Rate Of Heat Transfer Decreases Research Articles

Computational analysis magnetohydrodynamics natural convection flow round vertical thermally stratified jet: Finite difference method in conjunction with primitive variable formulation

The problem of magnetohydrodynamic free convective heat transfer mechanism across a laminar, round, vertical, and thermally stratified jet is examined. The boundary layer equations are non-dimensionalized, and then, using the primitive variable formulation, the finite difference method is used to find the numerical solution of the problem. The impact of Prandtl number, magnetic parameter, and stratification parameter on velocity distribution, temperature profile, and heat transfer rate is explained graphically and in tabular form. It is found that for increasing values of thermal stratification parameter S, the velocity profile increases while temperature distribution and rate of heat transfer decrease. Similarly, with an increase in the values of Prandtl number, velocity, and temperature distribution decrease, but the rate of heat transfer increases.

Linear regression analysis of MHD Maxwell nanofluid flow over a stretched surface of varying thickness with heat flux and chemical reaction

Non-Newtonian materials have been an appealing topic for researchers because of the variety of laboratory and industrial process involving these fluids. There are several kinds of non-Newtonian fluids classified according to their properties. In this study, the Maxwell fluid model is analyzed due to the unique properties and applications of this non-Newtonian material. We have considered the Buongiorno model for nanofluid, which is a two-phase model that accounts for the effects of Brownian motion and thermophoresis on the transport of nanoparticles in a fluid. A stretching surface holding a chemically reactive fluid is assumed. In addition, the study also considers the impacts of heat flux and magnetic fields. The influence of various physical factors on the flow fields is presented and graphically highlighted. Using linear regression and the data point approach, the relationship between the physical parameters, such as rate of heat and mass transfer, at the surface is investigated. The relationship between the various physical parameters was investigated using the t-test approach. The Maxwell fluid parameter influences heat transmission at the surface. As the magnetic field and heat source parameters increases, the rate of heat transfer decreases. Increasing the Deborah number, chemical reaction parameter and magnetic field parameter enhances the mass transfer rate at the surface. The fluid’s velocity decreases with rising magnetic field and Maxwell fluid parameters. The heat source parameter elevates fluid temperature, while inclusion of the chemical reactions parameter reduces nanoparticle concentration.

Significance of unsteady rotating flow of nanofluid with nanoparticles aggregation and impacts of slip conditions and variable viscosity

The unsteady nanofluid flow that rotates in both directions over a stretched surface could assist many technological and industrial processes. When the effects of slip conditions, aggregation, and changing viscosity are considered, the flow of nanofluid over a stretched surface can be used in surface coatings and deposition, energy harvesting devices, drug delivery systems, and cooling systems with better heat transfer. The major purpose of this study is to evaluate the influence that variable viscosity, slip conditions, and aggregation have on the flow behavior of nanofluids in three dimensions. This research looks specifically at non-axisymmetric stagnation point flows on stretched sheet. The governing equations are going to be modeled based on the assumptions that have been stated. Through a technique known as a similarity transformation, a complex system of nonlinear partial differential equations can be reduced to ordinary differential equations. This makes the system significantly easier to work with. The algorithm will be employed afterward to numerically solve the simplified set of equations. The results are obtained using the Runge–Kutta (RK-IV) and the shooting method. Graphical displays provide an easy way to examine how different parameters interact with one another and their impacts. With an increase in nanoparticle concentration, heat transfer rate shows an increasing trend. Due to the decrease in the instability parameter, rate of heat transfer decreases. Velocity profiles increases in both directions with increasing strain rate. A comparison of influences of nanoparticle aggregation with and without radiation is shown in the tables, highlighting the differences in Nusselt numbers. The results of the present study closely correspond to those reported in a prior publication for the same scenario, offering robust additional support for the findings.

Effect of aspect ratio on the onset of natural convection in porous trapezoidal enclosures

Understanding the impact of aspect ratio is the objective of this numerical inquiry and various temperature boundary conditions on fluid flow and buoyant heat transfer in a porous trapezoidal cavity. The upper wall is cool, the steep walls are adiabatic, and the base wall is subjected to uniform, linear, and non-uniformly varying temperatures. The study makes use of the Darcy model. Using a simple algorithm, the governing equations are resolved via the finite element technique. Numerous parameters are considered in the computations, and the results are displayed graphically. The results show that the various heating and aspect ratios (AR = H/L = 0.25, 05, 0.75, and 1) significantly affect the flow pattern within the enclosure. For increasing levels of the Rayleigh number, the rate of heat transfer increases with constant aspect ratio. As the aspect ratio rises, the rate of heat transfer decreases. The outcomes are presented as the local and mean Nusselt numbers, the stream's functions, and the isotherm functions. In addition, the obtained results compared with previous researchers and show good agreement. Present numerical solutions are more useful for mixed mode porous matrix in solar panels.

