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Article
Publication date: 3 December 2021

Shiva Singh and Subrata Kumar Ghosh

The study aims to use nanofluids as coolants for improving heat transfer peculiarities of plate heat exchangers (PHE). The experimental and numerical investigations are…

Abstract

Purpose

The study aims to use nanofluids as coolants for improving heat transfer peculiarities of plate heat exchangers (PHE). The experimental and numerical investigations are thoroughly performed using distilled water-based Al2O3, graphene nanoplatelet (GnP) and multi-walled carbon nanotubes (MWCNT) nanofluids.

Design/methodology/approach

The numerical simulation based on Single Phase Model (SPM) was performed on a realistic 3 D model of PHE having similar dimensions as of the actual plate. The standard k-epsilon turbulent model was used to solve the problem. The concentration and flow rate of nanofluids were ranging from 0.1 to 1 Vol.% and 1 to 5 lpm, respectively, at 30°C. Whereas, hot side fluid is distilled water at 2 lpm and 80°C. The heat transfer characteristics such as bulk cold outlet temperature, heat transfer rate (HTR), heat transfer coefficient (HTC), Nusselt number (Nu), pressure drop, pumping power, effectiveness and exergy loss were experimentally evaluated using nanofluids in a PHE.

Findings

The experimental results were then compared with the numerical model. The experimental results revealed maximum enhancement in an average heat transfer rate of 9.86, 14.86 and 17.27% using Al2O3, GnP and MWCNT nanofluids, respectively, at 1 Vol.%. The present computational fluid dynamics model accurately predicts HTR, and the results deviate <1.1% with experiments for all the cases. The temperature and flow distribution show promising results using nanofluids.

Originality/value

The study helps to visualise heat transfer and flow distribution in PHE using different nanofluids under different operating conditions.

Details

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

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Article
Publication date: 19 July 2021

Priyanka Agrawal, Praveen Kumar Dadheech, R.N. Jat, Dumitru Baleanu and Sunil Dutt Purohit

The purpose of this paper is to study the comparative analysis between three hybrid nanofluids flow past a permeable stretching surface in a porous medium with thermal…

Abstract

Purpose

The purpose of this paper is to study the comparative analysis between three hybrid nanofluids flow past a permeable stretching surface in a porous medium with thermal radiation. Uniform magnetic field is applied together with heat source and sink. Three set of different hybrid nanofluids with water as a base fluid having suspension of Copper-Aluminum Oxide (CuAl2O3), Silver-Aluminum Oxide (AgAl2O3) and Copper-Silver (CuAg) nanoparticles are considered. The Marangoni boundary condition is applied.

Design/methodology/approach

The governing model of the flow is solved by Runga–Kutta fourth-order method with shooting technique, using appropriate similarity transformations. Temperature and velocity field are explained by the figures for many flow pertinent parameters.

Findings

Almost same behavior is observed for all the parameters presented in this analysis for the three set of hybrid nanofluids. For increased mass transfer wall parameter ( fw) and Prandtl Number (Pr), heat transfer rate cuts down for all three sets of hybrid nanofluids, and reverse effect is seen for radiation parameter (R), and heat source/sink parameter ( δ).

Practical implications

The thermal conductivity of hybrid nanofluids is much larger than the conventional fluids; thus, heat transfer efficiency can be improved with these fluids and its implications can be seen in the fields of biomedical, microelectronics, thin-film stretching, lubrication, refrigeration, etc.

Originality/value

The current analysis is to optimize heat transfer of three different radiative hybrid nanofluids ( CuAl2O3/H2O, AgAl2O3/H2O and CuAg/H2O) over stretching surface after applying heat source/sink with Marangoni convection. To the best of the authors’ knowledge, this work is new and never published before.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 8
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 14 June 2021

LiJun Zhang, Tayyaba Nazar, M.M. Bhatti and Efstathios E. Michaelides

The flow and heat transfer of a hybrid nanofluid composed of kerosene and ZnO-Al2O3 nanoparticles (NPs) is investigated. The flow occurs over complex surfaces with…

Abstract

Purpose

The flow and heat transfer of a hybrid nanofluid composed of kerosene and ZnO-Al2O3 nanoparticles (NPs) is investigated. The flow occurs over complex surfaces with stretching and shrinking features. The base fluid is electrically conducting, and an external magnetic field is added so that the nanofluid and the electric field are in equilibrium. Irrotational flow with viscous dissipation effects is considered.

