Natural Convection From Protruding Heat Sources in a Channel

Author(s):  
Tunc Icoz ◽  
Qinghua Wang ◽  
Yogesh Jaluria

Natural convection has important implications in many applications like cooling of electronic equipment due to its low cost and easy maintenance. In the present study, two-dimensional natural convection heat transfer to air from multiple identical protruding heat sources, which simulate electronic components, located in a horizontal channel has been studied numerically. The fluid flow and temperature profiles, above the heating elements placed between an adiabatic lower plate and an isothermal upper plate, are obtained using numerical simulation. The effects of source temperatures, channel dimensions, openings, boundary conditions, and source locations on the heat transfer from and flow above the protruding sources are investigated. Different configurations of channel dimensions and separation distances of heat sources are considered and their effects on natural convection heat transfer characteristics are studied. The results show that the channel dimensions have a significant effect on fluid flow. However, their effects on heat transfer are found to be small. The separation distance is found to be an important parameter affecting the heat transfer rate. The numerical results of temperature profiles are compared with the experimental measurements performed using Filtered Rayleigh Scattering (FRS) technique in an earlier study, indicating good agreement. It is observed that adiabatic upper plate assumption leads to better temperature predictions than isothermal plate assumption.

2013 ◽  
Vol 302 ◽  
pp. 422-428
Author(s):  
Rached Ben-Mansour ◽  
Mohammed A. Habib

Natural convection heat transfer from discrete heat sources to nanofluids is of great importance because of its application in the cooling of electronic components. The presence of the nanoparticles in the fluids increases appreciably the effective thermal conductivity of the fluid and consequently enhances the heat transfer characteristics. The present study is aimed to investigate numerically the natural convection heat transfer from discrete heat sources to nanofluids. The behavior of nanofluids was investigated numerically inside a heated cavity to gain insight into convective recirculation and flow processes induced by a nanofluid. A computational model was developed to analyze heat transfer performance of nanofluids inside a cavity taking into account the solid particle dispersion. The model was validated through the comparison with available experimental data. The results showed good agreement. The influence of the solid volume fraction on the flow pattern and heat transfer inside the cavity was investigated. The results show that the intensity of the streamlines increases with the volume fraction. It is also indicated that higher velocities along the centerline of the enclosure are achieved as the volume of nanoparticles increases. The influence of the loading factor is more distinguished at the upper heaters and in particular at the highest heater. The heat transfer increases as the volume fraction of the nanoparticles increases from 2 to 10%.


1975 ◽  
Vol 97 (3) ◽  
pp. 372-377 ◽  
Author(s):  
J. C. Dutton ◽  
J. R. Welty

An experimental program was conducted to study natural convection heat transfer in an array of uniformly heated vertical cylinders in mercury. The cylinders were arranged in an equilateral triangular pattern, and three bundle spacings, P/D = 1.5, 1.3, and 1.1, were studied. The heat transfer results are presented as local Nusselt number—modified Grashof number correlations. The results indicate a strong dependence on cylinder spacing and the somewhat lesser effects of heat flux and circumferential position. In addition, mean radial temperature profiles were recorded for various conditions as well as the fluctuations in the fluid temperatures which were encountered. The influence of cylinder spacing and axial, radial, and circumferential position on these profiles and disturbances is discussed.


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