Conductive Baffle Research Articles

Heat transfer on MHD oscillatory flow in a vertical double-passage channel

Thermal propagation of MHD oscillatory flow of optically thin fluid in a vertical double-passage with varying temperature was investigated. The thermal distribution of the fluid flow is enhanced through a perfectly thin conductive baffle, which divides the channel into two passages. The equations governing the fluid flow are formulated based on purely oscillatory flow with pressure gradient. The flow velocity and thermal equations governing the flow are analytically solved. The closed-form results gotten were analysed for the influences of Reynolds number, magnetic term, thermal convection term, Peclet number and frequency of oscillation on the flow and heat transfer characteristics with the aid of graphs. It was observed that magnetic parameter reduces the flow rate in the channel.

Influence of tilt angles and different models of fluid viscosity on coupled natural convection in a differentially heated closed square cavity with a partition

This article investigates the behavior of various viscosity models under conjugated natural convection in a square cavity with a conductive baffle at various angles of inclination and differential heating of the side walls. Numerical simulations were performed using the finite volume method for a fluid having viscous properties similar to those of a non-Newtonian fluid. The slope angle of the computational domain and the choice of the non-Newtonian fluid model were considered as the main parameters. The inclination of the hull took on the values 0°, 30°, 45°, 60° and 90°. The received data illustrate that the increase in the velocity of convection flows is strongly influenced by the angles of inclination of 30° and 60°. By analyzing various non-Newtonian fluid models, the power low viscosity model predicted velocities more than other viscosity models. Whereas in the Herschel-Bulkley viscosity model, only the heat transfer process mainly occurred. Analysis of the obtained local Nusselt number showed that the values were higher on the cold wall. This is explained by more intense heat transfer due to convection on this wall. It should also be noted from the data obtained that when the region is tilted at α = 90° for the Carreau viscosity model, one can notice the complete absence of the convection process, and when using the Herschel–Bulkley viscosity model, no flow mixing occurred, which led to heat exchange solely due to heat transfer for different tilt angles.

Natural convection–thermal radiation interaction in a non-Newtonian nanofluid-filled square cavity with a conductive baffle

This research aims to investigate the combination of natural convection and surface and volumetric radiation in water-aluminum oxide nanofluid with non-Newtonian effects in a square cavity with a conductive baffle on its hot wall. The left wall is hot while the right one is cold. Moreover, the horizontal walls are insulated, and the internal walls are radiatively active. The mass, momentum, and energy conservation equations are solved numerically using the control-volume-based finite difference method and the SIMPLE algorithm considering the surface radiation for the interior surfaces of the cavity and volumetric radiation for the non-Newtonian nanofluid. The volumetric radiation term in the energy equation is approximated using the Rosseland method. The effect of the Rayleigh number (Ra), the power-law index, and the volumetric radiation parameter on the flow field and the heat transfer rate are investigated using the numerical analysis results. Based on the results, an increase in Ra and a decrease in the power-law index lead to a rise in the heat transfer rate at a constant radiation parameter. As the Ra rises in the range, the average Nusselt number increases to 10 times at n = 0.8. Moreover, a rise in the volumetric radiation parameter increases the radiative Nusselt number and decreases the convective Nusselt number in both shear thickening and shear thinning fluids, although it increases the overall Nu. Increasing the volumetric radiation parameter from 0 to 2 enhances the average Nusselt number by more than 2.5 times at Ra = 103 and less than 2 times at Ra = 105.

How a conductive baffle improves melting characteristic and heat transfer in a rectangular cavity filled with gallium