Design/methodology/approach

The governing equations of the system are formulated, and a similarity transformation is used to convert the system of equations into ordinary differential equations, which are solved numerically. The friction coefficient of the flow and the Nusselt number are calculated for a wide range of parameters, and the results are presented in graphical form. In addition, dual solutions of the problem were noticed to occur for a certain range of the unsteadiness parameter. A stability analysis has been performed and presented to elucidate the behavior of these dual solutions.

Findings

For the solution of the upper branch, the velocity and temperature profiles of the nanofluid are enhanced by increasing the magnetic field parameter M, but the same variables decrease in the solution of the lower branch. The same trend is detected for the velocity of the fluid with the suction parameter. The temperature of the nanofluid decreases in both branches of the solution by increasing the Prandtl number. Similarly, they decrease with the suction parameter. The temperature of the nanofluid slightly increases in both branches of the solution by increasing the Eckert number. With the stability analysis the authors performed, it was determined that the solution is stable in the upper branch, but unstable in the lower branch.

Originality/value

The kerosene nanofluid with hybrid Zinc/Aluminum-oxide is presented for the first time in the literature.

Details

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

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Article
Publication date: 7 May 2021

Mohammad M. Rahman, Ziad Saghir and Ioan Pop

This paper aims to investigate numerically the free convective heat transfer efficiency inside a rectotrapezoidal enclosure filled with Al2O3–Cu/water hybrid fluid. The…

Abstract

Purpose

This paper aims to investigate numerically the free convective heat transfer efficiency inside a rectotrapezoidal enclosure filled with Al2O3–Cu/water hybrid fluid. The bottom wall of the cavity is uniformly heated, the upper horizontal wall is insulated, and the remaining walls are considered cold. A new thermophysical relation determining the thermal conductivity of the hybrid nanofluid has been established, which produced results those match with experimental ones.

Design/methodology/approach

The governing partial differential equations are solved using the finite element method of Galerkin type. The simulated results in terms of streamlines, heat lines and isotherms are displayed for various values of the model parameters, which govern the flow.

Findings

The Nusselt number, friction factor and the thermal efficiency index are also determined for the pertinent parameters varying different ratios of the hybrid nanoparticles. The simulated results showed that thermal buoyancy significantly controls the heat transfer, friction factor and thermal efficiency index. The highest thermal efficiency is obtained for the lowest Rayleigh number.

Practical implications

This theoretical study is significantly relevant to the applications of the hybrid nanofluids electronic devices cooled by fans, manufacturing process, renewable energies, nuclear reactors, electronic cooling, lubrication, refrigeration, combustion, medicine, thermal storage, etc.

Originality/value

The results showed that nanoparticle loading intensified the rate of heat transfer and thermal efficiency index at the expense of the higher friction factor or higher pumping power. The results further show that the heat transmission in Al2O3–Cu/water hybrid nanofluid at a fixed value of intensified $\phi_{hnf}$ compared to the Al2O3/water nanofluid when an amount of higher conductivity nanoparticles (Cu) added to it. Besides, the rate of heat transfer in Cu/water nanofluid declines when the lower thermal conductivity Al2O3 nanoparticles are added to the mixture.

Details

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

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Article
Publication date: 14 June 2021

Pascalin Tiam Kapen, Cédric Gervais Njingang Ketchate, DIdier Fokwa and Ghislain Tchuen

This paper aims to investigate a linear and temporal stability analysis of hybrid nanofluid flow between two parallel plates filled with a porous medium and whose lower…

Abstract

Purpose

This paper aims to investigate a linear and temporal stability analysis of hybrid nanofluid flow between two parallel plates filled with a porous medium and whose lower plate is fixed and the upper plate animated by a uniform rectilinear motion.

