Entropy generation of mixed convection of SWCNT–water nanofluid filled an annulus with a rotating cylinder and porous lining under LTNE

Çiçek, Oktay; Baytaş, A. Filiz; Baytaş, A. Cihat

doi:10.1108/hff-04-2020-0229

Cited by 8 publications

(6 citation statements)

References 51 publications

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“…At the interface between the porous layer and free nanofluid region (Baytaş and Baytaş, 2017; Çiçek et al , 2020); 0≤x≤c y=d−s …”

Section: Mathematical Formulationmentioning

confidence: 99%

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Nanofluid jet impingement heating of a cooled surface with a constant heat flux in the presence of porous layer

Çiçek

Baytaş

2021

HFF

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Purpose The purpose of this study is to numerically investigate the confined single-walled carbon nanotube-water nanofluid jet impingement heating of a cooled surface with a uniform heat flux in the presence of a porous layer. The analysis of the convective heat transfer mechanism is introduced considering the buoyancy force effect under local thermal non-equilibrium conditions. Design/methodology/approach The governing equations for the nanofluid and solid phase are discretized by the finite volume method and the SIMPLE algorithm is used to solve these equations. Findings It is observed that there is an increase in a local variation of temperature along the upper wall with increasing Reynolds, Darcy and Grashof numbers. For given parameters, the optimum values of thermal conductivity ratio and porous layer thickness leading to better heating on the upper wall are found as Kr = 1.0 and S = 0.5, respectively. The maximum and minimum values of temperature on the upper wall are obtained in the case of higher nanoparticle volume fraction at Re = 100, however, the temperature values get higher along the upper wall with increasing nanoparticle volume fraction at Re = 300. Originality/value The effects of various parameters, such as Reynolds number, Darcy number and Grashof number, on thermal behavior and nanofluid flow are examined to determine the desirable heating conditions for the upper wall. This paper provides a solution to problems such as icing on the surface with a suitable thermal design and optimum geometric configuration.

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“…At the interface between the porous layer and free nanofluid region (Baytaş and Baytaş, 2017; Çiçek et al , 2020); 0≤x≤c y=d−s …”

Section: Mathematical Formulationmentioning

confidence: 99%

“…The non-dimensional initial and boundary conditions are expressed as: At upper surface (Alazmi and Vafai, 2002); 0 ≤ X ≤ C Y = 1 At interface between porous layer and free nanofluid region (Baytaş and Baytaş, 2017; Çiçek et al , 2020): …”

Section: Mathematical Formulationmentioning

confidence: 99%

Nanofluid jet impingement heating of a cooled surface with a constant heat flux in the presence of porous layer

Çiçek

Baytaş

2021

HFF

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“…The local entropy generation number for solid phase is given by (Çiçek and Baytaş, 2020; Çiçek et al , 2020): …”

Section: Mathematical Formulationmentioning

confidence: 99%

Local thermal non-equilibrium conjugate forced convection and entropy generation in an aircraft cabin with air channel partially filled porous insulation

Çiçek

Baytaş

2021

AEAT

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Purpose The purpose of this study is to numerically investigate heat transfer and entropy generation between airframe and cabin-cargo departments in an aircraft. The conjugate forced convection and entropy generation in a cylindrical cavity within air channel partly filled with porous insulation material as simplified geometry for airframe and cabin-cargo departments are considered under local thermal non-equilibrium condition. Design/methodology/approach The non-dimensional governing equations for fluid and porous media discretized by finite volume method are solved using the SIMPLE algorithm with pressure and velocity correction. Findings The effects of the following parameters on the problem are investigated; Reynolds number, Darcy number, the size of inlet and exit cross-section, thermal conductivity ratio for solid and fluid phases, angle between the vertical symmetry axis and the end of channel wall exit and the gap between adiabatic channel wall and horizontal adiabatic wall separating cabin and cargo sections. Originality/value This paper can provide a basic perspective and framework for thermal design between the fuselage and cabin-cargo sections. The minimum total entropy generation number is calculated for various Reynolds numbers and thermal conductivity ratios. It is observed that the channel wall temperature increases for high Reynolds number, low Darcy number, narrower exit cross-section and wider the gap between channel wall and horizontal.

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“…Entropy generation, about the efficiency and thermal performance of thermodynamic systems, emerges as a significant and pertinent subject within the context of convective processes involving the flow of hybrid nanofluids. Çiçek et al (2021) scrutinized the EGM of mixed convection for SWCNT–water nanofluid flow in an annulus with the heat-generating porous layer using the local thermal non-equilibrium approach. Dutta et al (2022) studied the mixed convection of Al 2 O 3 –Fe 3 O 4 Bingham plastic hybrid nanofluid in a ventilated enclosure.…”

Section: Introductionmentioning

confidence: 99%

Entropy generation minimization of hybrid nanofluid mixed convection flow in lid-driven square enclosure with heat-generating porous layer on inner walls

Çiçek,

Baytaş,

Baytaş

2023

HFF

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Purpose This study aims to numerically scrutinize the entropy generation minimization and mixed convective heat transfer of multi-walled carbon nanotubes–Fe3O4/water hybrid nanofluid flow in a lid-driven square enclosure with heat generation in the presence of a porous layer on inner surfaces, considering local thermal non-equilibrium (LTNE) approach and the non-Darcy flow model. Design/methodology/approach The dimensionless governing equations for hybrid nanofluid and solid phases are solved by applying the finite volume method and semi-implicit method for pressure-linked equations algorithm. Findings The roles of the internal heat generation in the porous layer, LTNE model and nanoparticles volume fraction on mixed convection phenomenon and entropy generation are introduced for lid-driven cavity hybrid nanofluid flow. Based on the investigation of entropy generation and heat transfer, the minimum total entropy generation and average Nusselt numbers are found at 1 ≤ Ri ≤ 10 where the effect of the forced and free convection flow directions being opposite each other is very significant. When considering various nanoparticle volume fractions, it becomes evident that the minimum entropy generation occurs in the case of φ = 0.1%. The outcomes of LTNE number reveal the operating parameters in which thermal equilibrium occurs between hybrid nanofluid and solid phases. Originality/value The analysis of entropy generation under various shear and buoyancy forces plays a significant role in the suitable thermal design and optimization of mixed convective heat transfer applications. This research significantly contributes to the optimization of design and the advancement of innovative solutions across diverse engineering disciplines, such as packed-bed thermal energy storage and thermal insulation.

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Entropy generation of mixed convection of SWCNT–water nanofluid filled an annulus with a rotating cylinder and porous lining under LTNE

Cited by 8 publications

References 51 publications

Nanofluid jet impingement heating of a cooled surface with a constant heat flux in the presence of porous layer

Nanofluid jet impingement heating of a cooled surface with a constant heat flux in the presence of porous layer

Local thermal non-equilibrium conjugate forced convection and entropy generation in an aircraft cabin with air channel partially filled porous insulation

Entropy generation minimization of hybrid nanofluid mixed convection flow in lid-driven square enclosure with heat-generating porous layer on inner walls

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