Modeling and Testing of an Integrated Evaporator-Condenser Device for CPU Cooling

2008 ◽  
Author(s):  
Mark Aaron Chan ◽  
Christopher R. Yap ◽  
Kim Choon Ng
Keyword(s):  
Thermal Resistance ◽  
Heat Dissipation ◽  
Air Flow ◽  
Thermal Design ◽  
Heat Sinks ◽  
Working Fluid ◽  
Air Cooling ◽  
Full Potential ◽  
Fully Integrated ◽  
Current Design

CPUs with high clock rates can dramatically increase heat dissipation within their encapsulation due to internal Joule heat from the transistors. The conventionally used air cooling systems for CPUs, such as the aluminum or copper extruded heat sink types, have severe heat transfer “bottlenecks” due to high thermal resistances and they easily reach their thermal design limits (TDL). Alternative cooling devices such as heat pipes and liquid cooling tends to have externally attached radiator/condenser and/or pump and such designs are cumbersome. This paper describes the modeling, design, and testing of a compact (about the size of the Intel stock cooler, diameter: 96mm, height: 50mm), fully integrated, orientation-free, evaporator-condenser device for CPU cooling, with excellent attributes of low thermal resistance from phase change phenomena and minimal vapor pressure drop. The prototype fabricated is designed to reject 200 W (twice the capacity of conventional heat sinks). It is made of copper and uses distilled water as the working fluid. The working fluid boils inside a porous structure clad evaporator and is transported radially to nearby air-cooled condenser sections; this unique arrangement minimizes space while providing adequate area for air convection. Testing was done by subjecting it to varying heat loads and air flow rates. A best performance of 0.206 K/W of the device’s thermal resistance was achieved at a fan air flow rate of 34.5 CFM under 203 W of cooling load, and moreover, these results are in good agreement with the simulation. Further improvement of the current design could yield significantly better performance as the device has yet to reach its full potential, especially with regard to the design of its air-cooled curvilinear fins and boiling enhancement.

Thermal Behaviors of Passively-Cooled Hybrid Fin Heat Sinks for Lightweight and High Performance Thermal Management

2015 ◽  
Author(s):  
Nico Setiawan Effendi ◽  
Kyoung Joon Kim
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
High Performance ◽  
Heat Dissipation ◽  
Computational Study ◽  
Heat Sinks ◽  
Channel Diameter ◽  
Internal Channel ◽  
Study Results ◽  
Parametric Effects

A computational study is conducted to explore thermal performances of natural convection hybrid fin heat sinks (HF HSs). The proposed HF HSs are a hollow hybrid fin heat sink (HHF HS) and a solid hybrid fin heat sink (SHF HS). Parametric effects such as a fin spacing, an internal channel diameter, a heat dissipation on the performance of HF HSs are investigated by CFD analysis. Study results show that the thermal resistance of the HS increases while the mass-multiplied thermal resistance of the HS decreases associated with the increase of the channel diameter. The results also shows the thermal resistance of the SHF HS is 13% smaller, and the mass-multiplied thermal resistance of the HHF HS is 32% smaller compared with the pin fin heat sink (PF HS). These interesting results are mainly due to integrated effects of the mass-reduction, the surface area enhancement, and the heat pumping via the internal channel. Such better performances of HF HSs show the feasibility of alternatives to the conventional PF HS especially for passive cooling of LED lighting modules.

Design of Optimum Plate-Fin Natural Convective Heat Sinks

2003 ◽  
Vol 125 (2) ◽  
pp. 208-216 ◽  
Author(s):  
Avram Bar-Cohen ◽  
Madhusudan Iyengar ◽  
Allan D. Kraus
Keyword(s):  
Nusselt Number ◽  
Specific Heat ◽  
Rectangular Plate ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Thermal Design ◽  
Heat Sinks ◽  
And Performance ◽  
Nusselt Number Correlation ◽  
The Impact

The effort described herein extends the use of least-material single rectangular plate-fin analysis to multiple fin arrays, using a composite Nusselt number correlation. The optimally spaced least-material array was also found to be the globally best thermal design. Comparisons of the thermal capability of these optimum arrays, on the basis of total heat dissipation, heat dissipation per unit mass, and space claim specific heat dissipation, are provided for several potential heat sink materials. The impact of manufacturability constraints on the design and performance of these heat sinks is briefly discussed.

