Orientation Effects on Thermal Performance of Radial Heat Sinks Subject to Natural Convection

2015 ◽  
Author(s):  
Bin Li ◽  
Chan Byon
Keyword(s):  
Nusselt Number ◽  
Natural Convection ◽  
Thermal Performance ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Heat Sinks ◽  
Concentric Ring ◽  
Radial Heat ◽  
Volume Method ◽  
High Influence

Numerical study is carried out on natural convection heat transfer from three radial heat sinks subject to the influence of orientation. A finite volume method (FVM) numerical model was used to analyze the thermal performance of the radial heat sinks under upward, sideward and downward orientations. The effects of orientation with respect to gravity, fin number (15–30), the thickness of concentric ring (0.15–0.60) and Elenbaas number (15–55) on Nusselt number are investigated. Numerical results indicate that radiation is non-negligible in this study due to its high influence on thermal performance. The Nusselt number is relatively insensitive to the smaller ring thickness. The sideward facing orientation yields the worst thermal performance despite fin number changing. It is found that the thermal performance of heat sinks in upward and downward orientations depend on the number of fins significantly.

Numerical Simulation of Natural Convection in a Mold

2010 ◽  
Vol 297-301 ◽  
pp. 456-461
Author(s):  
Mohsen Pirmohammadi ◽  
Ghanbar Ali Sheikhzadeh ◽  
Majid Ghassemi ◽  
Mohsen Hamedi
Keyword(s):  
Nusselt Number ◽  
Natural Convection ◽  
Numerical Study ◽  
Control Volume ◽  
Linear Equations ◽  
Convection Heat Transfer ◽  
Square Enclosure ◽  
Simpler Algorithm ◽  
Volume Method ◽  
Hot Surface

Numerical study of natural convection heat transfer inside a differentially heated square enclosure with adiabatic horizontal walls and vertical isothermal walls is investigated. Two insulated ribs are symmetrically located on horizontal walls. The governing non-linear equations are solved in a two-dimensional domain using a control volume method and the SIMPLER algorithm for the velocity–pressure coupling is employed. The results will be presented in forms of streamlines, isotherms and Nusselt number for Rayleigh number 106. It is shown that for small rib height the isotherms indicate the laminar boundary regime with high temperature gradient near the bottom of the hot surface and the top of cold one. However, as rib height increases this boundary layer is vanished. Also it is found that as the length and height of the ribs increase the mean Nusselt number decreases.

scholarly journals Natural convection in a differentially heated enclosure with triangular roof

1970 ◽  
Vol 39 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Sumon Saha ◽  
Noman Hasan ◽  
Chowdhury Md Feroz
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Natural Convection ◽  
Average Nusselt Number ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Element Analysis ◽  
Left Wall ◽  
Square Enclosure

A numerical study has been carried out for laminar natural convection heat transfer within a two-dimensional modified square enclosure having a triangular roof. The vertical sidewalls are differentially heated considering a constant flux heat source strip is flush mounted with the left wall. The opposite wall is considered isothermal having a temperature of the surrounding fluid. The rest of the walls are adiabatic. Air is considered as the fluid inside the enclosure. The solution has been carried out on the basis of finite element analysis by a non-linear parametric solver to examine the heat transfer and fluid flow characteristics. Different heights of the triangular roof have been considered for the present analysis. Fluid flow fields and isotherm patterns and the average Nusselt number are presented for the Rayleigh numbers ranging from 103 to 106 in order to show the effects of these governing parameters. The average Nusselt number computed for the case of isoflux heating is also compared with the case of isothermal heating as available in the literature. The outcome of the present investigation shows that the convective phenomenon is greatly influenced by the inclined roof height. Keywords: Natural convection, triangular roof, Rayleigh number, isoflux heating. Doi:10.3329/jme.v39i1.1826 Journal of Mechanical Engineering, vol. ME39, No. 1, June 2008 1-7

A Numerical Study of Natural Convection in a Cavity With Two Fins Attached to Its Vertical Walls

2007 ◽  
Author(s):  
G. A. Sheikhzadeh ◽  
M. Pirmohammadi ◽  
M. Ghassemi
Keyword(s):  
Nusselt Number ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Square Cavity ◽  
Vertical Walls ◽  
The Mean ◽  
Energy Equations ◽  
Rayleigh Numbers

Numerical study natural convection heat transfer inside a differentially heated square cavity with adiabatic horizontal walls and vertical isothermal walls is investigated. Two perfectly conductive thin fins are attached to the isothermal walls. To solve the governing differential mass, momentum and energy equations a finite volume code based on Pantenkar’s simpler method is developed and utilized. The results are presented in form of streamlines, isotherms as well as Nusselt number for Rayleigh number ranging from 104 up to 107. It is shown that the mean Nusselt number is affected by the position of the fins and length of the fins as well as the Rayleigh number. It is also observed that maximum Nusselt number occurs about the middle of the enclosure where Lf is grater the 0.5. In addition the Nusselt number stays constant and does not varies with width of the cavity (lf) when Lf is equal to 0.5 and Rayleigh number is equal to 104 and 107 as well as when Lf is equal to 0.6 and low Rayleigh numbers.

