Natural Convection Cooling of Multiple Heat Sources in Parallel Open-Top Cavities Filled With a Fluorinert Liquid

1998 ◽  
Vol 120 (1) ◽  
pp. 73-81 ◽  
Author(s):  
M. Behnia ◽  
A. A. Dehghan ◽  
H. Mishima ◽  
W. Nakayama
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Source ◽  
Alumina Ceramic ◽  
Heat Sources ◽  
Flow And Heat Transfer ◽  
Discrete Heat Sources ◽  
Vertical Walls ◽  
Convection Cooling ◽  
Lower Heat

Natural convection immersion cooling of discrete heat sources in a series of parallel interacting open-top cavities filled with a fluorinert liquid (FC–72) has been numerically studied. A series of open-top slots which are confined by conductive vertical walls with two heat sources on one side are considered. One of the slots is modeled and simulated. The effect of the separation between the heat sources on the flow and heat transfer characteristics of the wall and the effect of strength of the lower heat source (which location is upstream of the other one) on the flow and heat transfer of the upper heat source are considered. The wall thermal conductivity considered ranges from adiabatic to alumina-ceramic. The results of bakelite and alumina-ceramic are shown, which are commonly used as wiring boards in electronic equipment. It is found that conduction in the wall is very important and enhances the heat transfer performance.

scholarly journals Intensification of Heat Transfer in Cavity Partially Heated and Filled with Nanofluid (Cu-Water)

2015 ◽  
Vol 55 ◽  
pp. 173-179
Author(s):  
Ridha Jmai ◽  
Brahim Ben Beya ◽  
Taieb Lili
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Aspect Ratio ◽  
Heat Transfer Rate ◽  
Finite Volume ◽  
Transfer Rate ◽  
Heat Sources ◽  
Flow And Heat Transfer ◽  
Vertical Walls

Natural convection in a rectangular cavity with aspect ratio (Ax), partially heated and filled with a nanofluid (Cu-Water) has been studied numerically. Two heat sources with length (B) are placed on the opposite vertical walls; the remainder of the walls is maintained adiabatic while the horizontal walls are brought to a cold temperature. The equations governing the flow are solved using a finite volume home code using a multigrid technique. Among the parameters governing the flow, a detailed study on the effects of the aspect ratio (Ax) and the length of the source (B) on flow and heat transfer rate is given. The results are shown in terms of streamlines and isotherms. It was found that the transfer of heat significantly increases with the aspect ratio (Ax) and the length of the source (B). A correlation expressing the Nusselt number as a function of (Ax) and d is established.

Influence of Discrete Heat Source Location on Natural Convection Heat Transfer in a Vertical Square Enclosure

1991 ◽  
Vol 113 (3) ◽  
pp. 268-274 ◽  
Author(s):  
G. Refai Ahmed ◽  
M. M. Yovanovich
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Source ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Heat Sources ◽  
Convection Heat ◽  
Square Enclosure ◽  
Discrete Heat Sources ◽  
Scale Length

A numerical study is carried out to investigate the influence of discrete heat sources on natural convection heat transfer in a square enclosure filled with air. The enclosure has two vertical boundaries of height H; one of them is cooled at Tc and the other has discrete heat sources [isoflux (q = c) or isothermal (Th = c)]. The enclosure has two horizontal adiabatic boundaries of length L. Results are reported for 0 ≤ Ra ≤ 106, Pr = 0.72, A = 1, aspect ratio ε, the relative size of the heat source to the total height, lies in the range 0.25 ≤ ε ≤ 1 and the discrete heat sources are located at the top or the bottom of the enclosure. Verification of numerical results is obtained at Ra = 0 (conduction limit) with analytical conduction solutions. In addition, a comparison with experimental and numerical data is made which also shows good agreement. The relationships between both Nu, ΔNu (change of thermal conductance) and Ra based on scale length (the size of the heat source S divided by the aspect ratio A) are also investigated here. A relationship Nu and Ra, based on scale length obtained from analytical solutions is correlated as Nu = Nu(Ra, ε). In addition, extrapolation correlations of Nu over the very high range of Rayleigh numbers (Ra ≥ 108) are developed.

Fundamental Issues and Recent Advancements in Analysis of Aircraft Brake Natural Convective Cooling

1998 ◽  
Vol 120 (4) ◽  
pp. 840-857 ◽  
Author(s):  
M. P. Dyko ◽  
K. Vafai
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Flow Field ◽  
Three Dimensional ◽  
Convective Cooling ◽  
Cooling Flow ◽  
Physical Mechanisms ◽  
Braking System ◽  
Flow And Heat Transfer ◽  
Convection Cooling

