Second Law Analysis of Flow in a Circular Pipe With Uniform Suction and Magnetic Field Effects

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
G. Nagaraju ◽  
Srinivas Jangili ◽  
J. V. Ramana Murthy ◽  
O. A. Bég ◽  
A. Kadir
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Entropy Generation ◽  
Stokes Equations ◽  
Circular Pipe ◽  
Bejan Number ◽  
Magnetic Field Effects ◽  
Constant Wall Temperature ◽  
Entropy Generation Number ◽  
Uniform Suction

The present paper investigates analytically the two-dimensional heat transfer and entropy generation characteristics of axisymmetric, incompressible viscous fluid flow in a horizontal circular pipe. The flow is subjected to an externally applied uniform suction across the wall in the normal direction and a constant magnetic field. Constant wall temperature is considered as the thermal boundary condition. The reduced Navier–Stokes equations in a cylindrical coordinate system are solved to obtain the velocity and temperature distributions. The velocity distributions are expressed in terms of stream function and the solution is obtained using the homotopy analysis method (HAM). Validation with earlier nonmagnetic solutions in the literature is incorporated. The effects of various parameters on axial and radial velocities, temperature, axial and radial entropy generation numbers, and axial and radial Bejan numbers are presented graphically and interpreted at length. Streamlines, isotherms, pressure, entropy generation number, and Bejan number contours are also visualized. Increasing magnetic body force parameter shifts the peak of the velocity curve near to the axis, whereas it accelerates the radial flow. The study is relevant to thermodynamic optimization of magnetic blood flows and electromagnetic industrial flows featuring heat transfer.

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

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.

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

2013 ◽  
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.

Entropy generation and thermo-diffusion effects on unsteady chemically reactive slip flow between two rotating disks

2019 ◽  
Vol 29 (10) ◽  
pp. 3795-3821
Author(s):  
Sumaira Qayyum ◽  
Muhammad Ijaz Khan ◽  
Tasawar Hayat ◽  
Ahmed Alsaedi
Keyword(s):  
Magnetic Field ◽  
Entropy Generation ◽  
Stokes Equations ◽  
Tangential Velocity ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Bejan Number ◽  
Thermal Equation ◽  
Content Type ◽  
Flow Variables

Purpose The purpose of this study is to analyze the Entropy generation analysis and heat transport in three-dimensional flow between two stretchable disks. Joule heating and heat generation/absorption are incorporated in the thermal equation. Thermo-diffusion effect is also considered. Flow is conducting for time-dependent applied magnetic field. Induced magnetic field is not taken into consideration. Velocity and thermal slip conditions at both the disks are implemented. The flow problem is modeled by using Navier–Stokes equations with entropy generation rate and Bejan number. Design/methodology/approach Von Karman transformations are used to reduce the nonlinear governing expressions into an ordinary one and then tackled by homotopy analysis method for convergent series solutions. The nonlinear expressions for total entropy generation rate are obtained with appropriate transformations. The impacts of different flow variables on velocity, temperature, entropy generation rate and Bejan number are described graphically. Velocity, temperature and concentration gradients are discussed in the presence of flow variables. Findings Axial, radial and tangential velocity profiles show decreasing trend for larger values of velocity slip parameters. For a larger Brinkman number, the entropy generation increases, while a decreasing trend is noticed for Bejan number. Originality/value To the best of the authors’ knowledge, no such analyses have been reported in the literature.

scholarly journals Heat transfer and entropy generation analysis in a horizontal channel filled with a permeable medium in the presence of aligned magnetic field and temperature gradient heat source

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
K. S. Balamurugan ◽  
N. Udaya Bhaskara Varma ◽  
J. L. Ramaprasad
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Shear Stress ◽  
Temperature Gradient ◽  
Heat Source ◽  
Entropy Generation ◽  
Fluid Velocity ◽  
Horizontal Channel ◽  
Bejan Number ◽  
Aligned Magnetic Field

AbstractThe current investigation is concerned with heat transfer and entropy generation analysis in a horizontal channel brimming with porous medium in the existence of aligned magnetic field, viscous and joules dissipation and temperature gradient heat source. The boundary conditions are treated as constant values for velocity and temperature at lower and upper walls. An explicit solution of governing equations has been attained in closed system. The repercussions of pertinent parameters on the fluid velocity, temperature, entropy generation and Bejan number are conferred and scrutinized through graphs in detail. Additionally the expressions for shear stress and the rate of heat transfer coefficients at the channel walls are derived and results obtained are physically interpreted through tables. From the conquered results, it is addressed that Brinkman number Br enhances boundary layer thickness. Entropy generation increases with intensifying values of $$M$$ M , aligned angle ϕ, temperature gradient heat source parameter Q, characteristic temperature ration $$\omega$$ ω and permeability parameter K. The shear stress is same at both the lower and upper walls.

Entropy Analysis of MHD Variable Thermal Conductivity Fluid Flow Past a Convectively Heated Stretching Cylinder

2018 ◽  
Vol 387 ◽  
pp. 244-259 ◽  
Author(s):  
Sanatan Das ◽  
Subhajit Chakraborty ◽  
Oluwole Daniel Makinde ◽  
Rabindra Nath Jana
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Entropy Generation ◽  
Numerical Solutions ◽  
Fluid Velocity ◽  
Convective Heating ◽  
Bejan Number ◽  
Stretching Cylinder ◽  
Entropy Analysis ◽  
Entropy Generation Number

The present study is related to entropy analysis during magnetohydrodynamic (MHD) boundary layer flow of a viscous incompressible electrically conducting fluid past a stretching cylinder with convective heating in the presence of a transverse magnetic field. The governing boundary layer equations in cylindrical form are simplified by means of appropriate similarity transformations. Numerical solutions with high precision are obtained using Runge-Kutta fourth order scheme with eminent shooting technique. The effects of the pertinent parameters on the fluid velocity, temperature, entropy generation number, Bejan number as well as the shear stress at the surface of the cylinder are discussed graphically and quantitatively. It is examined that due to the presence of magnetic field, entropy generation can be controlled and reduced. Bejan number is plotted to present a comparative analysis of entropy generation due to heat transfer and fluid friction. It is found that Bejan number is an increasing function of Biot number.

