Analysis of combined radiation and convection heat transfer inside a porous medium with heat source electronic devices

2022 ◽  
pp. 095440622110467
Author(s):  
Ali Mokhtari Nahal ◽  
Mohammad Hassan Nobakhti ◽  
Cyrus Aghanajafi ◽  
Morteza Khayat
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Heat Source ◽  
Cooling Rate ◽  
Numerical Study ◽  
Electronic Devices ◽  
Convection Heat Transfer ◽  
Darcy Number ◽  
Flow Lines ◽  
Rayleigh Numbers

In this study, a numerical study is performed on the cooling phenomenon of three heat source electronic devices. The electronic devices are cooled in the form of natural heat transfer by the airflow in a porous medium. Electronic devices are installed on the boundary walls of a square environment. Cooling simulations are performed by drawing flow lines and constant temperature lines. Our main goal is to find the highest cooling rate in different Darcy numbers and different Rayleigh numbers in our investigation. The range of Darcy numbers and Rayleigh numbers is between 0.0001 to 0.01 and 1000 to 100,000, respectively. Our investigation showed the maximum cooling is obtained at the Darcy number of about 0.01. And also, by decreasing the value of Darcy number, a higher cooling rate for the hot boundary walls is achieved.

Natural Convection Inside a Bidisperse Porous Medium Enclosure

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Arunn Narasimhan ◽  
B. V. K. Reddy
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Natural Convection ◽  
Volume Fraction ◽  
Solid Phase ◽  
Darcy Number ◽  
The Core ◽  
Side Walls ◽  
Porous Blocks ◽  
Rayleigh Numbers

Bidisperse porous medium (BDPM) consists of a macroporous medium whose solid phase is replaced with a microporous medium. This study investigates using numerical simulations, steady natural convection inside a square BDPM enclosure made from uniformly spaced, disconnected square porous blocks that form the microporous medium. The side walls are subjected to differential heating, while the top and bottom ones are kept adiabatic. The bidispersion effect is generated by varying the number of blocks (N2), macropore volume fraction (ϕE), and internal Darcy number (DaI) for several enclosure Rayleigh numbers (Ra). Their effect on the BDPM heat transfer (Nu) is investigated. When Ra is fixed, the Nu increases with an increase in both DaI and DaE. At low Ra values, Nu is strongly affected by both DaI and ϕE. When N2 is fixed, at high Ra values, the porous blocks in the core region have negligible effect on the Nu. A correlation is proposed to evaluate the heat transfer from the BDPM enclosure, Nu, as a function of Raϕ, DaE, DaI, and N2. It predicts the numerical results of Nu within ±15% and ±9% in two successive ranges of modified Rayleigh number, RaϕDaE.

Forced Convection in a Porous Channel With Localized Heat Sources

1994 ◽  
Vol 116 (2) ◽  
pp. 465-472 ◽  
Author(s):  
A. Hadim
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Pressure Drop ◽  
Heat Source ◽  
Forced Convection ◽  
Numerical Study ◽  
Porous Channel ◽  
Heat Sources ◽  
Porous Layers ◽  
Channel Configuration

A numerical study is performed to analyze steady laminar forced convection in a channel filled with a fluid-saturated porous medium and containing discrete heat sources on the bottom wall. Hydrodynamic and heat transfer results are reported for two configurations: (1) a fully porous channel, and (2) a partially porous channel, which contains porous layers above the heat sources and is nonporous elsewhere. The flow in the porous medium is modeled using the Brinkman-Forchheimer extended Darcy model. Heat transfer rates and pressure drop are evaluated for wide ranges of Darcy and Reynolds numbers. Detailed results of the evolution of the hydrodynamic and thermal boundary layers are also provided. The results indicate that as the Darcy number decreases, a significant increase in heat transfer is obtained, especially at the leading edge of each heat source. For fixed Reynolds number, the length-averaged Nusselt number reaches an asymptotic value in the Darcian regime. In the partially porous channel, it is found that when the width of the heat source and the spacing between the porous layers are of the same magnitude as the channel height, the heat transfer enhancement is almost the same as in the fully porous channel while the pressure drop is significantly lower. These results suggest that the partially porous channel configuration is a potentially attractive heat transfer augmentation technique for electronic equipment cooling, an end that motivated this study.

scholarly journals Convection Heat Transfer Analysis in a Channel with an Open Trapezoidal Cavity: Heat Source Locations effect

2020 ◽  
Vol 330 ◽  
pp. 01006
Author(s):  
F. Mebarek-Oudina ◽  
H. Laouira ◽  
A. Aissa ◽  
A. K. Hussein ◽  
M. El Ganaoui
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
The Other ◽  
Heat Transfer Analysis ◽  
Convection Heat ◽  
Nusselt Numbers ◽  
Discrete Heat Source ◽  
Trapezoidal Enclosure

In this work, a numerical study of mixed convection inside a horizontal channel with an open trapezoidal enclosure subjected to a discrete heat source in different locations is carried out. The heat source with the length of ε = 0.75, is maintained at a constant temperature. The air flow with a fixed velocity and a cold temperature enters the channel horizontally. The other walls of the enclosure and the channel are adiabatic. The results are presented in the form of the contours of velocity, isotherms and Nusselt numbers profiles for various heat source locations, Prandtl number (Pr = 0.71) and Reynolds number (Re = 100) respectively. The distribution of the isotherms depends significantly on the position of the heat source. We noted that the best heat transfer is detected where the heat source is placed in the top of the left .

