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Special Issue "Entropy Generation in Nanofluid Flows II"

A special issue of Entropy (ISSN 1099-4300).

Deadline for manuscript submissions: closed (28 February 2019)

Special Issue Editors

Guest Editor
Prof. Dr. Giulio Lorenzini

Department of Industrial Engineering, University of Parma, Italy
Website | E-Mail
Interests: engineering design; Constructal Law; heat transfer optimization; advances in nanofluids
Guest Editor
Dr. Omid Mahian

School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an, China
Website | E-Mail
Interests: engineering design; constructal law; heat transfer optimization; advances in nanofluids.
Guest Editor
Dr. Saman Rashidi

Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad 91775-1111, Iran
Website | E-Mail
Interests: entropy generation analysis; nanofluid

Special Issue Information

Dear Colleagues,

Recent advances in nanotechnology have allowed the development of a new category of fluids named nanofluids. Using nanofluids is a promising method to achieve a higher heat transfer rate in different thermal systems such as heat exchangers. Nanofluid also can be used to develop better oils and lubricants in real applications. In addition, nanofluids can be employed in solar energy systems to enhance the efficiency of these systems and have some applications in medical process such as cancer therapy and safer surgery by heat treatment. Many researches are performed on the thermophysical characteristics of nanofluids and their applications in thermal systems, since 1995.

The entropy generation or second law analysis is a good method for evaluating a thermal system as the first law only deals with conservation of energy and does not discuss about possibility of destruction of the useful work during a heat transfer process. This analysis can be employed for the design, optimization, and yield assessment of different thermal devices. The first studies on entropy generation due to nanofluid flow have started from 2010. The aim of this Special Issue is to encourage the researchers to present their latest original researches on entropy generation and exergy analysis for nanofluid thermal systems. Both experimental and numerical methods can be used to perform an entropy generation analysis for these systems. Entropy generation analyses for Newtonian and Non-Newtonian nanofluid flows in simple or complex geometries with different sizes (e.g. micro to conventional) are welcome. Entropy generation analysis for different applications of nanofluids including renewable energy devices, heat exchangers, and medical processes can be considered for review process.

Existing literature indicates that the studies on these topics are still scant. In order to fill this gap, researchers are invited to contribute their original research and review papers in these topics.

Prof. Dr. Giulio Lorenzini
Dr. Omid Mahian
Dr. Saman Rashidi
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Entropy is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Analytical, experimental, and numerical methods for entropy generation and exergy analysis for nanofluid flow
  • Entropy generation and exergy analysis for laminar and turbulent nanofluid flows
  • Entropy generation and exergy analysis for Newtonian and non-Newtonian nanofluids
  • Entropy generation and exergy analysis for external and internal nanofluid flows
  • Entropy generation and exergy analysis for nanofluid flows in solar energy systems
  • Entropy generation and exergy analysis for nanofluid flows in medical processes

Related Special Issues

Published Papers (25 papers)

