Advanced Technology for Server Cooling

2005 ◽  
Author(s):  
Ralph L. Webb ◽  
Hasan Nasir
Keyword(s):  
Cooling Water ◽  
Heat Removal ◽  
Heat Sinks ◽  
Advanced Technology ◽  
Air Cooling ◽  
Performance Predictions ◽  
Micro Channels ◽  
Cooling Technology ◽  
Performance Results ◽  
Heat Loads

This paper reports work on advanced cooling technology for servers. The air cooling load on the rack may be enhanced using highly compact Copper/Brass “flat tube” water-cooled heat exchangers that are integrated into the rack frame. The cooling water is supplied by a water chiller. Analysis shows that it is possible to provide cooling (UA/Afr) in the range of 670–1000 W/m2-K, where the m2 is the core frontal area. Also analyzed and compared are advanced technology CPU heat sinks — a thermo-syphon concept and a liquid micro-channel heat sink. The thermo-syphon may be used in a compact thermal-bus concept for heat removal from multiple CPUs. Used with boiling on an enhanced copper boiling surface in a thermo-syphon, heat loads in excess of 75 W/m2-K are possible. The heat removed at each CPU in the chassis is rejected to water flow in a compact water cooled condenser. Performance results of the thermo-syphon concept are predicted, obstacles associated with increasing performance are discussed, and possible solutions are proposed. Performance predictions were also made for water cooled: (1) Copper micro-channels as an attached external sink and (2) Silicon micro-channels integral to the silicon CPU die. It is shown that micro-channels integrated into the silicon die do not offer significant advantage over copper micro-channels.   This paper was also originally published as part of the Proceedings of the ASME 2005 Heat Transfer Summer Conference.

Imminent Needs in Future Development of Air Cooled Microprocessors Heat Sinks

2010 ◽  
Vol 2010 (1) ◽  
pp. 000434-000439
Author(s):  
V. Ganescu ◽  
A. Pascu
Keyword(s):  
Heat Dissipation ◽  
Heat Removal ◽  
Leading Edge ◽  
Ambient Air ◽  
Heat Sinks ◽  
System Level ◽  
Air Cooling ◽  
Cfd Simulations ◽  
Constant Heat ◽  
Laminar Convection

This study reiterates the fact that revolutionary heat sink geometries, materials and overall exponentially higher performing alternatives are continuously and highly needed as applied to the air cooling of a typical computer system microprocessor. Attention was focused on forced convection regimes of operation and from a system level approach. Minor improvements in the performance of air cooled microprocessor heat sinks via typical small design improvements are discussed. Laminar convection and constant heat dissipation were looked at. The CFD simulations exemplified were completed for several power levels and ambient air characterized by a Pr = 0.71. The numerical results presented coincided in large with the experimentally derived documented data. In conclusion, the authors stress the fact that leading-edge alternatives in air-cooled heat removal of such applications are imperiously necessary.

Development of Heat Sinks for Air Cooling and Water Cooling Using Lotus-Type Porous Metals

2011 ◽  
Author(s):  
H. Chiba ◽  
T. Ogushi ◽  
H. Nakajima
Keyword(s):  
Heat Transfer ◽  
Porous Materials ◽  
Heat Sink ◽  
High Heat ◽  
Heat Sinks ◽  
Air Cooling ◽  
Water Cooling ◽  
Cooling Performance ◽  
High Heat Transfer ◽  
Micro Channels

In recent years, since heat dissipation rates and high frequency electronic devices have been increasing, a heat sink with high heat transfer performance is required to cool these devices. Heat sink utilizing micro-channels with several ten microns are expected to provide an excellent cooling performance because of their high heat transfer capacities due to small channel. Therefore, various porous materials such as cellular metals have been investigated for heat sink applications. However, heat sink using conventional porous materials has a high pressure drop because the cooling fluid flow through the pores is complex. Among the described porous materials, a lotus-type porous metal with straight pores is preferable for heat sinks due to the small pressured drop. In present work, cooling performance of the lotus copper heat sink for air cooling and water cooling is introduced. The experimental data for air cooling show 13.2 times higher than that for the conventional groove fins. And, the data for the water cooling show 1.7 times higher than that for the micro-channels. It is concluded that lotus copper heat sink is the most prospective candidate for high power electronics devices.

