Effect of flow separation of TiO2 nanofluid on heat transfer in the annular space of two concentric cylinders

Abdulrazzaq, Tuqa; Togun, Hussein; Safaei, Mohammad Reza; Newaz, Salim Kazi; Khairol, Mohd; Mariah, Nor Adam

doi:10.2298/tsci180709321a

Cited by 15 publications

(5 citation statements)

References 22 publications

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“…They found that ethylene glycol had higher heat transfer augmentation in comparison to water. Tuqa et al [32] have numerically studied turbulent TiO 2 -based nanofluid flow in an annular pipe with a sudden reduction. A rise in the surface heat transfer coefficient was found with growing nanoparticle volume fractions and Reynolds numbers.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer Improvement in a Double Backward-Facing Expanding Channel Using Different Working Fluids

et al. 2020

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This paper reports a numerical study on heat transfer improvement in a double backward-facing expanding channel using different convectional fluids. A finite volume method with the k-ε standard model is used to investigate the effects of step, Reynolds number and type of liquid on heat transfer enhancement. Three types of conventional fluids (water, ammonia liquid and ethylene glycol) with Reynolds numbers varying from 98.5 to 512 and three cases for different step heights at a constant heat flux (q = 2000 W/m2) are examined. The top wall of the passage and the bottom wall of the upstream section are adiabatic, while the walls of both the first and second steps downstream are heated. The results show that the local Nusselt number rises with the augmentation of the Reynolds number, and the critical effects are seen in the entrance area of the first and second steps. The maximum average Nusselt number, which represents the thermal performance, can be seen clearly in case 1 for EG in comparison to water and ammonia. Due to the expanding of the passage, separation flow is generated, which causes a rapid increment in the local skin friction coefficient, especially at the first and second steps of the downstream section for water, ammonia liquid and EG. The maximum skin friction coefficient is detected in case 1 for water with Re = 512. Trends of velocities for positions (X/H1 = 2.01, X/H2 = 2.51) at the first and second steps for all the studied cases with different types of convectional fluids are indicated in this paper. The presented findings also include the contour of velocity, which shows the recirculation zones at the first and second steps to demonstrate the improvement in the thermal performance.

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Section: Introductionmentioning

confidence: 99%

Heat Transfer Improvement in a Double Backward-Facing Expanding Channel Using Different Working Fluids

et al. 2020

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“…Nanofluids with fabricated geometries are increasingly employed to improve heat transfer in various applications [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Dadheech et al [ 6 ] studied natural convection in the attendance of an angled magnetic field and compared the thermal behavior of MoS 2 /C2H 6 O 2 and SiO 2 -MoS 2 /C 2 H 6 O 2 nanofluids.…”

Section: Introductionmentioning

confidence: 99%

Efficient Heat Transfer Augmentation in Channels with Semicircle Ribs and Hybrid Al2O3-Cu/Water Nanofluids

Togun

Homod

Yaseen‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬

et al. 2022

Nanomaterials

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Global technological advancements drive daily energy consumption, generating additional carbon-induced climate challenges. Modifying process parameters, optimizing design, and employing high-performance working fluids are among the techniques offered by researchers for improving the thermal efficiency of heating and cooling systems. This study investigates the heat transfer enhancement of hybrid “Al2O3-Cu/water” nanofluids flowing in a two-dimensional channel with semicircle ribs. The novelty of this research is in employing semicircle ribs combined with hybrid nanofluids in turbulent flow regimes. A computer modeling approach using a finite volume approach with k-ω shear stress transport turbulence model was used in these simulations. Six cases with varying rib step heights and pitch gaps, with Re numbers ranging from 10,000 to 25,000, were explored for various volume concentrations of hybrid nanofluids Al2O3-Cu/water (0.33%, 0.75%, 1%, and 2%). The simulation results showed that the presence of ribs enhanced the heat transfer in the passage. The Nusselt number increased when the solid volume fraction of “Al2O3-Cu/water” hybrid nanofluids and the Re number increased. The Nu number reached its maximum value at a 2 percent solid volume fraction for a Reynolds number of 25,000. The local pressure coefficient also improved as the Re number and volume concentration of “Al2O3-Cu/water” hybrid nanofluids increased. The creation of recirculation zones after and before each rib was observed in the velocity and temperature contours. A higher number of ribs was also shown to result in a larger number of recirculation zones, increasing the thermal performance.

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“…In the new decades, considered efforts done to verification help using nanofluids in disparate applications [24][25][26][27][28][29][30][31][32][33][34][35]. Kherbeet et al [36,37] conducted experimental and numerical study on laminar nanofluids flow and heat transfer over microscale FFS.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Al2O3-Cu/water nanofluid flow and heat transfer over vertical double forward-facing step

2021

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Turbulent heat transfer and hybrid Al2O3-Cu/nanofluid over vertical double forward facing-stepis numerically conducted. K-? standard model based on finite volume method in two dimensional are applied to investigate the influences of Reynolds number, step height, volume fractions hybrid Al2O3-Cu/nanofluid on thermal performance. In this paper, different step heights for three cases of vertical double FFS are adopted by five different of volume fractions of hybrid (Al2O3-Cu/water) nanofluid varied for 0.1, 0.33, 0.75, 1, and 2, while the Reynolds number different between 10000 to 40000 with temperature is constant. The main findings revealed that rise in local heat transfer coefficients with raised Reynolds number and maximum heat transfer coefficient was noticed at Re=40000. Also rises in heat transfer coefficient detected with increased volume concentrations of hybrid (Al2O3-Cu/water) nanofluid and the maximum heat transfer coefficient found at hybrid Al2O3-Cu/water nanofluid of 2% in compared with others. It?s also found that rise in surface heat transfer coefficient at 1ststep-case 2 was greater than at 1ststep-case 1 and 3 while was higher at 2ndstep-case 3. Average heat transfer coefficient with Reynolds number for all cases are presented in this paper and found that the maximum average heat transfer coefficient was at case 2 compared with case 1 and 3. Gradually increases in skin friction coefficient remarked at 1stand 2ndsteps of the channel and drop in skin friction coefficient was obtained with increased of Reynolds number. Counter of velocity was presented to show the recirculation regions at first and second steps as clarified the enrichment in heat transfer rate. Furthermore, the counter of turbulence kinetic energy contour was displayed to provide demonstration for achieving thermal performance at second step for all cases.

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Effect of flow separation of TiO2 nanofluid on heat transfer in the annular space of two concentric cylinders

Cited by 15 publications

References 22 publications

Heat Transfer Improvement in a Double Backward-Facing Expanding Channel Using Different Working Fluids

Heat Transfer Improvement in a Double Backward-Facing Expanding Channel Using Different Working Fluids

Efficient Heat Transfer Augmentation in Channels with Semicircle Ribs and Hybrid Al2O3-Cu/Water Nanofluids

Hybrid Al2O3-Cu/water nanofluid flow and heat transfer over vertical double forward-facing step

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