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Research

Open AccessArticle
Effects of Radiative Electro-Magnetohydrodynamics Diminishing Internal Energy of Pressure-Driven Flow of Titanium Dioxide-Water Nanofluid due to Entropy Generation
Entropy 2019, 21(3), 236; https://doi.org/10.3390/e21030236
Received: 13 February 2019 / Revised: 27 February 2019 / Accepted: 27 February 2019 / Published: 1 March 2019
Cited by 3 | PDF Full-text (5405 KB) | HTML Full-text | XML Full-text
Abstract
The internal average energy loss caused by entropy generation for steady mixed convective Poiseuille flow of a nanofluid, suspended with titanium dioxide (TiO2) particles in water, and passed through a wavy channel, was investigated. The models of thermal conductivity and viscosity [...] Read more.
The internal average energy loss caused by entropy generation for steady mixed convective Poiseuille flow of a nanofluid, suspended with titanium dioxide (TiO2) particles in water, and passed through a wavy channel, was investigated. The models of thermal conductivity and viscosity of titanium dioxide of 21 nm size particles with a volume concentration of temperature ranging from 15 °C to 35 °C were utilized. The characteristics of the working fluid were dependent on electro-magnetohydrodynamics (EMHD) and thermal radiation. The governing equations were first modified by taking long wavelength approximations, which were then solved by a homotopy technique, whereas for numerical computation, the software package BVPh 2.0 was utilized. The results for the leading parameters, such as the electric field, the volume fraction of nanoparticles and radiation parameters for three different temperatures scenarios were examined graphically. The minimum energy loss at the center of the wavy channel due to the increase in the electric field parameter was noted. However, a rise in entropy was observed due to the change in the pressure gradient from low to high. Full article
(This article belongs to the Special Issue Entropy Generation in Nanofluid Flows II)
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Open AccessArticle
Entropy Generation in MHD Mixed Convection Non-Newtonian Second-Grade Nanoliquid Thin Film Flow through a Porous Medium with Chemical Reaction and Stratification
Entropy 2019, 21(2), 139; https://doi.org/10.3390/e21020139
Received: 8 December 2018 / Revised: 23 January 2019 / Accepted: 30 January 2019 / Published: 1 February 2019
Cited by 8 | PDF Full-text (1531 KB) | HTML Full-text | XML Full-text
Abstract
Chemical reaction in mixed convection magnetohydrodynamic second grade nanoliquid thin film flow through a porous medium containing nanoparticles and gyrotactic microorganisms is considered with entropy generation. The stratification phenomena, heat and mass transfer simultaneously take place within system. Microorganisms are utilized to stabilize [...] Read more.
Chemical reaction in mixed convection magnetohydrodynamic second grade nanoliquid thin film flow through a porous medium containing nanoparticles and gyrotactic microorganisms is considered with entropy generation. The stratification phenomena, heat and mass transfer simultaneously take place within system. Microorganisms are utilized to stabilize the suspended nanoparticles through bioconvection. For the chemical reaction of species, the mass transfer increases. The governing equations of the problem are transformed to nonlinear differential equations through similarity variables, which are solved through a well known scheme called homotopy analysis method. The solution is expressed through graphs and illustrations which show the influences of all the parameters. The residual error graphs elucidate the authentication of the present work. Full article
(This article belongs to the Special Issue Entropy Generation in Nanofluid Flows II)
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Open AccessArticle
Entropy Generation of Carbon Nanotubes Flow in a Rotating Channel with Hall and Ion-Slip Effect Using Effective Thermal Conductivity Model
Entropy 2019, 21(1), 52; https://doi.org/10.3390/e21010052
Received: 23 November 2018 / Revised: 6 January 2019 / Accepted: 6 January 2019 / Published: 10 January 2019
Cited by 6 | PDF Full-text (7390 KB) | HTML Full-text | XML Full-text
Abstract
This article examines the entropy analysis of magnetohydrodynamic (MHD) nanofluid flow of single and multiwall carbon nanotubes between two rotating parallel plates. The nanofluid flow is taken under the existence of Hall current and ion-slip effect. Carbon nanotubes (CNTs) are highly proficient heat [...] Read more.
This article examines the entropy analysis of magnetohydrodynamic (MHD) nanofluid flow of single and multiwall carbon nanotubes between two rotating parallel plates. The nanofluid flow is taken under the existence of Hall current and ion-slip effect. Carbon nanotubes (CNTs) are highly proficient heat transmission agents with bordering entropy generation and, thus, are considered to be a capable cooling medium. Entropy generation and Hall effect are mainly focused upon in this work. Using the appropriate similarity transformation, the central partial differential equations are changed to a system of ordinary differential equations, and an optimal approach is used for solution purposes. The resultant non-dimensional physical parameter appear in the velocity and temperature fields discussed using graphs. Also, the effect of skin fraction coefficient and Nusselt number of enclosed physical parameters are discussed using tables. It is observed that increased values of magnetic and ion-slip parameters reduce the velocity of the nanofluids and increase entropy generation. The results reveal that considering higher magnetic forces results in greater conduction mechanism. Full article
(This article belongs to the Special Issue Entropy Generation in Nanofluid Flows II)
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Open AccessFeature PaperArticle