Parametric Study of Mixed Convection in a Porous Medium Between Vertical Concentric Cylinders

1991 ◽  
Vol 113 (1) ◽  
pp. 128-134 ◽  
Author(s):  
N. J. Kwendakwema ◽  
R. F. Boehm
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Particle Diameter ◽  
Darcy Law ◽  
Axial Distance ◽  
Concentric Cylinders

A numerical study has been performed to evaluate mixed convection heat transfer in a porous medium between two vertical concentric cylinders for a constant-temperature outer and an insulated inner boundary conditions. In modeling the flow in the bed a finite difference technique was utilized to represent the governing equations with appropriate boundary layer assumptions. The effects of flow inertia, variable porosity and properties, and the Brinkman friction were all taken into account. The model simulated the condition where water was the fluid flowing through the porous material. In all flow simulations the Darcy law condition was obeyed, i.e., the Reynolds number based on the particle diameter was less than unity. Results obtained include radial and axial velocity and temperature profiles in the bed. The dependence of local Nusselt number on the axial distance for several Reynolds numbers was also obtained. Correlations of the average Nusselt number against the Grashof, Peclet, and Darcy numbers were obtained for various radius ratios. Comparisons of the heat transfer predictions to data and calculations of others for special situations showed excellent agreement.

scholarly journals Numerical Investigation of Laminar Natural Convection in Inclined Square Enclosure with the Influence of Discrete Heat Source

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Chithra Devaraj ◽  
Eswaramurthi Muthuswamy ◽  
Sundararaj Kandasamy
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Heat Source ◽  
Average Nusselt Number ◽  
Convection Heat Transfer ◽  
Correlation Coefficients ◽  
Computational Procedure ◽  
Square Enclosure ◽  
Rayleigh Numbers

Natural convection heat transfer in a two-dimensional square enclosure at various angles of inclination is investigated numerically using a finite volume based computational procedure. The heat transfer is from a constant temperature heat source of finite length centred at one of the walls to the cold wall on the opposite side while the remaining walls are insulated. The effect of area ratio of the heat sourceAfrom 0.2 to 1.0, Rayleigh number Ra from 103to 107, and angle of inclination of the enclosureθvarying from 0° to 360° on the flow field and heat transfer characteristics are investigated. Streamline and isothermal line patterns are found to be similar at low Rayleigh numbers whereas at high Rayleigh numbers the differences are significant due to the influence of the parameters considered. Average Nusselt number decreases drastically as the position of the heat source is moved above the horizontal centre line of the enclosure. Correlation of the average Nusselt number which depends on the parameters of interest is obtained in the general formCRamAn. The correlation coefficients are determined by multiple regression analysis for the entire range of Rayleigh numbers analysed and the values found by correlation equations are in good agreement with the numerical results.

scholarly journals Numerical Solution for Mixed Convection Heat Transfer from a Vertical Heated Plate Embedded in a Sparsely Packed Porous Medium

2011 ◽  
Vol 10 (2) ◽  
pp. 37-52
Author(s):  
N. Nalinakshi ◽  
P.A. Dinesh ◽  
I.S. Shivakumara ◽  
D.V. Chandrashekar
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Mixed Convection ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Integration Scheme ◽  
Physical Parameters ◽  
Heated Plate ◽  
Similarity Transformations ◽  
Layer Flow

An improved numerical study on mixed convection from a heated vertical plate embedded in a Newtonian fluid saturated sparsely packed porous medium is undertaken by considering the variation of permeability, porosity and thermal conductivity. The boundary layer flow in the porous medium is governed by Lapwood – Forchheimer – Brinkman extended Darcy model. Similarity transformations are employed and the resulting ordinary differential equations are solved numerically by using shooting algorithm with Runge – Kutta – Fehlberg integration scheme to obtain velocity and temperature distributions. Besides, skin friction and Nusselt number are also computed for various physical parameters governing the problem under consideration. It is found that the inertial parameter has a significant influence in decreasing the flow field, whereas its influence is reversed on the rate of heat transfer for all values of permeability considered. Further, the obtained results under the limiting conditions were found to be in good agreement with the existing ones.

ANALYSIS OF NATURAL CONVECTION HEAT TRANSFER BETWEEN TWO HORIZONTAL CYLINDERS AND THEIR ENCLOSURE

1992 ◽  
Vol 16 (1) ◽  
pp. 17-32 ◽  
Author(s):  
M. Lacroix
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Nusselt Numbers ◽  
Horizontal Cylinders ◽  
Rayleigh Numbers

A numerical study has been conducted for natural convection heat transfer for air around two horizontal heated cylinders placed inside a rectangular enclosure cooled from the side. Three cylinder spacings were investigated. The local and overall Nusselt numbers were determined over the range of Rayleigh numbers from 104 to 106. It is found that the thermal performance of the unit is strongly influenced by the Rayleigh number and, to a lesser extent, by the cylinder spacing. A correlation is suggested for the overall Nusselt number.

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