Nanofluid flow of Alumina-Copper/Water through isotropic porous arrays of periodic square cylinders: mixed convection and competent array shape

2021 ◽  
pp. 1-38
Author(s):  
Mohd. Asif ◽  
Amit Dhiman
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Operating Conditions ◽  
Nanoparticle Volume Fraction ◽  
Array Configuration ◽  
Copper Water ◽  
Square Cylinders

Abstract The flow of hybrid Alumina-Copper/Water nanofluid with mixed convection heat transfer from multiple square cylinders arranged in three different types of arrays, namely equilateral triangle (ET), rotated square (RS), and rotated rhombus (RR) in a heat exchanger has never been studied before the present study. Navier-Stokes and energy equations with a periodic condition in transverse direction for three array types having the same porosity are solved with finite volume methodology. The combined effect of aiding buoyancy (Richardson number Ri 0-2), configuration of square cylinders, and hybrid nanoparticle volume fraction (0-0.06) on flow dynamics and their impact on the overall heat transfer phenomenon through three different array configurations is thoroughly elucidated. The arrays' overall drag and friction coefficient increases with an increase in the strength of aiding buoyancy and nanoparticle volume fraction. An increment in Ri, and nanoparticle volume fraction, causes thermal boundary layer thinning and results in higher heat transfer rates across three arrays. With an increase in Ri from 0 to 2 at a nanoparticle volume fraction of 0.06, mean Nusselt number of ET, RS and RR arrays is increased by 161%, 5% and 32% respectively. While, with an increase in nanoparticle volume fraction from 0 to 0.06 at Ri=2, mean Nusselt number of ET, RS and RR arrays is augmented by 17%, 6% and 9% respectively. Finally, the efficient array configuration in terms of fluid-thermal behavior is proposed to design various heat exchange systems under differing operating conditions.

Investigation of heat transfer of MHD Al2O3/water nanofluid in an enclosure with a semicircular wall and a heating obstacle

2019 ◽  
Vol 30 (12) ◽  
pp. 1950105 ◽  
Author(s):  
Yuan Ma ◽  
Zhigang Yang
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Rayleigh Number ◽  
Flow Pattern ◽  
Average Nusselt Number ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Nanoparticle Volume Fraction ◽  
Number Formula

Lattice Boltzmann method (LBM) was used to simulate two-dimensional MHD Al2O3/water nanofluid flow and heat transfer in an enclosure with a semicircular wall and a triangular heating obstacle. The effects of nanoparticle volume fraction ([Formula: see text]), Rayleigh number [Formula: see text], Hartmann number [Formula: see text] and heating obstacle position (Cases 1–7) on flow pattern, temperature distribution and rate of heat transfer were investigated. The results show that with the enhancing Rayleigh number, the increasing nanoparticle volume fraction and the reducing Hartmann number, an enhancement in the average Nusselt number and the heat transfer appeared. The effect of Ha on the average Nu increases by increasing the Ra. It can also be found that the action of changing the heating obstacle position on the convection heat transfer is more important than that on the conduction heat transfer. The higher obstacle position in Cases 6 and 7 leads to the small value of the average Nusselt number. Moreover, the effect of Ha on average Nu in Case 1 at [Formula: see text] is more significant than other cases because the flow pattern in Case 1 is changed as increasing Ha.

MHD mixed convection of nanofluid in a cubic cavity with a conductive partition for various nanoparticle shapes

2019 ◽  
Vol 29 (10) ◽  
pp. 3584-3610 ◽  
Author(s):  
Fatih Selimefendigil ◽  
Hakan F. Öztop ◽  
Ali J. Chamkha
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Richardson Number ◽  
Average Nusselt Number ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Nanoparticle Volume Fraction ◽  
Content Type ◽  
Particle Shapes

