Entropy generation due to the mixed convection flow of MWCNT−MgO/water hybrid nanofluid in a vented complex shape cavity

This paper reports a numerical study of mixed convection heat transfer with entropy generation in a vented complex shape cavity filled with MWCNT−MgO (15:85 vol %) /water hybrid nanofluid. A hot source is placed at the mid potion of the inclined plate of the enclosure, while the rest of the rigid walls are adiabatic. A thermo-dependent correlations proposed by [12] for the dynamic viscosity and the thermal conductivity, especially developed for the considered fluid, are used. After validation of the model, the analysis has been done for a Reynolds numbers ranging from 10 to 600 and total nanoparticles volume fraction ranging from 0.0 to 0.02 using the finite volume method. The predicted results of streamlines, isotherms, isentropic lines, average Nusselt number, average entropy generation and average Bejan number are the main focus of interest in the present paper.

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Numerical Study on Mixed Convection and Entropy Generation of a Nanofluid in a Lid-Driven Square Enclosure

Journal of Heat Transfer ◽

10.1115/1.4031178 ◽

2015 ◽

Vol 138 (1) ◽

Cited By ~ 26

Author(s):

R. K. Nayak ◽

S. Bhattacharyya ◽

I. Pop

Keyword(s):

Heat Transfer ◽

Mixed Convection ◽

Entropy Generation ◽

Volume Fraction ◽

Numerical Study ◽

Control Volume ◽

Transport Equations ◽

Bejan Number ◽

Square Enclosure ◽

Wide Range

A numerical investigation of mixed convection due to a copper–water nanofluid in an enclosure is presented. The mixed convection is governed by moving the upper lid of the enclosure and imposing a vertical temperature gradient. The transport equations for fluid and heat are modeled by using the Boussinesq approximation. A modified form of the control volume based SIMPLET algorithm is used for the solution of the transport equations. The fluid flow and heat transfer characteristics are studied for a wide range of Reynolds number and Grashof number so as to have the Richardson number greater or less than 1. The nanoparticle volume fraction is considered up to 20%. Heat flow patterns are analyzed through the energy flux vector. The rate of enhancement in heat transfer due to the addition of nanoparticles is analyzed. The entropy generation and Bejan number are evaluated to demonstrate the thermodynamic optimization of the mixed convection. We have obtained the enhancement rate in heat transfer and entropy generation in nanofluid for a wide range of parameter values.

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Free Convection Heat Transfer and Entropy Generation in an Odd-Shaped Cavity Filled with a Cu-Al2O3 Hybrid Nanofluid

Symmetry ◽

10.3390/sym13010122 ◽

2021 ◽

Vol 13 (1) ◽

pp. 122

Author(s):

Mohammad Ghalambaz ◽

Seyed Mohsen Hashem Zadeh ◽

Ali Veismoradi ◽

Mikhail A. Sheremet ◽

Ioan Pop

Keyword(s):

Heat Transport ◽

Entropy Generation ◽

Volume Fraction ◽

Convection Heat Transfer ◽

Hybrid Nanoparticles ◽

Width Ratio ◽

Hybrid Nanofluid ◽

Bejan Number ◽

Nanoparticles Concentration ◽

Rayleigh Numbers

The present paper aims to analyze the thermal convective heat transport and generated irreversibility of water-Cu-Al2O3 hybrid nanosuspension in an odd-shaped cavity. The side walls are adiabatic, and the internal and external borders of the enclosure are isothermally kept at high and low temperatures of Thand Tc, respectively. The control equations based on conservation laws are formulated in dimensionless form and worked out employing the Galerkin finite element technique. The outcomes are demonstrated using streamlines, isothermal lines, heatlines, isolines of Bejan number, as well as the rate of generated entropy and the Nusselt number. Impacts of the Rayleigh number, the hybrid nanoparticles concentration (ϕhnf), the volume fraction of the Cu nanoparticles to ϕhnf ratio (ϕr), width ratio (WR) have been surveyed and discussed. The results show that, for all magnitudes of Rayleigh numbers, increasing nanoparticles concentration intensifies the rate of entropy generation. Moreover, for high Rayleigh numbers, increasing WR enhances the rate of heat transport.

