FSW manufacturing process of cold plates compared to brazing for data center liquid cooling

The continued demand for increasing compute performance results in an increasing system power and power density of many computers. The increased power requires more efficient cooling solutions than traditionally used air cooling. Therefore, liquid cooling, which has traditionally been used for large data center deployments, is becoming more mainstream. Liquid cooling can be used selectively to cool the high power components or the whole compute system. In this paper, the example of a fully liquid cooled server is used to describe different ingredients needed, together with the design challenges associated with them. The liquid cooling ingredients are cooling distribution unit (CDU), fluid, manifold, quick disconnects (QDs), and cold plates. Intel is driving an initiative to accelerate liquid cooling implementation and deployment by enabling the ingredients above. The functionality of these ingredients is discussed in this paper, while cold plates are discussed in detail.

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Thermodynamic Analysis of Full Liquid-Cooled Data Centers

Volume 1: Thermal Management ◽

10.1115/ipack2015-48439 ◽

2015 ◽

Cited By ~ 2

Author(s):

A. Bhalerao ◽

A. P. Wemhoff

Keyword(s):

Thermodynamic Analysis ◽

Data Center ◽

Thermodynamic Efficiency ◽

Second Law ◽

Heat Output ◽

Cold Plate ◽

Liquid Cooling ◽

Second Law Analysis ◽

Cold Plates ◽

The Individual

One way to model the thermodynamic efficiency of a data center is to perform a second-law analysis using exergy calculations of the individual components. The in-house data center modeling tool Villanova Thermodynamic Analysis of Systems (VTAS) was applied to determine the effect of direct liquid cooling with cold plates on data center efficiency. The effectiveness of the cold plate as a function of the heat output of the servers was also examined. VTAS was used to study a configuration of two rows with eight racks each. Each rack was assumed to have twelve servers, each producing 200 W of heat. In addition to the cold plates and servers, this configuration also included a computer room air handling (CRAH) unit, a chiller, and a cooling tower. Preliminary results show that data center second-law efficiency increases as the cold plate removes more heat than the CRAH unit. Specifically, when using cold plates to remove all of the heat from the servers, the overall data center exergy destruction was reduced by over 30% compared to a configuration with only a CRAH unit and between 12–18% compared to a configuration with hybrid liquid-air technologies, thus showing that configurations with direct liquid cooling are thermodynamically more favorable. Furthermore, the effectiveness of the cold plate increases as the heat output of each server increases, suggesting that cold plates are most effective when removing a greater amount of heat.

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Corrosion Study on Single-Phase Liquid Cooling Cold Plates with Inhibited Propylene Glycol/Water Coolant for Data Centers

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4051059 ◽

2021 ◽

pp. 1-13

Author(s):

David Shia ◽

Jin Yang ◽

Sean Sivapalan ◽

Rithi Soeung ◽

Christian Amoah-Kusi

Keyword(s):

Propylene Glycol ◽

Manufacturing Process ◽

Single Phase ◽

Data Centers ◽

Galvanic Corrosion ◽

Cold Plate ◽

Liquid Cooling ◽

Friction Stir ◽

Corrosion Risk ◽

Cold Plates

Abstract Single phase cold plate based liquid cooling attracts more and more attention to high-performance computing (HPC) and general computing data centers for thermal management of modern microprocessors due to liquid's inherent advantage of higher specific heat compared to air. Deionized (DI) water is usually used as coolant for liquid cooling in data centers. On the contrary, propylene glycol/water is recommended as coolant for one-phase cold plate liquid cooling in this study for following reasons. The inhibited propylene glycol-based fluids of 25+% vol. have the benefit of being biostatic and not requiring addition of biocides. They also offer freeze protection in the usage of data centers in cold climates. The cold plates made from copper is prone to oxide even under room temperature and the dissimilarity between brazing material and copper can also cause galvanic corrosion in the usage. In this paper, a study was carried out to investigate cold plate corrosion with inhibited propylene glycol/water using design of experiments (DOE) method. This study shows manufacturing process plays an important role on corrosion risk of copper based cold plates and the corrosion risk can be mitigated by enabling new manufacturing processes, including friction stir welding (FSW) and nickel plating to the inside surface of the cold plate in the manufacturing process.

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Study on Copper Cold Plate Designs for Electronics Liquid Cooling System

Heat Transfer, Volume 1 ◽

10.1115/imece2006-16242 ◽

2006 ◽

Author(s):

Yi. Feng ◽

Y. Wang ◽

C. Y. Huang

Keyword(s):

Heat Transfer ◽

Thermal Performance ◽

Cooling System ◽

Pure Copper ◽

Cold Plate ◽

Performance Limits ◽

Liquid Cooling ◽

Cold Plates ◽

Management Approaches ◽

Liquid Cooling System

The increasing power consumption of microelectronic systems and the dense layout of semiconductor components leave very limited design spaces with tight constraints for the thermal solution. Conventional thermal management approaches, such as extrusion, fold-fin, and heat pipe heat sinks, are somehow reaching their performance limits, due to the geometry constraints. Currently, more studies have been carried out on the liquid cooling technologies, as the flexible tubing connection of liquid cooling system makes both the accommodation in constrained design space and the simultaneous cooling of multi heating sources feasible. To significantly improve the thermal performance of a liquid cooling system, heat exchangers with more liquid-side heat transfer area with acceptable flow pressure drop are expected. This paper focuses on the performance of seven designs of source heat exchanger (cold plate). The presented cold plates are all made in pure copper material using wire cutting, soldering, brazing, or sintering process. Enhanced heat transfer surfaces such as micro channel and cooper mesh are investigated. Detailed experiments have been conducted to understand the performance of these seven cooper cold plates. The same radiators, fan, and water pump were connected with each cooper cold plate to investigate the overall thermal performance of liquid cooling system. Water temperature readings at the inlets and outlets of radiators, pump, and colder plate have been taken to interpret the thermal resistance distribution along the cooling loop.

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Thermal Analysis of Cold Plate for Direct Liquid Cooling of High Performance Servers

Journal of Electronic Packaging ◽

10.1115/1.4044130 ◽

2019 ◽

Vol 141 (4) ◽

Cited By ~ 2

Author(s):

Bharath Ramakrishnan ◽

Yaser Hadad ◽

Sami Alkharabsheh ◽

Paul R. Chiarot ◽

Bahgat Sammakia

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Thermal Resistance ◽

High Heat ◽

High Heat Flux ◽

Cold Plate ◽

Liquid Cooling ◽

Maximum Heat ◽

Effective Heat ◽

Cold Plates

Data center energy usage keeps growing every year and will continue to increase with rising demand for ecommerce, scientific research, social networking, and use of streaming video services. The miniaturization of microelectronic devices and an increasing demand for clock speed result in high heat flux systems. By adopting direct liquid cooling, the high heat flux and high power demands can be met, while the reliability of the electronic devices is greatly improved. Cold plates which are mounted directly on to the chips facilitate a lower thermal resistance path originating from the chip to the incoming coolant. An attempt was made in the current study to characterize a commercially available cold plate which uses warm water in carrying the heat away from the chip. A mock package mimicking a processor chip with an effective heat transfer area of 6.45 cm2 was developed for this study using a copper block heater arrangement. The thermo-hydraulic performance of the cold plates was investigated by conducting experiments at varying chip power, coolant flow rates, and coolant temperature. The pressure drop (ΔP) and the temperature rise (ΔT) across the cold plates were measured, and the results were presented as flow resistance and thermal resistance curves. A maximum heat flux of 31 W/cm2 was dissipated at a flow rate of 13 cm3/s. A resistance network model was used to calculate an effective heat transfer coefficient by revealing different elements contributing to the total resistance. The study extended to different coolant temperatures ranging from 25 °C to 45 °C addresses the effect of coolant viscosity on the overall performance of the cold plate, and the results were presented as coefficient of performance (COP) curves. A numerical model developed using 6SigmaET was validated against the experimental findings for the flow and thermal performance with minimal percentage difference.

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