A generalized magnetohydrodynamic two-phase free convection flow of dusty Casson fluid between parallel plates

This article aims to investigate the combined effects of the heat transfer and magnetic field on the electrically conducting magnetohydrodynamic two-phase free convective flow of dusty Casson fluid between parallel plates. The flow is caused by buoyancy force with heat transfer due to free convection. Moreover, the left plate moves at uniform velocity while the right plate is stationary, and all dust particles with spherical forms are scattered evenly throughout the fluid. Mathematically, the flow is described as partial differential equations. A newly introduced fractional derivative, namely Caputo-Fabrizio fractional derivative, is used to generalize the given derived system of PDEs. The problem is solved using joint applications of finite sine Fourier and Laplace transforms. Exact solutions of velocity and temperature profile are obtained. Moreover, the impact of different parameters like a magnetic parameter, Grashof number, Dusty fluid parameter, Casson parameter, Peclet number, Reynold number, and particle's mass parameter on temperature, and dust particle and Casson fluid velocity have been discussed. The graphical results for Casson fluid, dusty fluid, and temperature profiles are plotted through Mathcad-15. The behavior of Casson fluid and dusty fluid is matching for different embedded parameters. Moreover, the Nusselt number and skin friction are also determined. It is shown in Table 1 that by increasing the value of the peclet number, the rate of heat transfer decreases. Furthermore, Table 2 shows that by increasing the magnetic parameter, the skin friction decreases. Graphical results conclude that fractional Casson fluid model described a more realistic aspect of the both (Fliud and dust particle) velocities profile, temperature profile, rate of heat transfer and skin friction than the classical Casson fluid model.

Two Dimensional Biomagnetic Fluid Flow and Heat Transfer over a Nonlinear Stretching Sheet with Temperature Dependent Viscosity

This investigated the flow and heat transfer of two dimensional biomagnetic fluid (blood) flow over a non-linear stretching sheet in the presence of magnetic dipole. It is assumed that the magnetic field is sufficiently strong enough to saturate the ferrofluid and variation of magnetization with temperature can be approximated by a linear function of temperature difference. The fluid viscosity is assumed to vary as an inverse linear function of the temperature. The governing boundary layer equations with boundary conditions are simplified to couple higher order equations using usual transformation. Numerical solutions are obtained by using bvp4c function technique in MATLAB software. The acquired results are shown graphically and were examined for several values of the dimensionless parameters. It is observed that for different values of ferromagnetic interaction parameter and variable viscosity parameter, the velocity distribution decreases while temperature distribution increases. The magnitude of skin friction coefficient and the rate of heat transfer decrease with the increasing values of radiation parameter and Prandtl number. The results are also compared for specific values of the parameters with others documented in literature.

Lattice Boltzmann Simulation of MHD Rayleigh-Bénard Natural Convection in a Cavity Filled With a Ferrofluid

In this study, we examine the effect of a uniform external magnetic field on Rayleigh-Bénard convection in a square cavity filled with a ferrofluid. Numerical simulations are based on the Lattice Boltzmann method. The effects of physical parameters, which are the Rayleigh number, the Hartmann number, and the angle of inclination of the magnetic field are studied. The results obtained are graphically illustrated and discussed for a volume fraction of four percent. These results show that the rate of heat transfer decreases by increasing the Hartmann number. For high Rayleigh number values, the maximum heat transfer rate was obtained for a specific Hartmann number when the Lorentz and buoyancy forces are perpendicular

Conduction Heat Rate Analysis of Tool in AISI 4340 TurningProcess

In the turning process a very high temperature is generated from the friction of cutting tool and workpiece. In the turning process there is also contain heat transfer reaction that occurs due to rising temperatures during the turning process. The high temperature in the cutting process has a very important influence on increasing the amount of heat that produce during the process of machining. Therefore it is necessary to analyze the effect of the rake angle and the use of LN2 and SCCO2 as a cooler to the heat transfer rate on the cutting tool using Autodesk simulation mechanical 2017 software. Based on the simulation results obtained temperature distribution values on the cutting tool during the AISI 4340 turning process using carbide tungsten as the cutting tool where the rake angle is 0°,5°, and 10°. Without using any coolant, the heat transfer rates are 30.613W, 28.386 W, and 26.160. By applying cooler such as SCCO2 and LN2 the rate of heat transfer decreases. With the application of the LN2 heat flow rate with rake angle 0°, 5°, and 10° decrease to 21.429 W, 19.191 W, and 16.965 W. The application of the SCCO2 heat flow rate on the tool with a rake angle 0°, 5°, and 10° will be 20.260 W, 18.479 W, and 16.252 W. Based on the result it is found that increased rake angle will cause a decrease in heat transfer rate. The application of SCCO2 and LN2 can reduce the heat transfer rate, therefore it can extend the cutting tool life.

