scholarly journals Comparative Analysis of Free Natural Convection Heat Transfer on Rectangular and Triangular Fins with and without Perforation

2018 ◽  
Vol 3 (5) ◽  
pp. 60
Author(s):  
Ogie Nosa Andrew ◽  
Joel Oluwayomi Oyejide
Keyword(s):  
Heat Transfer ◽  
Comparative Analysis ◽  
Natural Convection ◽  
Heat Dissipation ◽  
Nuclear Reactors ◽  
Research Work ◽  
Temperature Drop ◽  
Convection Heat Transfer ◽  
Engineering Application ◽  
Cylindrical Pipe

The importance of heat transfer by free natural convection can be found in many engineering application such as energy transfer in buildings, solar collectors, nuclear reactors and electronic packaging.  In this research work, we carried out the investigation and comparative analysis of heat transfer by natural convection on rectangular and triangular fins with and without circular perforation. A total of six (6) specimens were used.  Other materials that were used in this research work include four digital thermometers, one heating element, four thermocouple K-type and a power source.   The fins used in this research work were welded to a cylindrical pipe which served as the heat sink. The heat supplied was maintained at 2500C and the temperature drop through the fin was recorded for duration of 30minutes with intervals of 5minutes. It was observed that the temperature dropped more rapidly with the triangular fins than the rectangular fin. Also, the rate of heat dissipation increase with a corresponding increase in the number of perforation.

scholarly journals Natural-convection heat transfer enhancement of aluminum heat sink using nanocoating by electron beam method

2019 ◽  
Vol 23 (5 Part B) ◽  
pp. 3129-3141
Author(s):  
Senthil Pongiannan ◽  
Velraj Ramalingam ◽  
Latha Nagendran
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Electron Beam ◽  
Natural Convection ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Convection Heat Transfer ◽  
Safety Level ◽  
X Ray ◽  
Beam Method

The high power density and compactness of the next generation electronic devices necessitate efficient and effective cooling methods for heat dissipation in order to maintain the temperature at an acceptable safety level. In the present work, aluminum nanocoating was employed in a heat sink to study the heat transfer performance under natural-convection conditions. The nanocoating was achieved using an electron beam method while the characteristics of nanocoated surfaces were analysed using SEM, an energy dispersive X-ray spectroscopy, surface roughness profilometry equipment and by X-ray diffraction techniques. The heat dissipation from heat sink with and without nanocoating under natural-convection has been experimentally studied at different controllable surrounding temperatures. A uniform increase in the surface roughness by the nanocoating was seen in all cases. The conclusion from several experimental results was that the effect of nanocoating in augmenting the heat transfer is more pronounced only when there is a sufficient temperature driving potential.

Numerical analysis of heat dissipation from a heated vertical cylinder by natural convection

2015 ◽  
Vol 231 (3) ◽  
pp. 405-413 ◽  
Author(s):  
Jashanpreet Singh ◽  
Chanpreet Singh
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Boundary Layer ◽  
Natural Convection ◽  
Layer Thickness ◽  
Water Vapour ◽  
Boundary Layer Thickness ◽  
Heat Dissipation ◽  
Convection Heat Transfer ◽  
Vertical Cylinder

Natural convection heat transfer from a hot vertical hollow brass cylinder has been studied experimentally and numerically. The governing equations of continuity, momentum and energy are discretised by using an implicit finite difference technique. The velocity and temperature profiles, boundary layer thickness, local and average heat transfer coefficient are obtained using the numerical simulation. The predictions of the numerical simulation are compared with the experiments conducted on a laboratory-scale apparatus and with the results obtained from analytical solutions available in literature. The numerical simulation results are obtained for two fluids; air and water vapour whereas the experiments are conducted for air only. The induced flow is laminar in both the simulation and the experiments. The dependence of boundary layer thickness on Prandtl number is discussed. The numerically obtained Nusselt number is found quite close to the analytical one. The results show the heat dissipation from the cylinder to surrounding fluid is higher for air than for water vapour. The various factors that affect the comparison of the experimental results with the numerical simulation are discussed.

