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Article
Publication date: 30 April 2020

Darya Loenko, Aroon Shenoy and Mikhail Sheremet

This paper aims to study the mathematical modeling of passive cooling systems for electronic devices. Improving heat transfer is facilitated by the correct choice of the working…

85

Abstract

Purpose

This paper aims to study the mathematical modeling of passive cooling systems for electronic devices. Improving heat transfer is facilitated by the correct choice of the working fluid and the geometric configuration of the engineering cavity; therefore, this work is devoted to the analysis of the influence of the position of the heat-generating element and the tilted angle of the electronic cabinet on the thermal convection of a non-Newtonian fluid.

Design/methodology/approach

The area of interest is a square cavity with two cold vertical walls, while the horizontal boundaries are adiabatic. An element of constant volumetric heat generation is placed on the lower wall of the chamber. The problem is described by Navier–Stokes partial differential equations using dimensionless stream function and vorticity. The numerical solution is based on the developed computational code using the finite difference technique and a uniform rectangular grid.

Findings

The key conclusions of this work are the results of a detailed analysis of streamlines and isotherms, the average Nusselt number and profiles of the average heater temperature. It was found that more intensive cooling of the heat-generating element occurs when the cavity is filled with a pseudoplastic fluid (n < 1) and not inclined (α = 0). The Rayleigh number of Ra = 105 and the thermal conductivity ratio of k = 100 are characterized by the most positive effect.

Originality/value

The originality of the research lies in both the study of thermal convection in a square chamber filled with power-law fluid under the influence of a volumetric heat production element and the analysis of the influence of geometric and thermophysical parameters characterizing the considered process.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 11 July 2019

Mikhail A. Sheremet, Ioan Pop and A. Cihat Baytas

This study aims to numerically analyze natural convection of alumina-water nanofluid in a differentially-heated square cavity partially filled with a heat-generating porous…

236

Abstract

Purpose

This study aims to numerically analyze natural convection of alumina-water nanofluid in a differentially-heated square cavity partially filled with a heat-generating porous medium. A single-phase nanofluid model with experimental correlations for the nanofluid viscosity and thermal conductivity has been considered for the description of the nanoparticles transport effect in the present study. Local thermal non-equilibrium approach for the porous layer with the Brinkman-extended Darcy model has been used.

Design/methodology/approach

Dimensionless governing equations formulated using stream function, vorticity and temperature have been solved by the finite difference method. The effects of the Rayleigh number, Ostrogradsky number, Nield number and nanoparticles volume fraction on nanofluid flow, heat and mass transfer have been analyzed.

Findings

It has been revealed that the dimensionless heat transfer coefficient at the fluid/solid matrix interface can be a very good control parameter for the convective flow and heat transfer intensity. The present results are original and new for the study of non-equilibrium natural convection in a differentially-heated nanofluid cavity partially filled with a porous medium.

Originality/value

The results of this paper are new and original with many practical applications of nanofluids in the modern industry.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 8
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 18 July 2023

Alin V. Roşca, Natalia C. Roşca, Ioan Pop and Mikhail A. Sheremet

This paper aims to study numerically the steady natural convective heat transfer of a hybrid nanosuspension (Ag-MgO/H2O) within a partially heated/cooled trapezoidal region with…

190

Abstract

Purpose

This paper aims to study numerically the steady natural convective heat transfer of a hybrid nanosuspension (Ag-MgO/H2O) within a partially heated/cooled trapezoidal region with linear temperature profiles at inclined walls under an effect of uniform Lorentz force. This investigation is useful for researchers studying in the area of cavity flows to know features of the flow structures and nature of hybrid nanofluid characteristics. In addition, a detailed entropy generation analysis has been performed to highlight possible regimes with minimal entropy generation rates.

