Entropy Generation Analysis of Power-Law Non-Newtonian Fluid Flow Caused by Micropatterned Moving Surface

In the present study, the first and second law analyses of power-law non-Newtonian flow over embedded open parallel microchannels within micropatterned permeable continuous moving surface are examined at prescribed surface temperature. A similarity transformation is used to reduce the governing equations to a set of nonlinear ordinary differential equations. The dimensionless entropy generation number is formulated by an integral of the local rate of entropy generation along the width of the surface based on an equal number of microchannels and no-slip gaps interspersed between those microchannels. The velocity, the temperature, the velocity gradient, and the temperature gradient adjacent to the wall are substituted into this equation resulting from the momentum and energy equations obtained numerically by Dormand-Prince pair and shooting method. Finally, the entropy generation numbers, as well as the Bejan number, are evaluated. It is noted that the presence of the shear thinning (pseudoplastic) fluids creates entropy along the surface, with an opposite effect resulting from shear thickening (dilatant) fluids.

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Analysis of Entropy Generation for a Power-Law Fluid in Microchannels

ASME 2013 4th International Conference on Micro/Nanoscale Heat and Mass Transfer ◽

10.1115/mnhmt2013-22159 ◽

2013 ◽

Cited By ~ 2

Author(s):

L. Y. Tan ◽

G. M. Chen

Keyword(s):

Heat Transfer ◽

Entropy Generation ◽

Power Law ◽

Parallel Plate ◽

Circular Pipe ◽

Bejan Number ◽

Primary Concern ◽

Brinkman Number ◽

Power Law Fluid ◽

Dimensionless Entropy Generation

Entropy generation is tied to the exergy destroyed. Hence, the amount of entropy generation is of primary concern as it is related to unavailable work. Viscous dissipation is a form of heat generation due to work done by viscous forces. Its effect on the velocity and temperature profiles would have affected the entropy generation. In this work, second law analysis is carried out on a microchannel between parallel plates for a power-law fluid. The governing energy equation for a rectangular microchannel is first solved analytically. Analytical expression is obtained for the dimensionless entropy generation and Bejan number. Dimensionless entropy generation due to fluid flow irreversibility and heat transfer irreversibility are also computed and compared. The distribution of entropy generation due to heat transfer irreversibility and fluid friction irreversibility changes as Brinkman number increases. A comparison with a previous literature on a circular pipe for the same Brinkman number reveals that the total dimensionless entropy generation in parallel plate is more than the corresponding value in circular pipe. However, the Bejan number for a parallel plate is lower than a circular pipe.

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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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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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Numerical investigation of entropy generation in laminar forced convection flow over inclined backward and forward facing steps in a duct under bleeding condition

Thermal Science ◽

10.2298/tsci110531026a ◽

2014 ◽

Vol 18 (2) ◽

pp. 479-492 ◽

Cited By ~ 11

Author(s):

Meysam Atashafrooz ◽

Nassab Gandjalikhan ◽

Babak Ansari

Keyword(s):

Numerical Investigation ◽

Forced Convection ◽

Entropy Generation ◽

Fluid Dynamic ◽

Numerical Results ◽

Convection Flow ◽

Bejan Number ◽

Entropy Generation Number ◽

Forced Convection Flow ◽

Laminar Forced Convection

A numerical investigation of entropy generation in laminar forced convection of gas flow over a recess including two inclined backward and forward facing steps in a horizontal duct under bleeding condition is presented. For calculation of entropy generation from the second law of thermodynamics in a forced convection flow, the velocity and temperature distributions are primary needed. For this purpose, the two-dimensional Cartesian coordinate system is used to solve the governing equations which are conservations of mass, momentum and energy. These equations are solved numerically using the computational fluid dynamic techniques to obtain the temperature and velocity fields, while the blocked region method is employed to simulate the inclined surface. Discretized forms of these equations are obtained by the finite volume method and solved using the SIMPLE algorithm. The numerical results are presented graphically and the effects of bleeding coefficient and recess length as the main parameters on the distributions of entropy generation number and Bejan number are investigated. Also, the effect of Reynolds number and bleeding coefficient on total entropy generation which shows the amount of flow irreversibilities is presented for two recess length. The use of present results in the design process of such thermal system would help the system attain the high performance during exploitation. Comparison of numerical results with the available data published in open literature shows a good consistency.