Analysis of Entropy Generation of a Magneto-Hydrodynamic Flow Through the Operation of an Unlooped Pulsating Heat Pipe

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Mobadersani Farrokh ◽  
Toolabi Goodarz ◽  
Jafarmadar Samad ◽  
Nasiri Javid ◽  
Habibzadeh Amin
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Pipe ◽  
Entropy Generation ◽  
Uniform Magnetic Field ◽  
Pipe Diameter ◽  
Bejan Number ◽  
Pulsating Heat Pipe ◽  
Viscous Effects ◽  
Evaporator Temperature

The aim of the study is the analysis of a uniform magnetic field effect on fluid flow, heat transfer, and entropy generation through the operation of a pulsating heat pipe (PHP). An open loop PHP with three neighboring vapor plugs and two liquid slugs has been considered. The governing equations such as momentum, energy, and mass equations are solved using an explicit method except for the energy equation of liquid slugs. For each case study, Bejan number has been derived to find the heat transfer share in entropy generation. According to the results, the performance of the oscillating heat pipe decreases by applying uniform magnetic field. Moreover, the obtained results illustrate the effects of the applied magnetic field position on the heat transfer and the entropy generation. The latent and sensible heat transfer into the PHP enhance as a result of increase in the pipe diameter, so that the liquid slugs oscillate with high amplitudes. In addition, the entropy generation value increases with an augmentation in the value of the pipe diameter. The evaluated Bejan numbers indicate that the viscous effects in entropy generation decrease as the pipe diameter increases. Furthermore, the results depict that the heat transfer performance of PHP improves by increasing temperature difference between evaporator and condenser sections. With an increase in the value of the evaporator temperature, the Bejan number will increase, as a result, this phenomenon reveals the inconsiderable role of viscous impacts in high evaporator temperatures. In order to validate the calculations, the calculated results have been compared with the previous studies which show good agreement.

Interactions of Porosity-Magnetic Field and Viscous Dissipation in an Inclined Channel Type Flow

2010 ◽  
Author(s):  
Murat Havzali ◽  
Guven Komurgoz ◽  
Aytac Arikoglu ◽  
Haci Ibrahim Keser ◽  
Ibrahim Ozkol
Keyword(s):  
Magnetic Field ◽  
Viscous Dissipation ◽  
Entropy Generation ◽  
Thermal Characteristics ◽  
Darcy Number ◽  
Transverse Magnetic ◽  
Constant Heat Flux ◽  
Bejan Number ◽  
Entropy Generation Number ◽  
Inclined Channel

In this work, entropy generation due to laminar viscous incompressible flow of a conducting fluid in the presence of a transverse magnetic field in a porous inclined channel is investigated. Fully developed flow field is solved analytically whereas the solution of the energy equation is obtained by Finite Difference Method (FDM). The boundary conditions at the walls are considered to be constant heat flux. The influence of the applied magnetic field, porous medium and the viscous dissipation on velocity, temperature and entropy generation is examined. The dependence of flow and thermal characteristics on Peclet number (Pe), Brinkman number (Br), Darcy number (Da) and Hartman number (Ha) is analyzed through velocity and temperature distribution as well as Entropy generation number (Ns) and Bejan Number (Be) profiles.

Natural Convection and Entropy Generation in a Cavity Filled With Two Horizontal Layers of Nanofluid and Porous Medium in Presence of a Magnetic Field

2015 ◽  
Author(s):  
Ali Al-Zamily ◽  
M. Ruhul Amin
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Flux ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Rayleigh Number ◽  
Entropy Generation ◽  
Darcy Number ◽  
Bejan Number ◽  
Flow Heat

A numerical analysis is performed to study the fluid flow, heat transfer and entropy generation inside a square cavity embedded with heat flux and subject to the horizontal magnetic field. The cavity is consist of two same width layers: first layer filled with nanofluid (Al2O3+water) and second one is saturated porous media filled with a same nanofluid. The uniform constant heat flux is applied partly at the base wall, and the other parts of the base wall are assumed adiabatic. The upper horizontal wall kept adiabatic, while the vertical walls are maintained at constant cold temperature. Finite element method based on the variational formulation is employed to solve the main equations. The results of the present study are based on visualization of heat flow via isotherms and heatfunctions (heatlines), fluid flow via streamfunctions, and irreversibility via Bejan number. Comparisons with previously numerical and experimental published works are performed and the results are found to be in a good agreement. In this study, the effect of the main pertinent parameters, such as: nanoparticles volume fraction (0≤Φ≤0.15), Rayleigh number (104≤Ra≤107), Darcy number (10−1≤Da≤10−5), Hartmann number (0≤Ha≤60) on the fluid flow, heat transfer and entropy generation are investigated. The results show that the effect of the Hartmann on Nusselt number increases as Darcy number increases especially at high Rayleigh number. Also, at Ra=107 and Φ=0.15, the percentage decreasing in Nusselt number due to present magnetic field (Ha=40) are 85.89% at Da=10−1, 87.12% at Da=10−3 and 98.69% at Da=10−5.

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