Modelling Study on Internal Energy Loss Due to Entropy Generation for Non-Darcy Poiseuille Flow of Silver-Water Nanofluid: An Application of Purification
Entropy 2018, 20(11), 851; https://doi.org/10.3390/e20110851
Received: 20 September 2018 / Revised: 29 October 2018 / Accepted: 2 November 2018 / Published: 6 November 2018
Cited by 6 | PDF Full-text (4281 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, an analytical study of internal energy losses for the non-Darcy Poiseuille flow of silver-water nanofluid due to entropy generation in porous media is investigated. Spherical-shaped silver (Ag) nanosize particles with volume fraction 0.3%, 0.6%, and 0.9% are utilized. Four illustrative [...] Read more.
In this paper, an analytical study of internal energy losses for the non-Darcy Poiseuille flow of silver-water nanofluid due to entropy generation in porous media is investigated. Spherical-shaped silver (Ag) nanosize particles with volume fraction 0.3%, 0.6%, and 0.9% are utilized. Four illustrative models are considered: (i) heat transfer irreversibility (HTI), (ii) fluid friction irreversibility (FFI), (iii) Joule dissipation irreversibility (JDI), and (iv) non-Darcy porous media irreversibility (NDI). The governing equations of continuity, momentum, energy, and entropy generation are simplified by taking long wavelength approximations on the channel walls. The results represent highly nonlinear coupled ordinary differential equations that are solved analytically with the help of the homotopy analysis method. It is shown that for minimum and maximum averaged entropy generation, 0.3% by vol and 0.9% by vol of nanoparticles, respectively, are observed. Also, a rise in entropy is evident due to an increase in pressure gradient. The current analysis provides an adequate theoretical estimate for low-cost purification of drinking water by silver nanoparticles in an industrial process. Full article
(This article belongs to the Special Issue Entropy Generation in Nanofluid Flows II)
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Open AccessArticle
Analysis of Entropy Generation in Flow of Methanol-Based Nanofluid in a Sinusoidal Wavy Channel
Entropy 2017, 19(10), 490; https://doi.org/10.3390/e19100490
Received: 24 April 2017 / Revised: 5 July 2017 / Accepted: 14 July 2017 / Published: 8 October 2017
Cited by 11 | PDF Full-text (2660 KB) | HTML Full-text | XML Full-text
Abstract
The entropy generation due to heat transfer and fluid friction in mixed convective peristaltic flow of methanol-Al2O3 nano fluid is examined. Maxwell’s thermal conductivity model is used in analysis. Velocity and temperature profiles are utilized in the computation of the [...] Read more.
The entropy generation due to heat transfer and fluid friction in mixed convective peristaltic flow of methanol-Al2O3 nano fluid is examined. Maxwell’s thermal conductivity model is used in analysis. Velocity and temperature profiles are utilized in the computation of the entropy generation number. The effects of involved physical parameters on velocity, temperature, entropy generation number, and Bejan number are discussed and explained graphically. Full article
(This article belongs to the Special Issue Entropy Generation in Nanofluid Flows)
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Open AccessArticle
Entropy Analysis on Electro-Kinetically Modulated Peristaltic Propulsion of Magnetized Nanofluid Flow through a Microchannel
Entropy 2017, 19(9), 481; https://doi.org/10.3390/e19090481
Received: 4 August 2017 / Revised: 2 September 2017 / Accepted: 7 September 2017 / Published: 9 September 2017
Cited by 27 | PDF Full-text (5855 KB) | HTML Full-text | XML Full-text
Abstract
A theoretical and a mathematical model is presented to determine the entropy generation on electro-kinetically modulated peristaltic propulsion on the magnetized nanofluid flow through a microchannel with joule heating. The mathematical modeling is based on the energy, momentum, continuity, and entropy equation in [...] Read more.
A theoretical and a mathematical model is presented to determine the entropy generation on electro-kinetically modulated peristaltic propulsion on the magnetized nanofluid flow through a microchannel with joule heating. The mathematical modeling is based on the energy, momentum, continuity, and entropy equation in the Cartesian coordinate system. The effects of viscous dissipation, heat absorption, magnetic field, and electrokinetic body force are also taken into account. The electric field terms are helpful to model the electrical potential terms by means of Poisson–Boltzmann equations, ionic Nernst–Planck equation, and Debye length approximation. A perturbation method has been applied to solve the coupled nonlinear partial differential equations and a series solution is obtained up to second order. The physical behavior of all the governing parameters is discussed for pressure rise, velocity profile, entropy profile, and temperature profile. Full article
(This article belongs to the Special Issue Entropy Generation in Nanofluid Flows)
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Open AccessArticle
Effect of Slip Conditions and Entropy Generation Analysis with an Effective Prandtl Number Model on a Nanofluid Flow through a Stretching Sheet
Entropy 2017, 19(8), 414; https://doi.org/10.3390/e19080414
Received: 14 July 2017 / Revised: 8 August 2017 / Accepted: 9 August 2017 / Published: 11 August 2017
Cited by 3 | PDF Full-text (6756 KB) | HTML Full-text | XML Full-text
Abstract
This article describes the impact of slip conditions on nanofluid flow through a stretching sheet. Nanofluids are very helpful to enhance the convective heat transfer in a boundary layer flow. Prandtl number also play a major role in controlling the thermal and momentum [...] Read more.
