Entropy Generation In Nanofluid Flow Research Articles

Exploring heat transfer augmentation and entropy generation in nanofluid flow induced by vibration: Influence of velocity and rheological properties

This study numerically investigates the heat transfer and entropy generation of nanofluid flow under mechanical vibration, employing approved formulations to model the nanofluid density, specific heat, viscosity, and conductivity. Specifically, the impact of vibration on laminar forced convection thermal flow of both pure water and Al2O3-water nanofluid within a pipe is explored using CFD. Various Reynolds numbers are examined under constant heat flux conditions, with nanofluid properties determined using established correlations. Results indicate that applying Al2O3 nanofluid slurry instead of pure water at low Reynolds numbers reduces entropy generation, proving advantageous. Vibration enhances heat transfer by intensifying fluid agitation and promoting particle dispersion near the wall, resulting in a significantly more uniform temperature distribution along the pipe, approximately 100 times more than steady-state flow. Analysis reveals vibration’s effectiveness in reducing irreversibility, especially at lower Reynolds numbers, with substantial enhancements in heat transfer coefficients, up to approximately fivefold compared to steady-state flow, particularly for nanofluid flows. Optimal conditions for maximizing heat transfer enhancement emphasize nanoparticle size and concentration. Mechanical vibration with different frequencies produces significant improvements in heat transfer compared to amplitude variations, primarily influenced by the Reynolds number. Overall, this study offers valuable insights into the intricate relationship between vibration, fluid dynamics, and heat transfer in nanofluid flows, with practical implications for optimizing thermal management systems across various engineering applications.

Correction: Investigation of free convection heat transfer and entropy generation of nanofluid flow inside a cavity affected by magnetic field and thermal radiation

Correction: Investigation of free convection heat transfer and entropy generation of nanofluid flow inside a cavity affected by magnetic field and thermal radiation

Numerical solution of entropy generation in nanofluid flow through a surface with thermal radiation applications

The main purpose of this research is to investigate a mathematical model of nanofluid passing through a stretching sheet having titanium dioxide (TiO2), copper oxide (CuO), and carbon nanotubes (CNTs) as nanoparticles, and sodium alginate is used as a base fluid. The present model can be very useful for numerous fields like Bioengineering, science, and technology. The main reason for using titanium dioxide, copper oxide, and carbon nanotubes nanoparticles as nanomaterials they have many applications in several areas. Moreover, impacts of non-linear thermal radiation and entropy generations are taken into account. By utilizing the similarity transformation technique given system of governing PDEs are transformed into a set of ODE. Then dimensionless equations are numerically tackled via the Keller box method a built-in function in the computer tool MATLAB. To support the present study, physical and numerical interpretations of involved parameters against velocity, temperature, and entropy generation profiles are also presented. From the analysis it is concluded that the combination of a magnetic field and suction reduces the rate of fluid mobility due to the synchronization of the magnetic and electric fields generated by the formation of the Lorentz force. In addition, boosting the thermal radiation parameter raises the present authors' heat transfer rate. The velocity profile drops when the Casson parameter is raised, but the heat and entropy production profiles grow. When the porosity parameter is increased, the velocity profile falls, and the heat and entropy production profiles rise. Additionally the temperature distribution is boosted up with increasing the values of nanoparticles volume fraction. The good agreement between current results and published data is observed. It is necessary to investigate the thermophysical characteristics of the magnetite nanofluid (titanium dioxide, copper oxide, and carbon nanotubes-sodium alginate nanofluid) under various situations. The MHD flow of nanofluid is significant because of its wide range of industrial uses, including flows over the tips of rockets, planes, submarines, and oil tankers. The novelty of this work is to scrutinize the MHD flow and heat transfer analysis of a nanofluid towards a stretched surface. The features of magnetite nanofluid (titanium dioxide, copper oxide, and carbon nanotubes-sodium alginate nanofluid) under entropy generation, thermal radiation and velocity slip are investigated. All of this contributes to the work's uniqueness and novel.