Purpose This paper aims to numerically examine the mixed convection of SiO2-water nanofluid flow in a three-dimensional (3D) cubic cavity with a conductive partition considering various shapes of the particles (spherical, cylindrical, blade, brick). The purpose is to analyze the effects of various pertinent parameters such as Richardson number (between 0.1 and 10), Hartmann number (between 0 and 10), solid nanoparticle volume fraction (between 0 and 0.04), particle shape (spherical, cylindrical, blade, brick) and different heights and lengths of the conductive partition on the fluid flow and heat transfer characteristics. Design/methodology/approach The numerical simulation was performed by using Galerkin-weighted residual finite element method for various values of Richardson number, Hartmann number, solid nanoparticle volume fraction, particle shape (spherical, cylindrical, blade, brick) and different heights and lengths of the conductive partition. Two models for the average Nusselt number were proposed for nanofluids with spherical and cylindrical particle by using multi-layer feed-forward neural networks. Findings It was observed that the average Nusselt number reduces for higher values of Richardson number and Hartmann number, while enhances for higher values of nanoparticle volume fraction. Among various types of particle shapes, blade ones perform the worst and cylindrical ones perform the best in terms of heat transfer enhancement, but this is not significant which is less than 3 per cent. The average Nusselt number deteriorates by about 6.53per cent for nanofluid at the highest volume fraction of spherical particle shapes, but it is 11.75per cent for the base fluid when Hartmann number is increased from 0 to 10. Conductive partition geometrical parameters (length and height) do not contribute to much to heat transfer process for the 3D cavity, except for the case when height of the partition reaches 0.8 times the height of the cubic cavity, the average Nusselt number value reduces by about 25per cent both for base fluid and for nanofluid when compared to case with cavity height which is 0.2 times the height of the cubic cavity. Originality/value Based on the literature survey, a 3D configuration for MHD mixed convection of nanofluid flow in a cavity with a conductive partition considering the effects of various particle shapes has never been studied in the literature. This study is a first attempt to use a conductive partition with nanofluid of various particle shapes to affect the fluid flow and heat transfer characteristics in a 3D cubic cavity under the influence of magnetic field. Partial or all findings of this study could be used for the design and optimization of realistic 3D thermal configurations that are encountered in practice and some of the applications were already mentioned above. In this study, thermal performance of the system was obtained in terms of average heat transfer coefficient along the hot surface, and it is modeled with multi-layer feed-forward neural networks.

Effect of Nanofluid on Heat Transfer Enhancement for Mixed Convection Flow Over a Corrugated Surface

2020 ◽  
Vol 45 (4) ◽  
pp. 373-383
Author(s):  
Nepal Chandra Roy ◽  
Sadia Siddiqa
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Local Nusselt Number ◽  
Richardson Number ◽  
Thermal Boundary Layer ◽  
Volume Fraction ◽  
Convection Flow ◽  
Mixed Convection Flow

AbstractA mathematical model for mixed convection flow of a nanofluid along a vertical wavy surface has been studied. Numerical results reveal the effects of the volume fraction of nanoparticles, the axial distribution, the Richardson number, and the amplitude/wavelength ratio on the heat transfer of Al2O3-water nanofluid. By increasing the volume fraction of nanoparticles, the local Nusselt number and the thermal boundary layer increases significantly. In case of \mathrm{Ri}=1.0, the inclusion of 2 % and 5 % nanoparticles in the pure fluid augments the local Nusselt number, measured at the axial position 6.0, by 6.6 % and 16.3 % for a flat plate and by 5.9 % and 14.5 %, and 5.4 % and 13.3 % for the wavy surfaces with an amplitude/wavelength ratio of 0.1 and 0.2, respectively. However, when the Richardson number is increased, the local Nusselt number is found to increase but the thermal boundary layer decreases. For small values of the amplitude/wavelength ratio, the two harmonics pattern of the energy field cannot be detected by the local Nusselt number curve, however the isotherms clearly demonstrate this characteristic. The pressure leads to the first harmonic, and the buoyancy, diffusion, and inertia forces produce the second harmonic.

scholarly journals Study of convection heat transfer enhancement inside lid driven cavity utilizing fins and nanofluid

2017 ◽  
Vol 21 (6 Part A) ◽  
pp. 2431-2442
Author(s):  
Arash Lavasani ◽  
Mousa Farhadi ◽  
Darzi Rabienataj
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Richardson Number ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Thermal Conductivity Ratio ◽  
Convection Flow ◽  
Driven Cavity ◽  
Ratio Change ◽  
Hot Surface

In the present study, the effect of suspension of nanoparticle on mixed convection flow is investigated numerically in lid driven cavity with fins on its hot surface. Study is carried out for Richardson numbers ranging from 0.1 to 10, fin(s) height ratio change from 0.05 to 0.15 and volume fraction of nanoparticles from 0 to 0.03, respectively. The thermal conductivity ratio (kfin/kf) is equal to 330 and Grashof number is assumed to be constant (104) so that the Richardson numbers changes with Reynolds number. Results show that the heat transfer enhances by using nanofluid for all studied Richardson numbers. Adding fins on hot wall has different effects on heat transfer depend to Richardson number and height of fins. Use of low height fin in flow with high Richardson number enhances the heat transfer rate while by increasing the height of fin the heat transfer reduces even lower than it for pure fluid. The overall enhancement in Nusselt number by adding 3% nanoparticles and 3 fins is 54% at Ri=10. They cause reduction of Nusselt Number by 25% at Ri=0.1. Higher fins decrease the heat transfer due to blocking fluid at corners of fins.