This article describes the impact of slip conditions on nanofluid flow through a stretching sheet. Nanofluids are very helpful to enhance the convective heat transfer in a boundary layer flow. Prandtl number also play a major role in controlling the thermal and momentum boundary layers. For this purpose, we have considered a model for effective Prandtl number which is borrowed by means of experimental analysis on a nano boundary layer, steady, two-dimensional incompressible flow through a stretching sheet. We have considered γAl2O3-H2O and Al2O3-C2H6O2 nanoparticles for the governing flow problem. An entropy generation analysis is also presented with the help of the second law of thermodynamics. A numerical technique known as Successive Taylor Series Linearization Method (STSLM) is used to solve the obtained governing nonlinear boundary layer equations. The numerical and graphical results are discussed for two cases i.e., (i) effective Prandtl number and (ii) without effective Prandtl number. From graphical results, it is observed that the velocity profile and temperature profile increases in the absence of effective Prandtl number while both expressions become larger in the presence of Prandtl number. Further, numerical comparison has been presented with previously published results to validate the current methodology and results. Full article
(This article belongs to the Special Issue Entropy Generation in Nanofluid Flows)
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Open AccessArticle
Investigation of Oriented Magnetic Field Effects on Entropy Generation in an Inclined Channel Filled with Ferrofluids
Entropy 2017, 19(7), 377; https://doi.org/10.3390/e19070377
Received: 13 June 2017 / Revised: 10 July 2017 / Accepted: 18 July 2017 / Published: 23 July 2017
Cited by 7 | PDF Full-text (363 KB) | HTML Full-text | XML Full-text
Abstract
Dispersion of super-paramagnetic nanoparticles in nonmagnetic carrier fluids, known as ferrofluids, offers the advantages of tunable thermo-physical properties and eliminate the need for moving parts to induce flow. This study investigates ferrofluid flow characteristics in an inclined channel under inclined magnetic field and [...] Read more.
Dispersion of super-paramagnetic nanoparticles in nonmagnetic carrier fluids, known as ferrofluids, offers the advantages of tunable thermo-physical properties and eliminate the need for moving parts to induce flow. This study investigates ferrofluid flow characteristics in an inclined channel under inclined magnetic field and constant pressure gradient. The ferrofluid considered in this work is comprised of Cu particles as the nanoparticles and water as the base fluid. The governing differential equations including viscous dissipation are non-dimensionalised and discretized with Generalized Differential Quadrature Method. The resulting algebraic set of equations are solved via Newton-Raphson Method. The work done here contributes to the literature by searching the effects of magnetic field angle and channel inclination separately on the entropy generation of the ferrofluid filled inclined channel system in order to achieve best design parameter values so called entropy generation minimization is implemented. Furthermore, the effect of magnetic field, inclination angle of the channel and volume fraction of nanoparticles on velocity and temperature profiles are examined and represented by figures to give a thorough understanding of the system behavior. Full article
(This article belongs to the Special Issue Entropy Generation in Nanofluid Flows)
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Open AccessArticle
On Unsteady Three-Dimensional Axisymmetric MHD Nanofluid Flow with Entropy Generation and Thermo-Diffusion Effects on a Non-Linear Stretching Sheet
Entropy 2017, 19(7), 168; https://doi.org/10.3390/e19070168
Received: 22 February 2017 / Revised: 8 April 2017 / Accepted: 12 April 2017 / Published: 12 July 2017
Cited by 2 | PDF Full-text (508 KB) | HTML Full-text | XML Full-text
Abstract
The entropy generation in unsteady three-dimensional axisymmetric magnetohydrodynamics (MHD) nanofluid flow over a non-linearly stretching sheet is investigated. The flow is subject to thermal radiation and a chemical reaction. The conservation equations are solved using the spectral quasi-linearization method. The novelty of the [...] Read more.
The entropy generation in unsteady three-dimensional axisymmetric magnetohydrodynamics (MHD) nanofluid flow over a non-linearly stretching sheet is investigated. The flow is subject to thermal radiation and a chemical reaction. The conservation equations are solved using the spectral quasi-linearization method. The novelty of the work is in the study of entropy generation in three-dimensional axisymmetric MHD nanofluid and the choice of the spectral quasi-linearization method as the solution method. The effects of Brownian motion and thermophoresis are also taken into account. The nanofluid particle volume fraction on the boundary is passively controlled. The results show that as the Hartmann number increases, both the Nusselt number and the Sherwood number decrease, whereas the skin friction increases. It is further shown that an increase in the thermal radiation parameter corresponds to a decrease in the Nusselt number. Moreover, entropy generation increases with respect to some physical parameters. Full article
(This article belongs to the Special Issue Entropy Generation in Nanofluid Flows)
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Open AccessArticle
Natural Convection and Entropy Generation in a Square Cavity with Variable Temperature Side Walls Filled with a Nanofluid: Buongiorno’s Mathematical Model
Entropy 2017, 19(7), 337; https://doi.org/10.3390/e19070337
Received: 15 May 2017 / Revised: 19 June 2017 / Accepted: 26 June 2017 / Published: 5 July 2017
Cited by 15 | PDF Full-text (14331 KB) | HTML Full-text | XML Full-text
Abstract
Natural convection heat transfer combined with entropy generation in a square cavity filled with a nanofluid under the effect of variable temperature distribution along left vertical wall has been studied numerically. Governing equations formulated in dimensionless non-primitive variables with corresponding boundary conditions taking [...] Read more.