Si Vapor Chamber Integrated with Through Silicon Via for 3D Packaging

2013 ◽  
Vol 2013 (1) ◽  
pp. 000552-000557 ◽  
Author(s):  
Jun Taniguchi ◽  
Takeshi Shioga ◽  
Yoshihiro Mizuno
Keyword(s):  
Thermal Resistance ◽  
Heat Dissipation ◽  
Working Fluid ◽  
In Situ Observation ◽  
Vapor Chamber ◽  
Cover Glass ◽  
Through Silicon Via ◽  
Improvement Rate ◽  
Fine Pitch ◽  
3D Packaging

We demonstrate an etched silicon vapor chamber integrated with a through-silicon via (TSV) for 3D packaging. The Si vapor chamber chip enables low mismatch in the thermal expansion coefficient of a Si-LSI chip and provides a new heat dissipation path for 3D-LSI inter layer cooling. For the first prototype of the vapor chamber, an outside 33-mm × 33-mm chip consisting of a 25-mm × 25-mm area for the vapor chamber, a wick structure 30-μm high, and a vapor passage 100-μm high is developed. In-situ observation of the behavior of the working fluid through the cover glass and heat transfer enhancement is successfully demonstrated. The improvement rate of thermal resistance is 7.1% compared to a test chip without working fluid. Next, the fluid flow of a second vapor chamber prototype consisting of the first prototype integrated with a TSV structure using a Si pillar of 150-μm diameter is investigated. Thermal resistance and droplet observation conducted to evaluate the influence of the TSV. The operation of the vapor chamber is confirmed when a Si pillar is arranged to a coarse pitch of more than 500 μm. A droplet is generated and the vapor passage is partially obstructed. However, the droplet eventually degenerated and the performance of the vapor chamber is maintained. When the Si pillar is arranged to a fine pitch of 200 μm, the entire vapor passage is blocked during the liquid charging process, and no improvement is observed in the thermal resistance of the chip.

Enabling Thermal Management of High-Powered Server Processors Using Passive Thermosiphon Heat Sink

2019 ◽  
Author(s):  
Devdatta P. Kulkarni ◽  
Priyanka Tunuguntla ◽  
Guixiang Tan ◽  
Casey Carte
Keyword(s):  
Heat Pipe ◽  
High Power ◽  
Heat Sink ◽  
Capital Investment ◽  
Thermal Design ◽  
Heat Sinks ◽  
Air Cooling ◽  
Liquid Cooling ◽  
Two Phase ◽  
Pipe Heat

Abstract In recent years, rapid growth is seen in computer and server processors in terms of thermal design power (TDP) envelope. This is mainly due to increase in processor core count, increase in package thermal resistance, challenges in multi-chip integration and maintaining generational performance CAGR. At the same time, several other platform level components such as PCIe cards, graphics cards, SSDs and high power DIMMs are being added in the same chassis which increases the server level power density. To mitigate cooling challenges of high TDP processors, mainly two cooling technologies are deployed: Liquid cooling and advanced air cooling. To deploy liquid cooling technology for servers in data centers, huge initial capital investment is needed. Hence advanced air-cooling thermal solutions are being sought that can be used to cool higher TDP processors as well as high power non-CPU components using same server level airflow boundary conditions. Current air-cooling solutions like heat pipe heat sinks, vapor chamber heat sinks are limited by the heat transfer area, heat carrying capacity and would need significantly more area to cool higher TDP than they could handle. Passive two-phase thermosiphon (gravity dependent) heat sinks may provide intermediate level cooling between traditional air-cooled heat pipe heat sinks and liquid cooling with higher reliability, lower weight and lower cost of maintenance. This paper illustrates the experimental results of a 2U thermosiphon heat sink used in Intel reference 2U, 2 node system and compare thermal performance using traditional heat sinks solutions. The objective of this study was to showcase the increased cooling capability of the CPU by at least 20% over traditional heat sinks while maintaining cooling capability of high-power non-CPU components such as Intel’s DIMMs. This paper will also describe the methodology that will be used for DIMMs serviceability without removing CPU thermal solution, which is critical requirement from data center use perspective.