Effect of temperature dependent viscosity on biomagnetic fluid flow and heat transfer over a nonlinear stretching sheet

This investigated the flow and heat transfer of two-dimensional biomagnetic fluid (blood) flow over a nonlinear stretching sheet in the presence of magnetic dipole. It is assumed that the magnetic field is sufficiently strong enough to saturate the ferrofluid and variation of magnetization with temperature can be approximated by a linear function of temperature difference. The fluid viscosity is assumed to vary as an inverse linear function of the temperature. The governing boundary layer equations with boundary conditions are simplified to couple higher-order equations using usual transformation. Numerical solutions are obtained by using bvp4c function technique in MATLAB software. The acquired results are shown graphically and were examined for several values of the dimensionless parameters. It is observed that for different values of the ferromagnetic interaction parameter and variable viscosity parameter, the velocity distribution decreases while temperature distribution increases. The magnitude of skin friction coefficient and the rate of heat transfer decrease with the increasing values of radiation parameter and Prandtl number. The results are also compared for specific values of the parameters with others documented in literature.

Magnetohydrodynamic natural convection flow of a nanofluid due to sinusoidal surface temperature variations

We examine the natural convection flow that arises in an electrically conducting nanofluid due to the sinusoidal surface temperature variations along a vertical surface. The effect of thermal radiation is also incorporated. The reduced system of governing equations is solved using an efficient implicit finite difference method which is also known as the Keller box method. The results are presented in terms of the shear stress and the rate of heat transfer as well as the velocity and temperature profiles. In general, the amplitude of the undulation of the shear stress gradually decreases and that of the rate of heat transfer increases along the streamwise direction. The significant finding is that, with an increase in the volume fraction of nanoparticles, the shear stress diminishes, whereas the rate of heat transfer considerably increases. Due to the increase in the amplitude of oscillation of the surface temperature, conduction–radiation parameter, and surface temperature, a substantial increase is observed in both the shear stress and the rate of heat transfer. Contrary to this, the shear stress and the rate of heat transfer decrease with the increase in the magnetic field parameter. For any value of the relevant parameters, the use of nanoparticles in a pure fluid reduces the shear stress and enhances the rate of heat transfer. Moreover, when a nanofluid is used instead of pure fluid, the thicknesses of momentum and thermal boundary layers are found to increase, irrespective of the physical parameters.

Investigation of the effects of various parameters on the natural convection of nanofluids in various cavities exposed to magnetic fields: a comprehensive review

In this paper, a comprehensive review has been carried out on the natural convective heat transfer inside various cavities containing nanofluid affected by the magnetic field (M.F). First, an introduction has been presented on the nanofluids and their applications, and then the magnetic nanofluids and the numerical studies on them have been finally evaluated. Nanofluid numerical studies under the effect of the M.F are modeled in two states: single-phase (S.P) and two-phase. A S.P model is assumed without any slipping between the fluid and nanoparticles. But in the two-phase model, the particle slip and motion of the particles are considered. In fact, in this study, the classification of papers with a common geometry and effective parameters on the nanofluid exposed to the free convection and M.F effects of has been studied. According to the results obtained by the researchers, it can be concluded that the rate of heat transfer decreases by enhancing the M.F and reducing the volumetric fraction of the nanoparticle and reducing the buoyancy force.

Heat Transfer Coefficients Investigation for TiO2 Based Nanofluids

From a regression analysis perspective, this paper focused on literature about TiO2 nano particles. The particles on focus entailed those that had been suspended in ethylene glycol and water – at a ratio of 60:40. Indeed, regression analysis has gained application in contexts such as the turbulent Reynolds number, especially with the aim of establishing the impact of the ratio of the base fluid on heat transfer coefficients, as well as the target materials’ thermal properties. From the findings, this study infers that when the water-ethylene glycol mixture is used at a ratio of 60:40, the rate of heat transfer is higher than that which is obtained when water is used solely. Additional findings established from the examination of the impact of material concentration and temperature on the rate of nanofluids’ heat transfer suggested that as temperature increases, the rate of heat transfer decreases. However, it was noted that an increase in concentration exhibits a positive correlation with the nanofluids’ rate of heat transfer whereby an increase in the former parameter (concentration) leads to an increase in the latter (rate of nanofluids heat transfer).