Natural convection heat transfer combined with entropy generation in a square cavity filled with a nanofluid under the effect of variable temperature distribution along left vertical wall has been studied numerically. Governing equations formulated in dimensionless non-primitive variables with corresponding boundary conditions taking into account the Brownian diffusion and thermophoresis effects have been solved by finite difference method. Distribution of streamlines, isotherms, local entropy generation as well as Nusselt number has been obtained for different values of key parameters. It has been found that a growth of the amplitude of the temperature distribution along the left wall and an increase of the wave number lead to an increase in the average entropy generation. While an increase in abovementioned parameters for low Rayleigh number illustrates a decrease in average Bejan number. Full article
(This article belongs to the Special Issue Entropy Generation in Nanofluid Flows)
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Open AccessArticle
Effects of Movable-Baffle on Heat Transfer and Entropy Generation in a Cavity Saturated by CNT Suspensions: Three-Dimensional Modeling
Entropy 2017, 19(5), 200; https://doi.org/10.3390/e19050200
Received: 3 March 2017 / Revised: 21 April 2017 / Accepted: 26 April 2017 / Published: 29 April 2017
Cited by 17 | PDF Full-text (8165 KB) | HTML Full-text | XML Full-text
Abstract
Convective heat transfer and entropy generation in a 3D closed cavity, equipped with adiabatic-driven baffle and filled with CNT (carbon nanotube)-water nanofluid, are numerically investigated for a range of Rayleigh numbers from 103 to 105. This research is conducted for [...] Read more.
Convective heat transfer and entropy generation in a 3D closed cavity, equipped with adiabatic-driven baffle and filled with CNT (carbon nanotube)-water nanofluid, are numerically investigated for a range of Rayleigh numbers from 103 to 105. This research is conducted for three configurations; fixed baffle (V = 0), rotating baffle clockwise (V+) and rotating baffle counterclockwise (V−) and a range of CNT concentrations from 0 to 15%. Governing equations are formulated using potential vector vorticity formulation in its three-dimensional form, then solved by the finite volume method. The effects of motion direction of the inserted driven baffle and CNT concentration on heat transfer and entropy generation are studied. It was observed that for low Rayleigh numbers, the motion of the driven baffle enhances heat transfer regardless of its direction and the CNT concentration effect is negligible. However, with an increasing Rayleigh number, adding driven baffle increases the heat transfer only when it moves in the direction of the decreasing temperature gradient; elsewhere, convective heat transfer cannot be enhanced due to flow blockage at the corners of the baffle. Full article
(This article belongs to the Special Issue Entropy Generation in Nanofluid Flows)
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Open AccessArticle
3D Buoyancy-Induced Flow and Entropy Generation of Nanofluid-Filled Open Cavities Having Adiabatic Diamond Shaped Obstacles
Entropy 2016, 18(6), 232; https://doi.org/10.3390/e18060232
Received: 1 May 2016 / Revised: 14 June 2016 / Accepted: 15 June 2016 / Published: 21 June 2016
Cited by 23 | PDF Full-text (9468 KB) | HTML Full-text | XML Full-text
Abstract
A three dimensional computational solution has been obtained to investigate the natural convection and entropy generation of nanofluid-filled open cavities with an adiabatic diamond shaped obstacle. In the model, the finite volume technique was used to solve the governing equations. Based on the [...] Read more.
A three dimensional computational solution has been obtained to investigate the natural convection and entropy generation of nanofluid-filled open cavities with an adiabatic diamond shaped obstacle. In the model, the finite volume technique was used to solve the governing equations. Based on the configuration, the cavity is heated from the left vertical wall and the diamond shape was chosen as adiabatic. Effects of nanoparticle volume fraction, Rayleigh number (103 ≤ Ra ≤ 106) and width of diamond shape were studied as governing parameters. It was found that the geometry of the partition is a control parameter for heat and fluid flow inside the open enclosure. Full article
(This article belongs to the Special Issue Entropy in Nanofluids)
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Open AccessArticle
Entropy Generation on MHD Eyring–Powell Nanofluid through a Permeable Stretching Surface
Entropy 2016, 18(6), 224; https://doi.org/10.3390/e18060224
Received: 13 April 2016 / Revised: 2 June 2016 / Accepted: 2 June 2016 / Published: 8 June 2016
Cited by 55 | PDF Full-text (4008 KB) | HTML Full-text | XML Full-text
Abstract
In this article, entropy generation of an Eyring–Powell nanofluid through a permeable stretching surface has been investigated. The impact of magnetohydrodynamics (MHD) and nonlinear thermal radiation are also taken into account. The governing flow problem is modeled with the help of similarity transformation [...] Read more.
In this article, entropy generation of an Eyring–Powell nanofluid through a permeable stretching surface has been investigated. The impact of magnetohydrodynamics (MHD) and nonlinear thermal radiation are also taken into account. The governing flow problem is modeled with the help of similarity transformation variables. The resulting nonlinear ordinary differential equations are solved numerically with the combination of the Successive linearization method and Chebyshev spectral collocation method. The impact of all the emerging parameters such as Hartmann number, Prandtl number, radiation parameter, Lewis number, thermophoresis parameter, Brownian motion parameter, Reynolds number, fluid parameter, and Brinkmann number are discussed with the help of graphs and tables. It is observed that the influence of the magnetic field opposes the flow. Moreover, entropy generation profile behaves as an increasing function of all the physical parameters. Full article