Experimental Study of Entropy Generation of Nanofluid Flow in Minichannel

This study investigates the effects of ZnO, , and particles in the water-based fluid on entropy generation minimization in a minichannel heat exchanger. Distilled water has been chosen as the base fluid for nanoparticle volume concentration of 0.5% under the laminar and turbulent regime, steady-state flow, and the constant wall temperature. Dynamic viscosity, thermal conductivity, heat transfer, pressure drop, and total entropy generation rates of nanofluids have been experimentally analyzed in the minichannel (stainless steel), which has an inner diameter of and length of 20 cm, at the constant wall temperature (283 K). The nanofluid mixtures have been studied at different flow rates (from 10 to 50 ml/min) at the constant inlet (323 K) and constant channel wall temperature (283 K). The thermal performance, the pressure drop, and total entropy generation rates of the fluids have been compared for three different types of nanofluids. Maximum heat transfer enhancement of 16.04% was obtained using water-based . Results have shown that three nanofluids have less dimensionless entropy generation than pure water. In addition, compared to pure water with these three nanofluids, the minimum value of the total entropy generation has been obtained for with 5.54%.

Entropy generation of nanofluid flow in hexagonal microchannel

A new model for entropy generation number in hexagonal microchannel is developed going from the equation proposed by Bejan. The effect of Cu, CuO, Al2O3 and TiO2 mixed with pure water inside the microchannel is evaluated via entropy generation analysis. To show the contribution of entropy heat-transfer generation, Bejan number is also investigated. The effects of heat flux in the range of [2000–12000] W/m2, and volume fraction and nanoparticles size, respectively, on entropy generation numbers and Bejan number are all evaluated. The results demonstrate that increasing heat flux increases both thermal entropy generation and Bejan number but decreases the frictional entropy production. The results also show that thermal and friction entropy generation numbers exhibit an inverse variation trend when varying volume percentage and nanoparticle diameter.

Variable Viscosity and Thermal Conductivity Effects on Entropy Generation in Nanofluid Flow in an Inclined Channel: HAM Solution

This work investigates the entropy generation in nanofluid flow in a sloping channel with Navier slip and asymmetric wall temperatures. The viscosity and thermal conductivity are assumed to be dependent on temperature. The equations governing the flow, temperature are nonlinear and are solved using Homotopy Analysis Method (HAM) after non-dimensionalisation. Comparisons with existing literature have been produced and are found to be in excellent agreement, for special case of the current formulation. The impact of pertinent flow and fluid parameters on entropy generation, Bejan number, Nusselt number and skin friction is addressed, developed and displayed graphically.

Entropy generation in nanofluid flow due to double diffusive MHD mixed convection

This work is concerned with the numerical study of laminar, steady MHD mixed convection flow, and entropy generation analysis of Al2O3-water nanofluid flowing in a lid-driven trapezoidal enclosure. The aspect ratio of the cavity is taken very small. The cavity is differentially heated to study the fluid flow, heat, and mass transfer rate. The adiabatic upper wall of the enclosure is allowed to move with a constant velocity along the positive x-direction. The second-order finite difference approximation is employed to discretize the governing partial differential equations, and a stream-function velocity formulation is used to solve the coupled non-linear partial differential equations numerically. The simulated results are plotted graphically through streamlines, isotherms, entropy generation, Nusselt number, and Sherwood number. The computations indicate that the average Nusselt number and average Sherwood number are decreasing functions of Hartmann number, aspect ratio, and nanoparticle volume fraction. Significant changes in streamlines, temperature and concentration contours for high Richardson number are observed.

Comment on the paper “Entropy generation in nanofluid flow of Walters‐B fluid with homogeneous‐heterogeneous reactions, Sumaira Qayyum, Tasawar Hayat, Sumaira Jabeen, Ahmed Alsaedi, Mathematical Methods in the Applied Sciences 2020, 43: 5657–5672”

Some errors exist in the above paper.

