Numerical Study of Turbulent Flows and Convective Heat Transfer of Al2O3-Water Nanofluids In A Circular Tube

The objective of this work is the mathematical modelling and the numerical simulation of the stationary, laminar, and natural convection, in a confined square cavity (H = L) filled with two fluids (a mixture of nanoparticles of aluminum oxide and Al2O3 water) in one partition and pure water in the other partition. A porous conductive wall of thickness w (w = L/e) and thermal conductivity Keff constitutes the exchange surface between these two partitions. The fluid movement is modeled by the Navier-Stokes equations in the two partitions, while the porous medium is modelled by the Darcy–Brinkman equation. Comsol Multiphysics software is used to solve the system of differential equations that is based on the finite element method. The results are discussed with particular attention to the mean and local Nusselt number (Nu), streamlines and isotherms. A parametric study for Rayleigh number Ra (102 to 106), volume fraction j (0% to 10%), and Darcy number Da (10-7 to 10-2) is performed. The obtained findings show that the increase in Ra, Da, and j intensifies the flow and improves the thermal exchange on the cold wall. For Da £ 10-5, Nu remains practically low and the natural convection is being dominated by conduction. For Da > 10-5, an increase in Nu is observed and the flows tend towards a purely convective situation. Furthermore, an increase in the heat transfer coefficients is observed with the raise of the porous layer permeability, volume fraction and Rayleigh number.

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“…This improvement is more significant in the case of Da = 10 -2 . These results agree well with the literature [41][42][43].…”

Section: Tablesupporting

confidence: 93%

Study of Laminar Naturel Convection in Partially Porous Cavity in the Presence of Nanofluids

Douha

Draoui

Kaid³

et al. 2020

ARFMTS

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“…The − turbulence model is considered as the most common and applied turbulence model which has also been applied in the current study. Most of recent numerical studies that dealt with turbulent flow applied − turbulence model including the work by Liang [6] and Talbizadeh and Keshtkar [31] for disk bypass PIG simulation [26][27][28][29][30]. Therefore, − turbulence model was considered for this study also.…”

Section: The − Turbulence Modelmentioning

confidence: 99%

Flow Characteristics of Disk Bypass Pipeline Inspection Gauge (PIG) in Natural Gas Pipelines using Computational Fluid Dynamics

Rabby

Masuri

Kamal³

et al. 2021

CFDL

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Disk bypass pipeline inspection gauge (PIG) is considered as an efficient device for pigging operations including cleaning, maintaining and inspecting pipelines. The PIG performance is influenced by the fluid flow characteristics as PIG moves forward due to differential pressure of fluid around the PIG. This study focuses on flow characterization of fluid around disk bypass PIG for natural gases pipelines including methane, ethane, and butane using computational fluid dynamics approach. The control volume method with steady state Turbulent k-? model was applied for simulation purposes using ANSYS Fluent 19 software. Fluid velocities at different sections around PIG and differential pressure were investigated for various bypass opening percentages. The results showed that by increasing bypass opening percentages from 5% to 15%, fluid velocity at bypass opening section has reduced 28.28%, 40.43%, and 21.21% for ethane, butane, and methane, respectively, while differential pressure reduced 88%, 86% and 89%. This indicated that 15% bypass opening percentage provided the best flow characteristics among all cases considered. At 15% bypass opening percentage, methane resulted in the lowest fluid velocity at bypass opening section and lowest differential pressure compared to others. Additionally, a correlation of differential pressure of these gases as a function of bypass opening percentage and other parameters was also developed for first time. All results are important for design selection of PIG parameters for efficient pigging operation.

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“…Likewise, heat transfer enhancement is also gaining popularity so as to increase the thermal performance of the systems. ere are many studies conducted where heat transfer enhancement has been studied by utilizing nano-sized particles and V-ribs for solar panels [26][27][28][29][30][31][32][33]. Jet impingement also focusses on the enhancement of heat transfer using turbulence induced mixing as a means for increased heat transfer coefficient.…”

Section: Introductionmentioning

confidence: 99%

Computational Fluid Dynamics Analysis of Impingement Heat Transfer in an Inline Array of Multiple Jets

Singh

Grover

Agarwal

et al. 2021

Mathematical Problems in Engineering

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Amid all convective heat transfer augmentation methods employing single phase, jet impingement heat transfer delivers significantly higher coefficient of local heat transfer. The arrangement leading to nine jets in square array has been used to cool a plate maintained at constant heat flux. Numerical study has been carried out using RANS-based turbulence modeling in commercial CFD Fluent software. The turbulent models used for the study are three different “k-ε” models (STD, RNG, and realizable) and SST “k-ω” model. The numerical simulation output is equated with the experimental results to find out the most accurate turbulence model. The impact of variation of Reynolds number, inter-jet spacing, and separation distance has been considered for the geometry considered. These parameters affect the coefficient of heat transfer, temperature, and turbulent kinetic energy related to flow. The local “h” values have been noticed to decline with the rise in separation distance “H/D.” The SST “k-ω” model has been noticed to be in maximum agreement with the experimental results. The average value of heat transfer coefficient “h” reduces from 210 to 193 W/m2K with increase in “H/D” from 6 to 10 at “Re” = 9000 and S/D of 3. As per numerical results, inter-jet spacing “S/D” of 3 has been determined to be the most optimum value.

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Numerical Study of Turbulent Flows and Convective Heat Transfer of Al2O3-Water Nanofluids In A Circular Tube

Cited by 20 publications

References 28 publications

Study of Laminar Naturel Convection in Partially Porous Cavity in the Presence of Nanofluids

Study of Laminar Naturel Convection in Partially Porous Cavity in the Presence of Nanofluids

Flow Characteristics of Disk Bypass Pipeline Inspection Gauge (PIG) in Natural Gas Pipelines using Computational Fluid Dynamics

Computational Fluid Dynamics Analysis of Impingement Heat Transfer in an Inline Array of Multiple Jets

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