Synergistic effect of outer helical fins and hybrid nanofluid on hydrothermal performance of shell and two-coil heat exchanger

Heat exchangers are frequently utilized in industrial applications such as power plants, refrigeration, chemical processing, and alternative energy systems. Improving thermal efficiency is critical for reducing energy consumption and ensuring operational sustainability. Conical coil heat exchangers...

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Main Authors: Wajdi Rajhi, Aymen h. Salih, As'ad Alizadeh, Kuwar Mausam, Aashim Dhawan, Rifaqat Ali, Sachin Mittal, Kaouther Ghachem, Walid Aich
Format: Article
Language:English
Published: Elsevier 2025-08-01
Series:Case Studies in Thermal Engineering
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Online Access:http://www.sciencedirect.com/science/article/pii/S2214157X25004988
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author Wajdi Rajhi
Aymen h. Salih
As'ad Alizadeh
Kuwar Mausam
Aashim Dhawan
Rifaqat Ali
Sachin Mittal
Kaouther Ghachem
Walid Aich
author_facet Wajdi Rajhi
Aymen h. Salih
As'ad Alizadeh
Kuwar Mausam
Aashim Dhawan
Rifaqat Ali
Sachin Mittal
Kaouther Ghachem
Walid Aich
author_sort Wajdi Rajhi
collection DOAJ
description Heat exchangers are frequently utilized in industrial applications such as power plants, refrigeration, chemical processing, and alternative energy systems. Improving thermal efficiency is critical for reducing energy consumption and ensuring operational sustainability. Conical coil heat exchangers have gained popularity due to their ability to generate secondary flow effects, which enhance convective heat transfer. However, despite their potential, the optimal coil configuration and nanofluid selection for maximum performance remain unknown. Previous research has primarily focused on traditional straight and helical coil designs, with limited attention paid to the effects of twisted tape inserts and helical fins in conical coil geometries. Furthermore, hybrid nanofluids have emerged as a potential alternative for enhancing heat exchanger efficiency, although their relative effectiveness in various conical coil topologies remains unknown. The thermal performance of a shell-and-conical-coil heat exchanger is investigated numerically in this work using a finite volume model. Three conical coil designs were studied: Case A, which included a twisted tape inside the coil; Case B, which used a twisted tape on the coil body as a helical fin; and Case C, which was a simple cone-shaped coil. The working fluids included hybrid nanofluids composed of (i) single-wall carbon nanotube (SWCNT)-multi-wall carbon nanotube (MWCNT), (ii) aluminium oxide (Al2O3)-titanium dioxide (TiO2), and (iii) molybdenum disulfide (MoS2)-iron oxide (II, III) oxide (Fe3O4), with water as the base fluid. At both low (De = 2550) and high (De = 4200) Dean numbers, Case A outperformed Case B by 14.3 % and 10.5 %, and Case C by 33.3 % and 52.7 %, respectively. The SWCNT-MWCNT/Water nanofluid outperformed Al2O3-TiO2/Water, MoS2-Fe3O4/Water, and pure water by up to 21.9 % and 9.4 %, respectively. It achieved the maximum thermal performance factor for both low and high Dean numbers. These findings demonstrate the efficacy of Case A (coil tube with a twisted tape) and hybrid nanofluids in enhancing heat exchanger performance under various flow conditions, providing valuable insights for future thermal system designs.