Fluid Flow in Microchannel Heat Sinks for various Flow Configurations in Tapered Manifold Arrangements

2019 ◽  
Vol 11 (3) ◽  
Author(s):  
Harpreet Singh ◽  
Sushant Samir ◽  
Perminderjit Singh
Keyword(s):  
Heat Removal ◽  
Heat Sinks ◽  
Working Fluid ◽  
Thermal Engineering ◽  
Flow Configuration ◽  
Micro Channels ◽  
Type Flow ◽  
Flow Configurations ◽  
P Type ◽  
Better Than

Micro channels face several types of thermal engineering challenges from different levels of heat generation. The reduction of the available surface area for sufficient heat removal becomes mandatory. If the working temperature of the component becomes very high in the absence of the sufficient heat removal, leads to a critical failure. So working fluid and flow configuration plays an important role. In the present work, CFD analysis of flow on U, P, S type micro channels heat sinks with tapered manifold arrangements is presented. At Reynolds number 705-1410 and with different heat inputs, the P type flow configuration is better than U-type and then followed by S-type flow configuration.

Optimized Ionic Wind-Based Cooling Microfabricated Devices for Improving a Measured Coefficient of Performance

2011 ◽  
Author(s):  
Andojo Ongkodjojo ◽  
Alexis R. Abramson ◽  
Norman C. Tien
Keyword(s):  
Three Dimensional ◽  
Heat Removal ◽  
Temperature Data ◽  
Coefficient Of Performance ◽  
Comsol Multiphysics ◽  
Air Cooling ◽  
Ionic Wind ◽  
Cooling Systems ◽  
Removal Capacity ◽  
Cooling Technology

This work is a continuation of previous investigations aimed at developing an innovative microfabricated air-cooling technology that employs an electrohydrodynamic corona discharge (i.e. ionic wind pump) [1], [2]. This technology enables the miniaturization of cooling systems for next generation electronics. Our single ionic wind pump element consists of two parallel collecting electrodes between which a single emitting tip is positioned. Two-dimensional (2-D) and three-dimensional (3-D) simulations using COMSOL Multiphysics™ are additionally employed to predict the temperature distribution, the flow field, and the heat removal capacity of the device in operation. One such model utilizes a small gap between collector and emitter electrodes and demonstrates an improvement in the COP (coefficient of performance) of a single device. Comparisons are made with experimental temperature data on an actual device. The purpose of this work is therefore to optimize the performance of a single microfabricated ionic wind pump to enable the development of an array of these elements for use in larger-scale heat transfer applications.

High Efficiency Heat Sinks from Polycrystalline Diamond Grown by CVD Method

2006 ◽  
Vol 956 ◽  
Author(s):  
Oleg A. Voronov ◽  
Gary S. Tompa ◽  
Veronika Veress
Keyword(s):  
Heat Transfer ◽  
Semiconductor Lasers ◽  
High Efficiency ◽  
Heat Removal ◽  
High Heat ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Measuring System ◽  
High Heat Transfer ◽  
Micro Channels

ABSTRACTWhile absolute power levels in microelectronic devices are relatively modest (a few tens to a few hundred watts), heat fluxes can be significant (through 50 W/cm2 in current electronic chips and up to 2000 W/cm2 in semiconductor lasers). Diamond heat sinks enable heat transfer rates well above what is possible with standard thermal management devices. We have fabricated heat sinks using diamond, which has the highest temperature thermal conductivity of any known material. Polycrystalline diamonds manufactured by chemical vapor deposition (CVD) are machined by laser and combined with metallic or ceramic tiles. Cooling by fluid flow through micro-channels enhances heat removal. These unique attributes make diamond based heat sinks prime contenders for the next generation of high heat load sinks. Such devices could be utilized for efficient cooling in a variety of applications requiring high heat transfer capability, including semiconductor lasers, microprocessors, multi-chip modules in computers, laser-diode arrays, radar systems, and high-flux optics, among other applications. This paper will review test designs, heat flux measuring system, and measured heat removal values.