MHD graphene-polydimethylsiloxane Maxwell nanofluid flow in a squeezing channel with thermal radiation effects

The magnetohydrodynamic (MHD) graphene-polydimethylsiloxane (PDMS) nanofluid flow between two squeezing parallel plates in the presence of thermal radiation effects is investigated. The energy efficiency of the system via the Bejan number is studied extensively. The governing partial differential equations are converted by using the similarity transformations into a set of coupled ordinary differential equations. The set of these converted equations is solved by using the differential transform method (DTM). The entropy generation in terms of the Bejan number, the coefficient of skin-friction, and the heat transfer rate is furthermore investigated under the effects of various physical parameters of interest. The present study shows that the Bejan number, the velocity and thermal profiles, and the rate of heat transfer decrease with a rise in the Deborah number De while the skin-friction coefficient increases. It is also observed that the entropy generation due to frictional forces is higher than that due to thermal effects. Thus, the study bears the potential application in powder technology as well as in biomedical engineering.

Boundary layer flow and melting heat transfer of Prandtl fluid over a stretching surface by considering Joule heating effect

PurposeThe purpose of this paper is to study the impact of Joule heating on boundary layer flow and melting heat transfer of Prandtl fluid over a stretching sheet in the presence of fluid particles suspension. The transformed boundary layer equations are solved numerically by RKF-45 method. The influence of the non-dimensional parameters on velocity and temperature growths in the boundary layer region is analyzed in detail and the results are shown graphically. The results indicate that the larger estimation ofαandβreduces for both velocity and temperature profile. Further, the rate of heat transfer decreases by increasing melting parameter.Design/methodology/approachThe converted set of boundary layer equations is solved numerically by RKF-45 method. Obtained numerical results for flow and heat transfer characteristics are deliberated for various physical parameters. Furthermore, the skin friction coefficient and Nusselt number are also presented.FindingsIt is found that the heat transfer rates are advanced in the occurrence of non-linear radiation camper to linear radiation. Also, it is noticed that velocity profile increases by increasing Prandtl parameter but establishes opposite results for temperature profile.Originality/valueThe authors intend to analyze the boundary layer flow and melting heat transfer of a Prandtl fluid over a stretching surface in the presence of fluid particles suspension. The governing systems of partial differential equations have been transformed to a set of coupled ordinary differential equations by applying appropriate similarity transformations. The reduced equations are solved numerically. The pertinent parameters are discussed through graphs and plotted graphs. The present results are compared with the existing limiting solutions, showing good agreement with each other.

Eyring-Powell fluid flow through a wall jet in the presence of viscous dissipation

The present study is conducted by keeping in view the applications of heat transfer through a wall jet flow in the field of engineering, biomedicine, industries and cooling-heating systems. We have investigated the laminar and steady flow of an incompressible Eyring-Powell fluid through a wall jet with viscous dissipation. To obtain the numerical solution of the problem by the RK coupled with the shooting method, we have utilized boundary layer approximation to reduce the governing equations along with appropriate boundary conditions. Fluid parameter m acts as a resistive force for the flow of the fluid. Variation in the temperature profile due the Prandtl number also predicts that for its higher values the rate of heat transfer decreases. The viscous dissipation parameter known to be the local Eckert number helps to obtain increased thermal boundary layer thickness and a decrease in the rate of heat transfer.

Characteristics of melting heat transfer during flow of Carreau fluid induced by a stretching cylinder.

This article provides a comprehensive analysis of the energy transportation by virtue of the melting process of high-temperature phase change materials. We have developed a two-dimensional model for the boundary layer flow of non-Newtonian Carreau fluid. It is assumed that flow is caused by stretching of a cylinder in the axial direction by means of a linear velocity. Adequate local similarity transformations are employed to determine a set of non-linear ordinary differential equations which govern the flow problem. Numerical solutions to the resultant non-dimensional boundary value problem are computed via the fifth-order Runge-Kutta Fehlberg integration scheme. The solutions are captured for both zero and non-zero curvature parameters, i.e., for flow over a flat plate or flow over a cylinder. The flow and heat transfer attributes are witnessed to be prompted in an intricate manner by the melting parameter, the curvature parameter, the Weissenberg number, the power law index and the Prandtl number. We determined that one of the possible ways to boost the fluid velocity is to increase the melting parameter. Additionally, both the velocity of the fluid and the momentum boundary layer thickness are higher in the case of flow over a stretching cylinder. As expected, the magnitude of the skin friction and the rate of heat transfer decrease by raising the values of the melting parameter and the Weissenberg number.

