scholarly journals Effects of non-uniform nanoparticle concentration on entropy generation

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.

scholarly journals Study of Entropy Generation with Multi-Slip Effects in MHD Unsteady Flow of Viscous Fluid Past an Exponentially Stretching Surface

Symmetry ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 426 ◽  
Author(s):  
Sajjad Haider ◽  
Adnan Saeed Butt ◽  
Yun-Zhang Li ◽  
Syed Muhammad Imran ◽  
Babar Ahmad ◽  
...  
Keyword(s):  
Differential Equations ◽  
Viscous Fluid ◽  
Entropy Generation ◽  
Slip Flow ◽  
Physical Parameters ◽  
Bejan Number ◽  
Entropy Generation Number ◽  
Linear Differential ◽  
Exponentially Stretching ◽  
The Impact

The current study aims to probe the impacts of entropy in a hydromagnetic unsteady slip flow of viscous fluid past an exponentially stretching sheet. Appurtenant similarity variables are employed to transmute the governing partial differential equations into a system of non-linear differential equations, which are analytically solved by utilizing the homotopy analysis method (HAM). Moreover, a shooting technique with fourth–fifth order Runge–Kutta method is deployed to numerically solve the problem. The impact of the physical parameters that influence the flow and heat transmission phenomena are sketched, tabulated and discussed briefly. Additionally, the impact of these parameters on entropy generation is thoroughly discussed by plotting graphs of the local entropy generation number and the Bejan number.

scholarly journals Aspects of Chemical Entropy Generation in Flow of Casson Nanofluid between Radiative Stretching Disks

Entropy ◽  
2020 ◽  
Vol 22 (5) ◽  
pp. 495 ◽  
Author(s):  
Nargis Khan ◽  
Iram Riaz ◽  
Muhammad Sadiq Hashmi ◽  
Saed A. Musmar ◽  
Sami Ullah Khan ◽  
...  
Keyword(s):  
Entropy Generation ◽  
Fluid Velocity ◽  
Axisymmetric Flow ◽  
Casson Fluid ◽  
Physical Parameters ◽  
Bejan Number ◽  
Axial Component ◽  
Radiation Chemical ◽  
Casson Nanofluid ◽  
The Impact

The appropriate utilization of entropy generation may provoke dipping losses in the available energy of nanofluid flow. The effects of chemical entropy generation in axisymmetric flow of Casson nanofluid between radiative stretching disks in the presence of thermal radiation, chemical reaction, and heat absorption/generation features have been mathematically modeled and simulated via interaction of slip boundary conditions. Shooting method has been employed to numerically solve dimensionless form of the governing equations, including expressions referring to entropy generation. The impacts of the physical parameters on fluid velocity components, temperature and concentration profiles, and entropy generation number are presented. Simulation results revealed that axial component of velocity decreases with variation of Casson fluid parameter. A declining variation in Bejan number was noticed with increment of Casson fluid constant. Moreover, a progressive variation in Bejan number resulted due to the impact of Prandtl number and stretching ratio constant.

scholarly journals Entropy Generation in MHD Radiative Flow of CNTs Casson Nanofluid in Rotating Channels with Heat Source/Sink

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Poom Kumam ◽  
Zahir Shah ◽  
Abdullah Dawar ◽  
Haroon Ur Rasheed ◽  
Saeed Islam
Keyword(s):  
Heat Source ◽  
Entropy Generation ◽  
Second Law Of Thermodynamics ◽  
Entropy Generation Rate ◽  
Physical Parameters ◽  
Bejan Number ◽  
Surface Drag ◽  
Casson Nanofluid ◽  
Source Sink ◽  
The Impact

We presented the applications of entropy generation for SWCNTs and MWCNTs based on kerosene oil for Casson nanofluid flow by rotating channels. Kerosene oil has advanced thermal conductivity and exclusive features and has a lot of practical uses due to its unique behavior. That is why we have used kerosene oil as a based fluid. For the entropy generation second law of thermodynamics is applied and implemented for the nanofluid transport mechanism. In the presence of magnetic field, the effects of thermal radiations and heat source/sink on the temperature profiles are studied. The fluid flow is supposed in steady state. With the help of suitable similitude parameters, the leading equations have been transformed to a set of differential equations. The solution of the modeled problem has been carried out with the homotopic approach. The physical properties of carbon nanotubes are shown through tables. The effects of the imbedded physical parameters on the velocities, temperature, entropy generation rate, and Bejan number profiles are investigated and presented through graphs. Moreover, the impact of significant parameters on surface drag force and heat transfer rate is tabulated.

scholarly journals Entropy Generation on MHD Flow and Heat Transfer of Non-Newtonian Fluid Flow Over a Non-Linear Radially Stretching Sheet

2018 ◽  
Vol 7 (4.10) ◽  
pp. 863
Author(s):  
S. Sreenadh ◽  
V. Ramesh Babu ◽  
G. Gopi Krishna ◽  
S. R.Mishra ◽  
A. N.S.Srinivas
Keyword(s):  
Newtonian Fluid ◽  
Entropy Generation ◽  
Stretching Sheet ◽  
Magnetic Parameter ◽  
Mhd Flow ◽  
Physical Parameters ◽  
Bejan Number ◽  
Entropy Generation Number ◽  
Non Linear ◽  
Flow Phenomena

An investigation is made for analyzing the behavior of MHD flow phenomena of a non-Newtonian fluid over a non-linear radially stretching sheet by using numerical technique. Magnetic field is considered in normal direction to the stretching sheet. With use of similarity transformations, the pdes are transformed into odes. The solution of theses odes are performed by using fourth order Runge - Kutta method along with shooting technique. The significance of different physical parameters characterizes the flow phenomena are analyzed with the use of graphs. The Jeffrey parameter  and magnetic parameter  has significant effect on velocity and temperature distribution over a non-linear stretching sheet. It is noticed that, the higher magnetic parameter results the increase in entropy generation number where the opposite nature is noticed in the case of Bejan number.  