Design/methodology/approach

The governing equations formulated using the Oberbeck–Boussinesq approach and single-phase nanoliquid model are transformed to a non-dimensional form by using non-dimensional variables. The obtained equations with appropriate boundary conditions are resolved by the finite difference technique. The developed code has been validated comprehensively. Analysis has been performed for a wide range of governing parameters, including Rayleigh number (Ra = 105), Prandtl number (Pr = 6.82), Hartmann number (Ha = 0–100), magnetic field inclination angle (φ = 0–?/2) and nanoparticles volume fraction (φhnf = 0 and 2%).

Findings

It has been shown that inclined magnetic field can be used to manage the energy transport performance. An inclusion of nanoparticles without Lorentz force influence allows forming more stable convective regime with descending heat plume in the central zone, while such a regime was performed for clear fluid only for moderate and high Hartmann numbers. Moreover, the average overall entropy generation can be decreased with a growth of the Hartmann number, while an addition of hybrid nanoparticles allows reducing this parameter for Ha = 30 and 50. The average Nusselt number can be increased with a growth of the nanoparticles concentration for low values of the magnetic field intensity.

Originality/value

Governing equations written using the conservation laws and dimensionless non-primitive variables have been resolved by the finite difference approach. The created numerical code has been verified by applying the grid independence test and computational outcomes of other researchers. The comprehensive analysis for various key parameters has been performed.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 34 no. 2
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 12 September 2008

M.A. Shenoy and D.J. D'Melo

The purpose of this paper is to study the effect of acrylated guar gum (GG) compared with GG in acrylic emulsions with reference to its viscosity, film properties such as…

245

Abstract

Purpose

The purpose of this paper is to study the effect of acrylated guar gum (GG) compared with GG in acrylic emulsions with reference to its viscosity, film properties such as mechanical strength, weathering properties and clarity.

Design/methodology/approach

The acrylate derivatives were synthesised and characterised and then incorporated in acrylic emulsions and their rheology studied. Films were analysed for their clarity and mechanical properties. The films were then subjected to UV radiation and the influence of these additives on the weathering properties was studied.

Findings

The viscosity of acrylated GGs in emulsions was lower than that of GG in emulsion because of the increased hydrophobic nature and hence reduced water‐binding capacity. The mechanical properties of acrylated GGs were superior compared with GG due to increased compatibility of the additive with the polymer binder. This was further confirmed with increased clarity of the films. Acrylated GG was found to act as a protective additive with reference to UV degradation of the coatings.

Research limitations/implications

The performance of these additives was analysed on un‐pigmented coating formulations, which may not conform with pigmented coatings.

Practical implications

These biodegradable additives synthesised from renewable resources could be used to increase the mechanical strength as UV stabilisers and in some cases also as rheology modifiers.

Originality/value

The use of acrylated polysaccharides to increase mechanical and weathering properties allows the use of biodegradable, renewable resources as opposed to petroleum‐based compounds.

Details

Pigment & Resin Technology, vol. 37 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 25 February 2014

Dawid J. D'Melo, Anagha S. Sabnis, Mohan A. Shenoy and Mukesh S. Kathalewar

The purpose of this paper is to evaluate the efficiency of acrylated guar gum (AGG) as an additive in alkyd resin for improved mechanical properties and to optimize the results of…

94

Abstract

Purpose

The purpose of this paper is to evaluate the efficiency of acrylated guar gum (AGG) as an additive in alkyd resin for improved mechanical properties and to optimize the results of such an addition.

Design/methodology/approach

For studying the effect of AGG on coating properties, guar gum was modified to various degrees of esterification and various compositions of alkyd systems were made by incorporating different concentrations of AGG. The mechanical and solvent absorption of the unmodified and modified alkyd systems were characterized.

Findings

The incorporation of AGG into alkyd coating showed significant improvement of mechanical properties over the unmodified one. The modification caused an additional crosslink site through its unsaturation which led to increased crosslink density without phase separation of additive from the alkyd system which was confirmed by SEM scans.

Research limitations/implications

The reactive additive, AGG used in the present study was synthesised using acryloyl chloride. Besides, it could also be synthesised from methacryloyl chloride and the effect of methyl substitution on water and solvent absorption could be studied.

Practical implications

The method developed provided a simple and practical solution to improving the mechanical properties of alkyd coatings.

