Effect of Uncertainties in Physical Properties on Entropy Generation Between Two Rotating Cylinders With Nanofluids

In this paper, the effects of uncertainties in physical properties on predicting entropy generation for a steady laminar flow of Al2O3–ethylene glycol nanofluid (0≤φ≤6 %) between two concentric rotating cylinders are investigated. For this purpose, six different models by combining of three relations for thermal conductivity (Bruggeman, Hamilton–Crosser, and Yu–Choi) and two relations for dynamic viscosity (Brinkman and Maiga et al.) are applied. The governing equations with reasonable assumptions in cylindrical coordinates are simplified and solved to obtain analytical expressions for average entropy generation (NS)ave and average Bejan number (Be)ave. The results show that, when the contribution of heat transfer to entropy generation for the base fluid is dominant, a critical radius ratio (ΠC) can be determined at which all six models predict the reduction in entropy generation with increases of volume fraction of nanoparticles. It is also found that, when the contribution of viscous effects to entropy generation is adequately high for the base fluid (φ=0), all models predict the increase of entropy generation with increases of particle loading.

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Thermodynamic optimization of nanoﬂuid ﬂow over a non-isothermal wedge with nonlinear radiation and activation energy

Physica Scripta ◽

10.1088/1402-4896/ac45aa ◽

2021 ◽

Author(s):

M R Acharya ◽

P Mishra ◽

Satyananda Panda

Keyword(s):

Heat Transfer ◽

Activation Energy ◽

Reynolds Number ◽

Entropy Generation ◽

Volume Fraction ◽

Mathematical Formulation ◽

Bejan Number ◽

Nanofluid Flow ◽

Entropy Generation Number ◽

Generation Number

Abstract This paper analyses the augmentation entropy generation number for a viscous nanofluid flow over a non-isothermal wedge including the effects of non-linear radiation and activation energy. We discuss the influence of thermodynamically important parameters during the study, namely, the Bejan number, entropy generation number, and the augmentation entropy generation number. The mathematical formulation for thermal conductivity and viscosity of nanofluid for Al2O3 − EG mixture has been considered. The results were numerically computed using implicit Keller-Box method and depicted graphically. The important result is the change in augmentation entropy generation number with Reynolds number. We observed that adding nanoparticles (volume fraction) tend to enhance augmentation entropy generation number for Al2O3 − EG nanofluid. Further, the investigation on the thermodynamic performance of non-isothermal nanofluid flow over a wedge reveals that adding nanoparticles to the base fluid is effective only when the contribution of heat transfer irreversibility is more than fluid friction irreversibility. This work also discusses the physical interpretation of heat transfer irreversibility and pressure drop irreversibility. This dependency includes Reynolds number and volume fraction parameter. Other than these, the research looked at a variety of physical characteristics associated with the flow of fluid, heat and mass transfer.

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Mixed Convection and Entropy Generation of an Ag-Water Nanofluid in an Inclined L-Shaped Channel

Energies ◽

10.3390/en12061150 ◽

2019 ◽

Vol 12 (6) ◽

pp. 1150 ◽

Cited By ~ 5

Author(s):

Taher Armaghani ◽

Muneer Ismael ◽

Ali Chamkha ◽

Ioan Pop

Keyword(s):

Nusselt Number ◽

Mixed Convection ◽

Entropy Generation ◽

Richardson Number ◽

Volume Fraction ◽

Governing Equations ◽

Nanoparticles Volume Fraction ◽

The Mean ◽

The Right ◽

Volume Method

This paper investigates the mixed convection and entropy generation of an Ag-water nanofluid in an L-shaped channel fixed at an inclination angle of 30° to the horizontal axis. An isothermal heat source was positioned in the middle of the right inclined wall of the channel while the other walls were kept adiabatic. The finite volume method was used for solving the problem’s governing equations. The numerical results were obtained for a range of pertinent parameters: Reynolds number, Richardson number, aspect ratio, and the nanoparticles volume fraction. These results were Re = 50–200; Ri = 0.1, 1, 10; AR = 0.5–0.8; and φ = 0.0–0.06, respectively. The results showed that both the Reynolds and the Richardson numbers enhanced the mean Nusselt number and minimized the rate of entropy generation. It was also found that when AR. increased, the mean Nusselt number was enhanced, and the rate of entropy generation decreased. The nanoparticles volume fraction was predicted to contribute to increasing both the mean Nusselt number and the rate of entropy generation.