A heightened awareness of the importance of natural convective cooling as a driving factor in design and thermal management of aircraft braking systems has emerged in recent years. As a result, increased attention is being devoted to understanding the buoyancy-driven flow and heat transfer occurring within the complex air passageways formed by the wheel and brake components, including the interaction of the internal and external flow fields. Through application of contemporary computational methods in conjunction with thorough experimentation, robust numerical simulations of these three-dimensional processes have been developed and validated. This has provided insight into the fundamental physical mechanisms underlying the flow and yielded the tools necessary for efficient optimization of the cooling process to improve overall thermal performance. In the present work, a brief overview of aircraft brake thermal considerations and formulation of the convection cooling problem are provided. This is followed by a review of studies of natural convection within closed and open-ended annuli and the closely related investigation of inboard and outboard subdomains of the braking system. Relevant studies of natural convection in open rectangular cavities are also discussed. Both experimental and numerical results obtained to date are addressed, with emphasis given to the characteristics of the flow field and the effects of changes in geometric parameters on flow and heat transfer. Findings of a concurrent numerical and experimental investigation of natural convection within the wheel and brake assembly are presented. These results provide, for the first time, a description of the three-dimensional aircraft braking system cooling flow field.

A comprehensive review on natural convection flow and heat transfer

2019 ◽  
Vol 29 (3) ◽  
pp. 834-877 ◽  
Author(s):  
Alireza Rahimi ◽  
Ali Dehghan Saee ◽  
Abbas Kasaeipoor ◽  
Emad Hasani Malekshah
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Industrial Applications ◽  
Convection Flow ◽  
Heat Sources ◽  
Comprehensive Review ◽  
Content Type ◽  
Thermal Boundary Conditions ◽  
Flow And Heat Transfer ◽  
Different Types

PurposeThe purpose of this paper is to carry out a comprehensive review of some latest studies devoted to natural convection phenomenon in the enclosures because of its significant industrial applications.Design/methodology/approachGeometries of the enclosures have considerable influences on the heat transfer which will be important in energy consumption. The most useful geometries in engineering fields are treated in this literature, and their effects on the fluid flow and heat transfer are presented.FindingsA great variety of geometries included with different physical and thermal boundary conditions, heat sources and fluid/nanofluid media are analyzed. Moreover, the results of different types of methods including experimental, analytical and numerical are obtained. Different natures of natural convection phenomenon including laminar, steady-state and transient, turbulent are covered. Overall, the present review enhances the insight of researchers into choosing the best geometry for thermal process.Originality/valueA comprehensive review on the most practical geometries in the industrial application is performed.

An Experimental Study of Transient Heat Transfer From Discrete Heat Sources in Water Cooled Vertical Rectangular Channel

2004 ◽  
Vol 127 (3) ◽  
pp. 193-199 ◽  
Author(s):  
H. Bhowmik ◽  
K. W. Tou
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Source ◽  
Rectangular Channel ◽  
Convection Heat Transfer ◽  
Uniform Heat Flux ◽  
Heat Sources ◽  
Discrete Heat Sources ◽  
Wide Range ◽  
Transfer Behavior

Experiments are performed to study the single-phase transient forced convection heat transfer on an array of 4×1 flush-mounted discrete heat sources in a vertical rectangular channel during the pump-on transient operation. Water is the coolant media and the flow covers the wide range of laminar flow regime with Reynolds number, based on heat source length, from 800 to 2625. The applied uniform heat flux ranges from 1 to 7W∕cm2. For flush-mounted heaters the heat transfer characteristics are studied and correlations are presented for four chips as well as for overall data in the transient regime. The experimental results indicate that the heat transfer coefficient is affected strongly by the number of chips and the Reynolds number. Finally the general impacts of heat source protrusions (B=1, 2 mm) on heat transfer behavior of four chips are investigated by comparing the results obtained from flush-mounted (B=0) heaters.

Mixed Convection Heat Transfer From Thermal Sources Mounted on Horizontal and Vertical Surfaces

1990 ◽  
Vol 112 (4) ◽  
pp. 975-987 ◽  
Author(s):  
S. S. Tewari ◽  
Y. Jaluria
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Source ◽  
Mixed Convection ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Finite Width ◽  
Heat Sources ◽  
Wide Range ◽  
Thermal Sources

An experimental study is carried out on the fundamental aspects of the conjugate, mixed convective heat transfer from two finite width heat sources, which are of negligible thickness, have a uniform heat flux input at the surface, and are located on a flat plate in the horizontal or the vertical orientation. The heat sources are wide in the transverse direction and, therefore, a two-dimensional flow circumstance is simulated. The mixed convection parameter is varied over a fairly wide range to include the buoyancy-dominated and the mixed convection regimes. The circumstances of pure natural convection are also investigated. The convective mechanisms have been studied in detail by measuring the surface temperatures and determining the heat transfer coefficients for the two heated strips, which represent isolated thermal sources. Experimental results indicate that a stronger upstream heat source causes an increase in the surface temperature of a relatively weaker heat source, located downstream, by reducing its convective heat transfer coefficient. The influence of the upstream source is found to be strongly dependent on the surface orientation, especially in the pure natural convection and the buoyancy dominated regimes. The two heat sources are found to be essentially independent of each other, in terms of thermal effects, at a separation distance of more than about three strip widths for both the orientations. The results obtained are relevant to many engineering applications, such as the cooling of electronic systems, positioning of heating elements in furnaces, and safety considerations in enclosure fires.

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