Impact of variable viscosity on peristaltic motion with entropy generation

Entropy generation is a crucial aspect of every heat transfer processes. It helps to reduce irreversibility factor in a system. Entropy generation analysis is important in many conventional industrial sectors wherever heat transfer and fluid flows are involved. Therefore, present investigation addresses the analysis of entropy generation for nanofluid flow driven by peristaltic mechanism through an asymmetric channel. Governing equations included the effects of thermophoresis, mixed convection and Brownian motion. Temperature dependent viscosity is also included. Buongiorno's model for the analysis of nanofluids is employed. Mathematical modeling incorporates long wavelength approximation. Built-in numerical solver NDSolve is utilized to obtain numerical results of arising nonlinear differential equations. Analysis has been presented for temperature, Bejan number, entropy generation, concentration profile, velocity profile, heat and mass transfer rates at channel wall. Outcomes exhibit effective decrease in entropy generation and temperature with an increment in viscosity parameter. Further, velocity and rate of heat transfer at boundary increase by enhancing the values of temperature Grashoff number.

Investigation of Forced Convection Enhancement and Entropy Generation of Nanofluid Flow through a Corrugated Minichannel Filled with a Porous Media.

Corrugating channel wall is considered to be an efficient procedure for achieving improved heat transfer. Further enhancement can be obtained through the utilization of nanofluids and porous media with high thermal conductivity. This paper presents the effect of geometrical parameters for the determination of an appropriate configuration. Furthermore, the optimization of forced convective heat transfer and fluid/nanofluid flow through a sinusoidal wavy-channel inside a porous medium is performed through the optimization of entropy generation. The fluid flow in porous media is considered to be laminar and Darcy–Brinkman–Forchheimer model has been utilized. The obtained results were compared with the corresponding numerical data in order to ensure the accuracy and reliability of the numerical procedure. As a result, increasing the Darcy number leads to the increased portion of thermal entropy generation as well as the decreased portion of frictional entropy generation in all configurations. Moreover, configuration with wavelength of 10 mm, amplitude of 0.5 mm and phase shift of 60° was selected as an optimum geometry for further investigations on the addition of nanoparticles. Additionally, increasing trend of average Nusselt number and friction factor, besides the decreasing trend of performance evaluation criteria (PEC) index, were inferred by increasing the volume fraction of the nanofluid (Al2O3 and CuO).

Entropy generation in nanofluid flow of Walters‐B fluid with homogeneous‐heterogeneous reactions

Research on optimization of entropy generation in nanofluid flow gained much interest. In this study, the Walter's‐B nanofluid flow is considered to analyze the irreversibility in cubic autocatalysis. Fluid motion is considered in presence of viscous dissipation, magnetohydrodynamics (MHD), radiation, and heat generation absorption. Homotopy analysis method (HAM) is employed to solve nonlinear ordinary differential system. Results show that fluid flow reduces for larger Weissenberg and Hartman numbers. Temperature gradually enhances for larger Weissenberg number and radiation parameter. For higher estimation of thermophoresis parameter, the temperature and concentration are enhanced. Opposite impact of Hartman and Weissenberg numbers is noticed for entropy generation and Bejan number. Disorderedness and Bejan number are reduced near the sheet, while the opposite trend is seen away from the sheet.

Entropy generation of nanofluid flow and heat transfer driven through a paralleled microchannel

In this paper, a fully-developed, immiscible nanofluid flow in a paralleled microchannel in the presence of a magnetic field is investigated. Buongiorno’s model is applied to describe the behaviors of the nanofluid flow. Different from most previous studies on microchannel flow, here the pressure term is considered as unknown, which makes the current model compatible with the commonly accepted channel flow models. The influences of various physical parameters on important physical quantities are given. The entropy generation analysis is performed. Variations of local and global entropy generations with the magnetic field parameter, the electric field, and the viscous dissipation parameter under various ratios of the thermophoresis parameter to the Brownian motion parameter are illustrated. The results indicate that the entropy generation rate strongly depends on the thermophoresis and the Brownian motion parameters. Their increase enhances the total irreversibility of entropy generation.

