scholarly journals Influence of Ambient Temperature on Radiative and Convective Heat Dissipation Ratio in Polymer Heat Sinks

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2286
Author(s):  
Jan Kominek ◽  
Martin Zachar ◽  
Michal Guzej ◽  
Erik Bartuli ◽  
Petr Kotrbacek
Keyword(s):  
Heat Transfer ◽  
Ambient Temperature ◽  
Convective Heat ◽  
Heat Dissipation ◽  
High Surface ◽  
Heat Sinks ◽  
Fourth Power ◽  
Molding Process ◽  
Ambient Temperatures ◽  
University Of Technology

Miniaturization of electronic devices leads to new heat dissipation challenges and traditional cooling methods need to be replaced by new better ones. Polymer heat sinks may, thanks to their unique properties, replace standardly used heat sink materials in certain applications, especially in applications with high ambient temperature. Polymers natively dispose of high surface emissivity in comparison with glossy metals. This high emissivity allows a larger amount of heat to be dissipated to the ambient with the fourth power of its absolute surface temperature. This paper shows the change in radiative and convective heat transfer from polymer heat sinks used in different ambient temperatures. Furthermore, the observed polymer heat sinks have differently oriented graphite filler caused by their molding process differences, therefore their thermal conductivity anisotropies and overall cooling efficiencies also differ. Furthermore, it is also shown that a high radiative heat transfer leads to minimizing these cooling efficiency differences between these polymer heat sinks of the same geometry. The measurements were conducted at HEATLAB, Brno University of Technology.

A Review On Rectangular Heat Sinks Under Natural Convection

2019 ◽  
Vol 118 (7) ◽  
pp. 44-49
Author(s):  
Rajshekhar V Unni ◽  
Vijay S Majali
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Ambient Temperature ◽  
Temperature Difference ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Cost Effective ◽  
Heat Sinks ◽  
Maximum Heat ◽  
Fin Spacing

In the paper review of studies of heat sinks under natural convection is taken up. The discussions are mainly on experimental works carried out on rectangular fin arrays, optimization of heat sink dimensions and heat transfer enhancement. The geometries of heat sinks, fin spacing, fin height, fin length, fin thickness and fin material and base to ambient temperature difference are the important parameters on which heat transfer rate depends. So the design and optimization of the heat sink geometries becomes essential. It was found that the optimum fin  spacing is ranging from 6.1- 11.9mm which gives maximum heat dissipation; the base to ambient temperature difference is 20-1500C. During most of the experimental work carried out a good thermal conductivity material which is cost-effective was chosen.

Forced Convective Heat Transfer for Partially-Confined Compact PPF Heat Sinks With Top-Bypass Effect

2005 ◽  
Author(s):  
T. Y. Wu ◽  
M. P. Wang ◽  
J. T. Horng ◽  
S. F. Chang ◽  
Y. H. Hung
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Steady State ◽  
Convective Heat ◽  
Average Nusselt Number ◽  
Heat Dissipation ◽  
Heat Sinks ◽  
Nusselt Numbers ◽  
Transient Period ◽  
State Average

A series of experimental investigations with a stringent measurement method on the study of the fluid flow and heat transfer for confined compact heat sinks in forced convection have been successfully conducted. From the results, the thermal capacity of the heat sink and the convective heat dissipation play the major roles for dominating the transient thermal behavior in the beginning of power-on transient period; while, the convective heat dissipation finally becomes the solely dominating term at the end of power-on transient period. The transient/steady-state local and average Nusselt numbers increase with increasing Grs, H/Hc ratio or Re. As compared with the steady-state average Nusselt number for non-compact heat sink (Fin-Al/ Base-Al), the steady-state heat transfer enhancement for compact heat sinks (Fin-Al/Base-Al) is 185.74%. Furthermore, a new correlation of steady-state average Nusselt number in terms of relevant influencing parameters for confined compact PPF heat sinks in forced convection is proposed. As compared with two existing correlations of steady-state average Nusselt numbers for unconfined and confined non-compact PPF heat sinks, the heat transfer enhancements for the present confined compact PPF heat sinks of H/Hc = 0.47 are 423.29% and 219.93%, respectively.