The configuration of a latent heat thermal energy storage (LHTES) is an important factor considered by manufacturers of heat storage systems. In this study, an applicable and low-cost way of improving melting behavior in a rectangular cavity was remarked. There was a preconceived idea that with a single conductive baffle, embedded on the upper wall of the cavity, the melting rate and the amount of heat storage could improve. Therefore, for different locations as well as lengths of a baffle, the heat transfer and melting characteristic of gallium as a phase change material (PCM) in a rectangular cavity were investigated numerically. The cavity has the insulated upper and bottom walls. The sidewalls are regarded to have constant temperatures one higher and another lower than the melting point of gallium. The phase change process is modeled with the fixed grid-based enthalpy-porosity method coupled with the semi-implicit method for pressure-linked equations (SIMPLE) algorithm. The isotherm lines and streamlines, as well as the liquid fraction and Nusselt number on the hot wall, are considered to present the results at a constant Rayleigh number equal to 106. The results show the baffle imposes noticeable improvement on the melting process of gallium in a rectangular cavity by influencing the feature of convective heat transfer. Investigating the different baffle’s locations (LX/L = 0.2 to 0.9) revealed that when the baffle located at the right half of the cavity, melting initiates from the left side, the more amount of PCM melts in comparison with the other cases. Ultimately, the dimensionless location of LX/L = 0.8 demonstrates the best melting characteristic and the most final liquid fraction. The more liquid-fraction, the more energy storing concluded. It also observed a dimensionless height of LY/L = 0.4 represents the most liquid-fraction compared to the heights of LY/L = 0.2, 0.3, and 0.4.

Effect of viscous dissipation on mixed convection flow in a vertical double passage channel using Robin boundary conditions

The laminar fully developed flow in a vertical double passage channel filled with clear fluid has been discussed using Robin boundary conditions. The thin perfectly conductive baffle is inserted in the channel. The governing equations of the fluid which are coupled and nonlinear are solved analytically by the perturbation method and semi analytically using differential transform method (DTM). The reference temperature of the external fluid is considered to be equal and different. The perturbation method which is valid for small values of perturbation parameter is used to find the combined effects of buoyancy forces and viscous dissipation. The limitation imposed on the perturbation parameter is relaxed by solving the basic equations using differential transform method. The influence of mixed convection parameter, Biot number for symmetric and asymmetric wall temperatures on the velocity, temperature and the Nusselt number is explored at different positions of the baffle. The solutions obtained by differential transform method are justified by comparing with the solutions obtained by perturbation method and the solutions agree very well for small values of the perturbation parameter.Keywords: Baffle, Differential Transform Method, Perturbation Method, Viscous dissipation, Robin Boundary Conditions, Double passage channel.

Numerical Study of Natural Convection and Entropy Generation of Al2O3-Water Nanofluid within a Cavity Equipped with a Conductive Baffle

Numerical Study of Natural Convection and Entropy Generation of Al2O3-Water Nanofluid within a Cavity Equipped with a Conductive Baffle

Effect of Electromagnetic Field on Forced Convective Heat Transfer in a Vertical Wavy Channel Divided by a Perfectly Conductive Baffle

Effect of Electromagnetic Field on Forced Convective Heat Transfer in a Vertical Wavy Channel Divided by a Perfectly Conductive Baffle

Effect of Electro-Magnetic Field on Free Convective Heat Transfer in a Vertical wavy Channel Divided by a Perfectly Conductive Baffle

Analytical solutions for the fully developed MHD free convection flow in open-ended vertical wavy channel in the presence of applied electric filed is presented. The channel is divided into two passages by means of a thin, perfectively plane baffle and hence the velocity will be individual in each stream. The coupled, nonlinear partial differential equations are solved analytically valid for small values of amplitude and frequency parameter. The effects of Grashof number, wall temperature ratio, Hartman number, electric field load parameter and product of wave number and space co-ordinate at different positions of the baffle are presented and discussed in detail. The skin friction and the heat transfer rate for the system is also explored. The increase in Grashof number and wall temperature ratio enhances the flow whereas the Hartman number and electric filed load parameter suppress the flow at all the baffle positions.