Design/methodology/approach

The nanofluid is composed of water as a regular fluid, silver (Ag) and alumina (Al2O3) as nanoparticles. The mathematical model takes into account other effects such as the magnetic field and the aspiration (injection/suction). Under the assumption of a low magnetic Reynolds number, a modified Orr–Sommerfeld-type eigenvalue differential equation governing flow stability was derived and solved numerically by Chebyshev’s spectral collocation method. The effects of parameters such as volume fraction, Darcy number, injection/suction Reynolds number, Hartmann number were analyzed.

Findings

It was found the following: the Darcy number affects the stability of the flow, the injection/suction Reynolds number has a negligible effect, the volume fraction damped disturbances and the magnetic field plays a very important role in enlarging the area of flow stability.

Originality/value

The originality of this work resides in the linear and temporal stability analysis of hydromagnetic Couette flow for hybrid nanofluid through porous media with small suction and injection effects.

Details

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

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Article
Publication date: 17 May 2021

Fazle Mabood, Anum Shafiq, Waqar Ahmed Khan and Irfan Anjum Badruddin

This study aims to investigate the irreversibility associated with the Fe3O4–Co/kerosene hybrid-nanofluid past a wedge with nonlinear radiation and heat source.

Abstract

Purpose

This study aims to investigate the irreversibility associated with the Fe3O4–Co/kerosene hybrid-nanofluid past a wedge with nonlinear radiation and heat source.

Design/methodology/approach

This study reports the numerical analysis of the hybrid nanofluid model under the implications of the heat source and magnetic field over a static and moving wedge with slips. The second law of thermodynamics is applied with nonlinear thermal radiation. The system that comprises differential equations of partial derivatives is remodeled into the system of differential equations via similarity transformations and then solved through the Runge–Kutta–Fehlberg with shooting technique. The physical parameters, which emerges from the derived system, are discussed in graphical formats. Excellent proficiency in the numerical process is analyzed by comparing the results with available literature in limiting scenarios.

Findings

The significant outcomes of the current investigation are that the velocity field uplifts for higher velocity slip and magnetic strength. Further, the heat transfer rate is reduced with the incremental values of the Eckert number, while it uplifts with thermal slip and radiation parameters. An increase in Brinkmann’s number uplifts the entropy generation rate, while that peters out the Bejan number. The results of this study are of importance involving in the assessment of the effect of some important design parameters on heat transfer and, consequently, on the optimization of industrial processes.

Originality/value

This study is original work that reports the hybrid nanofluid model of Fe3O4–Co/kerosene.

Details

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

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Article
Publication date: 14 June 2021

Faraz Afshari, Azim Doğuş Tuncer, Adnan Sözen, Halil Ibrahim Variyenli, Ataollah Khanlari and Emine Yağız Gürbüz

Using suspended nanoparticles in the base fluid is known as one of the most efficient ways for heat transfer augmentation and improving the thermal efficiency of various…

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Abstract

Purpose

Using suspended nanoparticles in the base fluid is known as one of the most efficient ways for heat transfer augmentation and improving the thermal efficiency of various heat exchangers. Different types of nanofluids are available and used in different applications. The main purpose of this study is to investigate the effects of using hybrid nanofluid and number of plates on the performance of plate heat exchanger. In this study, TiO2/water single nanofluid and TiO2-Al2O3/water hybrid nanofluid with 1% particle weight ratio have been used to prepare hybrid nanofluid to use in plate type heat exchangers with three various number of plates including 8, 12 and 16.

Design/methodology/approach

The experiments have been conducted with the aim of examining the impact of plates number and used nanofluids on heat transfer enhancement. The performance tests have been done at 40°C, 45°C, 50°C and 55°C set outlet temperatures and in five various Reynolds numbers between 1,600 and 3,800. Also, numerical simulation has been applied to verify the heat and flow behavior inside the heat exchangers.