Role of suction/injection on steady fully developed mixed convection flow in a vertical parallel plate microchannel

Abstract This paper examined the hydrodynamic and thermal behaviour of steady fully developed mixed convection flow in a vertical parallel-plate micro-porous-channel (MPC) in the presence of suction/injection with velocity slip and temperature jump at the boundaries. The exact solutions of the energy and momentum equations are obtained. The influence of each governing parameter on dimensionless velocity, temperature, volume flow rate, rate of heat transfer and skin friction at the micro-porous-channel surfaces is discussed. During the course of numerical computation, it is observed that as suction/injection at the micro-porous-channel surfaces increases, the volume flow rate increases while rate of heat transfer decreases. Furthermore, it is found that the probability of reverse flow formation decreases at cold wall of the micro-porous-channel as Knudsen number or fluid–wall interaction parameter increases.

OPTIMUM INSULATION THICKNESS FOR BUILDING ENVELOPE- A REVIEW

Through this paper an important issue that what should be the level of insulation for energy conservation in conditioned building envelope is being address. It is well established from the earlier studies of heat transfer across the composite walls that as insulation thickness increases the corresponding resistance to heat flow increases so the rate of heat transfer decreases. The corresponding cost of maintain temperature through artificial means decreases but this is achieve at the cost of insulation which also increases as its thickness increases. The thickness of insulation where total cost of heating/ cooling and insulation cost over the life time becomes minimum is known as optimum insulation thickness. Answer to this question of thermal insulation level in the building envelope components like external wall or roof from economy point of view is being reviewed. Different angles of research in this field being discuss like methods of analyzing annual heating/ cooling loads, insulation material point of view, effect of climate, effect of energy source on optimum insulation thickness. Further different methods used for determination of optimum insulation thickness being reviewed. The effect of solar radiation on optimum insulation thickness is an area which needs further research in Indian context. There is a great need of not only insulating building envelope components like external wall or roof but from economical point of view there is a need to optimize insulation thickness. Further there is need to analyze two insulation materials in combination for maximizing savings.

MHD viscous Casson fluid flow and heat transfer with second-order slip velocity and thermal slip over a permeable stretching sheet in the presence of internal heat generation/absorption and thermal radiation

This article is devoted to describing the boundary layer flow and heat transfer for an electrically conducting Casson fluid over a permeable stretching surface with second-order slip velocity model and thermal slip conditions in the presence of internal heat generation/absorption and thermal radiation. The basic equations governing the flow and heat transfer are in the form of partial differential equations; the same have been reduced to a set of highly non-linear ordinary differential equations by applying suitable similarity transformations. Exact solution corresponding to momentum equation is obtained, and, in the case of no slip conditions, we get the exact solutions for both momentum and energy equation. The resulting similarity equations are solved numerically by shooting method. Comparisons with previously published work are performed and the results are found to be in excellent agreement. In the present work the effect of magnetic parameter, suction/injection parameter, Casson parameter, slip parameters, radiation parameter, internal heat generation/absorption parameter and the Prandtl number on flow and heat transfer characteristics have been discussed. Also, the local skin-friction coefficient and the local Nusselt number at the sheet are computed and discussed. It is found that the temperature rises to a higher value when the Casson parameter increases but the reverse is true for the velocity distribution. Finally, increasing the velocity and thermal slip parameters makes the rate of heat transfer decrease.

Myth about nano-fluid heat transfer enhancement

The paper examines a few claims about the merit of using nano-particles to enhance the rate of heat transfer. In the literature, a few mechanisms were put forward to explain the magic of enhancing the rate of heat transfer by many folds compared with a clear fluid by adding a few percentages of nano-particles to the working fluid. In this work, a few introduced mechanisms is examined in the light of classical physics of the thermal diffusion and the fluid mechanics. Yet, no one able to break those simple physics; therefore, they should be valid for particles floating in a fluid. The paper for the first time reports the effect of particle alignment with the direction of heat flow (temperature gradient) effects on the effective thermal conductivity, which is significant. Furthermore, forced and natural convections are examined based on the classical theory of heat transport. We demonstrated the reason of why the rate of heat transfer decreases by adding nano-particles for a fluid experiencing natural convection.