(This article belongs to the Special Issue Entropy in Nanofluids)
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Open AccessArticle
Numerical Simulation of Entropy Generation with Thermal Radiation on MHD Carreau Nanofluid towards a Shrinking Sheet
Entropy 2016, 18(6), 200; https://doi.org/10.3390/e18060200
Received: 8 April 2016 / Revised: 15 May 2016 / Accepted: 19 May 2016 / Published: 24 May 2016
Cited by 50 | PDF Full-text (3877 KB) | HTML Full-text | XML Full-text
Abstract
In this article, entropy generation with radiation on non-Newtonian Carreau nanofluid towards a shrinking sheet is investigated numerically. The effects of magnetohydrodynamics (MHD) are also taken into account. Firstly, the governing flow problem is simplified into ordinary differential equations from partial differential equations [...] Read more.
In this article, entropy generation with radiation on non-Newtonian Carreau nanofluid towards a shrinking sheet is investigated numerically. The effects of magnetohydrodynamics (MHD) are also taken into account. Firstly, the governing flow problem is simplified into ordinary differential equations from partial differential equations with the help of similarity variables. The solution of the resulting nonlinear differential equations is solved numerically with the help of the successive linearization method and Chebyshev spectral collocation method. The influence of all the emerging parameters is discussed with the help of graphs and tables. It is observed that the influence of magnetic field and fluid parameters oppose the flow. It is also analyzed that thermal radiation effects and the Prandtl number show opposite behavior on temperature profile. Furthermore, it is also observed that entropy profile increases for all the physical parameters. Full article
(This article belongs to the Special Issue Entropy in Nanofluids)
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Open AccessArticle
Analytical Modeling of MHD Flow over a Permeable Rotating Disk in the Presence of Soret and Dufour Effects: Entropy Analysis
Entropy 2016, 18(5), 131; https://doi.org/10.3390/e18050131
Received: 15 February 2016 / Revised: 28 March 2016 / Accepted: 1 April 2016 / Published: 26 April 2016
Cited by 8 | PDF Full-text (3877 KB) | HTML Full-text | XML Full-text
Abstract
The main concern of the present article is to study steady magnetohydrodynamics (MHD) flow, heat transfer and entropy generation past a permeable rotating disk using a semi numerical/analytical method named Homotopy Analysis Method (HAM). The results of the present study are compared with [...] Read more.
The main concern of the present article is to study steady magnetohydrodynamics (MHD) flow, heat transfer and entropy generation past a permeable rotating disk using a semi numerical/analytical method named Homotopy Analysis Method (HAM). The results of the present study are compared with numerical quadrature solutions employing a shooting technique with excellent correlation in special cases. The entropy generation equation is derived as a function of velocity, temperature and concentration gradients. Effects of flow physical parameters including magnetic interaction parameter, suction parameter, Prandtl number, Schmidt number, Soret and Dufour number on the fluid velocity, temperature and concentration distributions as well as entropy generation number are analysed and discussed in detail. Results show that increasing the Soret number or decreasing the Dufour number tends to decrease the temperature distribution while the concentration distribution is enhanced. The averaged entropy generation number increases with increasing magnetic interaction parameter, suction parameter, Prandtl number, and Schmidt number. Full article
(This article belongs to the Special Issue Entropy in Nanofluids)
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Open AccessArticle
Heat Transfer Enhancement and Entropy Generation of Nanofluids Laminar Convection in Microchannels with Flow Control Devices
Entropy 2016, 18(4), 134; https://doi.org/10.3390/e18040134
Received: 15 February 2016 / Revised: 31 March 2016 / Accepted: 7 April 2016 / Published: 21 April 2016
Cited by 18 | PDF Full-text (4193 KB) | HTML Full-text | XML Full-text
Abstract
The heat transfer enhancement and entropy generation of Al2O3-water nanofluids laminar convective flow in the microchannels with flow control devices (cylinder, rectangle, protrusion, and v-groove) were investigated in this research. The effects of the geometrical structure of the microchannel, [...] Read more.
The heat transfer enhancement and entropy generation of Al2O3-water nanofluids laminar convective flow in the microchannels with flow control devices (cylinder, rectangle, protrusion, and v-groove) were investigated in this research. The effects of the geometrical structure of the microchannel, nanofluids concentration φ(0%–3%), and Reynolds number Re (50–300) were comparatively studied by means of performance parameters, as well as the limiting streamlines and temperature contours on the modified heated surfaces. The results reveal that the relative Fanning frictional factor f/f0 of the microchannel with rectangle and protrusion devices are much larger and smaller than others, respectively. As the nanofluids concentration increases, f/f0 increases accordingly. For the microchannel with rectangle ribs, there is a transition Re for obtaining the largest heat transfer. The relative Nusselt number Nu/Nu0 of the cases with larger nanofluids concentration are greater. The microchannels with cylinder and v-groove profiles have better heat transfer performance, especially at larger Re cases, while, the microchannel with the protrusion devices is better from an entropy generation minimization perspective. Furthermore, the variation of the relative entropy generation S′/S′0 are influenced by not only the change of Nu/Nu0 and f/f0, but also the physical parameters of working substances. Full article
