Numerical investigation of conjugate heat transfer and entropy generation of MHD natural convection of nanofluid in an inclined enclosure

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Amin Kardgar
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Fluid Flow ◽  
Natural Convection ◽  
Entropy Generation ◽  
Wall Thickness ◽  
Conjugate Heat Transfer ◽  
Volume Fraction ◽  
Content Type ◽  
Inclined Enclosure

Purpose The purpose of this paper is to investigate conjugate heat transfer of natural convection and entropy generation of nanofluid in the presence of external magnetic field via numerical approach in an inclined square cavity enclosure. Design/methodology/approach Control volume finite volume method with collocated arrangement of grids was used for discretization of continuity, momentum, solid and fluid energy equations. Rhie and Chow interpolation technique was applied to avoid checkerboard problem in pressure field and the well-established SIMPLE algorithm was followed to deal with the pressure and velocity coupling. The cavity is filled with water and nanoparticles of the aluminum oxide (Al2O3). This study has been conducted for the certain pertinent parameters of the volume fraction of nanoparticle (φ = 0–0.08), the angle of inclination (ϴ = 0°–330°), the Ra number (Ra = 103–108), the solid to fluid conductivity ratio (ksf = 1–400), the Ha number (Ha = 0–80) and the wall thickness ratio (δ/L = 0–0.3). Findings The results indicate that averaged Nu number increases by approximately 9% by increasing volume fraction from 0.0 to 0.08. Nu increases with an increasing inclination angle to 40° and decreases abruptly in 90° because of the formation of two weaker vorticity with opposite circulation pattern intensifying the density of isotherm curves in a vertical direction. Nu increases sharply with increasing Ra more than 105. Nu also augments almost 67% by increasing ksf = 1 to ksf = 50 and remains constant by increasing ksf more than 50. Nu number reduction is almost 72% with a variation of wall thickness ratio from d/L = 0 to 0.3. Entropy generation because of fluid flow, magnetic field and heat transfer reduces linearly almost 30%, 19% and 16% by increasing volume fraction, respectively. With increasing ksf, entropy generation because of fluid flow, magnetic field and heat transfer increases asymptotically, but Bejan number decreases. Originality/value A brief review of conducted research studies in nanofluid flow and heat transfer reveals that the effect of wall thermal inertia was not investigated in MHD natural convection of nanofluids in an inclined enclosure. The aim of the present study is to analyze conjugate heat transfer in an inclined cavity filled with water and Al2O3.

Fluid flow and heat transfer of a stratified system during natural convection – influence of chamfered corners

2019 ◽  
Vol 29 (2) ◽  
pp. 470-486 ◽  
Author(s):  
Alireza Rahimi ◽  
Aravindhan Surendar ◽  
Aygul Z. Ibatova ◽  
Abbas Kasaeipoor ◽  
Emad Hasani Malekshah
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Natural Convection ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Three Dimensional ◽  
Immiscible Fluids ◽  
Content Type ◽  
Flow And Heat Transfer

Purpose This paper aims to investigate the three-dimensional natural convection and entropy generation in the rectangular cuboid cavities included by chamfered triangular partition made by polypropylene. Design/methodology/approach The enclosure is filled by multi-walled carbon nanotubes (MWCNTs)-H2O nanofluid and air as two immiscible fluids. The finite volume approach is used for computation. The fluid flow and heat transfer are considered with combination of local entropy generation due to fluid friction and heat transfer. Moreover, a numerical method is developed based on three-dimensional solution of Navier–Stokes equations. Findings Effects of side ratio of triangular partitions (SR = 0.5, 1 and 2), Rayleigh number (103 < Ra < 105) and solid volume fraction (f = 0.002, 0.004 and 0.01 Vol.%) of nanofluid are investigated on both natural convection characteristic and volumetric entropy generation. The results show that the partitions can be a suitable method to control fluid flow and energy consumption, and three-dimensional solutions renders more accurate results. Originality/value The originality of this work is to study the three-dimensional natural convection and entropy generation of a stratified system.