Effect of magnetohydrodynamics on heat transfer intensification and entropy generation of nanofluid flow inside two interacting open rectangular cavities

MHD mixed convection heat transfer and entropy generation analysis for Cu–water nanofluid inside two interacting open cavities are numerically investigated. The right and the left walls of each cavity are heated or cooled at uniform but different heat flux densities. The nanofluid flow is described by the Buongiorno model in order to take into account the thermophoresis effect and the Brownian motion. The governing equations are solved using the finite volume method with the SIMPLE algorithm. The effects of relevant parameters including the Hartmann number (Ha), the Richardson number (Ri), the opening ratio (R), the heat flux ratio (Rq) and the nanoparticles volume fraction (ϕi) are analyzed. The results show that the flow pattern resulting from the simultaneous action of the magnetic field and the buoyancy force is heightened by the decrease in Ha and R and the increase in Ri and Rq. The heat transfer, which evolves in a non-monotonous way with the Hartmann number, is enhanced by the rise of the Richardson number, the heat flux ratio and the nanoparticles volume fraction, as well as by the reduction in the opening ratio. It is also observed that, overall, the thermodynamic disorder is dominated by the thermal irreversibility which decreases at high Ha with the augmentations of Ri and ϕi and the reductions in R and Rq.

Mixed convection and entropy generation of nanofluid flow in a vented cavity under the influence of inclined magnetic field

In this study, mixed convection and entropy generation in a vented cavity with inlet and outlet ports are examined under the effects of an inclined magnetic field. Galerkin weighted finite element method was used for the solution of the governing equations. The numerical simulations are performed for various values of Reynolds numbers (between 100 and 500), Hartmann number (between 0 and 50) and solid particle volume fractions of CuO nanoparticles (between 0 and $$4\%$$). Different walls and domains of the computational model are considered for the heat transfer and entropy generation analysis. It was observed that at low Reynolds number number, magnetic field has the potential to enhance the heat transfer at the highest strength while the effect of magnetic field is to reduce the convection at higher Reynolds number. The contributions of different hot walls to the overall heat transfer change considerably with the change of Hartmann number while the effect of magnetic inclination angle is marginal. Inclusion of nanoparticle results in heat transfer enhancement in the absence and presence of magnetic field and the amount of enhancement is 25–27% at the highest value of solid nanoparticle volume fraction. Different parts of the cavity contribute differently to the overall entropy generation when Hartmann number varies while the overall entropy generation first decreases and then increases when the value of Hartmann number increases. The addition of nanoparticles increases the overall entropy generation rate.

Investigation of free convection heat transfer and entropy generation of nanofluid flow inside a cavity affected by magnetic field and thermal radiation

In this paper, the effect of the presence of radiation on the convection heat transfer rate and the nanofluid entropy generation within a diagonal rectangular chamber is investigated numerically in the presence of a magnetic field. The governing equations have been solved via finite volume method using the simple algorithm. In this paper, the effects of Rayleigh number, Hartmann number, magnetic field angle changes, chamber angle changes, entropy parameter, radiation parameter and volume percent of nanoparticles on the entropy generation and heat transfer have been investigated. The results show that with increasing Rayleigh number and decreasing the Hartmann number, the Nusselt number and entropy generation increase and the Bejan number decreases. By increasing the angle of the magnetic field, the heat transfer rate and the entropy generation are reduced and the Bejan number increases. By increasing the angle of the chamber at high Rayleigh numbers, the heat transfer rate increases, or by adding 6% of the nanoparticles to the base fluid, the heat transfer rate increases by 9.3% and the entropy generation increases by 15.5% in the absence of radiation. This increase in the Rd = 3 radiation parameter is 5.4% and 6.2%, respectively. It was also observed that the Nusselt number and the entropy generation increased, and with increasing the radiation parameter, the Bejan number decreased. Increasing the heat transfer rate is more significant at higher Rayleigh numbers by increasing the radiation parameter.

Analysis of entropy generation for nanofluid flow over a stretching sheet with an inclined magnetic field and uniform heat source/sink

This investigation presents an analytical study of entropy generation of the nanofluid over a stretching sheet with inclined magnetic field and uniform heat generation/absorption. Similarity variables are used to convert the governing PDEs into ODEs. Then it solved analytically by hyper geometric function. The effect of physical parameters such as nanosolid volume fraction, aligned angle, magnetic, slip and suction parameters are discussed for both temperature and velocity profiles. Also, the effects of the same parameters and uniform generation/absorption and dimensionless group parameters on entropy generation are discussed for Ag nanofluid.