An Analytical Convergence Study of the Forced Air Cooling in Electronic Packaging

2016 ◽  
Vol 819 ◽  
pp. 34-41 ◽  
Author(s):  
K.A. Ong ◽  
Mohd Zulkifly Abdullah
Keyword(s):  
Thermal Resistance ◽  
Air Flow ◽  
Simulation Method ◽  
Input Power ◽  
Junction Temperature ◽  
Air Cooling ◽  
Element Analysis ◽  
Total Thermal Resistance ◽  
Minimum Number ◽  
Forced Air

A forced air thermal cooling model has been developed by using Ansys software, to study at each step of the input power, what will be the corresponding junction temperature? Few approaches were used to ensure the accuracy of the thermal simulation method, ranging from the minimum number of simulation iterations required in the finite element analysis, to the residuals target in terms of the momentum, continuity and energy equations, the objective is to ensure the simulations are converged and provide the reasonable results, which is also an indication of how the partial equations have successfully been solved with analytic method. The thermal resistance network in the model has also been established, mainly to understand the next level details in this thermal model by analyzing the correlation between the air flow and the thermal resistance at each junction, and also to understand the effect of the air flow with respect to the total thermal resistance. The thermal analytic model that built has proven to be healthy and it requires 200 iterations to achieve steady state with the reasonable temperature output, and there is no convergence issue in which the continuity, momentum and energy graphs showed the healthy trend, it achieved 10-7 for continuity, energy and momentum equations. it shows that when the air flow reduces the overall thermal resistance increases, in other word, reducing the air flow will increase the thermal resistance

scholarly journals Experimental Set up of Two Closed Loop Pulsating Heat Pipe (CLPHP) with Water base Fluids

2019 ◽  
Vol 8 (12S) ◽  
pp. 715-719
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Heat Dissipation ◽  
Heat Pipes ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Water Mixture ◽  
Working Fluids ◽  
Pure Fluids ◽  
Acetone Water

Heat pipes are deliberated to be effective heat dissipation devices compared to other types of heat sinks due to their high effective thermal conductivity. Because of the flexibility in the design and layout of heat pipe turns along the heat source, pulsating heat pipes have gained popularity. One of the parameters that have the mainimpact on the presentation of CLPHP is the thermo physical properties of the working fluid. The properties of the working fluid affect the temperature difference between the evaporator and the condenser which in turn affect the thermal resistance of the CLPHP. In this connection, the influence of different working fluids is experimentally investigated on a two loop CLPHP, varying the evaporator heat flux. Pure fluids, viz., water, acetone, benzene and binary mixture, viz., Acetone-water and Benzene-water are utilized on working fluids. The heat input considered at the evaporator is 32W, 48W and 60W. The filling ratio is kept as 50 %. The results show that among the working fluids considered for the study, acetone exhibits least thermal resistance among the pure fluids at all heat fluxes considered in the analysis, while Acetone-water mixture has exhibited least thermal resistance among the water based mixtures.

scholarly journals A Comparative Study of Silicon Carbide Merged PiN Schottky Diodes with Electrical-Thermal Coupled Considerations

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2669
Author(s):  
Jiupeng Wu ◽  
Na Ren ◽  
Qing Guo ◽  
Kuang Sheng
Keyword(s):  
Silicon Carbide ◽  
Comparative Study ◽  
Thermal Resistance ◽  
Heat Dissipation ◽  
Schottky Diodes ◽  
Layout Design ◽  
Thermal Design ◽  
Junction Temperature ◽  
Bipolar Conduction ◽  
Surge Current

