Heat Transfer and Entropy Generation Characteristics of a Non-Newtonian Fluid Squeezed and Extruded Between Two Parallel Plates

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
P Kaushik ◽  
Pranab Kumar Mondal ◽  
Sukumar Pati ◽  
Suman Chakraborty
Keyword(s):  
Heat Transfer ◽  
Newtonian Fluid ◽  
Entropy Generation ◽  
Bejan Number ◽  
Engineering Systems ◽  
Power Law Model ◽  
Parallel Plates ◽  
Unsteady Heat Transfer ◽  
Thermodynamic Performance ◽  
Fluid Rheology

This study investigates the unsteady heat transfer and entropy generation characteristics of a non-Newtonian fluid, squeezed and extruded between two parallel plates. In an effort to capture the underlying thermo-hydrodynamics, the power-law model is used here to describe the constitutive behavior of the non-Newtonian fluid. The results obtained from the present analysis reveal the intricate interplay between the fluid rheology and the squeezing dynamics, toward altering the Nusselt number and Bejan number characteristics. Findings from this study may be utilized to design optimal process parameters for enhanced thermodynamic performance of engineering systems handling complex fluids undergoing simultaneous extrusion and squeezing.

Entropy Generation Minimization in an Electroosmotic Flow of Non-Newtonian Fluid: Effect of Conjugate Heat Transfer

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Prakash Goswami ◽  
Pranab Kumar Mondal ◽  
Anubhab Datta ◽  
Suman Chakraborty
Keyword(s):  
Heat Transfer ◽  
Newtonian Fluid ◽  
Entropy Generation ◽  
Conjugate Heat Transfer ◽  
Transfer Problem ◽  
Heat Removal ◽  
Entropy Generation Rate ◽  
Fluidic Channel ◽  
Thermal Boundary Conditions ◽  
Fluid Rheology

We investigate the entropy generation characteristics of a non-Newtonian fluid in a narrow fluidic channel under electrokinetic forcing, taking the effect of conjugate heat transfer into the analysis. We use power-law model to describe the non-Newtonian fluid rheology, in an effort to capture the essential thermohydrodynamics. We solve the conjugate heat transfer problem in an analytical formalism using the thermal boundary conditions of third kind at the outer surface of the walls. We bring out the alteration in the entropy generation behavior as attributable to the rheology-driven alteration in heat transfer, coupled with nonlinear interactions between viscous dissipation and Joule heating originating from electroosmotic effects. We unveil optimum values of different parameters, including both the geometric as well as thermophysical parameters, which lead to the minimization of the entropy generation rate in the system. We believe that the inferences obtained from the present study may bear far ranging consequences in the design of various cooling and heat removal devices/systems, for potential use in microscale thermal management.

Conjugate Free Convection Heat Transfer and Thermodynamic Analysis of Infrared Suppression Device with Cylindrical Funnels

2022 ◽  
Author(s):  
Vikrant Chandrakar ◽  
Arnab Mukherjee ◽  
Jnana Ranjan Senapati ◽  
Ashok Kumar Barik
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Convection Heat Transfer ◽  
Navier Stokes ◽  
Bejan Number ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Geometric Ratio ◽  
Flow Rate Increase ◽  
Free Convection Heat

Abstract A convection system can be designed as an energy-efficient one by making a considerable reduction in exergy losses. In this context, entropy generation analysis is performed on the infrared suppression system numerically. In addition, results due to heat transfer are also shown. The numerical solution of the Navier-stokes equation, energy equation, and turbulence equation is executed using ANSYS Fluent 15.0. To perform the numerical analysis, different parameters such as the number of funnels, Rayleigh number (Ra), inner surface temperature, and geometric ratio are varied in the practical range. Results are shown in terms of heat transfer, entropy generation, irreversibility (due to heat transfer and fluid friction), and Bejan number with some relevant parameters. Streamlines and temperature contours are also provided for better visualization of temperature and flow field around the device. Results show that heat transfer and mass flow rate increase with the increase in Ra. Entropy generation and the irreversibility rise with an increase in the number of funnels and geometric ratio. Also, the Bejan number decreases with an increase in Ra and the number of funnels. A cooling time is also obtained using the lumped capacitance method.

scholarly journals Entropy Analysis on a Three-Dimensional Wavy Flow of Eyring–Powell Nanofluid: A Comparative Study

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Arshad Riaz ◽  
Ahmed Zeeshan ◽  
M. M. Bhatti
Keyword(s):  
Viscous Dissipation ◽  
Newtonian Fluid ◽  
Entropy Generation ◽  
Pressure Rise ◽  
Software Tool ◽  
Bejan Number ◽  
Mathematical Treatment ◽  
Cylindrical Domain ◽  
Special Cases ◽  
The Impact

The thermal management of a system needs an accurate and efficient measurement of exergy. For optimal performance, entropy should be minimized. This study explores the enhancement of the thermal exchange and entropy in the stream of Eyring–Powell fluid comprising nanoparticles saturating the vertical oriented dual cylindrical domain with uniform thermal conductivity and viscous dissipation effects. A symmetrical sine wave over the walls is used to induce the flow. The mathematical treatment for the conservation laws are described by a set of PDEs, which are, later on, converted to ordinary differential equations by homotopy deformations and then evaluated on the Mathematica software tool. The expression of the pressure rise term has been handled numerically by using numerical integration by Mathematica through the algorithm of the Newton–Cotes formula. The impact of the various factors on velocity, heat, entropy profile, and the Bejan number are elaborated pictorially and tabularly. The entropy generation is enhanced with the variation of viscous dissipation but reduced in the case of the concentration parameter, but viscous dissipation reveals opposite findings for the Newtonian fluid. From the abovementioned detailed discussion, it can be concluded that Eyring–Powell shows the difference in behavior in the entropy generation and in the presence of nanoparticles due to the significant dissipation effects, and also, it travels faster than the viscous fluid. A comparison between the Eyring-Powell and Newtonian fluid are also made for each pertinent parameter through special cases. This study may be applicable for cancer therapy in biomedicine by nanofluid characteristics in various drugs considered as a non-Newtonian fluid.