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Effects of non-uniform nanoparticle concentration on entropy generation

Revista Mexicana de Física ◽

10.31349/revmexfis.68.010601 ◽

2021 ◽

Vol 68 (1 Jan-Feb) ◽

Author(s):

Ahmer Mehmood ◽

Sajid Khan ◽

Muhammad Usman

Keyword(s):

Entropy Production ◽

Entropy Generation ◽

Working Fluid ◽

Physical Parameters ◽

Bejan Number ◽

Total Entropy ◽

Entropy Generation Number ◽

Self Similar Solution ◽

Nanoparticles Concentration ◽

The Impact

The entropy generation analysis of a thermal process is capable of determining the efficiency of that process and is therefore helpful to optimize the thermal system operating under various conditions. There are several ingredients upon which the phenomenon of entropy generation can depend, such as the nature of flow and the fluid, the assumed conditions, and the material properties of the working fluid. However, the dependence of entropy generation phenomenon upon such properties has so far not been fully realized, in view of the existing literature. On the other hand, based upon the existing studies, it has been established that the non-uniform concentration of nanoparticles in the base fluid does cause to enhance the heat transfer rate. Therefore, it is logical to investigate the entropy production under the impact of non-homogenous distribution of nanoparticles. Based upon this fact the aim of current study is to explore a comprehensive detail about the influence of non-homogeneous nanoparticles concentration on entropy production phenomenon by considering a laminar viscous flow past a moving continuous flat plate. Non-uniform concentration is considered in the nanofluid modeling in which the Brownian and thermophoretic diffusions are considered which impart significant effects on velocity and temperature profiles. An exact self-similar solution to this problem is observed to be possible and is reported. The effects of various controlling physical parameters such as Brinkman number, Schmidt number, Prandtl number, diffusion parameter, and concentration parameter on both local as well as total entropy generation number and Bejan number are elaborated by several graphs and Tables. The obtained results reveal a significant impact of all aforementioned parameters on entropy generation characteristics. It is observed that by a 20% increase in nanoparticles concentration the total entropy generation is increased up to 67% for a set of fixed values of remaining parameters.

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Regular perturbation solution of Couette flow (non-Newtonian) between two parallel porous plates: a numerical analysis with irreversibility

Applied Mathematics and Mechanics ◽

10.1007/s10483-021-2677-9 ◽

2020 ◽

Vol 42 (1) ◽

pp. 127-142

Author(s):

M. Nazeer ◽

M. I. Khan ◽

S. Kadry ◽

Yuming Chu ◽

F. Ahmad ◽

...

Keyword(s):

Pressure Gradient ◽

Entropy Generation ◽

Shear Thickening ◽

Second Law Of Thermodynamics ◽

Perturbation Solution ◽

Bejan Number ◽

Regular Perturbation ◽

Thickening Behavior ◽

Upper Lid ◽

The Given

AbstractThe unavailability of wasted energy due to the irreversibility in the process is called the entropy generation. An irreversible process is a process in which the entropy of the system is increased. The second law of thermodynamics is used to define whether the given system is reversible or irreversible. Here, our focus is how to reduce the entropy of the system and maximize the capability of the system. There are many methods for maximizing the capacity of heat transport. The constant pressure gradient or motion of the wall can be used to increase the heat transfer rate and minimize the entropy. The objective of this study is to analyze the heat and mass transfer of an Eyring-Powell fluid in a porous channel. For this, we choose two different fluid models, namely, the plane and generalized Couette flows. The flow is generated in the channel due to a pressure gradient or with the moving of the upper lid. The present analysis shows the effects of the fluid parameters on the velocity, the temperature, the entropy generation, and the Bejan number. The nonlinear boundary value problem of the flow problem is solved with the help of the regular perturbation method. To validate the perturbation solution, a numerical solution is also obtained with the help of the built-in command NDSolve of MATHEMATICA 11.0. The velocity profile shows the shear thickening behavior via first-order Eyring-Powell parameters. It is also observed that the profile of the Bejan number has a decreasing trend against the Brinkman number. When ηi → 0 (i = 1, 2, 3), the Eyring-Powell fluid is transformed into a Newtonian fluid.

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On the Enhancement of Heat Transfer and Reduction of Entropy Generation by Asymmetric Slip in Pressure-Driven Non-Newtonian Microflows

Journal of Heat Transfer ◽

10.1115/1.4042157 ◽

2018 ◽

Vol 141 (2) ◽

Cited By ~ 2

Author(s):

Vishal Anand ◽

Ivan C. Christov

Keyword(s):