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Nonhomogeneous Model for the Mixed Convection and Entropy Generation of a Nanofluid in a Lid-Driven Inclined Enclosure With Discrete Heat Source

Journal of Heat Transfer ◽

10.1115/1.4045070 ◽

2019 ◽

Vol 142 (1) ◽

Author(s):

S. Dutta ◽

S. Bhattacharyya ◽

I. Pop

Keyword(s):

Heat Transfer ◽

Mixed Convection ◽

Entropy Generation ◽

Inclination Angle ◽

Volume Fraction ◽

Numerical Study ◽

Homogeneous Model ◽

Staggered Grid ◽

Brownian Diffusion ◽

Bejan Number

Abstract A numerical study on the mixed convection of Al2O3–water nanofluid in a lid-driven inclined square enclosure partially heated from below is performed based on Buongiorno's two phase model. The velocity of the nanoparticles relative to the base fluid is considered due to thermophoresis and Brownian diffusion. The thermophysical properties of the nanofluid are assumed to be dependent on temperature as well as the nanoparticle volume fraction. A control volume method over a staggered grid arrangement is used to discretize the governing equations. The discretized equations of two-dimensional continuity, momentum, energy, and volume fraction are solved through a pressure-correction-based semi-implicit method for pressure linked equations (SIMPLE) algorithm. The effects of relevant parameters such as nanoparticle diameter (25 nm ≤ dp ≤ 90 nm), Richardson number (0.1≤Ri≤5), nanoparticle bulk volume fraction (0 ≤φb≤ 0.05) on the mixed convection of the nanofluid is studied by considering the inclination angle of the enclosure to vary between 0 deg and 60 deg. The entropy generation as well as the Bejan number is evaluated to illustrate the thermodynamic optimization of the mixed convection. Both the heat transfer and entropy generation are higher in the nanofluid compared to the clear fluid and the rate of increment in entropy generation remains lower than the rate by which the heat transfer is augmented in the nanofluid. We find that due to the presence of the Brownian diffusion and thermophoresis in the nonhomogeneous model, a higher heat transfer is yielded as compared to the homogeneous model. The discrepancy between the homogeneous and nonhomogeneous models is significant when the mixed convection is dominated by the shear force. When the mixed convection is dominated by the thermal buoyancy, an increase in positive inclination angle of the enclosure creates a significant increment in the heat transfer.

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Entropy generation of a hybrid nanofluid on MHD mixed convection is a lid-driven cavity with partial heating having two rounded corners

E3S Web of Conferences ◽

10.1051/e3sconf/202132102004 ◽

2021 ◽

Vol 321 ◽

pp. 02004

Author(s):

Zakaria Korei ◽

Smail Benissaad

Keyword(s):

Thermal Conductivity ◽

Reynolds Number ◽

Mixed Convection ◽

Entropy Generation ◽

Volume Fraction ◽

Object Oriented ◽

Reynolds Numbers ◽

Hybrid Nanofluid ◽

Driven Cavity ◽

Partial Heating

This research aims to investigate thermal and flow behaviors and entropy generation of magnetohydrodynamic Al2O3-Cu/water hybrid nanofluid in a lid-driven cavity having two rounded corners. A solver based on C ++ object-oriented language was developed where the finite volume was used. Parameter’s analysis is provided by varying Reynolds numbers (Re), Hartmann numbers (Ha), the volume fraction of hybrid nanofluid (ϕ), radii of the rounded corners. The findings show that reducing the radii of the rounded corners minimizes the irreversibility. Furthermore, the thermal conductivity and dynamic viscosity of hybrid nanofluid contribute to increasing the irreversibility. Finally, the entropy generation is decreased by increasing the Hartman number and increases by rising the Reynolds number.

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Three-dimensional numerical study of mixed convection within a ventilated cavity (Shape ‘ L ‘) crossed by a nanofluid under the effect of a magnetic field

MATEC Web of Conferences ◽

10.1051/matecconf/202030701027 ◽

2020 ◽

Vol 307 ◽

pp. 01027

Author(s):

S. KHERROUBI ◽

K. RAGUI ◽

N. LABSI ◽

Y.K. BENKAHLA ◽

A. BOUTRA

Keyword(s):

Magnetic Field ◽

Mixed Convection ◽

Volume Fraction ◽

Numerical Study ◽

Vertical Wall ◽

Three Dimensional ◽

Convection Heat Transfer ◽

Left Wall ◽

Ventilated Cavity ◽

The Right

The present work is dedicated to the three-dimensional numerical study of mixed convection heat transfer, taking place within a ventilated cavity (of shape L) crossed by Cu-water nanofluid. The enclosure is subjected to the action of a magnetic field. The ventilation is assured by two openings of the same size. The cold flow enters by an opening practiced at the top of the left wall, and exits by another opening practiced at the bottom of the right vertical wall. All the cavity walls are maintained at the same temperature, superior to that of the entering flow, except the side walls which are considered as adiabatic. The control parameters are: the Reynolds number and the Hartmann number as well as the nanoparticles volume fraction.