(This article belongs to the Special Issue Entropy in Nanofluids)
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Open AccessArticle
Entropy Generation and Heat Transfer Performances of Al2O3-Water Nanofluid Transitional Flow in Rectangular Channels with Dimples and Protrusions
Entropy 2016, 18(4), 148; https://doi.org/10.3390/e18040148
Received: 25 February 2016 / Revised: 8 April 2016 / Accepted: 13 April 2016 / Published: 19 April 2016
Cited by 5 | PDF Full-text (4032 KB) | HTML Full-text | XML Full-text
Abstract
Nanofluid has great potentials in heat transfer enhancement and entropy generation decrease as an effective cooling medium. Effects of Al2O3-water nanofluid flow on entropy generation and heat transfer performance in a rectangular conventional channel are numerically investigated in this [...] Read more.
Nanofluid has great potentials in heat transfer enhancement and entropy generation decrease as an effective cooling medium. Effects of Al2O3-water nanofluid flow on entropy generation and heat transfer performance in a rectangular conventional channel are numerically investigated in this study. Four different volume fractions are considered and the boundary condition with a constant heat flux is adopted. The flow Reynolds number covers laminar flow, transitional flow and turbulent flow. The influences of the flow regime and nanofluid volume fraction are examined. Furthermore, dimples and protrusions are employed, and the impacts on heat transfer characteristic and entropy generation are acquired. It is found that the average heat transfer entropy generation rate descends and the average friction entropy generation rate rises with an increasing nanofluid volume fraction. The effect of nanofluid on average heat transfer entropy generation rate declines when Reynolds number ascends, which is inverse for average friction entropy generation rate. The average wall temperature and temperature uniformity both drop accompanied with increasing pumping power with the growth in nanofluid volume fraction. The employment of dimples and protrusions significantly decreases the average entropy generation rate and improve the heat transfer performance. The effect of dimple-case shows great difference with that of protrusion-case. Full article
(This article belongs to the Special Issue Entropy in Nanofluids)
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Open AccessArticle
Entropy Generation on MHD Casson Nanofluid Flow over a Porous Stretching/Shrinking Surface
Entropy 2016, 18(4), 123; https://doi.org/10.3390/e18040123
Received: 24 February 2016 / Revised: 28 March 2016 / Accepted: 30 March 2016 / Published: 6 April 2016
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Abstract
In this article, entropy generation on MHD Casson nanofluid over a porous Stretching/Shrinking surface has been investigated. The influences of nonlinear thermal radiation and chemical reaction have also taken into account. The governing Casson nanofluid flow problem consists of momentum equation, energy equation [...] Read more.
In this article, entropy generation on MHD Casson nanofluid over a porous Stretching/Shrinking surface has been investigated. The influences of nonlinear thermal radiation and chemical reaction have also taken into account. The governing Casson nanofluid flow problem consists of momentum equation, energy equation and nanoparticle concentration. Similarity transformation variables have been used to transform the governing coupled partial differential equations into ordinary differential equations. The resulting highly nonlinear coupled ordinary differential equations have been solved numerically with the help of Successive linearization method (SLM) and Chebyshev spectral collocation method. The impacts of various pertinent parameters of interest are discussed for velocity profile, temperature profile, concentration profile and entropy profile. The expression for local Nusselt number and local Sherwood number are also analyzed and discussed with the help of tables. Furthermore, comparison with the existing is also made as a special case of our study. Full article
(This article belongs to the Special Issue Entropy in Nanofluids)
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Open AccessArticle
Entropy Generation on MHD Blood Flow of Nanofluid Due to Peristaltic Waves
Entropy 2016, 18(4), 117; https://doi.org/10.3390/e18040117
Received: 19 January 2016 / Revised: 24 March 2016 / Accepted: 24 March 2016 / Published: 1 April 2016
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Abstract
This present study describes the entropy generation on magnetohydrodynamic (MHD) blood flow of a nanofluid induced by peristaltic waves. The governing equation of continuity, equation of motion, nano-particle and entropy equations are solved by neglecting the inertial forces and taking long wavelength approximation. [...] Read more.
This present study describes the entropy generation on magnetohydrodynamic (MHD) blood flow of a nanofluid induced by peristaltic waves. The governing equation of continuity, equation of motion, nano-particle and entropy equations are solved by neglecting the inertial forces and taking long wavelength approximation. The resulting highly non-linear coupled partial differential equation has been solved analytically with the help of perturbation method. Mathematical and graphical results of all the physical parameters for velocity, concentration, temperature, and entropy are also presented. Numerical computation has been used to evaluate the expression for the pressure rise and friction forces. Currently, magnetohydrodynamics is applicable in pumping the fluids for pulsating and non-pulsating continuous flows in different microchannel designs and it also very helpful to control the flow. Full article