A comparative study of surge current reliability of 1200 V/5 A 4H-SiC (silicon carbide) MPS (Merged PiN Schottky) diodes with different technologies is presented. The influences of device designs in terms of electrical and thermal aspects on the forward conduction performance and surge current capability were studied. Device forward characteristics were simulated and measured. Standard single-pulse surge current tests and thermal impedance measurements were carried to show their surge capability and thermal design differences. An advanced thermal RC (thermal resistance-capacitance) model, with the consideration of current distribution non-uniformity effects, is proposed to accurately calculate the device junction temperature during surge events. It was found that a thinner substrate and a hexagonal layout design are beneficial to the improvement of the bipolar conduction performance in high current mode, as well as the surge current capability. The thinner substrate design also has advantages on thermal aspects, as it presents the lowest thermal resistance. The calculated failure temperature during the surge tests is consistent with the aluminum melting phenomenon, which is regarded as the failure mechanism. It was demonstrated that, for a SiC MPS diode, higher bipolar conduction performance is conducive to restraining the joule heat, and a lower thermal resistance design is able to accelerate the heat dissipation and limit the junction temperature during surge events. In this way, the MPS diode using a thinner substrate and advanced layout design technology is able to achieve 60% higher surge current density capability compared to the other technologies.

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.

Experimentally Validated Numerical Model of a Fully-Enclosed Hybrid Cooled Server Cabinet

2015 ◽  
Author(s):  
Kourosh Nemati ◽  
Husam A. Alissa ◽  
Bruce T. Murray ◽  
Bahgat Sammakia ◽  
Mark Seymour
Keyword(s):  
Data Centers ◽  
Heat Dissipation ◽  
Cooling System ◽  
Air Flow ◽  
Sensitivity Study ◽  
Average Error ◽  
Air Cooling ◽  
Cfd Validation ◽  
Air Cooling System ◽  
Good Agreement

Because of the rapid growth in the number of data centers combined with the high density heat dissipation in the IT and telecommunications equipment, energy efficient thermal management of data centers has become a key research focus in the electronics packaging community. Traditional legacy data centers still rely largely on chilled air flow delivered to the IT equipment racks through perforated tiles from the raised floor plenum. When there is large variation in the amount of heat dissipated by the racks in a given aisle, the standard air cooling approach requires over-provisioning. Localized hybrid air-water cooling is one approach to more effectively control the cooling when there is wide variation in the amount of dissipation in neighboring racks. In a closed hybrid air-water cooled server cabinet, the generated heat is removed by a self-contained system that does not interact with the room level air cooling system. In this study, a comprehensive procedure for CFD validation in a close coupled hybrid cooled enclosed cabinet is described. The commercial enclosure has been characterized experimentally in an earlier study, where the effectiveness values were applied as boundary conditions to the compact heat exchanger model. Here, the previously obtained experimental data are used to validate the results from computational modeling. Two cases with different air flow rates are compared. Very good agreement is achieved, with the maximum overall average error less than 4%. Due to relatively high pressure inside the cabinet, it is possible that air leakage from the cabinet may be responsible for the discrepancy between the model and experimental results. A sensitivity study was applied to the validated model to investigate the effect leakage had on the cabinet’s performance.

Thermal Design and Performance of Two-Phase Meso-Scale Heat Exchangers

2005 ◽  
Author(s):  
Robert Hannemann ◽  
Joseph Marsala ◽  
Martin Pitasi
Keyword(s):  
Heat Exchangers ◽  
Thermal Design ◽  
Low Flow ◽  
Commercial Application ◽  
Working Fluid ◽  
Small Scale ◽  
Air Cooling ◽  
Cold Plate ◽  
Two Phase ◽  
Meso Scale

Dramatically increased power dissipation in electronic and electro-optic devices has prompted the development of advanced thermal management approaches to replace conventional air cooling using extended surfaces. One such approach is Pumped Liquid Multiphase Cooling (PLMC), in which a refrigerant is evaporated in a cold plate in contact with the devices to be cooled. Heat is then rejected in an air or water-cooled condenser and the working fluid is returned to the cold plate. Reliable, highly efficient, small-scale components are required for the commercial application of this technology. This paper presents experimental results for two-phase meso-scale heat exchangers (cold plates) for use in electronics cooling. The configurations studied include single and multi-pass designs using R134a as the working fluid. With relatively low flow rates, low effective thermal resistances were achieved at power levels as high as 376 W. The results confirm the efficacy of PLMC technology for cooling the most powerful integrated circuits planned for the next decade.

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