Entropy generation of nanofluid flow in a microchannel heat sink

Abstract Present study aims to investigate the effects of the presence of nano sized TiO2 particles in the base fluid on entropy generation rate in a microchannel heat sink. Pure water was chosen as base fluid, and TiO2 particles were suspended into the pure water in five different particle volume fractions of 0.25%, 0.5%, 1.0%, 1.5% and 2.0%. Under laminar, steady state flow and constant heat flux boundary conditions, thermal, frictional, total entropy generation rates and entropy generation number ratios of nanofluids were experimentally analyzed in microchannel flow for different channel heights of 200 µm, 300 µm, 400 µm and 500 µm. It was observed that frictional and total entropy generation rates increased as thermal entropy generation rate were decreasing with an increase in particle volume fraction. In microchannel flows, thermal entropy generation could be neglected due to its too low rate smaller than 1.10e−07 in total entropy generation. Higher channel heights caused higher thermal entropy generation rates, and increasing channel height yielded an increase from 30% to 52% in thermal entropy generation. When channel height decreased, an increase of 66%–98% in frictional entropy generation was obtained. Adding TiO2 nanoparticles into the base fluid caused thermal entropy generation to decrease about 1.8%–32.4%, frictional entropy generation to increase about 3.3%–21.6%.

Numerical investigation of porous rib arrangement on heat transfer and entropy generation of nanofluid flow in an annulus using a two-phase mixture model

ABSTRACTThe effect of porous rib arrays on the heat transfer and entropy generation of laminar nanofluid flow inside annuli is studied numerically, using a two-phase mixture model for nanofluid flow simulation. Porous media, nanoparticles, and vortex formation are simultaneously affecting the characteristics of the system. Results showed that the permeability and height of porous ribs have significant effects on the thermal performance of system. Vortex zones also affect the trend of variation of entropy and performance numbers, and local optimums exist for these two parameters. The role of nanofluid in heat transfer enhancement in recirculating zones is more significant for higher volume fractions.

Exact-solution of entropy generation for MHD nanofluid flow induced by a stretching/shrinking sheet with transpiration: Dual solution

In this article, attempts are made to present an exact solution for the fluid flow and heat transfer and also entropy generation analysis of the steady laminar magneto-hydrodynamics (MHD) nanofluid flow induced by a stretching/shrinking sheet with transpiration. This paper is the first contribution to the study of entropy generation for the nanofluid flow via exact solution approach. The governing partial differential equations are transformed into nonlinear coupled ordinary differential equations via appropriate similarity transformations. The current exact solution illustrates very good correlation with those of the previously published studies in the especial cases. The entropy generation equation is derived as a function of the velocity and the temperature gradients. The influences of the different flow physical parameters including the nanoparticle volume fraction parameter, the magnetic parameter, the mass suction/injection parameter, the stretching/shrinking parameter, and the nanoparticle types on the fluid velocity component, the temperature distribution, the skin friction coefficient, the Nusselt number and also the averaged entropy generation number are discussed in details. This study specifies that nanoparticles in the base fluid offer a potential in increasing the convective heat transfer performance of the various liquids. The results show that the copper and the aluminum oxide nanoparticles have the largest and the lowest averaged entropy generation number, respectively, among all the nanoparticles considered.

Viscous Dissipation Effect on Streamwise Entropy Generation of Nanofluid Flow in Microchannel Heat Sinks

The effects of viscous dissipation on the entropy generation of water–alumina nanofluid convection in circular microchannels subjected to exponential wall heat flux are investigated. Closed-form solutions of the temperature distributions in the streamwise direction are obtained for the models with and without viscous dissipation term in the energy equation. The two models are compared by analyzing their relative deviations in entropy generation for different Reynolds numbers and nanoparticle volume fractions. The incorporation of viscous dissipation prominently affects the temperature distribution and consequently the entropy generation. When the viscous dissipation effect is neglected, the total entropy generation and the fluid friction irreversibility are nearly twofold overrated while the heat transfer irreversibility is underestimated significantly. By considering the viscous dissipation effect, the exergetic effectiveness for forced convection of nanofluid in microchannels attenuates with the increasing nanoparticle volume fraction and nanoparticle diameter. The increase in the entropy generation of nanofluid is mainly attributed to the intensification of fluid friction irreversibility. From the aspect of the second-law of thermodynamics, the widespread conjecture that nanofluids possess advantage over pure fluid associated with higher overall effectiveness is invalidated.