Nonhomogeneous model for conjugate mixed convection of nanofluid and entropy generation in an enclosure in presence of inclined magnetic field with Joule heating

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Subhasree Dutta ◽  
Somnath Bhattacharyya ◽  
Ioan Pop
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Mixed Convection ◽  
Entropy Generation ◽  
Joule Heating ◽  
Conjugate Heat Transfer ◽  
Inclined Magnetic Field ◽  
Content Type ◽  
The Impact ◽  
The Magnetic Field

Purpose This study aims to numerically analyse the impact of an inclined magnetic field and Joule heating on the conjugate heat transfer because of the mixed convection of an Al2O3–water nanofluid in a thick wall enclosure. Design/methodology/approach A horizontal temperature gradient together with the shear-driven Flow creates the mixed convection inside the enclosure. The nonhomogeneous model, in which the nanoparticles have a slip velocity because of thermophoresis and Brownian diffusion, is adopted in the present study. The thermal performance is evaluated by determining the entropy generation, which includes the contribution because of magnetic field. A control volume method over a staggered grid arrangement is adopted to compute the governing equations. Findings The Lorentz force created by the applied magnetic field has an adverse effect on the flow and thermal field, and consequently, the heat transfer and entropy generation attenuate because of the presence of magnetic force. The Joule heating enhances the fluid temperature but attenuates the heat transfer. The impact of the magnetic field diminishes as the angle of inclination of the magnetic field is increased, and it manifests as the volume fraction of nanoparticles is increased. Addition of nanoparticles enhances both the heat transfer and entropy generation compared to the clear fluid with enhancement in entropy generation higher than the rate by which the heat transfer augments. The average Bejan number and mixing-cup temperature are evaluated to analyse the thermodynamic characteristics of the nanofluid. Originality/value This literature survey suggests that the impact of an inclined magnetic field and Joule heating on conjugate heat transfer based on a two-phase model has not been addressed before. The impact of the relative slip velocity of nanoparticles diminishes as the magnetic field becomes stronger.

Lattice Boltzmann simulation of 3D natural convection in a cuboid filled with KKL-model predicted nanofluid using Dual-MRT model

2019 ◽  
Vol 29 (1) ◽  
pp. 365-387 ◽  
Author(s):  
Alireza Rahimi ◽  
Abbas Kasaeipoor ◽  
Emad Hasani Malekshah ◽  
Mohammad Mehdi Rashidi ◽  
Abimanyu Purusothaman
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Natural Convection ◽  
Lattice Boltzmann Method ◽  
Entropy Generation ◽  
Lattice Boltzmann ◽  
Three Dimensional ◽  
Local Heat Transfer ◽  
Content Type ◽  
Boltzmann Method

Purpose This study aims to investigate the three-dimensional natural convection and entropy generation in a cuboid enclosure filled with CuO-water nanofluid. Design/methodology/approach The lattice Boltzmann method is used to solve the problem numerically. Two different multiple relaxation time (MRT) models are used to solve the problem. The D3Q7–MRT model is used to solve the temperature field, and the D3Q19 is used to solve the fluid flow of natural convection within the enclosure. Findings The influences of different Rayleigh numbers (103 < Ra < 106) and solid volume fractions (0 < f < 0.04) on the fluid flow, heat transfer, total entropy generation, local heat transfer irreversibility and local fluid friction irreversibility are presented comprehensively. To predict thermo–physical properties, dynamic viscosity and thermal conductivity, of CuO–water nanofluid, the Koo–Kleinstreuer–Li (KKL) model is applied to consider the effect of Brownian motion on nanofluid properties. Originality/value The originality of this work is to analyze the three-dimensional natural convection and entropy generation using a new numerical approach of dual-MRT-based lattice Boltzmann method.