Numerical investigation of Cu-water nanofluid natural convection and entropy generation within a cavity with an embedded conductive baffle

This article presents a numerical study of natural convection and entropy generation of Cu-water nanofluid within an enclosure with a conductive baffle embedded on bottom hot wall. The governing equations are solved numerically with Finite Volume Method using the SIMPLER algorithm. Effects of Rayleigh number, position of conductive baffle and volume fraction of nanoparticles on the streamlines, isotherms, mean Nusselt number, entropy generation, Bejan number and irreversibility factor have been studied. At Ra=104 the convection heat transfer is very weak and the dominant conduction weakens by displacing the baffle toward the center of the cavity, thus the mean Nusselt number decreases. At higher Rayleigh numbers due to enhanced convection, the improved mean Nusselt number increases by increasing the volume fraction and displacing the baffle toward the center of the cavity. The effect of volume fraction and position of the baffle on entropy generation and Bejan number at Ra=104 is different from Ra=105 and 106. This is due to the effects of addition of nanoparticles on the effective viscosity and conductivity of nanofluid and conduction dominance. It has been shown that assuming a constant irreversibility factor, χ, with change of Ra and φ is not correct.

Developing laminar convection in a vertical double-passage channel

The effect of the presence of a thin, perfectly conductive baffle on the development of laminar convection in a vertical channel has been investigated numerically. The channel has different constant wall temperatures which are higher than those at the entrance. Velocity and temperature profiles have been presented. The effect of the different parameters on heat transfer in the channel has been discussed. The occurrence of flow reversal has been observed in some cases but examination of this phenomenon has been considered to be beyond the scope of the present work. For long channels, the numerical solutions approach the fully developed flow analytical solution. Finally, the results showed that higher values of Nuh can be obtained when the baffle is near the hot wall.

Effects of wall conduction, internal heat sources and an internal baffle on natural convection heat transfer in a rectangular enclosure

Conjugate natural convection heat transfer in a two-dimensional, air-filled enclosure containing discrete internal heat sources and an internal baffle is examined. The enclosure formed of finite conductive walls is designed to simulate the behavior of an experimental window calorimeter in order to correct for losses from the calorimeter. The equations are solved using a finite-volume method for a wide range of Rayleigh numbers, internal-extemal heat source ratios, solid-fluid conductivity ratios and baffle heights. The influences on the heat transfer and the flow characteristics resulting from the internal heat sources as well as the conductive baffle are discussed. Measurements of temperature distributions in the window calorimeter are also reported. The comparison between numerical predictions and experimental measurements shows that it is inappropriate to specify simple boundary conditions on the window surface of the calorimeter and to neglect the conduction through the baffle, window, and walls. A modified procedure for calculating the temperature distributions on the window surface improves the predicted results and yields good agreement with the measured data.

Mixed convection of micropolar fluid in a vertical double-passage channel

The effect of the presence of a thin perfectly conductive baffle on the fully developed laminar mixed convection in a vertical channel containing micropolar fluid is analyzed. The channel has different constant wall temperatures. Analytical expressions for velocity and microrotation velocity are obtained. The solutions are evaluated numerically and shown graphically for the ratio of Grashof number to Reynolds number, material parameter and the baffle position on the velocity and microrotation velocity. It is found that the ratio of Grashof number to Reynolds number promotes the velocity whereas it suppresses the microrotation velocity and the material parameter is invariant on velocity but it promotes the microrotation velocity. Flow reversal can also be found in the double-passage channel with suitable choice of the ratio of Grashof number to Reynolds number.

Effect of viscous dissipation on mixed convection flow in a vertical double passage channel using Robin boundary conditions

The laminar fully developed flow in a vertical double passage channel filled with clear fluid has been discussed using Robin boundary conditions. The thin perfectly conductive baffle is inserted in the channel. The governing equations of the fluid which are coupled and nonlinear are solved analytically by the perturbation method and semi analytically using differential transform method (DTM). The reference temperature of the external fluid is considered to be equal and different. The perturbation method which is valid for small values of perturbation parameter is used to find the combined effects of buoyancy forces and viscous dissipation. The limitation imposed on the perturbation parameter is relaxed by solving the basic equations using differential transform method. The influence of mixed convection parameter, Biot number for symmetric and asymmetric wall temperatures on the velocity, temperature and the Nusselt number is explored at different positions of the baffle. The solutions obtained by differential transform method are justified by comparing with the solutions obtained by perturbation method and the solutions agree very well for small values of the perturbation parameter.Keywords: Baffle, Differential Transform Method, Perturbation Method, Viscous dissipation, Robin Boundary Conditions, Double passage channel.