Free convection on a horizontal plate in a saturated porous medium with prescribed heat transfer coefficient

1991 ◽  
Vol 87 (1-2) ◽  
pp. 73-80 ◽  
Author(s):  
G. Ramanaiah ◽  
G. Malarvizhi
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Heat Transfer Coefficient ◽  
Free Convection ◽  
Transfer Coefficient ◽  
Saturated Porous Medium ◽  
Horizontal Plate

Effects of Surface Mass Transfer on Free Convection Flow Over Vertical Cylinder Embedded in a Saturated Porous Medium

1985 ◽  
Vol 107 (3) ◽  
pp. 394-396 ◽  
Author(s):  
M.-J. Huang ◽  
C.-K. Chen
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Porous Medium ◽  
Heat Transfer Coefficient ◽  
Free Convection ◽  
Saturated Porous Medium ◽  
Vertical Cylinder ◽  
Surface Mass ◽  
Surface Mass Transfer ◽  
The Heat Transfer Coefficient

The heat-transfer characteristics for free convection associated with isothermal vertical cylinder with surface mass transfer (blowing or suction) embedded in a saturated porous medium are analyzed. The nonsimilar equations are solved by using a suitable variable transformation and employing an implicit finite difference method. The numerical results for Nusselt number are expressed as functions of the parameters, ξ and γ, which represent the effects of the cylinder curvature and the surface mass transfer, respectively. It is found that the local Nusselt numbers for a vertical cylinder are less sensitive to the surface mass transfer than those for a vertical plate. Blowing of mass decreases the heat transfer coefficient but the suction of mass increases the heat transfer coefficient.

scholarly journals Darcy-Brinkman free convection about a wedge and a cone subjected to a mixed thermal boundary condition

1992 ◽  
Vol 15 (4) ◽  
pp. 789-794 ◽  
Author(s):  
G. Ramanaiah ◽  
V. Kumaran
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Heat Flux ◽  
Porous Medium ◽  
Heat Transfer Coefficient ◽  
Free Convection ◽  
Transformation Group ◽  
Darcy Number ◽  
Thermal Boundary Condition ◽  
High Porosity

The Darcy-Brinkman free convection near a wedge and a cone in a porous medium with high porosity has been considered. The surfaces are subjected to a mixed thermal boundary condition characterized by a parameterm;m=0,1,∞correspond to the cases of prescribed temperature, prescribed heat flux and prescribed heat transfer coefficient respectively. It is shown that the solutions for differentmare dependent and a transformation group has been found, through which one can get solution for anymprovided solution for a particular value ofmis known. The effects of Darcy number on skin friction and rate of heat transfer are analyzed.

Mixed Convective Heat Transfer From a Heated Horizontal Plate in a Porous Medium Near an Impermeable Surface

1988 ◽  
Vol 110 (2) ◽  
pp. 390-394 ◽  
Author(s):  
P. H. Oosthuizen
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Saturated Porous Medium ◽  
Forced Flow ◽  
Horizontal Plate ◽  
Flowing Fluid ◽  
Buoyancy Forces ◽  
Two Dimensional Flow

Two-dimensional flow over a horizontal plate in a saturated porous medium mounted near an impervious adiabatic horizontal surface and subjected to a horizontal forced flow has been numerically investigated. The plate is heated to a uniform temperature that is higher than the temperature of the flowing fluid. The conditions considered are such that the buoyancy forces have an effect on the flow and, therefore, on the heat transfer rate from the plate. The full governing equations, written in dimensionless form, have been solved for a range of values of the governing parameters using the finite element method. The heat transfer rate from the plate is influenced both by the dimensionless depth of the plate below the surface and the importance of the buoyancy forces, the latter having been characterized by a parameter which is equal to the ratio of the Darcy–Rayleigh number to Peclet number. The conditions under which these parameters have a negligible effect on the heat transfer rate are discussed.

Analytical Solution of Nonequilibrium Heat Conduction in Porous Medium Incorporating a Variable Porosity Model With Heat Generation

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
M. Nazari ◽  
F. Kowsary
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Heat Transfer Coefficient ◽  
Heat Conduction ◽  
Analytical Solution ◽  
Transfer Coefficient ◽  
Heat Generation ◽  
Conductivity Ratio ◽  
Variable Porosity ◽  
Porosity Model

This paper is concerned with the conduction heat transfer between two parallel plates filled with a porous medium with uniform heat generation under a nonequilibrium condition. Analytical solution is obtained for both fluid and solid temperature fields at constant porosity incorporating the effects of thermal conductivity ratio, porosity, and a nondimensional heat transfer coefficient at pore level. The two coupled energy equations for the case of variable porosity condition are transformed into a third order ordinary equation for each phase, which is solved numerically. This transformation is a valuable solution for heat conduction regime for any distribution of porosity in the channel. The effects of the variable porosity on temperature distribution are shown and compared with the constant porosity model. For the case of the exponential decaying porosity distribution, the numerical results lead to a correlation incorporating conductivity ratio and interstitial heat transfer coefficient.

Finned Metal Foam Heat Sinks for Electronics Cooling in Forced Convection

2002 ◽  
Vol 124 (3) ◽  
pp. 155-163 ◽  
Author(s):  
A. Bhattacharya ◽  
R. L. Mahajan
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Forced Convection ◽  
Metal Foam ◽  
Experimental Results ◽  
Heat Sinks ◽  
The Heat Transfer Coefficient

In this paper, we present recent experimental results on forced convective heat transfer in novel finned metal foam heat sinks. Experiments were conducted on aluminum foams of 90 percent porosity and pore size corresponding to 5 PPI (200 PPM) and 20 PPI (800 PPM) with one, two, four and six fins, where PPI (PPM) stands for pores per inch (pores per meter) and is a measure of the pore density of the porous medium. All of these heat sinks were fabricated in-house. The forced convection results show that heat transfer is significantly enhanced when fins are incorporated in metal foam. The heat transfer coefficient increases with increase in the number of fins until adding more fins retards heat transfer due to interference of thermal boundary layers. For the 20 PPI samples, this maximum was reached for four fins. For the 5 PPI heat sinks, the trends were found to be similar to those for the 20 PPI heat sinks. However, due to larger pore sizes, the pressure drop encountered is much lower at a particular air velocity. As a result, for a given pressure drop, the heat transfer coefficient is higher compared to the 20 PPI heat sink. For example, at a Δp of 105 Pa, the heat transfer coefficients were found to be 1169W/m2-K and 995W/m2-K for the 5 PPI and 20 PPI 4-finned heat sinks, respectively. The finned metal foam heat sinks outperform the longitudinal finned and normal metal foam heat sinks by a factor between 1.5 and 2, respectively. Finally, an analytical expression is formulated based on flow through an open channel and incorporating the effects of thermal dispersion and interfacial heat transfer between the solid and fluid phases of the porous medium. The agreement of the proposed relation with the experimental results is promising.

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