Augmentation of Pure Mixed Convection Heat Transfer in a Non-newtonian Power-law Fluid Filled Lid-driven Trapezoidal Cavity with Double Rotating Cylinders

2021 ◽  
Author(s):  
Hasib Ahmed Prince ◽  
Didarul Ahasan Redwan ◽  
Enamul Hasan Rozin ◽  
Sudipta Saha ◽  
Mohammad Arif Hasan Mamun
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Numerical Investigation ◽  
Power Law ◽  
Convection Heat Transfer ◽  
Cavity Surface ◽  
Rotating Cylinders ◽  
Power Law Fluid ◽  
Driven Cavity

Abstract In this study, a numerical investigation on mixed convection inside a trapezoidal cavity with a pair of rotating cylinders has been conducted. Three different power-law fluid indexes (n = 1.4, 1.0, and 0.6) have been considered to model different sets of non-Newtonian fluids. Four separate cases are considered dependent on the rotation orientation of the cylinders within the cavity. In the first two cases, the cylinders rotate in the same direction, i.e., both counter-clockwise (CCW), and both clockwise (CW), whereas, in the other two cases, cylinders rotate in opposite directions (CW-CCW and CCW-CW). Simulations have been carried out over a broad range of Reynolds number (from 0.5 to 500) and angular speeds (a dimensionless value from 0 to 10). The average Nusselt number values at the isothermal hot inclined cavity surface are determined to evaluate heat transfer performance in various circumstances. Streamlines and isotherm contours are also plotted for better understandings of the effects of different cases for various parameters on thermal and fluid flow fields. It is found that the Nusselt number varies non-linearly with different angular speeds of the cylinders. The combined effect of the mixing induced by cylinder rotation and viscosity characteristics of the fluid dictates the heat transfer in the system. Predictions from the numerical investigation provide insights onto the sets of key parametric configuration that have dominant influence on the thermal performance of lid driven cavity with double rotating cylinders.

Numerical Investigation of Mixed Convection Heat Transfer in Steady Flow Past a Row of Three Square Cylinders

2018 ◽  
Vol 389 ◽  
pp. 164-175
Author(s):  
Houssem Laidoudi ◽  
Bilal Blissag ◽  
Mohamed Bouzit
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Mixed Convection ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Thermal Buoyancy ◽  
Flow And Heat Transfer ◽  
Square Cylinders ◽  
Laminar Mixed Convection ◽  
Mixed Convection Heat Transfer

In this paper, the numerical simulations of laminar mixed convection heat transfer from row of three isothermal square cylinders placed in side-by-side arrangement are carried out to understand the behavior of fluid flow around those cylinders under gradual effect of thermal buoyancy and its effect on the evacuation of heat energy. The numerical results are presented and discussed for the range of these conditions: Re = 10 to 40, Ri = 0 to 2 at fixed value of Prandtl number of Pr = 1 and at fixed geometrical configuration. In order to analyze the effect of thermal buoyancy on fluid flow and heat transfer characteristics the main results are illustrated in terms of streamline and isotherm contours. The total drag coefficient as well as average Nusselt number of each cylinder are also computed to determine exactly the effect of buoyancy strength on hydrodynamic force and heat transfer evacuation of each cylinder.

scholarly journals Effects of a Rotating Cone on the Mixed Convection in a Double Lid-Driven 3D Porous Trapezoidal Nanofluid Filled Cavity under the Impact of Magnetic Field

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 449 ◽  
Author(s):  
Ali J. Chamkha ◽  
Fatih Selimefendigil ◽  
Hakan F. Oztop
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Nusselt Number ◽  
Aspect Ratio ◽  
Mixed Convection ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Rotational Velocity ◽  
Rotating Cone ◽  
The Impact