ENTROPY GENERATION FOR A NON-NEWTONIAN SHEAR THINNING FLUID WITH VISCOUS HEATING EFFECTS

2017 ◽  
Vol 41 (4) ◽  
pp. 593-607
Author(s):  
Muharrem Imal ◽  
Coskun Ozalp ◽  
Bulent Yaniktepe ◽  
Mohammed Mehdi-Rashidi ◽  
Ertac Hurdogan
Keyword(s):  
Temperature Dependence ◽  
Entropy Generation ◽  
Pseudospectral Method ◽  
Shear Thinning ◽  
Bejan Number ◽  
Parallel Plates ◽  
Heating Effects ◽  
Exponential Temperature Dependence ◽  
Power Law Index ◽  
Shear Thinning Fluid

This paper reports the entropy generation of a two-dimensional, non-isothermal, steady, hydrodynamically and thermally fully-developed flow of an incompressible, non-Newtonian shear thinning fluid between two infinite parallel plates. The inelastic fluid is modeled by a two parameter Carreau constitutive equation with an exponential temperature dependence of viscosity. Temperature dependence of the fluid is modeled through Arrhenius law. Momentum and energy balance equations, which govern the flow, are coupled, and this nonlinear boundary value problem is solved numerically using a Pseudospectral method based on the Chebyshev polynomials. The effect of various flow controlling parameters on velocity, temperature and entropy generation is analyzed. The results indicated that Brinkman number and activation energy have opposite effects on entropy generation due to heat transfer. In contrast to the power-law index, an increase in the material time constant results in a decrease in the Bejan Number.

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.

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

Entropy ◽  
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.

scholarly journals Numerical Study of Nanofluid Irreversibilities in a Heat Exchanger Used with an Aqueous Medium

Entropy ◽  
2020 ◽  
Vol 22 (1) ◽  
pp. 86
Author(s):  
Guillermo Efren Ovando-Chacon ◽  
Sandy Luz Ovando-Chacon ◽  
Abelardo Rodriguez-Leon ◽  
Mario Diaz-Gonzalez ◽  
Jorge Arturo Hernandez-Zarate ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Aqueous Medium ◽  
Entropy Generation ◽  
Numerical Study ◽  
Oil Extraction ◽  
Hot Water ◽  
Bejan Number ◽  
Extraction Properties ◽  
And Performance

Heat exchangers play an important role in different industrial processes; therefore, it is important to characterize these devices to improve their efficiency by guaranteeing the efficient use of energy. In this study, we carry out a numerical analysis of flow dynamics, heat transfer, and entropy generation inside a heat exchanger; an aqueous medium used for oil extraction flows through the exchanger. Hot water flows on the shell side; nanoparticles have been added to the water in order to improve heat transfer toward the cold aqueous medium flowing on the tube side. The aqueous medium must reach a certain temperature in order to obtain its oil extraction properties. The analysis is performed for different Richardson numbers (Ri = 0.1–10), nanofluid volume fractions (φ = 0.00–0.06), and heat exchanger heights (H = 0.6–1.0). Results are presented in terms of Nusselt number, total entropy generation, Bejan number, and performance evaluation criterion. Results showed that heat exchanger performance increases with the increase in Ri when Ri > 1 and when reducing H.

scholarly journals Numerical Assessment of Heat Transfer and Entropy Generation of a Porous Metal Heat Sink for Electronic Cooling Applications

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3851
Author(s):  
Hamed Rasam ◽  
Prosun Roy ◽  
Laura Savoldi ◽  
Shabnam Ghahremanian
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Entropy Generation ◽  
Heat Sink ◽  
Cooling System ◽  
Solid Phase ◽  
Porous Metal ◽  
Electronic Equipment ◽  
Bejan Number ◽  
Pore Density

In the present study, the thermal performance of an electronic equipment cooling system is investigated. The heat sink used in the current cooling system consists of a porous channel with a rectangular cross-section that is assumed to be connected directly to the hot surface of an electronic device. In this modeling, a fully developed flow assumption is used. The Darcy–Brinkman model was used to determine the fluid flow field. Since using the local thermal equilibrium (LTE) model may provide results affected by the error in metal foams, in the present research, an attempt has first been made to examine the validity range of this model. The local thermal non-equilibrium (LTNE) model taking into account the viscous dissipation effect was then used to determine the temperature field. To validate the numerical solution, the computed results were compared with other studies, and an acceptable agreement was observed. Analysis of the temperature field shows that if the fluid–solid-phase thermal conductivity ratio is 1 or the Biot number has a large value, the difference between the temperature of the solid phase and the fluid phase decreases. Moreover, the effect of important hydrodynamic parameters and the porous medium characteristics on the field of hydrodynamic, heat, and entropy generation was studied. Velocity field analysis shows that increasing the pore density and reducing the porosity cause an increase in the shear stress on the walls. By analyzing the entropy generation, it can be found that the irreversibility of heat transfer has a significant contribution to the total irreversibility, leading to a Bejan number close to 1. As a guideline for the design of a porous metal heat sink for electronic equipment, the use of porous media with low porosity reduces the total thermal resistance and improves heat transfer, reducing the total irreversibility and the Bejan number. Moreover, the increasing of pore density increases the specific porous surface; consequently, it reduces the total irreversibility and Bejan number and improves the heat transfer.

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