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.

scholarly journals ASSOCIATED EFFECT OF PERFORATION POSITION AND DIAMETER ON THERMAL PERFORMANCE OF PLANE FIN UNDER NATURAL CONVECTION ENVIRONMENT

2020 ◽  
Vol 82 (5) ◽  
Author(s):  
Osamah Raad Skheel Al-khafaji ◽  
Nizar F.O. Al-Muhsen
Keyword(s):  
Nusselt Number ◽  
Natural Convection ◽  
Surface Temperature ◽  
Thermal Performance ◽  
Convection Heat Transfer ◽  
Heat Fluxes ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Wide Range ◽  
The Mean

The fin perforation represents an efficient way to reduce fins weight and enhance its thermal performance. In this study, rectangular plane fins were designed and fabricated aiming to experimentally investigate the effect of the perforation, perforations position and diameter on the solid fins thermal performance under natural convection heat transfer conditions. The experiments were conducted at a wide range of the supplied heat fluxes, and also covered three perforations positions (bottom, middle, top) and perforations diameters (3, 5, 7) mm. At all the used diameters, results showed that the middle position for perforations performed the best in terms of the Nusselt number and mean surface temperature. The maximum Nusselt number and mean surface temperature were 662.08 and 71.95 oC respectively when the heat flux was 4181.82 W/m2, and the perforation diameter was 3.0 mm. The thermal performance of the top-perforated fins was slightly smaller than that of the middle-perforated fins. Besides, the bottom perforated fins demonstrated the worst thermal performance in terms of Nusselt number and the mean surface temperature. Regarding the effect of the perforation diameter, the 3.0 mm showed superior thermal performance compared with 5.0 mm, and 7.0 mm regardless of the perforation’s positions.

scholarly journals Effect of Al2O3 Nanoparticles and Cylindrical Pins on Natural Convection Heat Transfer in a C-Shaped Enclosure

2020 ◽  
Vol 12 (4) ◽  
pp. 499-515
Author(s):  
M. Y. Arafat ◽  
F. Faisal
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Al2o3 Nanoparticles ◽  
Simpler Algorithm

A numerical study has been conducted to investigate the transport mechanism of natural convection in a C-shaped enclosure filled with water-Al2O3 nanofluid for various pertinent parameters. The effects of the volume fraction of the Al2O3 nanoparticles, Rayleigh number, and radius of inserted cylindrical pins on the temperature, velocity, heat flux profiles and average Nusselt number have been investigated. General correlations for the effective thermal conductivity and viscosity of nanofluids are used for this analysis. The governing mass, momentum and energy equations are solved numerically with the finite volume method using the SIMPLER algorithm. The results show that addition of nanoparticle improves the heat transfer performance. Insertion of cylindrical pins of lower radius increases the average Nusselt number irrespective of Rayleigh number. But anomaly has been observed while pins of higher radius are inserted due to enormous disturbance in the fluid.

An Investigation of the Effect of interrupted fin arrangements on the Thermal Performance of a Heat Sink under a Free Convection Condition

2019 ◽  
Vol 7 (1) ◽  
pp. 43-53
Author(s):  
Abbas Jassem Jubear ◽  
Ali Hameed Abd
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Natural Convection ◽  
Thermal Performance ◽  
Heat Sink ◽  
Numerical Study ◽  
Ansys Fluent ◽  
Fluent Software ◽  
Steady State Heat ◽  
Steady State Heat Transfer

The heat sink with vertically rectangular interrupted fins was investigated numerically in a natural convection field, with steady-state heat transfer. A numerical study has been conducted using ANSYS Fluent software (R16.1) in order to develop a 3-D numerical model.  The dimensions of the fins are (305 mm length, 100 mm width, 17 mm height, and 9.5 mm space between fins. The number of fins used on the surface is eight. In this study, the heat input was used as follows: 20, 40, 60, 80, 100, and 120 watts. This study focused on interrupted rectangular fins with a different arrangement and angle of the fins. Results show that the addition of interruption in fins in various arrangements will improve the thermal performance of the heat sink, and through the results, a better interruption rate as an equation can be obtained.

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