Heat transfer and entropy generation of natural convection on non-Newtonian nanofluids in a porous cavity

Kefayati, Gholamreza

doi:10.1016/j.powtec.2016.05.032

Cited by 148 publications

(44 citation statements)

References 72 publications

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“…The subscripts 'p', 'f ' and 'nf ' indicate nanoparticles, base uids and nano uids respectively. Equation (3) has been adopted to determine the e ective thermal conductivity of aqueous solutions with spherical nanoparticles [20].…”

Section: Physical Properties Of Non-newtonian Fluidmentioning

confidence: 99%

“…It was found that the local Nusselt number at the interface of solid wall and porous medium is directly related to ve key parameters. The Finite Di erence Lattice Boltzmann Method was rst used to conduct the research of heat transfer and entropy behavior by Kefayati et al [3]. This work simulated the natural convection of non-Newtonian laminar ow in a square-shaped porous cavity.…”

Section: Introductionmentioning

confidence: 99%

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Flow Characteristic and Heat Transfer for Non-Newtonian Nanofluid in Rectangular Microchannels with Teardrop Dimples/Protrusions

et al. 2017

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Porous cavity technology is one of the e ective ways to improve local ow structures and thus the overall heat transfer of heat exchanging devices. In the present investigation, the ow characteristics and heat transfer in a microchannel heat sink with teardrop dimples/protrusions are studied with a numerical method. The working substances are Al O -water nano uids, which are de ned by power-law shear-thinning model. The relative depth and positive eccentricity of dimples/protrusions arranged in the microchannels are 0.2 and 0.3 respectively. The inlet velocity varies in the range of 1.41 m·s − to 8.69 m·s − and the volume fraction ranges from 0.5% to 3.5%. The e ects of the ow and heat transfer characteristics are investigated by analyzing the limiting streamlines structures and temperature distributions. The overall thermal performance is evaluated by parameters of Fanning friction factor, Nusselt number and thermal performance. It is shown that the combination of teardrop dimple/protrusion structure and Al O -water nano uids could e ectively strengthen heat transfer with low pressure loss. Moreover, in order to obtain the best overall thermal performance, working substances with volume faction of 3.5% is preferred for the proposed microchannel structure.

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Section: Physical Properties Of Non-newtonian Fluidmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Flow Characteristic and Heat Transfer for Non-Newtonian Nanofluid in Rectangular Microchannels with Teardrop Dimples/Protrusions

et al. 2017

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“…There have been many other researches on the Nanofluid such as Refs. [27][28][29][30][31][32][33][34]. Some other studies on the entropy generation and flows with heat transfer, which we regard them as natural and forced convection, could be found in the works of Haddad et al [31], Khalkhali et al [32], Abu-Hijleh et al [33], Abu-Hijleh and Heilen [34] and Mahmud and Island [35].…”

Section: Introductionmentioning

confidence: 99%

Different shapes of Fe3O4 nanoparticles on the free convection and entropy generation in a wavy-wall square cavity filled by power-law non-Newtonian nanofluid

Hatami¹

2018

IJHT

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The goal of this paper is to investigate the influences of Nanoparticles volume fraction, Nanoparticles shape, amplitude and wavelength of wavy surface, Hartmann number and the Angle of magnetic field on the Nusselt number, Bejan number and the entropy generation rate in a wavy wall cavity, numerically. The nanoparticles are considered Fe3O4 which are magnetic in presence of magnetic and the base fluid is considered as a power-law non-Newtonian nanofluid which its density variation is approximated by the standard Boussinesq model. The wavy wall is maintained in low temperatures while the right wall has high temperature and up/down walls is insulated. The problem is solved by finite element method using FlexPDE commercial code and found that the highest average Nusselt number is observed for the Nanofluid with brick shaped particles; however, the Nanofluid with spherical shaped particles is found to have the lowest Nusselt. Furthermore, Minimum and maximum Bejan numbers were observed for brick and spherical nanoparticles, respectively.

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“…Mahin et al [13] estimated, both theoretically and experimentally, the values of the average Nusselt number and heat transfer coe cient ratio for natural convection of silica-water nano uid in the square or triangular cavities. Kefayati [14] utilized the Finite Di erence Lattice Boltzmann Method (FDLBM) to study heat transfer and the entropy generation of non-Newtonian nano uids in a porous square cavity. His results show that heat transfer and entropy generation increase as Rayleigh number enhances.…”

Section: Introductionmentioning

confidence: 99%

Natural convection and entropy generation of ultrafine atmospheric aerosols in the presence of hydrodynamic partial slip and thermal radiation due to solar energy

Ghaffarpasand

2017

Scientia Iranica

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Abstract. Combined e ects of hydrodynamic partial slip, thermal radiation due to solar energy, and nanoparticles volume fraction on natural convection and entropy generation of atmospheric ultra ne aerosols sample enclosed within a two-sided lid-driven cavity are studied numerically in the present contribution. Partial slip e ect is taken into account along the two horizontal moving walls, and thermal radiation is considered through Rosseland approximation. The governing equations are solved using an accurate nite volume method based on SIMPLE algorithm. The impact of Brownian motion of nanoparticles is also considered in this study, whereby KKL (Koo-Kleinstreuer-Li) correlation is utilized for simulating the e ective thermal conductivity and viscosity of nano uid. The heatline visualization technique is also utilized to study the energy ux within the cavity. A comprehensive study is conducted on the controlling parameters, including partial slip coe cient ( = 0 5), radiation parameter (Rd = 0 2), and nanoparticles volume fraction ( = 0 4%), which in uence the ow and heat transfer characteristics. Results show that the partial slip usually eliminates the e ect of mechanical forces provoked by the moving lids. Moreover, thermal radiation homogenizes the medium thermally, which results in decreasing the average entropy generation. It is also observed that the e ect of carbon-black nanoparticles on the atmospheric heat transfer manifests a wide variety of fashions mainly dependent on the presence or absence of thermal radiation due to solar energy.

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Heat transfer and entropy generation of natural convection on non-Newtonian nanofluids in a porous cavity

Cited by 148 publications

References 72 publications

Flow Characteristic and Heat Transfer for Non-Newtonian Nanofluid in Rectangular Microchannels with Teardrop Dimples/Protrusions

Flow Characteristic and Heat Transfer for Non-Newtonian Nanofluid in Rectangular Microchannels with Teardrop Dimples/Protrusions

Different shapes of Fe3O4 nanoparticles on the free convection and entropy generation in a wavy-wall square cavity filled by power-law non-Newtonian nanofluid

Natural convection and entropy generation of ultrafine atmospheric aerosols in the presence of hydrodynamic partial slip and thermal radiation due to solar energy

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