Analysis of Microchannel Heat Sink Performance for Electronics Cooling Based on Thermodynamics

2006 ◽  
Author(s):  
Hessamoddin Abbassi ◽  
Mohammad H. Saidi ◽  
Pouya Zageneh Kazemi
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Entropy Generation ◽  
Heat Sink ◽  
Closed Form Solution ◽  
Electronics Cooling ◽  
Bejan Number ◽  
Microchannel Heat Sink ◽  
Entropy Generation Number ◽  
The Impact

Present investigation analyzes the issue of entropy generation in a uniformly heated microchannel heat sink (MCHS). Analytical approach used to solve forced convection problem across MCHS, is porous medium model based on modified Darcy equation for fluid flow and two-equation model for heat transfer between solid and fluid phases. Furthermore, closed form solution of velocity distribution is employed to capture z-direction velocity gradient of flow, which plays a salient role on entropy generation through fluid flow. Analytical expressions for total and thermal entropy generation number (stems from heat transfer), and Bejan number are derived and cast into dimensionless form using velocity and temperature distributions. Besides, entropy generation characteristics in MCHS and the impact of various influential parameters on entropy production have been investigated. Finally, In order to examine the accuracy of analysis, the results of thermal evaluation are compared to one of the previous investigations conducted for thermal optimization of MCHS.

scholarly journals Thermodynamical Analysis of the Flow and Heat Transfer over a Static and a Moving Wedge

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Adnan Saeed Butt ◽  
Asif Ali
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Temperature Fields ◽  
Entropy Production Rate ◽  
Physical Parameters ◽  
Bejan Number ◽  
Entropy Generation Number ◽  
Flow And Heat Transfer ◽  
Generation Number ◽  
Moving Wedge

The first and second law characteristics of fluid flow and heat transfer over a static and a moving wedge are investigated. With the help of suitable similarity transformations, the governing boundary layer equations for the velocity and temperature fields are transformed into ordinary differential equations and are solved numerically. The velocity and the temperature profiles are obtained for various parameters and are utilized to compute the entropy generation number Ns and the Bejan number Be. The effects of various physical parameters on the entropy generation number and the Bejan number are depicted through graphs and are discussed qualitatively. It is observed that the entropy production rate is less in case of wedge moving in the opposite direction to flow as compared to static wedge.

Theoretical and experimental investigation of an organic Rankine cycle for a waste heat recovery system

2009 ◽  
Vol 223 (5) ◽  
pp. 523-533 ◽  
Author(s):  
W Gu ◽  
Y Weng ◽  
Y Wang ◽  
B Zheng
Keyword(s):  
Heat Source ◽  
Entropy Generation ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Entropy Generation Rate ◽  
Working Fluid ◽  
Total Entropy ◽  
Waste Heat Recovery System ◽  
Cycle Efficiency

This article describes and evaluates an organic Rankine cycle (ORC) for a waste heat recovery system by both theoretical and experimental studies. Theoretical analysis of several working fluids shows that cycle efficiency is very sensitive to evaporating pressure, but insensitive to expander inlet temperature. Second law analysis was carried out using R600a as a working fluid and a flow of hot air as a heat source, which is not isothermal, along the evaporator. The result discloses that the evaporator's internal and external entropy generation is the main source of total entropy generation. The effect of the heat source temperature, evaporating pressure, and evaporator size on the entropy generation rate is also presented. The obtained useful power is directly linked to the total entropy generation rate according to the Gouy—Stodola theorem. The ORC testing system was established and operated using R600a as a working fluid and hot water as a heat source. The maximum cycle efficiency of the testing system is 5.2 per cent, and the testing result also proves that cycle efficiency is insensitive to heat source temperature, but sensitive to evaporating pressure. The entropy result also shows that internal and external entropy of the evaporator is the main source of total entropy generation.

Effects of Manufacturing Tolerances on Regenerative Exchanger Number of Transfer Units and Entropy Generation

2005 ◽  
Vol 128 (3) ◽  
pp. 585-598 ◽  
Author(s):  
Wei Shang ◽  
Robert W. Besant
Keyword(s):  
Entropy Generation ◽  
Flow Channel ◽  
Operating Conditions ◽  
Channel Diameter ◽  
Pressure Drops ◽  
Entropy Generation Number ◽  
Compact Heat Exchangers ◽  
Prime Concern ◽  
Manufacturing Tolerances ◽  
The Impact

A prime concern with the design of ultra-compact heat exchangers is the impact on performance of flow channel variations due to flow channel hydraulic diameter variations caused by manufacturing tolerances. This paper uses analytical methods to show that as the standard deviation in flow channel sizes, caused by manufacturing tolerances in a rotary regenerative exchanger, is increased compared to the average flow channel diameter the effective number of transfer units decreases. Depending on the operating conditions, the entropy generation number either increases or decreases with increasing flow channel size variations. These findings extend previous findings that showed that flow channel variations cause lower pressure drops and effectiveness.

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.

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.

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