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spelling doaj-art-cf62f18ed2844c3da7c4143fd65766132025-08-20T02:28:40ZengElsevierCase Studies in Thermal Engineering2214-157X2025-08-017210623810.1016/j.csite.2025.106238Synergistic effect of outer helical fins and hybrid nanofluid on hydrothermal performance of shell and two-coil heat exchangerWajdi Rajhi0Aymen h. Salih1As'ad Alizadeh2Kuwar Mausam3Aashim Dhawan4Rifaqat Ali5Sachin Mittal6Kaouther Ghachem7Walid Aich8Department of Mechanical Engineering, College of Engineering, University of Ha'il, Ha'il City, Saudi ArabiaAir Conditioning Engineering Department, College of Engineering, University of Warith Al-Anbiyaa, Karbala , IraqDepartment of Civil Engineering, College of Engineering, Cihan University-Erbil, Erbil, Iraq; Corresponding author.Department of Mechanical Engineering, Institute of Engineering and Technology, GLA University, Mathura (U.P.) , IndiaCentre of Research Impact and Outcome, Chitkara University, Rajpura, 140417, Punjab, IndiaDepartment of Mathematics, Applied College in Mohayil Asir, King Khalid University, Abha, Saudi ArabiaChitkara Centre for Research and Development, Chitkara University, Himachal Pradesh, 174103, IndiaDepartment of Industrial and Systems Engineering, College of Engineering, Princess Nourah bint Abdulrahman University, P.O.Box 84428, Riyadh, 11671, Saudi ArabiaDepartment of Mechanical Engineering, College of Engineering, University of Ha'il, Ha'il City, Saudi ArabiaHeat exchangers are frequently utilized in industrial applications such as power plants, refrigeration, chemical processing, and alternative energy systems. Improving thermal efficiency is critical for reducing energy consumption and ensuring operational sustainability. Conical coil heat exchangers have gained popularity due to their ability to generate secondary flow effects, which enhance convective heat transfer. However, despite their potential, the optimal coil configuration and nanofluid selection for maximum performance remain unknown. Previous research has primarily focused on traditional straight and helical coil designs, with limited attention paid to the effects of twisted tape inserts and helical fins in conical coil geometries. Furthermore, hybrid nanofluids have emerged as a potential alternative for enhancing heat exchanger efficiency, although their relative effectiveness in various conical coil topologies remains unknown. The thermal performance of a shell-and-conical-coil heat exchanger is investigated numerically in this work using a finite volume model. Three conical coil designs were studied: Case A, which included a twisted tape inside the coil; Case B, which used a twisted tape on the coil body as a helical fin; and Case C, which was a simple cone-shaped coil. The working fluids included hybrid nanofluids composed of (i) single-wall carbon nanotube (SWCNT)-multi-wall carbon nanotube (MWCNT), (ii) aluminium oxide (Al2O3)-titanium dioxide (TiO2), and (iii) molybdenum disulfide (MoS2)-iron oxide (II, III) oxide (Fe3O4), with water as the base fluid. At both low (De = 2550) and high (De = 4200) Dean numbers, Case A outperformed Case B by 14.3 % and 10.5 %, and Case C by 33.3 % and 52.7 %, respectively. The SWCNT-MWCNT/Water nanofluid outperformed Al2O3-TiO2/Water, MoS2-Fe3O4/Water, and pure water by up to 21.9 % and 9.4 %, respectively. It achieved the maximum thermal performance factor for both low and high Dean numbers. These findings demonstrate the efficacy of Case A (coil tube with a twisted tape) and hybrid nanofluids in enhancing heat exchanger performance under various flow conditions, providing valuable insights for future thermal system designs.http://www.sciencedirect.com/science/article/pii/S2214157X25004988Heat exchangerConical coilTwisted tapeHelical finThermal performanceNumerical analysis
spellingShingle Wajdi Rajhi
Aymen h. Salih
As'ad Alizadeh
Kuwar Mausam
Aashim Dhawan
Rifaqat Ali
Sachin Mittal
Kaouther Ghachem
Walid Aich
Synergistic effect of outer helical fins and hybrid nanofluid on hydrothermal performance of shell and two-coil heat exchanger
Case Studies in Thermal Engineering
Heat exchanger
Conical coil
Twisted tape
Helical fin
Thermal performance
Numerical analysis
title Synergistic effect of outer helical fins and hybrid nanofluid on hydrothermal performance of shell and two-coil heat exchanger
title_full Synergistic effect of outer helical fins and hybrid nanofluid on hydrothermal performance of shell and two-coil heat exchanger
title_fullStr Synergistic effect of outer helical fins and hybrid nanofluid on hydrothermal performance of shell and two-coil heat exchanger
title_full_unstemmed Synergistic effect of outer helical fins and hybrid nanofluid on hydrothermal performance of shell and two-coil heat exchanger
title_short Synergistic effect of outer helical fins and hybrid nanofluid on hydrothermal performance of shell and two-coil heat exchanger
title_sort synergistic effect of outer helical fins and hybrid nanofluid on hydrothermal performance of shell and two coil heat exchanger
topic Heat exchanger
Conical coil
Twisted tape
Helical fin
Thermal performance
Numerical analysis
url http://www.sciencedirect.com/science/article/pii/S2214157X25004988
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