Originality/value

The method for enhancing mechanical properties of cured alkyd system was novel and could find numerous applications in surface coatings.

Details

Pigment & Resin Technology, vol. 43 no. 2
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 3 July 2020

Mikhail A. Sheremet, Teodor Grosan and Ioan Pop

The purpose of this paper is to study numerically the steady thermal convection in a chamber filled with a nanoliquid affected by a chemical reaction using the single-phase…

103

Abstract

Purpose

The purpose of this paper is to study numerically the steady thermal convection in a chamber filled with a nanoliquid affected by a chemical reaction using the single-phase nanofluid approximation.

Design/methodology/approach

Water was considered as a host fluid while nanoparticles are aluminum oxide. Homogeneous reactions are analyzed. The nonlinear partial differential equations describing the considered problem are simulated using the finite difference technique.

Findings

The results of streamlines, isotherms, isoconcentrations, nanofluid flow rate, mean Nusselt and Sherwood numbers are discussed. The data demonstrate that the mean Sherwood number increases with the homogeneous reaction rate. Further, nanofluid flow rate can be increased with nanoparticles concentration for high Rayleigh numbers owing to the homogeneous chemical reaction inside the cavity.

Originality/value

Searching the existent references illustrates that the homogeneous-heterogeneous reactions influence on the nanoliquid motion and energy transport within enclosures has not been investigated before. The results of this paper are completely original and the numerical results of the present paper were never published by any researcher.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 November 2006

M.A. Shenoy, A. Sabnis and D.J. D'Melo

To study the effect of addition of free diols and triols in the coating formulation on coating properties.

1752

Abstract

Purpose

To study the effect of addition of free diols and triols in the coating formulation on coating properties.

Design/methodology/approach

Polyester resins were synthesised from maleic anhydride, dimerised fatty acid, neopentyl glycol and tris (2‐hydroxyethyl) isocyanurate (THEIC). Then, ethylene glycol, propylene glycol, glycerol, trimethylol propane and THEIC were added as reactive components to the coating formulation. These coatings were then analysed for various coating properties and compared with those obtained with the base resins.

Findings

The coatings obtained with the addition of these reactive components were found to have improved properties compared with those of the base resins except in cases where the reactive component itself contributed to a reduction in performance, e.g. reduced alkali resistance with the addition of THEIC.

Research limitations/implications

The addition of the free diols and triols required a corresponding increase in the amount of the curing agent to be added.

Practical implications

This process would allow for the tailoring of coatings to suit requirements to a certain extent without modifying the base resin. The addition of low molecular weight components in the coating formulation, which is then incorporated in coatings, could reduce the solvent requirement.

Originality/value

Although polyesters are an established polymeric system in coatings, the use of reactive diluents has not been investigated with the exception of unsaturated polyesters, whose curing chemistry is fundamentally different from that of polyesters focused on in this paper.

Details

Pigment & Resin Technology, vol. 35 no. 6
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 20 June 2018

Mikhail Sheremet and Sivaraj Chinnasamy

The purpose of this study is to examine the radiation effect on the natural convective heat transfer of an alumina–water nanofluid in a square cavity in the presence of centered…

99

Abstract

Purpose

The purpose of this study is to examine the radiation effect on the natural convective heat transfer of an alumina–water nanofluid in a square cavity in the presence of centered nonuniformly heated plate.

Design/methodology/approach

The square cavity filled with alumina–water nanofluid has a nonuniformly heated plate placed horizontally or vertically at its center. The plate is heated isothermally with linearly varying temperature. The vertical walls are cooled isothermally with a constant temperature, while the horizontal walls are insulated. The governing equations have been discretized using finite volume method on a uniformly staggered grid system. Simulations were carried out for different values of the heated plate nonuniformity parameter (λ = –1, 0 and 1), the nanoparticles solid volume fraction (Φ = 0.01 − 0.04) and the radiation parameter (Rd = 0 – 2) at the Rayleigh number of Ra = 1e+07.

