Hot Spot Mitigating With Oblique Finned Microchannel Heat Sink

2010 ◽  
Author(s):  
Yong-Jiun Lee ◽  
Poh-Seng Lee ◽  
Siaw-Kiang Chou
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Sink ◽  
Hot Spot ◽  
Local Heat Transfer ◽  
Local Heat ◽  
High Heat ◽  
Secondary Flows ◽  
High Heat Flux ◽  
Microchannel Heat Sink

Sectional oblique fins are employed in contrast to continuous fins in order to modulate the flow in microchannel heat sink. The breakage of continuous fin into oblique sections leads to re-initialization of boundary layers and generation of secondary flows which significantly enhance the cooling performance of the heat sink. In addition, oblique finned microchannel heat sink has the flexibility to tailor local heat transfer performance by varying its oblique fin pitch. Clusters of oblique fins at higher density can be created in order to promote greater degree of boundary layers redevelopment and secondary flows generation to provide more effective cooling at the high heat flux region. Thus the varying of oblique fin pitch can be exploited for hot spots mitigation. Simulation studies of silicon chip with hot spot shows more than 100% increment in local heat transfer coefficient at the high heat flux region for the variable pitch oblique finned microchannel compared with the conventional microchannel heat sink. Both the maximum temperature and its temperature gradient are reduced by 12.4°C as a result. Interestingly, there is only little or negligible pressure drop penalty associated with this novel heat transfer enhancement scheme in contrast to conventional enhancement techniques.

Investigation of On-Chip Hot Spot Cooling Using Microchannel Heat Sink

2013 ◽  
Vol 455 ◽  
pp. 466-469
Author(s):  
Yun Chuan Wu ◽  
Shang Long Xu ◽  
Chao Wang
Keyword(s):  
Heat Flux ◽  
Heat Sink ◽  
Hot Spots ◽  
Hot Spot ◽  
High Heat ◽  
High Heat Flux ◽  
Microchannel Heat Sink ◽  
Three Dimensional Model ◽  
Spot Cooling ◽  
On Chip

With the increase of performance demands, the nonuniformity of on-chip power dissipation becomes greater, causing localized high heat flux hot spots that can degrade the processor performance and reliability. In this paper, a three-dimensional model of the copper microchannel heat sink, with hot spot heating and background heating on the back, was developed and used for numerical simulation to predict the hot spot cooling performance. The hot spot is cooled by localized cross channels. The pressure drop, thermal resistance and effects of hot spot heat flux and fluid flow velocity on the cooling of on-chip hot spots, are investigated in detail.

Enhanced Microchannel Heat Sinks Using Oblique Fins

2009 ◽  
Author(s):  
Yong-Jiun Lee ◽  
Poh-Seng Lee ◽  
Siaw-Kiang Chou
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Leading Edge ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Secondary Flows ◽  
Heat Sinks ◽  
Microchannel Heat Sink ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

Oblique fins created in a microchannel heat sink can serve to modulate the flow, resulting in local and global heat transfer enhancement. Numerical analysis of laminar flow and heat transfer in such modified microchannel heat sink showed that significant enhancement of heat transfer can be achieved with negligible pressure drop penalty. The breakage of continuous fin into oblique sections causes the thermal boundary layers to be re-initialized at the leading edge of each oblique fin and reduces the boundary-layer thickness. This regeneration of the entrance effect causes the flow to be always in a developing state thus resulting in better heat transfer. In addition, the presence of the smaller oblique channels causes a fraction of the flow to branch into the adjacent main channels. The secondary flows thus created improve fluid mixing which serves to further enhance the heat transfer. The combination of the entrance and secondary flow effect results in a much improved heat transfer performance (the average and local heat transfer coefficients are enhanced by as much as 80%). Both the maximum wall temperature and temperature gradient are substantially decreased as a result.

Numerical Study of Turbulent Heat Transfer and Pressure Drop Characteristics in a Water-Cooled Minichannel Heat Sink

2006 ◽  
Vol 129 (3) ◽  
pp. 247-255 ◽  
Author(s):  
X. L. Xie ◽  
W. Q. Tao ◽  
Y. L. He
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Wall Thickness ◽  
Heat Sink ◽  
Channel Wall ◽  
High Heat ◽  
Coolant Fluid ◽  
High Heat Flux ◽  
It Industry

With the rapid development of the Information Technology (IT) industry, the heat flux in integrated circuit (IC) chips cooled by air has almost reached its limit at about 100W∕cm2. Some applications in high technology industries require heat fluxes well beyond such a limitation. Therefore, the search for a more efficient cooling technology becomes one of the bottleneck problems of the further development of the IT industry. The microchannel flow geometry offers a large surface area of heat transfer and a high convective heat transfer coefficient. However, it has been hard to implement because of its very high pressure head required to pump the coolant fluid through the channels. A normal channel size could not give high heat flux, although the pressure drop is very small. A minichannel can be used in a heat sink with quite a high heat flux and a mild pressure loss. A minichannel heat sink with bottom size of 20mm×20mm is analyzed numerically for the single-phase turbulent flow of water as a coolant through small hydraulic diameters. A constant heat flux boundary condition is assumed. The effect of channel dimensions, channel wall thickness, bottom thickness, and inlet velocity on the pressure drop, temperature difference, and maximum allowable heat flux are presented. The results indicate that a narrow and deep channel with thin bottom thickness and relatively thin channel wall thickness results in improved heat transfer performance with a relatively high but acceptable pressure drop. A nearly optimized structure of heat sink is found that can cool a chip with heat flux of 350W∕cm2 at a pumping power of 0.314W.

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