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Entropy Generation and Natural Convection Flow of Hybrid Nanofluids in a Partially Divided Wavy Cavity Including Solid Blocks

Energies ◽

10.3390/en13112942 ◽

2020 ◽

Vol 13 (11) ◽

pp. 2942 ◽

Cited By ~ 9

Author(s):

Ammar I. Alsabery ◽

Ishak Hashim ◽

Ahmad Hajjar ◽

Mohammad Ghalambaz ◽

Sohail Nadeem ◽

...

Keyword(s):

Entropy Generation ◽

Convection Flow ◽

Hybrid Nanofluid ◽

Bejan Number ◽

The Finite Element Method ◽

Governing Equations ◽

Flow And Heat Transfer ◽

Hybrid Nanofluids ◽

Wavy Cavity ◽

Rayleigh Numbers

The present investigation addressed the entropy generation, fluid flow, and heat transfer regarding Cu-Al 2 O 3 -water hybrid nanofluids into a complex shape enclosure containing a hot-half partition were addressed. The sidewalls of the enclosure are made of wavy walls including cold isothermal temperature while the upper and lower surfaces remain insulated. The governing equations toward conservation of mass, momentum, and energy were introduced into the form of partial differential equations. The second law of thermodynamic was written for the friction and thermal entropy productions as a function of velocity and temperatures. The governing equations occurred molded into a non-dimensional pattern and explained through the finite element method. Outcomes were investigated for Cu-water, Al 2 O 3 -water, and Cu-Al 2 O 3 -water nanofluids to address the effect of using composite nanoparticles toward the flow and temperature patterns and entropy generation. Findings show that using hybrid nanofluid improves the Nusselt number compared to simple nanofluids. In the case of low Rayleigh numbers, such enhancement is more evident. Changing the geometrical aspects of the cavity induces different effects toward the entropy generation and Bejan number. Generally, the global entropy generation for Cu-Al 2 O 3 -water hybrid nanofluid takes places between the entropy generation values regarding Cu-water and Al 2 O 3 -water nanofluids.

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Numerical Study of Combined Radiation and Turbulent Mixed Convection Heat Transfer in a Compartment Containing Participating Media

Journal of Mechanics ◽

10.1017/jmech.2015.24 ◽

2015 ◽

Vol 31 (4) ◽

pp. 467-480 ◽

Cited By ~ 3

Author(s):

A. Asghari ◽

S. A. Gandjalikhan Nassab ◽

A. B. Ansari

Keyword(s):

Mixed Convection ◽

Stokes Equations ◽

Numerical Study ◽

Fluid Dynamic ◽

Convection Heat Transfer ◽

Simple Algorithm ◽

Convection Flow ◽

Algebraic Equations ◽

Mixed Convection Flow ◽

Participating Media

AbstractThe effect of radiation on turbulent mixed convection flow, generated by two plane wall jets with different temperatures inside a cavity was studied numerically. The medium is treated as a gray, absorbing, emitting and scattering. The two-dimensional Reynolds-average Navier-Stokes equations, coupled with the energy equation are solved by using the computational fluid dynamic (CFD) techniques, while the AKN low-Reynolds-number model is employed for computation of turbulence fluctuations. The Boussinesq approximation is used to calculate the buoyancy term, and the radiation part of the problem is solved by numerical solution of the radiative transfer equation (RTE) with the well known discrete ordinate method (DOM). The governing equations are discretized by the finite volume technique into algebraic equations and solved with the SIMPLE algorithm. The effects of radiation conduction parameter, scattering albedo, optical thickness and Richardson number on the thermal behavior of the system are carried out. Results show that the gas radiation has a significant effect on the temperature distribution inside the turbulent mixed convection flow.