Hydrothermal investigation of a stratified system in enclosure with jagged surface for application in lead-acid batteries

2019 ◽  
Vol 15 (1) ◽  
pp. 283-303 ◽  
Author(s):  
Mahmoud Salari ◽  
Emad Hasani Malekshah ◽  
Mohammad Reza Sarlak ◽  
Masoud Hasani Malekshah ◽  
Mohammad Pilfoush
Keyword(s):  
Nusselt Number ◽  
Fluid Flow ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Content Type ◽  
Lead Acid Batteries ◽  
Lead Acid

Purpose The purpose of this paper is to investigate the three-dimensional natural convection and entropy generation in a cuboid enclosure filled with two immiscible fluids of nanofluid and air. Design/methodology/approach One surface of the enclosure is jagged and another one is smooth. The finite volume approach is applied for computation. There are two partially side heaters. Furthermore, the Navier–Stokes equations and entropy generation formulation are solved in the 3D form. Findings The effects of different governing parameters, such as the jagged surface (JR=0, 0.02, 0.04, 0.08, 0.12 and 0.16), Rayleigh number (103⩽Ra⩽106) and solid volume fraction of nanofluid (φ=1, 1.5, 2 vol%), on the fluid flow, temperature field, Nusselt number, volumetric entropy generation and Bejan number are presented, comprehensively. The results indicate that the average Nusselt number increases with the increase in the Rayleigh number and solid volume fraction of nanofluid. Moreover, the flow structure is significantly affected by the jagged surface. Originality/value The originality of this work is to analyze the natural-convection fluid flow and heat transfer under the influence of jagged surfaces of electrodes in high-current lead–acid batteries.

Lattice Boltzmann simulation of free convection in nanofluid filled cavity with partially active walls – entropy generation and heatline visualization

2018 ◽  
Vol 28 (10) ◽  
pp. 2254-2283 ◽  
Author(s):  
Alireza Rahimi ◽  
Abbas Kasaeipoor ◽  
Emad Hasani Malekshah ◽  
Lioua Kolsi
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Entropy Generation ◽  
Lattice Boltzmann ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Convection Heat Transfer ◽  
Content Type ◽  
Lattice Boltzmann Simulation

Purpose This paper aims to perform the lattice Boltzmann simulation of natural convection heat transfer in cavities included with active hot and cold walls at the side walls and internal hot and cold obstacles. Design/methodology/approach The cavity is filled with double wall carbon nanotubes (DWCNTs)-water nanofluid. Different approaches such as local and total entropy generation, local and average Nusselt number and heatline visualization are used to analyze the natural convection heat transfer. The cavity is filled with DWCNTs-water nanofluid and the thermal conductivity and dynamic viscosity are measured experimentally at different solid volume fractions of 0.01 per cent, 0.02 per cent, 0.05 per cent, 0.1 per cent, 0.2 per cent and 0.5 per cent and at a temperature range of 300 to 340 (K). Findings Two sets of correlations for these parameters based on temperature and solid volume fraction are developed and used in the numerical simulations. The influences of different governing parameters such as Rayleigh number, solid volume fraction and different arrangements of active walls on the fluid flow, heat transfer and entropy generation are presented, comprehensively. It is found that the different arrangements of active walls have pronounced influence on the flow structure and heat transfer performance. Furthermore, the Nusselt number has direct relationship with Rayleigh number and solid volume fraction. On the other hand, the total entropy generation has direct and reverse relationship with Rayleigh number and solid volume fraction, respectively. Originality/value The originality of this work is to analyze the two-dimensional natural convection using lattice Boltzmann method and different approaches such as entropy generation and heatline visualization.