Design, Modeling, and Optimization for Highly Efficient Ionic Wind-Based Cooling Microfabricated Devices

2010 ◽  
Author(s):  
Andojo Ongkodjojo ◽  
Alexis R. Abramson ◽  
Norman C. Tien
Keyword(s):  
Three Dimensional ◽  
Heat Removal ◽  
Power Input ◽  
Air Cooling ◽  
Ionic Wind ◽  
Electronic Components ◽  
Dimensional Array ◽  
Overall Heat Transfer Coefficient ◽  
Cooling Effects ◽  
Cooling Technology

The purpose of this work is to re-design, model and optimize a single microfabricated ionic wind pump device [1]. The device could then be employed in a three-dimensional array for use in larger-scale microchip cooling and enhanced thermal spreading applications. The innovative microfabricated air-cooling technology employs an electrohydrodynamic corona discharge (i.e. ionic wind pump) for efficient heat removal from electronic components. Our single ionic wind pump element consists of two parallel collecting electrodes between which a single emitting tip is positioned. The collector electrodes are patterned with a grid structure, which enhances the overall heat transfer coefficient and facilitates a batch and IC compatible process. Various design configurations are explored and modeled computationally to investigate their influence on the cooling phenomenon. In particular, COMSOL Multiphysics™ is employed to computationally explore the effects of collector-emitter configuration on the electrohydrodynamic phenomenon, the flow field and resulting cooling effects. Using both computational and experimental results, we estimate that a two-dimensional array of microfabricated ionic wind pumps covering approximately 2″ square should be able to dissipate greater than 2 W of heat, using about 1/5 the power input as a conventional fan.

Experimental and Analytical Investigation of Compact Liquid Cooled Heat Sinks

2004 ◽  
Author(s):  
M. Zugic ◽  
J. R. Culham ◽  
P. Teertstra ◽  
Y. Muzychka ◽  
K. Horne ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Tests ◽  
Reynolds Numbers ◽  
High Heat ◽  
Analytical Investigation ◽  
Boundary Resistance ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Air Cooling ◽  
Design Tools

Compact, liquid cooled heat sinks are used in applications where high heat fluxes and boundary resistance preclude the use of more traditional air cooling techniques. Four different liquid cooled heat sink designs, whose core geometry is formed by overlapped ribbed plates, are examined. The objective of this analysis is to develop models that can be used as design tools for the prediction of overall heat transfer and pressure drop of heat sinks. Models are validated for Reynolds numbers between 300 and 5000 using experimental tests. The agreement between the experiments and the models ranges from 2.35% to 15.3% RMS.

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2003 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase ◽  
Micro Channels

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406 × 2.032 mm cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal that the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Annual flow is identified as the dominant flow pattern for conditions relevant to two-phase micro-channel heat sinks, and forms the basis for development of a theoretical model for both pressure drop and heat transfer in micro-channels. Features unique to two-phase micro-channel flow, such as laminar liquid and gas flows, smooth liquid-gas interface, and strong entrainment and deposition effects are incorporated into the model. The model shows good agreement with experimental data for water-cooled heat sinks.

Design of Complex Structured Monolithic Heat Sinks for Enhanced Air Cooling

2012 ◽  
Vol 2 (2) ◽  
pp. 266-277 ◽  
Author(s):  
Shankar Krishnan ◽  
Domhnaill Hernon ◽  
Marc Hodes ◽  
John Mullins ◽  
Alan M. Lyons
Keyword(s):  
Heat Sinks ◽  
Air Cooling
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