NATURAL CONVECTIVE HEAT TRANSFER IN A POROUS MEDIUM WITHIN A TWO DIMENSIONAL ENCLOSURE

Mehdi Ahmadi

doi:10.31436/iiumej.v18i2.593

Abstract

In this paper, to achievement the effect of increase number of heating components arrangement on the rate of heat transfer of natural convection, that others have been less noticed. Therefore, in each stage increase the number of heating components so much the space occupied by them remains constant. Then by calculating the amount of heat transfer in different Rayleigh number became clear that minify and distributing heating solid phase in the enclosure increases the total Nusselt number and heat transfer, One reason could be high intensity of fluid motion in corners and near walls of the enclosure. In the next section with the solid phases on the enclosure can be made porous media model. As the results showed an increase in average Rayleigh number, Nusselt number has increased. Also be seen in the lower Darcy numbers, speed of increase in Nusselt number with increase in average Rayleigh number is higher. It can be said that in enclosure by any number of solid pieces with certain Darcy number, with an increase in average Rayleigh number, circular flow inside the enclosure becomes more intense and isothermal lines near walls with constant temperature are so dense, that represents an increase in rate of heat transfer. Also by increasing the Darcy number, rate of heat transfer from the porous media has decreased, as regards that a large share of heat transfer in porous media is done by conduction, although increasing Darcy number increases heat transfer of natural convection but decrease a heat transfer of conduction, therefore decrease total of heat transfer.

Highlights

Heat transfer and flow convection, forced and combined for numerous applications in the industry are widely studied by researchers
Natural convection plays an important role in porous models, which are frequently used in engineering and environmental sciences
The determination of the critical Rayleigh number and the frequency of oscillatory flow has been found in the works of Ghernaout et al [3] who studied the effect of the buoyancy ratio on the oscillatory double-diffusive convection in binary mixture, and in [4], investigated the effect of an external magnetic field on the 3D oscillatory natural convection during phase change

Summary

Introduction

Heat transfer and flow convection, forced and combined for numerous applications in the industry are widely studied by researchers. Deng [2] numerically investigated the effects of the aspect ratio, location and arrangement of multiple discrete sources mounted on the vertical sidewalls. They found that the total heat transfer was closely related to the number of eddies in the enclosure. A steady laminar natural convection in 2D enclosures heated from below and cooled from above for a wide variety of thermal boundary conditions at the sidewalls has been carried numerically by Corcione [5]. An experimental and numerical study of free convective heat transfer in a square enclosure characterized by a discrete heating at lower wall and cooled from the vertical walls have been analyzed by Calgagni et al [7]. A numerical investigation of natural convection of air in a vertical square cavity with localized isothermal heating from below and symmetrical cooling from the side walls was investigated by Aydin and Yang [8]

Methods

Results

Conclusion