

A numerical investigation is carried out to study the mixed convection of Al2O3-Cu/water hybrid-nanofluid in a vertical tube fitted with elliptical-cut twisted tape inserts (TECT). Thermodynamic irreversibilities are evaluated by calculating the Bejan number, as well as the system’s local and total entropy generation. Heat transfer, friction factor, thermal performance factor, and entropy generation analyses are conducted for a range of volumetric concentrations of nanoparticles and flow Reynolds numbers between 7000 and 15,000. The realizable k-ε model is employed to simulate the turbulent and heat transferring flow computationally. The results clearly demonstrate the influence of mixed convection on heat transfer and entropy generation. In particular, mixed convection simulations predict greater Nusselt number, friction factor, and thermal performance factor than the corresponding forced convection simulations. Further, it is shown that the Nusselt number and the thermal performance factor for mixed convection are 4.6% and 5.5% higher than those for forced convection, respectively. The results also reveal that at Reynolds numbers of 7000, 9000, and 11,000, the thermal entropy production dominates the total irreversibility of the system. Likewise, frictional entropy production is the dominant mode of total irreversibility in the system at high Reynolds numbers of 13,000 and 15,000.

• Item Type: Articles
• Additional Information: The work was supported by the Ministry of Higher Education and Scientific Research in Libya.
• Keywords: Entropy generation, Bejan number, heat transfer augmentation, turbulent mixed convection, hybrid nanofluids.
• 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: Energy Sources Part A: Recovery, Utilization, and Environmental Effects
• Publisher: Taylor and Francis
• ISSN: 1556-7036
• ISSN (Online): 1556-7230
• Published Online: 09 April 2023
• Copyright Holders: Copyright © 2023 Taylor & Francis
• First Published: First published in Energy Sources Part A: Recovery, Utilization, and Environmental Effects 45(2):3369-3391
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher