Thermal and Flow Characteristics in a Concentric Annular Heat Pipe Heat Sink

A concentric annular heat pipe heat sink (AHPHS) was proposed and fabricated to investigate its thermal behavior. The present AHPHS consists of two concentric pipes of different diameters, which create vacuumed annular vapor space. The main advantage of the AHPHS as a heat sink is that it can largely increase the heat transfer area for cooling compared to conventional heat pipes. In the current AHPHS, condensation takes place along the whole annular space from the certain heating area as the evaporator section. Therefore, the whole inner space of the AHPHS except the heating area can be considered the condenser. In the present study, AHPHSs of different diameters were fabricated and studied experimentally. Basic studies were carried out with a 50 mm-long stainless steel AHPHS with diameter ratios of 1.1 and 1.3 and the same inner tube diameter of 76 mm. Several experimental parameters such as volume fractions of 10–70%, different air flow velocity, flow configurations, and 10–50 W heat inputs were investigated to find their effects on the thermal performance of an AHPHS. Experimental results show that a 10% filling ratio was found to be the optimum charged amount in terms of temperature profile with a low heater surface temperature and water as the working fluid. For the methanol, a 40% filling ratio shows better temperature behavior. Internal working behavior shows not only circular motion but also 3-D flow characteristics moving in axial and circular directions simultaneously.

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Experimental Study on Applied Thin Vapor Chamber and Embedded Heat Pipe Heat Sinks

ASME 2009 InterPACK Conference, Volume 2 ◽

10.1115/interpack2009-89191 ◽

2009 ◽

Author(s):

Garrett A. Glover ◽

Yongguo Chen ◽

Annie Luo ◽

Herman Chu

Keyword(s):

Heat Pipe ◽

Heat Sink ◽

High Performance ◽

Structural Integrity ◽

Heat Pipes ◽

Electronic Cooling ◽

Working Fluid ◽

Vapor Chamber ◽

Trade Offs ◽

Pipe Heat

The current work is a survey of applied applications of passive 2-phase technologies, such as heat pipe and vapor chamber, in heat sink designs with thin base for electronic cooling. The latest improvements of the technologies and manufacturing processes allow achievable heat sink base thickness of 3 mm as compared to around 5 mm previously. The key technical challenge has been on maintaining structural integrity for adequate hollow space for the working fluid vapor in order to retain high performance while reducing the thickness of the overall vapor chamber or flattened heat pipe. Several designs of thin vapor chamber base heat sink and embedded heat pipe heat sink from different vendors are presented for a moderate power density application of a 60 W, 13.2 mm square heat source. Numerous works have been published by both academia and commercial applications in studying the fundamental science of passive 2-phase flow technologies; their performance has been compared to solid materials, like aluminum and copper. These works have established the merits of using heat pipes and vapor chambers in electronic cooling. The intent of this paper is to provide a methodical approach to help to accelerate the process in evaluating the arrays of different commercial designs of these devices in our product design cycle. In this paper, the trade-offs between the different types of technologies are discussed for parameters such as performance advantages, physical attributes, and some cost considerations. This is a bake-off evaluation of the complete heat sink solutions from the various vendors and not a fundamental research of vapor chambers and heat pipes — for that, it is best left to the vendors and universities.

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An experimental investigation on a novel high-performance integrated heat pipe–heat sink for high-flux chip cooling

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2007.05.010 ◽

2008 ◽

Vol 28 (5-6) ◽

pp. 433-439 ◽

Cited By ~ 24

Author(s):

X.L. Xie ◽

Y.L. He ◽

W.Q. Tao ◽

H.W. Yang

Keyword(s):

Experimental Investigation ◽

Heat Pipe ◽

Heat Sink ◽

High Performance ◽

High Flux ◽

Chip Cooling ◽

Pipe Heat

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Experimental Investigation of Integrated Heat Pipe Heat Sink for Multi-chip LED Module in Natural Convection

Chinese Journal of Luminescence ◽

10.3788/fgxb20143511.1394 ◽

2014 ◽

Vol 35 (11) ◽

pp. 1394-1400

Author(s):

周驰 ZHOU Chi ◽

左敦稳 ZUO Dun-wen ◽

孙玉利 SUN Yu-li

Keyword(s):

Experimental Investigation ◽

Natural Convection ◽

Heat Pipe ◽

Heat Sink ◽

Pipe Heat

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Integration of a Pulsating Heat Pipe in a Flat Plate Heat Sink

ASME 2014 12th International Conference on Nanochannels, Microchannels and Minichannels ◽

10.1115/icnmm2014-21233 ◽

2014 ◽

Author(s):

Mitchell P. Hoesing ◽

Gregory J. Michna

Keyword(s):

Thermal Resistance ◽

Flat Plate ◽

Heat Pipe ◽

Heat Sink ◽

New Technologies ◽

Operating Conditions ◽

Working Fluid ◽

High Heat Flux ◽

Pulsating Heat Pipe ◽

Plate Heat

The ongoing development of faster and smaller electronic components has led to a need for new technologies to effectively dissipate waste thermal energy. The pulsating heat pipe (PHP) shows potential to meet this need, due to its high heat flux capacity, simplicity, and low cost. A 20-turn flat plate PHP was integrated into an aluminum flat plate heat sink with a simulated electronic load. The PHP heat sink used water as the working fluid and had 20 parallel channels with dimensions 2 mm × 2 mm × 119 mm. Experiments were run under various operating conditions, and thermal resistance of the PHP was calculated. The performance enhancement provided by the PHP was assessed by comparing the thermal resistance of the heat sink with no working fluid to that of it charged with water. Uncharged, the PHP was found to have a resistance of 1.97 K/W. Charged to a fill ratio of approximately 75% and oriented vertically, the PHP achieved a resistance of .49 K/W and .53 K/W when the condenser temperature was set to 20°C and 30°C, respectively. When the PHP was tilted to 45° above horizontal the PHP had a resistance of .76 K/W and .59 K/W when the condenser was set 20°C and 30°C, respectively. The PHP greatly improves the heat transfer properties of the heat sink compared to the aluminum plate alone. Additional considerations regarding flat plate PHP design are also presented.

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Metallic Mesh as Capillary Structure Applied in Heat Pipe Heat Exchanger for Heat Recovery

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1082.309 ◽

2014 ◽

Vol 1082 ◽

pp. 309-314 ◽

Cited By ~ 3

Author(s):

Diogo L.F. Santos ◽

Larissa S. Marquardt ◽

Paulo H.D. Santos ◽

Thiago Antonini Alves

Keyword(s):

Stainless Steel ◽

Heat Exchanger ◽

Heat Pipe ◽

Heat Pipes ◽

Working Fluid ◽

Capillary Structure ◽

Porous Wick ◽

Metallic Mesh ◽

Heat Loads ◽

Pipe Heat

This work presents a theoretical and experimental analysis of a heat exchanger assisted by five heat pipes made of copper with a metallic mesh 100 of stainless steel which was used as capillary structure. All heat pipes used water as the working fluid and were designed based on the capillary limit model. The heat pipes were developed and tested under heat loads varying from 20 to 50 W before application into the heat exchanger. The theoretical and experimental results were compared and all heat pipes worked satisfactorily. Thereafter, it is presented the development of heat pipe heat exchanger which was tested under heat loads varying from 100 to 250 W. The highest temperature measured on the external surface of the heat pipes was 90 oC and the heat exchanger thermal efficiency varied from 74 to 80%. It is showed that the use of a stainless steel mesh as a porous wick was proved to work successfully in heat pipes.

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Experimental Investigation of Thermal Conduction Performance on Silicon-Based Micro Flat Heat Pipe

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.645-646.1032 ◽

2015 ◽

Vol 645-646 ◽

pp. 1032-1037

Author(s):

Cong Ming Li ◽

Yi Luo ◽

Chuan Peng Zhou ◽

Liang Liang Zou ◽

Xiao Dong Wang ◽

...

Keyword(s):

Thermal Conductivity ◽

Heat Pipe ◽

Effective Thermal Conductivity ◽

Thermal Performance ◽

Axial Direction ◽

Filling Ratio ◽

Parallel Structure ◽

Working Fluid ◽

Vacuum Degree ◽

Structure Dimension

There are several factors that affect heat transfer of heat pipe, for example, structure dimension, filling ratio and vacuum degree of charging. This paper studied the thermal conductivity of micro flat heat pipes (MFHPs) with different structure dimension and with different filling ratio, when the charging vacuum degree of MFHP was decided. When electric power was 2W or 4W, MFHPs with parallel grooves and nonparallel grooves, charged by working fluid with different filling ratio, were carried out. And the filling ratio is 30%, 40% and 50%, respectively. The better thermal performance of MFHP can be evaluated by lower thermal resistance and higher effective thermal conductivity. The experiment results show that MFHP has the highest effective thermal conductivity when the filling ratio is 40%; and the thermal performance of MFHP with nonparallel structure in axial direction is better than that of MFHP with parallel structure.

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

ASME 2019 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems ◽

10.1115/ipack2019-6530 ◽

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.

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Experimental Investigation of the Thermal Performance of a Wickless Heat Pipe Operating with Different Fluids: Water, Ethanol, and SES36. Analysis of Influences of Instability Processes at Working Operation Parameters

Energies ◽

10.3390/en12010080 ◽

2018 ◽

Vol 12 (1) ◽

pp. 80 ◽

Cited By ~ 3

Author(s):

Rafal Andrzejczyk

Keyword(s):

Heat Pipe ◽

Input Power ◽

Liquid Pool ◽

Filling Ratio ◽

Working Fluid ◽

Operating Pressure ◽

Two Phase ◽

Condenser Section ◽

Transfer Resistance ◽

Working Fluids

In this study, the influences of different parameters on performance of a wickless heat pipe have been presented. Experiments have been carried out for an input power range from 50 W to 300 W, constant cooling water mass flow rate of 0.01 kg/s, and constant temperature at the inlet to condenser of 10 °C. Three working fluids have been tested: water, ethanol, and SES36 (1,1,1,3,3-Pentafluorobutane) with different filling ratios (0.32, 0.51, 1.0). The wall temperature in different locations (evaporation section, adiabatic section, and condenser section), as well as operating pressure inside two phase closed thermosyphon have been monitored. The wickless heat pipe was made of 0.01 m diameter copper tube, which consists of an evaporator, adiabatic, and condensation sections with the same length (0.4 m). For all working fluids, a dynamic start-up effect caused by heat conduction towards the liquid pool was observed. Only the thermosyphon filled with SES36 was observed to have operation limitation caused by achieving the boiling limit in TPCTs (two-phase closed thermosyphons). The geyser boiling effect has been observed only for thermosyphon filled with ethanol and for a high filling ratio. The performance of the thermosyphon determined the form of the heat transfer resistance of the TPCT and it was found to be dependent of input power and filling ratio, as well as the type of working fluid and AR (aspect ratio). Comparison with other authors would seem to indicate that lower AR results in higher resistance; however, the ratio of condenser section length to inside diameter of pipe is also a very important parameter. Generally, performance of the presented thermosyphon is comparable to other constructions.

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