(This article belongs to the Special Issue Entropy in Nanofluids)
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Open AccessArticle
Analysis of Entropy Generation in the Flow of Peristaltic Nanofluids in Channels With Compliant Walls
Entropy 2016, 18(3), 90; https://doi.org/10.3390/e18030090
Received: 22 December 2015 / Revised: 21 February 2016 / Accepted: 3 March 2016 / Published: 11 March 2016
Cited by 30 | PDF Full-text (2518 KB) | HTML Full-text | XML Full-text
Abstract
Entropy generation during peristaltic flow of nanofluids in a non-uniform two dimensional channel with compliant walls has been studied. The mathematical modelling of the governing flow problem is obtained under the approximation of long wavelength and zero Reynolds number (creeping flow regime). The [...] Read more.
Entropy generation during peristaltic flow of nanofluids in a non-uniform two dimensional channel with compliant walls has been studied. The mathematical modelling of the governing flow problem is obtained under the approximation of long wavelength and zero Reynolds number (creeping flow regime). The resulting non-linear partial differential equations are solved with the help of a perturbation method. The analytic and numerical results of different parameters are demonstrated mathematically and graphically. The present analysis provides a theoretical model to estimate the characteristics of several Newtonian and non-Newtonian fluid flows, such as peristaltic transport of blood. Full article
(This article belongs to the Special Issue Entropy in Nanofluids)
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Open AccessArticle
Sensitivity Analysis of Entropy Generation in Nanofluid Flow inside a Channel by Response Surface Methodology
Entropy 2016, 18(2), 52; https://doi.org/10.3390/e18020052
Received: 20 December 2015 / Revised: 18 January 2016 / Accepted: 27 January 2016 / Published: 5 February 2016
Cited by 18 | PDF Full-text (2504 KB) | HTML Full-text | XML Full-text
Abstract
Nanofluids can afford excellent thermal performance and have a major role in energy conservation aspect. In this paper, a sensitivity analysis has been performed by using response surface methodology to calculate the effects of nanoparticles on the entropy generation. For this purpose, the [...] Read more.
Nanofluids can afford excellent thermal performance and have a major role in energy conservation aspect. In this paper, a sensitivity analysis has been performed by using response surface methodology to calculate the effects of nanoparticles on the entropy generation. For this purpose, the laminar forced convection of Al2O3-water nanofluid flow inside a channel is considered. The total entropy generation rates consist of the entropy generation rates due to heat transfer and friction loss are calculated by using velocity and temperature gradients. The continuity, momentum and energy equations have been solved numerically using a finite volume method. The sensitivity of the entropy generation rate to different parameters such as the solid volume fraction, the particle diameter, and the Reynolds number is studied in detail. Series of simulations were performed for a range of solid volume fraction 0 ≤ ϕ ≤ 0.05 , particle diameter 30  nm ≤ d p ≤ 90 ​ nm , and the Reynolds number 200 ≤ Re ≤ 800. The results showed that the total entropy generation is more sensitive to the Reynolds number rather than the nanoparticles diameter or solid volume fraction. Also, the magnitude of total entropy generation, which increases with increase in the Reynolds number, is much higher for the pure fluid rather than the nanofluid. Full article
(This article belongs to the Special Issue Entropy in Nanofluids)
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Open AccessArticle
Entropy Generation and Natural Convection of CuO-Water Nanofluid in C-Shaped Cavity under Magnetic Field
Entropy 2016, 18(2), 50; https://doi.org/10.3390/e18020050
Received: 28 November 2015 / Revised: 10 January 2016 / Accepted: 27 January 2016 / Published: 5 February 2016
Cited by 37 | PDF Full-text (3608 KB) | HTML Full-text | XML Full-text
Abstract
This paper investigates the entropy generation and natural convection inside a C-shaped cavity filled with CuO-water nanofluid and subjected to a uniform magnetic field. The Brownian motion effect is considered in predicting the nanofluid properties. The governing equations are solved using the finite [...] Read more.
This paper investigates the entropy generation and natural convection inside a C-shaped cavity filled with CuO-water nanofluid and subjected to a uniform magnetic field. The Brownian motion effect is considered in predicting the nanofluid properties. The governing equations are solved using the finite volume method with the SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm. The studied parameters are the Rayleigh number (1000 ≤ Ra ≤ 15,000), Hartman number (0 ≤ Ha ≤ 45), nanofluid volume fraction (0 ≤ φ ≤ 0.06), and the cavity aspect ratio (0.1 ≤ AR ≤ 0.7). The results have shown that the nanoparticles volume fraction enhances the natural convection but undesirably increases the entropy generation rate. It is also found that the applied magnetic field can suppress both the natural convection and the entropy generation rate, where for Ra = 1000 and φ = 0.04, the percentage reductions in total entropy generation decreases from 96.27% to 48.17% for Ha = 45 compared to zero magnetic field when the aspect ratio is increased from 0.1 to 0.7. The results of performance criterion have shown that the nanoparticles addition can be useful if a compromised magnetic field value represented by a Hartman number of 30 is applied. Full article
(This article belongs to the Special Issue Entropy in Nanofluids)
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