Findings

The results indicated that using both nanofluids raised the thermal performance of all tested exchangers which have a various number of plates. While the major outcomes of this study showed that TiO2-Al2O3/water hybrid nanofluid has priority when compared to TiO2/water single type nanofluid. Utilization of TiO2-Al2O3/water nanofluid led to obtaining an average improvement of 7.5%, 9.6% and 12.3% in heat transfer of heat exchangers with 8, 12 and 16 plates, respectively.

Originality/value

In the present work, experimental and numerical analyzes have been conducted to investigate the influence of using TiO2-Al2O3/water hybrid nanofluid in various plate heat exchangers. The attained findings showed successful utilization of TiO2-Al2O3/water nanofluid. Based on the obtained results increasing the number of plates in the heat exchanger caused to obtain more increment by using both types of nanofluids.

Details

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

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Article
Publication date: 18 May 2021

Rajesh Choudhary, Naveen Sharma and Sudhakar Subudhi

This study aims to deal with the optimization of experimental parameters to obtain maximum heat transfer rate in a Rayleigh–Bénard enclosure filled with the water-based Al2

Abstract

Purpose

This study aims to deal with the optimization of experimental parameters to obtain maximum heat transfer rate in a Rayleigh–Bénard enclosure filled with the water-based Al2O3 nanofluids using the Taguchi method.

Design/methodology/approach

The particle size and particle concentration of the Al2O3 nanoparticles are 40 nm and 0.01 Vol. %, respectively. A two-step approach has been used to prepare the nanofluids of the required concentration by mixing the nanoparticles in the distilled water (DW). A Rayleigh–Bénard enclosure, having a hot bottom and a cold top copper plate with insulated side walls, is used for the experiments. Experiments have been conducted first with the DW, for the validation of experimental facility, and second with nanofluid (Al2O3 + DW), for the heat transfer improvement, at three different values of enclosure aspect ratios (ratio of height to width of an enclosure), i.e. 0.5, 1.0 and 1.5.

Findings

Signal-to-noise ratio (SNR) analysis has been used to determine the optimal levels of design parameters and their contribution toward heat transfer augmentation. The heat transfer, i.e. Nusselt number, is determined for L9 (33) orthogonal array designed by Taguchi method along with corresponding SNR values. The SNR values are plotted for DW and nanofluid to study the effect of different parameters and to identify their optimal levels. It was found that the aspect ratio has the maximum contribution ratio of 78% for the nanofluid and 76.12% for the DW, followed by the heat flux and the height.

Originality/value

The present results demonstrated the great reliability of the Taguchi method in the optimization of the thermal system to save the time and cost of experiments.

Details

World Journal of Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 26 February 2021

Subhasree Dutta, Somnath Bhattacharyya and Ioan Pop

The purpose of this study is to analyze the heat transfer and flow enhancement of an Al2O3-water nanofluid filling an inclined channel whose lower wall is embedded with…

Abstract

Purpose

The purpose of this study is to analyze the heat transfer and flow enhancement of an Al2O3-water nanofluid filling an inclined channel whose lower wall is embedded with periodically placed discrete hydrophobic heat sources. Formation of a thin depletion layer of low viscosity over each hydrophobic heated patch leads to the velocity slip and temperature jump condition at the interface of the hydrophobic patch.

Design/methodology/approach

The mixed convection of the nanofluid is analysed based on the two-phase non-homogeneous model. The governing equations are solved numerically through a control volume approach. A periodic boundary condition is adopted along the longitudinal direction of the modulated channel. A velocity slip and temperature jump condition are imposed along with the hydrophobic heated stripes. The paper has validated the present non-homogeneous model with existing experimental and numerical results for particular cases. The impact of temperature jump condition and slip velocity on the flow and thermal field of the nanofluid in mixed convection is analysed for a wide range of governing parameters, namely, Reynolds number (50 ≤ Re ≤ 150), Grashof number ( 103Gr5×104), nanoparticle bulk volume fraction ( 0.01φb0.05), nanoparticle diameter ( 30dp60) and the angle of inclination ( 60°σ60°).