Study on fluid flow and heat transfer in fluid channel filled with KKL model-based nanofluid during natural convection using FVM

2019 ◽  
Vol 29 (8) ◽  
pp. 2622-2641
Author(s):  
Yongsheng Rao ◽  
Zehui Shao ◽  
Alireza Rahimi ◽  
Abbas Kasaeipoor ◽  
Emad Hasani Malekshah
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Natural Convection ◽  
Entropy Generation ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Temperature Fields ◽  
Bejan Number ◽  
Content Type ◽  
Flow And Heat Transfer

PurposeA comprehensive study on the fluid flow and heat transfer in a nanofluid channel is carried out. The configuration of the channel is as like as quarter channel. The channel is filled with CuO–water nanofluid.Design/methodology/approachThe Koo–Kleinstreuer–Li model is used to estimate the dynamic viscosity and consider the Brownian motion. On the other hand, the influence of nanoparticles’ shapes on the heat transfer rate is considered in the simulations. The channel is included with the injection pipes which are modeled as active bodies with constant temperature in the 2D simulations.FindingsThe Rayleigh number, nanoparticle concentration and the thermal arrangements of internal pipes are the governing parameters. The hydrothermal aspects of natural convection are investigation using different approaches such as average Nusselt number, total entropy generation, Bejan number, streamlines, temperature fields, local heat transfer irreversibility, local fluid friction irreversibility and heatlines.Originality/valueThe originality of this work is investigation of fluid flow, heat transfer, entropy generation and heatline visualization within a nanofluid-filled channel using a finite volume method.

Thermophoresis and Brownian effects on natural convection of nanofluids in a square enclosure with two pairs of heat source/sink

2015 ◽  
Vol 25 (5) ◽  
pp. 1030-1046 ◽  
Author(s):  
Aminreza Noghrehabadi ◽  
Amin Samimi Behbahan ◽  
I. Pop
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Heat Source ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Numerical Results ◽  
Content Type ◽  
Source Sink

Purpose – The purpose of this paper is to study natural convection heat transfer and fluid flow in a square cavity filled with CuO-water nanofluid. Design/methodology/approach – The entire length of the bottom wall of the cavity is covered by two pairs of heat source-sink, whereas the other walls are insulated. The governing equations of fluid flow are discretized using a finite volume method with a collocated grid arrangement. The coupling between velocity and pressure is solved using the SIMPLEC and the Rhie and Chow interpolation is used to avoid the checker-board solutions for the pressure. Findings – The numerical results are reported for the effect of Rayleigh number, solid volume fraction and both presence and absence of thermophoresis and Brownian motion effects. The numerical results show an improvement in heat transfer rate for the whole range of Rayleigh numbers when Brownian and thermophoresis effects are considered. Furthermore, an increase in the Rayleigh number and nanoparticle volume fraction in both cases – when Brownian and thermophoresis effects are neglected or considered – has an excellent influence on heat transfer of nanofluids. Originality/value – The area of nanofluids is very original.

Entropy generation optimization for MHD natural convection of a nanofluid in porous media-filled enclosure with active parts and viscous dissipation

2017 ◽  
Vol 27 (2) ◽  
pp. 379-399 ◽  
Author(s):  
M.A. Mansour ◽  
Sameh Elsayed Ahmed ◽  
Ali J. Chamkha
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Viscous Dissipation ◽  
Entropy Generation ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Convection Flow ◽  
Negative Effects ◽  
Content Type ◽  
Volume Method

Purpose This paper aims to investigate the entropy generation due to magnetohydrodynamic natural convection flow and heat transfer in a porous enclosure filled with Cu-water nanofluid in the presence of viscous dissipation effect. The left and right walls of the cavity are thermally insulated. There are heated and cold parts, and these are placed on the bottom and top wall, respectively, whereas the remaining parts are thermally insulated. Design/methodology/approach The finite volume method is used to solve the dimensionless partial differential equations governing the problem. A comparison with previously published woks is presented and is found to be in an excellent agreement. Findings The minimization of entropy generation and local heat transfer according to different values of the governing parameters are presented in details. It is found that the presence of magnetic field has negative effects on the local entropy generation because of heat transfer and the local total entropy generation. Also, the increase in the heated part length leads to a decrease in the local Nusselt number. Originality/value This problem is original, as it has not been considered previously.

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