Experimental Study of a Single Microchannel Flow Under Non-Uniform Heat Flux

2017 ◽  
Author(s):  
Ahmed Eltaweel ◽  
Abdulla Baobeid ◽  
Ibrahim Hassan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Dissipation ◽  
Hot Spot ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Uniform Heat Flux ◽  
Maximum Heat ◽  
Uniform Heat ◽  
Microchannel Heat Sinks

Non-uniform heat fluxes are commonly observed in thermo-electronic devices that require distinct thermal management strategies for effective heat dissipation and robust performance. The limited research available on non-uniform heat fluxes focus mostly on microchannel heat sinks while the fundamental component, i.e. a single microchannel, has received restricted attention. In this work, an experimental setup for the analysis of variable axial heat flux is used to study the heat transfer in a single microchannel with fully developed flow under the effect of different heat flux profiles. Initially a hot spot at different locations, with a uniform background heat flux, is studied at different Reynolds numbers while varying the maximum heat fluxes in order to compute the heat transfer in relation to its dependent variables. Measurements of temperature, pressure, and flow rates at a different locations and magnitudes of hot spot heat fluxes are presented, followed by a detailed analysis of heat transfer characteristics of a single microchannel under non-uniform heating. Results showed that upstream hotspots have lower tube temperatures compared to downstream ones with equal amounts of heat fluxes. This finding can be of importance in enhancing microchannel heat sinks effectiveness in reducing maximum wall temperatures for the same amount of heat released, by redistributing spatially fluxes in a descending profile.

Optimization of Heat Transfer Rate in the Rectangular Microchannel of Different Aspect Ratios With Constant Cross Sectional Area

2008 ◽  
Author(s):  
F. Kowsary ◽  
N. Noroozi ◽  
M. Rezaei Barmi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Reynolds Numbers ◽  
Cross Sectional Area ◽  
Heat Sinks ◽  
Sectional Area ◽  
Cross Sectional ◽  
Aspect Ratios

The increased power dissipation and reduced dimensions of microelectronics devices have emphasized the need for highly efficient compact cooling technologies. Microchannel heat sinks are of particular interest due to the very high rates of heat transfer they enable in conjunction with greatly reduced heat sink length scales and coolant mass flow rate. Therefore, in the present work, optimization of laminar convective heat transfer in the microchannel heat sinks is investigated for uniform heat flux and different cross sectional areas of different aspect ratios. Three-dimensional numerical simulations of general form of energy equation were performed to predict Nusselt number in the laminar flow regime. Using these results, an optimum forced convective heat transfer coefficient was computed for several cross sectional areas and Reynolds numbers, utilizing the univariable search method. Different aspect ratios have different influences on Nusselt number in thermally developing and fully developed regions for different cross sectional areas and Reynolds numbers. There exists an optimum Nusselt number for each Reynolds number and cross sectional area by varying aspect ratio. Thus, optimized state is computed and related graphs are presented.

Improved Heat Dissipation Capability on Electronic Motor Control Devices

2005 ◽  
Author(s):  
Wei Tong
Keyword(s):  
Heat Transfer ◽  
Motor Control ◽  
Heat Dissipation ◽  
Electronic Devices ◽  
Heat Sinks ◽  
Vortex Generators ◽  
Maximum Temperature ◽  
Complex Heat Transfer ◽  
Pin Fins ◽  
Control Devices

Heat sinks have been widely used in electronic industry to maintain the operation temperatures of electronic devices lower than their allowable values and thus are often critical to the device performance and life. However, it is difficult to design heat sinks to satisfy all design specifications optimally under complex heat transfer phenomena. The present work discloses a new design of heat sinks to improve heat dissipation capability for electric motor control devices. The heat sink contains a plurality of raindrop-shaped pin fins, acting as vortex generators to increase the rate of heat transfer and in turn, to increase the cooling efficiency of the heat sinks. Numerical results have shown that with the new designed heat sinks, the maximum temperature can reduce about 30% over the conventional heat sinks.

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