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Optimal Design of Nanoparticle Enhanced Phan-Thien–Tanner Flow of a Viscoelastic Fluid in a Microchannel

Entropy ◽

10.3390/e20120895 ◽

2018 ◽

Vol 20 (12) ◽

pp. 895

Author(s):

Mohammad Abdollahzadeh Jamalabadi

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Entropy Generation ◽

Volume Fraction ◽

Circular Cross Section ◽

Major Influence ◽

Parameter Study ◽

Bejan Number ◽

Total Entropy ◽

Minimum Entropy

The excellent thermal characteristics of nanoparticles have increased their application in the field of heat transfer. In this paper, a thermophysical and geometrical parameter study is performed to minimize the total entropy generation of the viscoelastic flow of nanofluid. Entropy generation with respect to volume fraction (<0.04), the Reynolds number (20,000–100,000), and the diameter of the microchannel (20–20,000 μm) with the circular cross-section under constant flux are calculated. As is shown, most of the entropy generation owes to heat transfer and by increasing the diameter of the channel, the Bejan number increases. The contribution of heat entropy generation in the microchannel is very poor and the major influence of entropy generation is attributable to friction. The maximum quantity of in-channel entropy generation happens in nanofluids with TiO2, CuO, Cu, and Ag nanoparticles, in turn, despite the fact in the microchannel this behavior is inverted, the minimum entropy generation occurs in nanofluids with CuO, Cu, Ag, and TiO2 nanoparticles, in turn. In the channel and microchannel for all nanofluids except water-TiO2, increasing the volume fraction of nanoparticles decreases entropy generation. In the channel and microchannel the total entropy generation increases by augmentation the Reynolds number.

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Entropy Analysis in Double-Diffusive Convection in Nanofluids through Electro-osmotically Induced Peristaltic Microchannel

Entropy ◽

10.3390/e21100986 ◽

2019 ◽

Vol 21 (10) ◽

pp. 986 ◽

Cited By ~ 3

Author(s):

Noreen ◽

Waheed ◽

Hussanan ◽

Keyword(s):

Brownian Motion ◽

Entropy Generation ◽

Volume Fraction ◽

Motion Parameter ◽

Bejan Number ◽

Double Diffusive Convection ◽

Grashof Number ◽

Diffusive Convection ◽

Double Diffusive ◽

Brownian Motion Parameter

A theoretical study is presented to examine entropy generation in double-diffusive convection in an Electro-osmotic flow (EOF) of nanofluids via a peristaltic microchannel. Buoyancy effects due to change in temperature, solute concentration and nanoparticle volume fraction are also considered. This study was performed under lubrication and Debye-Hückel linearization approximation. The governing equations are solved exactly. The effect of dominant hydrodynamic parameters (thermophoresis, Brownian motion, Soret and Dufour), Grashof numbers (thermal, concentration and nanoparticle) and electro-osmotic parameters on double-diffusive convective flow are discussed. Moreover, trapping, pumping, entropy generation number, Bejan number and heat transfer rate were also examined under the influence of pertinent parameters such as the thermophoresis parameter, the Brownian motion parameter, the Soret parameter, the Dufour parameter, the thermal Grashof number, the solutal Grashof number, the nanoparticle Grashof number, the electro-osmotic parameter and Helmholtz–Smoluchowski velocity. The electro-osmotic parameter powerfully affected the velocity profile. The magnitude of total entropy generation increased as the thermophoresis parameter and Brownian motion parameter increased. Soret and the Dufour parameter had a strong tendency to control the temperature profile and Bejan number. The findings of the present analysis can be used in clinical purposes such as cell therapy, drug delivery systems, pharmaco-dynamic pumps and particles filtration.

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Entropy Generation and Natural Convection Flow of Hybrid Nanofluids in a Partially Divided Wavy Cavity Including Solid Blocks

Energies ◽

10.3390/en13112942 ◽

2020 ◽

Vol 13 (11) ◽

pp. 2942 ◽

Cited By ~ 9

Author(s):

Ammar I. Alsabery ◽

Ishak Hashim ◽

Ahmad Hajjar ◽

Mohammad Ghalambaz ◽

Sohail Nadeem ◽

...