Heat Transfer ◽

Entropy Generation ◽

Shear Thickening ◽

Slip Boundary Condition ◽

Heat Fluxes ◽

Bejan Number ◽

Slip Boundary ◽

The Difference ◽

Analytical Expressions ◽

Pressure Driven

We study hydrodynamics, heat transfer, and entropy generation in pressure-driven microchannel flow of a power-law fluid. Specifically, we address the effect of asymmetry in the slip boundary condition at the channel walls. Constant, uniform but unequal heat fluxes are imposed at the walls in this thermally developed flow. The effect of asymmetric slip on the velocity profile, on the wall shear stress, on the temperature distribution, on the Bejan number profiles, and on the average entropy generation and the Nusselt number are established through the numerical evaluation of exact analytical expressions derived. Specifically, due to asymmetric slip, the fluid momentum flux and thermal energy flux are enhanced along the wall with larger slip, which, in turn, shifts the location of the velocity's maximum to an off-center location closer to the said wall. Asymmetric slip is also shown to redistribute the peaks and plateaus of the Bejan number profile across the microchannel, showing a sharp transition between entropy generation due to heat transfer and due to fluid flow at an off-center-line location. In the presence of asymmetric slip, the difference in the imposed heat fluxes leads to starkly different Bejan number profiles depending on which wall is hotter, and whether the fluid is shear-thinning or shear-thickening. Overall, slip is shown to promote uniformity in both the velocity field and the temperature field, thereby reducing irreversibility in this flow.

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Entropy Generation in MHD Conjugate Flow with Wall Shear Stress over an Infinite Plate: Exact Analysis

Entropy ◽

10.3390/e21040359 ◽

2019 ◽

Vol 21 (4) ◽

pp. 359 ◽

Cited By ~ 2

Author(s):

Arshad Khan ◽

Faizan ul Karim ◽

Ilyas Khan ◽

Tawfeeq Alkanhal ◽

Farhad Ali ◽

...

Keyword(s):

Shear Stress ◽

Wall Shear Stress ◽

Entropy Generation ◽

Infinite Plate ◽

Mhd Flow ◽

Bejan Number ◽

Grashof Number ◽

Entropy Generation Number ◽

Mass And Heat Transfer ◽

Wall Shear

The current work will describe the entropy generation in an unsteady magnetohydrodynamic (MHD) flow with a combined influence of mass and heat transfer through a porous medium. It will consider the flow in the XY plane and the plate with isothermal and ramped wall temperature. The wall shear stress is also considered. The influences of different pertinent parameters on velocity, the Bejan number and on the total entropy generation number are reported graphically. Entropy generation in the fluid is controlled and reduced on the boundary by using wall shear stress. It is observed in this paper that by taking suitable values of pertinent parameters, the energy losses in the system can be minimized. These parameters are the Schmitt number, mass diffusion parameter, Prandtl number, Grashof number, magnetic parameter and modified Grashof number. These results will play an important role in the heat flow of uncertainty and must, therefore, be controlled and managed effectively.

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Numerical study of mixed convection and entropy generation in the Poiseulle-Benard channel in different angles

Thermal Science ◽

10.2298/tsci1002329n ◽

2010 ◽

Vol 14 (2) ◽

pp. 329-340 ◽

Cited By ~ 12

Author(s):

Mostafa Nourollahi ◽

Mousa Farhadi ◽

Kurosh Sedighi

Keyword(s):

Nusselt Number ◽

Entropy Generation ◽

Numerical Study ◽

Navier Stokes ◽

Bejan Number ◽

Optimum Angle ◽

Velocity Gradients ◽

Negative Effect ◽

Energy Equations ◽

Rayleigh Numbers

The issue of entropy generation and Nusselt number in Poiseuille-Benard channel flow are analyzed by solving numerically Navier-Stokes and energy equations with the use of the classic Boussinesq incompressible approximation. The Nusselt number is studied as a function of q. In addition variations of entropy generation and the Bejan number as a function of q and j are studied. The channel angle (q) and irreversibility (j) were changed from -25 to 30 and from 10-5 to 1, respectively, whereas Reynolds, Peclet, and Rayleigh numbers were fixed at Re = 10, Pe = 20/3, and Ra = 104. More over the positive and negative effect of buoyancy force on flow field, Nusselt number and entropy generation are discussed. Optimum angle for dif- ferent irreversibilities are specified by definition h as the rate of the Nusselt number to the entropy generation, the optimum angle was distinguished for different irreversibility. Results show that the Nusselt number changes very slightly and is almost constant when q changes from -10 to 10 and the Nusselt number decreases sharply when q increases from 20 to 30 or decreases from -15 to -25. Moreover it has been found that the entropy generation due to heat transfer is localized at areas where heat exchanged between the walls and the flow is maximum, while the entropy generation due to fluid friction is maximum at areas where the velocity gradients are maximum such as vortex centers. Consequently when q is decreased from -15 to -25 or is increased from 20 to 30 entropy generation for small irreversibilities decreases and increases sharply for large irreversibilities.

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