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Prandtl Number Effects on the Entropy Generation During the Transient Mixed Convection in a Square Cavity Heated from Below

Periodica Polytechnica Mechanical Engineering ◽

10.3311/ppme.17563 ◽

2021 ◽

Author(s):

Nawal Ferroudj ◽

Hasan Koten ◽

Sacia Kachi ◽

Saadoun Boudebous

Keyword(s):

Heat Transfer ◽

Prandtl Number ◽

Mixed Convection ◽

Entropy Generation ◽

Numerical Study ◽

Convection Heat Transfer ◽

Working Fluid ◽

Square Cavity ◽

Nusselt Numbers ◽

The Impact

This numerical study considers the mixed convection, heat transfer and the entropy generation within a square cavity partially heated from below with moving cooled vertical sidewalls. All the other horizontal sides of the cavity are assumed adiabatic. The governing equations, in stream function–vorticity form, are discretized and solved using the finite difference method. Numerical simulations are carried out, by varying the Richardson number, to show the impact of the Prandtl number on the thermal, flow fields, and more particularly on the entropy generation. Three working fluid, generally used in practice, namely mercury (Pr = 0.0251), air (Pr = 0.7296) and water (Pr = 6.263) are investigated and compared. Predicted streamlines, isotherms, entropy generation, as well as average Nusselt numbers are presented. The obtained results reveal that the impact of the Prandtl number is relatively significant both on the heat transfer performance and on the entropy generation. The average Nusselt number increase with increasing Prandtl number. Its value varies thereabouts from 3.7 to 3.8 for mercury, from 5.5 to 13 for air and, from 12.5 to 15 for water. In addition, it is found that the total average entropy generation is significantly higher in the case of mercury (Pr«1) and water (Pr»1) than in the case of air (Pr~1). Its value varies approximately from 700 to 1100 W/m3 K for mercury, from 200 to 500 W/m3 K for water and, from 0.03 to 5 W/m3 K for air.

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Impact of periodic magnetic source on natural convection and entropy generation of ferrofluids in a baffled cavity

International Journal of Numerical Methods for Heat &amp Fluid Flow ◽

10.1108/hff-10-2020-0671 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Harun Zontul ◽

Hudhaifa Hamzah ◽

Besir Sahin

Keyword(s):

Natural Convection ◽

Entropy Generation ◽

Numerical Study ◽

Magnetic Domain ◽

Vertical Direction ◽

Convection Flow ◽

Bejan Number ◽

Content Type ◽

Domain Structures ◽

Magnetic Source

Purpose This paper aims to exhibit a numerical study to analyze the influence of a periodic magnetic source on free convection flow and entropy generation of a ferrofluid in a baffled cavity. In this study, ferrofluid nanofluid was selected due to its ability to image magnetic domain structures within the cavity. The non-uniform magnetic source is considered as a sinusoidal distribution in the vertical direction. Design/methodology/approach The finite volume technique is used to evaluate the steady two-dimensional partial differential equations that govern the flow with its corresponding boundary conditions. Findings The obtained results indicate that a significant increase in the average Nusselt number can be achieved with the use of the periodic magnetic source instead of a uniform case. In addition, the effectiveness of the adiabatic baffle notably depends on its position and Rayleigh number. Regardless of the values of period and Hartmann numbers, the periodic magnetic source has a higher entropy generation and lower Bejan number than the uniform magnetic source. Originality/value The novelty of this research lies in applying a periodic magnetic source on the natural convection of ferrofluids in a baffled cavity.

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Entropy generation analysis of mixed convection with considering magnetohydrodynamic effects in an open C-shaped cavity

Thermal Science ◽

10.2298/tsci171213112a ◽

2019 ◽

Vol 23 (6 Part A) ◽

pp. 3455-3465 ◽

Cited By ~ 1

Author(s):

Taher Armaghani ◽

Abbas Kasaeipoor ◽

Usef Mohammadpoor

Keyword(s):

Heat Transfer ◽

Aspect Ratio ◽

Mixed Convection ◽

Entropy Generation ◽

Thermal Performance ◽

Volume Fraction ◽

Solid Volume Fraction ◽

Convection Heat Transfer ◽

Coefficient Of Performance ◽

Mixed Convection Heat Transfer

This paper studies the effect of a constant magnetic field on the mixed convection heat transfer and the entropy generation of CuO-water nanofluid in an open C-shaped cavity with a numerical method. The governing equations are presented by control volume method and they are solved simultaneously by the SIMPLE algorithm. This study examines the effect of the Hartman number, aspect ratio, Reynolds number, and Richardson number parameters for different solid volume fraction of nanoparticles. Also Nusselt number, entropy generation, thermal performance criteria and coefficient of performance is studied in this research. The calculated parameters are the Hartman number, aspect ratio, Reynolds number, Richardson number, nanofluid solid volume fraction, Nusselt number, and coefficient of performance. The results show that increasing the Hartmann number reduces the entropy generation. However, the thermal performance increases. Increasing the aspect ratio raises heat transfer and thermal performance. The effects of nanofluid solid volume fraction on mixed convection heat transfer and entropy generation are also investigated and discussed.

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