Keyword(s):

Entropy Generation ◽

Convection Flow ◽

Hybrid Nanofluid ◽

Bejan Number ◽

The Finite Element Method ◽

Governing Equations ◽

Flow And Heat Transfer ◽

Hybrid Nanofluids ◽

Wavy Cavity ◽

Rayleigh Numbers

The present investigation addressed the entropy generation, fluid flow, and heat transfer regarding Cu-Al 2 O 3 -water hybrid nanofluids into a complex shape enclosure containing a hot-half partition were addressed. The sidewalls of the enclosure are made of wavy walls including cold isothermal temperature while the upper and lower surfaces remain insulated. The governing equations toward conservation of mass, momentum, and energy were introduced into the form of partial differential equations. The second law of thermodynamic was written for the friction and thermal entropy productions as a function of velocity and temperatures. The governing equations occurred molded into a non-dimensional pattern and explained through the finite element method. Outcomes were investigated for Cu-water, Al 2 O 3 -water, and Cu-Al 2 O 3 -water nanofluids to address the effect of using composite nanoparticles toward the flow and temperature patterns and entropy generation. Findings show that using hybrid nanofluid improves the Nusselt number compared to simple nanofluids. In the case of low Rayleigh numbers, such enhancement is more evident. Changing the geometrical aspects of the cavity induces different effects toward the entropy generation and Bejan number. Generally, the global entropy generation for Cu-Al 2 O 3 -water hybrid nanofluid takes places between the entropy generation values regarding Cu-water and Al 2 O 3 -water nanofluids.

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Effects of circular corners and aspect-ratio on entropy generation due to natural convection of nanofluid flows in rectangular cavities

Thermal Science ◽

10.2298/tsci130201034s ◽

2015 ◽

Vol 19 (5) ◽

pp. 1621-1632 ◽

Cited By ~ 7

Author(s):

Mahmoud Salari ◽

Ali Mohammadtabar ◽

Mohammad Mohammadtabar

Keyword(s):

Natural Convection ◽

Rayleigh Number ◽

Aspect Ratio ◽

Entropy Generation ◽

Volume Fraction ◽

Solid Volume Fraction ◽

Bejan Number ◽

Total Entropy ◽

Aspect Ratios ◽

Corner Radius

In this paper, entropy generation induced by natural convection of cu-water nanofluid in rectangular cavities with different circular corners and different aspect-ratios were numerically investigated. The governing equations were solved using a finite volume approach and the SIMPLE algorithm was used to couple the pressure and velocity fields. The results showed that the total entropy generation increased with the increase of Rayleigh number, irreversibility coefficient, aspect ratio or solid volume fraction while it decreased with the increase of the corner radius. It should be noted that the best way for minimizing entropy generation is decreasing Rayleigh number. This is the first priority for minimizing entropy generation. The other parameters such as radius, volume fraction, etc are placed on the second priority. However, Bejan number had an inverse trend compared with total entropy generation. As an exception, Bejan number and total entropy number had the same trend whenever solid volume fraction increased. Moreover, Nusselt number increased as Rayleigh number, solid volume fraction or aspect ratio increased whereas it decreases with the increase of corner radius.

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Effects of Entropy Generation, Thermal Radiation and Moving-Wall Direction on Mixed Convective Flow of Nanofluid in an Enclosure

Mathematics ◽

10.3390/math8091471 ◽

2020 ◽

Vol 8 (9) ◽

pp. 1471

Author(s):

Sivasankaran Sivanandam ◽

Ali J. Chamkha ◽

Fouad O. M. Mallawi ◽

Metib S. Alghamdi ◽

Aisha M. Alqahtani

Keyword(s):

Thermal Radiation ◽

Entropy Generation ◽

Energy Transport ◽

Volume Fraction ◽

Control Volume ◽

Bejan Number ◽

Moving Wall ◽

Mixed Convective Flow ◽

The Right ◽

The Impact

A numeric investigation is executed to understand the impact of moving-wall direction, thermal radiation, entropy generation and nanofluid volume fraction on combined convection and energy transfer of nanoliquids in a differential heated box. The top wall of the enclosed box is assumed to move either to the left or the right direction which affects the stream inside the box. The horizontal barriers are engaged to be adiabatic. The derived mathematical model is solved by the control volume technique. The results are presented graphically to know the impact of the dissimilar ways of moving wall, Richardson number, Bejan number, thermal radiation, cup mixing and average temperatures. It is concluded that the stream and the thermal distribution are intensely affected by the moving-wall direction. It is established that the thermal radiation enhances the convection energy transport inside the enclosure.