Effects of a rotating cone in 3D mixed convection of CNT-water nanofluid in a double lid-driven porous trapezoidal cavity is numerically studied considering magnetic field effects. The numerical simulations are performed by using the finite element method. Impacts of Richardson number (between 0.05 and 50), angular rotational velocity of the cone (between −300 and 300), Hartmann number (between 0 and 50), Darcy number (between 10 − 4 and 5 × 10 − 2 ), aspect ratio of the cone (between 0.25 and 2.5), horizontal location of the cone (between 0.35 H and 0.65 H) and solid particle volume fraction (between 0 and 0.004) on the convective heat transfer performance was studied. It was observed that the average Nusselt number rises with higher Richardson numbers for stationary cone while the effect is reverse for when the cone is rotating in clockwise direction at the highest supped. Higher discrepancies between the average Nusselt number is obtained for 2D cylinder and 3D cylinder configuration which is 28.5% at the highest rotational speed. Even though there are very slight variations between the average Nu values for 3D cylinder and 3D cone case, there are significant variations in the local variation of the average Nusselt number. Higher enhancements in the average Nusselt number are achieved with CNT particles even though the magnetic field reduced the convection and the value is 84.3% at the highest strength of magnetic field. Increasing the permeability resulted in higher local and average heat transfer rates for the 3D porous cavity. In this study, the aspect ratio of the cone was found to be an excellent tool for heat transfer enhancement while 95% enhancements in the average Nusselt number were obtained. The horizontal location of the cone was found to have slight effects on the Nusselt number variations.

Heat Transfer by Mixed Convection Opposing Laminar Flow From the Inside Surface of Uniformly Heated Inclined Circular Tube

2006 ◽  
Author(s):  
H. Mohammed ◽  
T. Yusaf
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Flow Direction ◽  
Convection Heat Transfer ◽  
Heat Transfer Process ◽  
Secondary Flows ◽  
Opposed Flow ◽  
Wide Range

This paper aims to investigate the effect of the flow pattern on the mixed convection heat transfer. A 28 thermocouples wire were installed along a 900mm copper tube to measure the temperature distribution. Three insulation layers of fiber glass, asbestos and gypsum were used to minimize to heat lost to the surrounding. A forced convection at the entrance region of a fully developed opposing laminar air flow was investigated to evaluate the flow direction effect on the Nusselt number. The investigation covered a wide range of Reynolds number from 410 to 1600 and heat flux varied from 63W/m2 to 1260W/m2, with different angles of tube inclination of 30°, 45°, 60°, and 90°. It was found that the surface temperature variation along the tube for opposed flow higher than the assisted flow but lower than the horizontal orientation. The Reynolds number has a significant effect on Nusselt number in opposed flow while the effect of Reynolds number was found to be small in the case of assisted flow. The Nusselt number values were lower for opposed flow than the assisted flow. The temperature profiles results have revealed that the secondary flows created by natural convection have a significant effect on the heat transfer process. The obtained average Nusselt number values were correlated by dimensionless groups as Log Nu against Log Ra/Re.

scholarly journals Prediction of Natural Convection Heat Transfer Phenomena of Nanofluids in Corrugated Annulus

2020 ◽  
Author(s):  
Sattar Aljobair ◽  
Akeel Abdullah Mohammed ◽  
Israa Alesbe
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Outer Cylinder ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat

Abstract The natural convection heat transfer and fluid flow characteristic of water based Al2O3 nano-fluids in a symmetrical and unsymmetrical corrugated annulus enclosure has been studied numerically using CFD. The inner cylinder is heated isothermally while the outer cylinder is kept constant cold temperature. The study includes eight models of corrugated annulus enclosure with constant aspect ratio of 1.5. The governing equations of fluid motion and heat transfer are solved using stream-vorticity formulation in curvilinear coordinates. The range of solid volume fractions of nanoparticles extends from PHI=0 to 0.25, and Rayleigh number varies from 104 to 107. Streamlines, isotherms, local and average Nusselt number of inner and outer cylinder has been investigated in this study. Sixty-four correlations have been deduced for the average Nusselt number for the inner and outer cylinders as a function of Rayleigh number have been deduced for eight models and five values of volume fraction of nano particles with an accuracy range 6-12 %. The results show that, the average heat transfer rate increases significantly as particle volume fraction and Rayleigh number increase. Also, increase the number of undulations in unsymmetrical annuli reduces the heat transfer rates which remain higher than that in symmetrical annuli. There is no remarkable change in isotherms contour with increase of volume fraction of nanofluid.

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