Heat transfer enhancement and pressure drop performance of Al2O3 nanofluid in a laminar flow tube with deep dimples under constant heat flux: An experimental approach
This study examines the heat transfer enhancement and pressure drop of Al2O3 nanofluid in deep dimpled tubes in both longitudinal and circumferential directions. It explores mechanisms that improve the thermal performance of this novel tube geometry. Experiments were conducted using plain and deep d...
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| Language: | English |
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Elsevier
2024-11-01
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| Series: | International Journal of Thermofluids |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2666202724002684 |
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| author | Alireza Khashaei Mohammad Ameri Shahram Azizifar |
| author_facet | Alireza Khashaei Mohammad Ameri Shahram Azizifar |
| author_sort | Alireza Khashaei |
| collection | DOAJ |
| description | This study examines the heat transfer enhancement and pressure drop of Al2O3 nanofluid in deep dimpled tubes in both longitudinal and circumferential directions. It explores mechanisms that improve the thermal performance of this novel tube geometry. Experiments were conducted using plain and deep dimpled tubes under laminar flow with Reynolds numbers from 500 to 2250, a constant heat flux of 10,000 W/m2, and nanofluid concentrations from 0.1 wt% to 1 wt%. The findings indicate that local velocity enhancement, vortex generation, and flow rotation and mixing are the three main mechanisms that improve the thermal performance of deep dimpled tubes. The results demonstrate that a deep dimpled tube with 1 wt% nanofluid can increase the convective heat transfer coefficient by up to 3.42 times compared to a smooth tube at Re = 2250. At this Reynolds number, the Nusselt number reaches a maximum of 41.80, and the friction factor ratio increases by only 1.82. Additionally, circumferential analysis reveals how dimple-induced vortices enhance heat transfer. The results also indicate that the tube geometry modification changes the flow regime zones, allowing turbulent flow at lower Reynolds numbers near Re = 2000, as identified by Nusselt number and friction factor plots. The deep dimpled tube has a low improvement penalty, with the highest friction factor of 0.38 at Re = 500 and high thermal enhancement, resulting in a performance evaluation criterion (PEC) of up to 2.80 in the studied region. However, the deep dimpled tube is unsuitable for Reynolds numbers below 1000. For higher velocities, replacing simple tubes with deep dimpled tubes in traditional heat exchangers is highly recommended. |
| format | Article |
| id | doaj-art-c0dc579c82fb42dd8ac88ca64caf66b1 |
| institution | Kabale University |
| issn | 2666-2027 |
| language | English |
| publishDate | 2024-11-01 |
| publisher | Elsevier |
| record_format | Article |
| series | International Journal of Thermofluids |
| spelling | doaj-art-c0dc579c82fb42dd8ac88ca64caf66b12024-12-13T11:03:56ZengElsevierInternational Journal of Thermofluids2666-20272024-11-0124100827Heat transfer enhancement and pressure drop performance of Al2O3 nanofluid in a laminar flow tube with deep dimples under constant heat flux: An experimental approachAlireza Khashaei0Mohammad Ameri1Shahram Azizifar2Energy Conversion Department, Faculty of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, IranCorresponding author.; Energy Conversion Department, Faculty of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, IranEnergy Conversion Department, Faculty of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, IranThis study examines the heat transfer enhancement and pressure drop of Al2O3 nanofluid in deep dimpled tubes in both longitudinal and circumferential directions. It explores mechanisms that improve the thermal performance of this novel tube geometry. Experiments were conducted using plain and deep dimpled tubes under laminar flow with Reynolds numbers from 500 to 2250, a constant heat flux of 10,000 W/m2, and nanofluid concentrations from 0.1 wt% to 1 wt%. The findings indicate that local velocity enhancement, vortex generation, and flow rotation and mixing are the three main mechanisms that improve the thermal performance of deep dimpled tubes. The results demonstrate that a deep dimpled tube with 1 wt% nanofluid can increase the convective heat transfer coefficient by up to 3.42 times compared to a smooth tube at Re = 2250. At this Reynolds number, the Nusselt number reaches a maximum of 41.80, and the friction factor ratio increases by only 1.82. Additionally, circumferential analysis reveals how dimple-induced vortices enhance heat transfer. The results also indicate that the tube geometry modification changes the flow regime zones, allowing turbulent flow at lower Reynolds numbers near Re = 2000, as identified by Nusselt number and friction factor plots. The deep dimpled tube has a low improvement penalty, with the highest friction factor of 0.38 at Re = 500 and high thermal enhancement, resulting in a performance evaluation criterion (PEC) of up to 2.80 in the studied region. However, the deep dimpled tube is unsuitable for Reynolds numbers below 1000. For higher velocities, replacing simple tubes with deep dimpled tubes in traditional heat exchangers is highly recommended.http://www.sciencedirect.com/science/article/pii/S2666202724002684Heat transfer enhancementDimpled tubeAl2O3/water nanofluidExperimental setupForced convectionPerformance evaluation criteria |
| spellingShingle | Alireza Khashaei Mohammad Ameri Shahram Azizifar Heat transfer enhancement and pressure drop performance of Al2O3 nanofluid in a laminar flow tube with deep dimples under constant heat flux: An experimental approach International Journal of Thermofluids Heat transfer enhancement Dimpled tube Al2O3/water nanofluid Experimental setup Forced convection Performance evaluation criteria |
| title | Heat transfer enhancement and pressure drop performance of Al2O3 nanofluid in a laminar flow tube with deep dimples under constant heat flux: An experimental approach |
| title_full | Heat transfer enhancement and pressure drop performance of Al2O3 nanofluid in a laminar flow tube with deep dimples under constant heat flux: An experimental approach |
| title_fullStr | Heat transfer enhancement and pressure drop performance of Al2O3 nanofluid in a laminar flow tube with deep dimples under constant heat flux: An experimental approach |
| title_full_unstemmed | Heat transfer enhancement and pressure drop performance of Al2O3 nanofluid in a laminar flow tube with deep dimples under constant heat flux: An experimental approach |
| title_short | Heat transfer enhancement and pressure drop performance of Al2O3 nanofluid in a laminar flow tube with deep dimples under constant heat flux: An experimental approach |
| title_sort | heat transfer enhancement and pressure drop performance of al2o3 nanofluid in a laminar flow tube with deep dimples under constant heat flux an experimental approach |
| topic | Heat transfer enhancement Dimpled tube Al2O3/water nanofluid Experimental setup Forced convection Performance evaluation criteria |
| url | http://www.sciencedirect.com/science/article/pii/S2666202724002684 |
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