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MHD Flow of Cu-Al2O3/Water Hybrid Nanofluid in Porous Channel: Analysis of Entropy Generation

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.377.42 ◽

2017 ◽

Vol 377 ◽

pp. 42-61 ◽

Cited By ~ 45

Author(s):

Sanatan Das ◽

Rabindra Nath Jana ◽

Oluwole Daniel Makinde

Keyword(s):

Entropy Generation ◽

Mhd Flow ◽

Transverse Magnetic ◽

Porous Channel ◽

Hybrid Nanofluid ◽

Bejan Number ◽

Governing Equations ◽

Transfer Enhancement ◽

Entropy Generation Number ◽

Channel Analysis

In this investigation, a magnetohydrodynamic (MHD) flow of AlO /water nanofluid and Cu-AlO /water hybrid nanofluid through a porous channel is analyzed in the presence of a transverse magnetic field. An exact solution of the governing equations has been obtained in closed form. The entropy generation number and the Bejan number are also obtained. The influences of each of the governing parameters on velocity, temperature, entropy generation and Bejan number are displayed graphically and the physical aspects are discussed. In addition, a comparison of the heat transfer enhancement level due to the suspension of AlO and Cu nanoparticles in water as regular nanofluids and as hybrid Cu-AlO /water nanofluid is reported.

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Numerical Investigation of Entropy Generation in Unsteady MHD Generalized Couette Flow with Variable Electrical Conductivity

The Scientific World JOURNAL ◽

10.1155/2013/364695 ◽

2013 ◽

Vol 2013 ◽

pp. 1-11 ◽

Cited By ~ 6

Author(s):

T. Chinyoka ◽

O. D. Makinde

Keyword(s):

Electrical Conductivity ◽

Couette Flow ◽

Entropy Generation ◽

Fluid Velocity ◽

Bejan Number ◽

Governing Equations ◽

Entropy Generation Number ◽

Thermophysical Parameters ◽

Second Law Analysis ◽

Finite Difference Techniques

The thermodynamic second law analysis is utilized to investigate the inherent irreversibility in an unsteady hydromagnetic generalized Couette flow with variable electrical conductivity in the presence of induced electric field. Based on some simplified assumption, the model nonlinear governing equations are obtained and solved numerically using semidiscretization finite difference techniques. Effects of various thermophysical parameters on the fluid velocity, temperature, current density, skin friction, the Nusselt number, entropy generation number, and the Bejan number are presented graphically and discussed quantitatively.

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Entropy Generation in Couette Flow Through a Deformable Porous Channel

Applied Mathematics and Nonlinear Sciences ◽

10.2478/amns.2019.2.00054 ◽

2019 ◽

Vol 4 (2) ◽

pp. 575-590 ◽

Cited By ~ 1

Author(s):

G. Gopi Krishna ◽

S. Sreenadh ◽

A.N.S. Srinivas

Keyword(s):

Porous Medium ◽

Temperature Distribution ◽

Couette Flow ◽

Entropy Generation ◽

Volume Fraction ◽

Fluid Velocity ◽

Porous Channel ◽

Injection Velocity ◽

Bejan Number ◽

Parallel Plates

AbstractThe present study examines the entropy generation on Couette flow of a viscous fluid in parallel plates filled with deformable porous medium. The fluid is injected into the porous channel perpendicular to the lower wall with a constant velocity and is sucked out of the upper wall with same velocity .The coupled phenomenon of the fluid flow and solid deformation in the porous medium is taken in to consideration. The exact expressions for the velocity of fluid, solid displacement and temperature distribution are found analytically. The effect of pertinent parameters on the fluid velocity, solid displacement and temperature profiles are discussed in detail. In the deformable porous layer, it is noticed that the velocity of fluid, solid displacement and temperature distribution are decreases with increasing the suction/injection velocity parameter. The results obtained for the present flow characteristic reveal several interesting behaviors that warrant further study on the deformable porous media. Furthermore, the significance of drag and the volume fraction on entropy generation number and Bejan number are discussed with the help of graphs.

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