Findings

It is found that the total heat transfer rate is enhanced with an increase in the radiation parameter for both the horizontal and vertical plates. The role of nanoparticles addition to the base fluid can have dual effects on the heat transfer rate by augmenting and dampening for the absence of radiation while it dampens the heat transfer rate for the presence of radiation.

Originality/value

The originality of this work is to analyze steady natural convection in a square cavity filled with a water-based nanofluid in the presence of centered nonuniformly heated plate. The results would benefit scientists and engineers to become familiar with the analysis of convective heat and mass transfer in nanofluids, and the way to predict the properties of nanofluid convective flow in advanced technical systems, in industrial sectors including transportation, power generation, chemical sectors, electronics, etc.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 28 no. 6
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 28 September 2018

Mikhail A. Sheremet, Marina S. Astanina and Ioan Pop

The purpose of this paper is a numerical analysis of natural convection in a square porous cavity filled with a water-based magnetic fluid of geothermal viscosity under the effect…

124

Abstract

Purpose

The purpose of this paper is a numerical analysis of natural convection in a square porous cavity filled with a water-based magnetic fluid of geothermal viscosity under the effect of inclined uniform magnetic field.

Design/methodology/approach

The domain of interest includes the square porous cavity filled with a water-based magnetic fluid (W40). Horizontal walls are supposed to be adiabatic, while right vertical wall is kept at constant low temperature and left vertical wall is kept at constant high temperature. An inclined uniform magnetic field affects the fluid flow and heat transfer inside the cavity. The viscosity of the working fluid is proportional to the linearly decreasing function of depth (vertical coordinate) and inversely proportional to the linear function of temperature. It is assumed in the analysis that the flow is laminar. The fluid is Newtonian and the Boussinesq approximation is valid. The governing equations have been discretized using the finite difference method with the uniform grid. Simulations have been carried out for different values of the Rayleigh number, Hartmann number, Darcy number, magnetic field inclination angle and viscosity variation parameters.

Findings

It has been revealed that an increase in the viscosity parameters leads to the heat transfer enhancement and convective flow intensification. At the same time, this intensification is more essential for high values of the Rayleigh number.

Originality/value

The originality of this work is to analyze MHD natural convection in a square porous cavity filled with a water-based magnetic fluid of geothermal viscosity. The results would benefit scientists and engineers to become familiar with the analysis of convective heat and mass transfer in nanofluids, and the way to predict the properties of nanofluid convective flow in advanced technical systems, in industrial sectors including transportation, power generation, chemical sectors and electronics.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 28 no. 9
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 3 October 2019

Mikhail A. Sheremet, Hakan F. Öztop and Nidal Abu-Hamdeh

The purpose of this study is to work on heat transfer enhancement within different engineering cavities is the major aim of most technical solutions. Such intensification can be…

105

Abstract

Purpose

The purpose of this study is to work on heat transfer enhancement within different engineering cavities is the major aim of most technical solutions. Such intensification can be obtained by using “smart” liquids known as nanoliquids and solid fins. Therefore, free convective thermal transmission within square nanoliquid chamber under the influence of complex fins is studied. The considered fins are the combination of wall-mounted adiabatic fin and an adiabatic block over this fin.

Design/methodology/approach

Influences of the Rayleigh number, location of the local adiabatic block and nanoparticles concentration on liquid motion and energy transport are studied. Finite difference technique was used to solve the governing equations.

Findings

It has been ascertained that the energy transport intensification can be reached for the middle position of this local block within the cavity.

Originality/value

The main originality of this work is to use intermittent block in a nanofluid filled cavity under differentially heated conditions. One constant and location of one of the passive element is constant and other one is fixed, which is the intermittent block, is used to control heat and fluid flow. Thus, distance between blocks is allowed to control of the velocity and kinetic energy. In this way, temperature distribution also can be controlled inside the square cross-sectional closed space. Another originality of the work is to use nanoparticle added main flow for this geometry. Thus, energy efficiency can be controlled via adiabatic intermittent blocks without spending any extra energy.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 3
Type: Research Article
ISSN: 0961-5539

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