Findings

The presence of the thin depletion layer above the heated stripes reduces the heat transfer and augments the volume flow rate. Consideration of the nanofluid as a coolant enhances the rate of heat transfer, as well as the entropy generation and friction factor compared to the clear fluid. However, the rate of increment in heat transfer suppresses by a significant margin of the loss due to enhanced entropy generation and friction factor. Heat transfer performance of the channel diminishes as the channel inclination angle with the horizontal is increased. The paper has also compared the non-homogeneous model with the corresponding homogeneous model. In the non-homogeneous formulation, the nanoparticle distribution is directly affected by the slip conditions by virtue of the no-normal flux of nanoparticles on the slip planes. For this, the slip stripes augment the impact of nanoparticle volume fraction compared to the no-slip case.

Originality/value

This paper finds that the periodically arranged hydrophobic heat sources on the lower wall of the channel create a significant augmentation in the volume flow rate, which may be crucial to augment the transport process in mini- or micro-channels. This type of configuration has not been addressed in the existing literature.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 9
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 18 December 2020

Thameem Basha Hayath, Sivaraj Ramachandran, Ramachandra Prasad Vallampati and O. Anwar Bég

Generally, in computational thermofluid dynamics, the thermophysical properties of fluids (e.g. viscosity and thermal conductivity) are considered as constant. However, in…

Abstract

Purpose

Generally, in computational thermofluid dynamics, the thermophysical properties of fluids (e.g. viscosity and thermal conductivity) are considered as constant. However, in many applications, the variability of these properties plays a significant role in modifying transport characteristics while the temperature difference in the boundary layer is notable. These include drag reduction in heavy oil transport systems, petroleum purification and coating manufacturing. The purpose of this study is to develop, a comprehensive mathematical model, motivated by the last of these applications, to explore the impact of variable viscosity and variable thermal conductivity characteristics in magnetohydrodynamic non-Newtonian nanofluid enrobing boundary layer flow over a horizontal circular cylinder in the presence of cross-diffusion (Soret and Dufour effects) and appreciable thermal radiative heat transfer under a static radial magnetic field.

Design/methodology/approach

The Williamson pseudoplastic model is deployed for rheology of the nanofluid. Buongiorno’s two-component model is used for nanoscale effects. The dimensionless nonlinear partial differential equations have been solved by using an implicit finite difference Keller box scheme. Extensive validation with earlier studies in the absence of nanoscale and variable property effects is included.

Findings

The influence of notable parameters such as Weissenberg number, variable viscosity, variable thermal conductivity, Soret and Dufour numbers on heat, mass and momentum characteristics are scrutinized and visualized via graphs and tables.

Research limitations/implications

Buongiorno (two-phase) nanofluid model is used to express the momentum, energy and concentration equations with the following assumptions. The laminar, steady, incompressible, free convective flow of Williamson nanofluid is considered. The body force is implemented in the momentum equation. The induced magnetic field strength is smaller than the external magnetic field and hence it is neglected. The Soret and Dufour effects are taken into consideration.

Practical implications

The variable viscosity and thermal conductivity are considered to investigate the fluid characteristic of Williamson nanofluid because of viscosity and thermal conductivity have a prime role in many industries such as petroleum refinement, food and beverages, petrochemical, coating manufacturing, power and environment.

Social implications

This fluid model displays exact rheological characteristics of bio-fluids and industrial fluids, for instance, blood, polymer melts/solutions, nail polish, paint, ketchup and whipped cream.

Originality/value

The outcomes disclose that the Williamson nanofluid velocity declines by enhancing the Lorentz hydromagnetic force in the radial direction. Thermal and nanoparticle concentration boundary layer thickness is enhanced with greater streamwise coordinate values. An increase in Dufour number or a decrease in Soret number slightly enhances the nanofluid temperature and thickens the thermal boundary layer. Flow deceleration is induced with greater viscosity parameter. Nanofluid temperature is elevated with greater Weissenberg number and thermophoresis nanoscale parameter.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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