Natural Convection Heat Transfer From Horizontal Rectangular Inverted Notched Fin Arrays

2009 ◽  
Vol 131 (8) ◽  
Author(s):  
Sanjeev D. Suryawanshi ◽  
Narayan K. Sane
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Dissipation ◽  
Convection Heat Transfer ◽  
Average Heat Transfer Coefficient ◽  
Enhancement Of Heat Transfer ◽  
Computational Fluid Dynamics Analysis ◽  
Convection Cooling ◽  
Fin Spacing ◽  
Bottom Portion

The variables for natural convection cooling with the help of finned surfaces are orientation and geometry. In lengthwise short array (L/H∼5), where single chimney flow pattern is present, a stagnant zone is created at the central bottom portion of fin array channel and hence it does not contribute much in heat dissipation. Hence it is removed in the form of inverted notch at the central bottom portion of fin to modify its geometry for enhancement of heat transfer. An experimental setup is developed for studying the investigation on normal and inverted notched fin arrays (INFAs). Fin spacing, heater input, and percentage of area removed in the form of inverted notch are the parameters. For few spacing, it is verified by computational fluid dynamics analysis (Course Notes on Introduction to Commercial CFD of Tridiagonal Solutions, Pune), and the results are well matching. It is found that the average heat transfer coefficient for INFAs is nearly 30–40% higher as compared with normal array.

Experimental Investigation of Perforated Enclosures in Confined Natural Convection

2017 ◽  
Author(s):  
Ribhu Bhatia ◽  
Vinayak Malhotra
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Dissipation ◽  
Flow Behavior ◽  
Convective Heat Transfer Coefficient ◽  
Convection Heat Transfer ◽  
Rate Variation ◽  
Engineering Systems ◽  
Physical Insight ◽  
Novel Design

The work attempts to address excessive heating and related risks in most of the engineering systems. Perforations are well known to boost heat transfer. Present work is an attempt to pact optimization of perforated enclosures for internal natural convection heat transfer. Heat dissipation effect is experimented over a flat plate and implications are understood with variation in convective heat transfer coefficient. Controlling parameters viz., plate orientation, perforation shape and size, enclosures in diverse configurations are varied systematically aiming enhanced heat transfer. Results confirm fact that perforated enclosures significantly affect the heat transportation. Enclosures with varying perforations are found to yield distinct heat sink characteristics. For varying perforation shape, size and plate orientation, the heat transfer rate variation is owed by the resultant flow behavior which governs the energy transference. The complied results are noted as excellent physical insight and optimized to propose a novel design for operations under varying heat transfer requirements for wide-ranging applications.

Numerical Computation on Natural Convection Heat Transfer from an Isothermal Sphere with Semi-Circular Ribs

2021 ◽  
Author(s):  
Subrat Garnayak ◽  
Subhasisa Rath
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Average Nusselt Number ◽  
Heat Dissipation ◽  
Convection Heat Transfer ◽  
Critical Parameters ◽  
Light Sources ◽  
Sphere Diameter ◽  
Practical Applications

Abstract For the very first time, the present study attempts to address the heat dissipation from an isothermal ribbed sphere under the action of pure natural convection. Semi-circular ribs of different radius are superimposed azimuthally on the outer surface of a sphere. The addition of ribs on the sphere serves a dual purpose in its practical applications; beautification of electronic devices such as spherical light sources and also increase the heat dissipation from the hot surface, which prevents the electronic component from getting overheated. Finite-volume method (FVM) based axisymmetric numerical simulations are performed in the laminar flow regime for the following ranges of non-dimensional parameters: Rayleigh number (102≤=Ra≤=108), inter rib-spacing to sphere diameter (0.191≤=P/D≤=0.785), and rib-radius to sphere diameter (0.03≤=R/D≤=0.083). The main target of this study is to identify the critical parameters for heat transfer enhancement from the ribbed sphere compared to a conventional plane sphere. The results obtained from the present work show that the average Nusselt number increases with an increase in Ra and P/D, whereas it decreases as R/D increases. Effectiveness of the ribs (εrib) and critical Rayleigh numbers (Racr), corresponding to εrib=1, are also calculated. Ribs are more effective in heat dissipation at low Ra and P/D and high R/D. A correlation for the average Nusselt number is also developed in this work, which would help design a better thermal management system.

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