An Experimental Investigation on the Fluid Distribution in a Two-Phase Cooled Rack Under Steady and Transient Information Technology Loads

Abstract Increasing power densities in data centers due to the rise of artificial intelligence, high-performance computing, and machine learning compel engineers to develop new cooling strategies and designs for high-performance information technology (IT) equipment. Two-phase cooling is a promising technology that exploits the latent heat of the coolant which is significantly more effective in removing high heat fluxes than when using the sensible heat of the fluid. Also, utilizing the latent heat allows operating at lower coolant flow rates and implies more uniformity in the temperature of heated surfaces. Despite the benefits of two-phase cooling, the phase change adds complexities to a system when multiple evaporators (exposed to different heat fluxes potentially) are connected to a single coolant distribution unit. In this article, a commercial coolant distribution unit is used to investigate pumped two-phase cooling in rack scale. Seventeen two-rack unit servers from two distinct models are retrofitted with 34 impinging jet evaporators and deployed in a rack. Four case studies are presented to provide insights into the complex behavior of a pumped two-phase cooling system with several evaporators. The flow rates and pressure distribution across the rack are studied in various filling ratios. Also, investigated is the transient behavior of the cooling system due to a step change in the IT workload. Finally, a control system is designed to regulate the temperature of the supplied coolant in response to the step change in the IT workload and is tested.

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An Experimental Investigation on the Fluid Distribution in a Two-Phase Cooled Rack Under Steady and Transient IT Load

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

10.1115/ipack2019-6463 ◽

2019 ◽

Author(s):

Sadegh Khalili ◽

Srikanth Rangarajan ◽

Bahgat Sammakia ◽

Vadim Gektin

Keyword(s):

Latent Heat ◽

High Performance ◽

Data Centers ◽

Cooling System ◽

Heated Surface ◽

Transient Behavior ◽

Heat Fluxes ◽

Fluid Distribution ◽

Two Phase ◽

Two Phase Cooling

Abstract Increasing power densities in data centers due to the rise of Artificial Intelligence (AI), high-performance computing (HPC) and machine learning compel engineers to develop new cooling strategies and designs for high-density data centers. Two-phase cooling is one of the promising technologies which exploits the latent heat of the fluid. This technology is much more effective in removing high heat fluxes than when using the sensible heat of fluid and requires lower coolant flow rates. The latent heat also implies more uniformity in the temperature of a heated surface. Despite the benefits of two-phase cooling, the phase change adds complexities to a system when multiple evaporators (exposed to different heat fluxes potentially) are connected to one coolant distribution unit (CDU). In this paper, a commercial pumped two-phase cooling system is investigated in a rack level. Seventeen 2-rack unit (RU) servers from two distinct models are retrofitted and deployed in the rack. The flow rate and pressure distribution across the rack are studied in various filling ratios. Also, investigated is the transient behavior of the cooling system due to a step change in the information technology (IT) load.

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Electronics Thermal Management Using Advanced Hybrid Two-Phase Loop Technology

ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference, Volume 2 ◽

10.1115/ht2007-32962 ◽

2007 ◽

Cited By ~ 3

Author(s):

Chanwoo Park ◽

Aparna Vallury ◽

Jon Zuo ◽

Jeffrey Perez ◽

Paul Rogers

Keyword(s):

Thermal Management ◽

High Performance ◽

Cooling System ◽

Active Flow Control ◽

Heat Pipes ◽

High Heat ◽

Heat Fluxes ◽

Significant Advance ◽

Two Phase ◽

Phase Loop

The paper discusses an advanced Hybrid Two-Phase Loop (HTPL) technology for electronics thermal management. The HTPL combined active mechanical pumping with passive capillary pumping realizing a reliable yet high performance cooling system. The evaporator developed for the HTPL used 3-dimensional metallic wick structures to enhance boiling heat transfer by passive capillary separation of liquid and vapor phases. Through the testing using various prototype hybrid loops, it was demonstrated that the hybrid loops were capable of removing high heat fluxes from multiple heat sources with large surface areas up to 135cm2 and 10kW heat load. Because of the passive capillary phase separation, the hybrid loop operation didn’t require any active flow control of the liquid in the evaporator, even at highly transient and asymmetrical heat inputs between the evaporators. These results represent the significant advance over state-of-the-art heat pipes, loop heat pipes and evaporative spray cooling devices in terms of performance, robustness and simplicity.

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A Pumped Two-Phase Cooling System for Spacecraft

10.4271/831099 ◽

1983 ◽

Author(s):

S. Ollendorf ◽

F. A. Costello

Keyword(s):

Cooling System ◽

Two Phase ◽

Two Phase Cooling

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Model Predictive Control of a Pumped Two-Phase Cooling System With Microchannel Heat Exchangers

Volume 2: Control and Optimization of Connected and Automated Ground Vehicles; Dynamic Systems and Control Education; Dynamics and Control of Renewable Energy Systems; Energy Harvesting; Energy Systems; Estimation and Identification; Intelligent Transportation and Vehicles; Manufacturing; Mechatronics; Modeling and Control of IC Engines and Aftertreatment Systems; Modeling and Control of IC Engines and Powertrain Systems; Modeling and Management of Power Systems ◽

10.1115/dscc2018-9143 ◽

2018 ◽

Author(s):

Oyuna Angatkina ◽

Andrew Alleyne

Keyword(s):

Heat Flux ◽

Model Predictive Control ◽

Predictive Control ◽

Heat Exchangers ◽

Cooling System ◽

High Heat ◽

High Heat Flux ◽

Two Phase ◽

Cooling Systems ◽

Two Phase Cooling

Two-phase cooling systems provide a viable technology for high–heat flux rejection in electronic systems. They provide high cooling capacity and uniform surface temperature. However, a major restriction of their application is the critical heat flux condition (CHF). This work presents model predictive control (MPC) design for CHF avoidance in two-phase pump driven cooling systems. The system under study includes multiple microchannel heat exchangers in series. The MPC controller performance is compared to the performance of a baseline PI controller. Simulation results show that while both controllers are able to maintain the two-phase cooling system below CHF, MPC has significant reduction in power consumption compared to the baseline controller.

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A Two-Phase Cooling System for the Jetfoil Visual Augmentation System

10.4271/831123 ◽

1983 ◽

Author(s):

Robert H. Hamasaki ◽

Janet L. Abe ◽

James L. Franklin

Keyword(s):

Cooling System ◽

Two Phase ◽

Two Phase Cooling

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Cooling performance of a pump-driven two phase cooling system for free cooling in data centers

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2015.11.002 ◽

2016 ◽

Vol 95 ◽

pp. 143-149 ◽

Cited By ~ 29

Author(s):

Yuezheng Ma ◽

Guoyuan Ma ◽

Shuang Zhang ◽

Feng Zhou

Keyword(s):

Data Centers ◽

Cooling System ◽

Two Phase ◽

Cooling Performance ◽

Free Cooling ◽

Two Phase Cooling

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Experimental Validation and Design Simulations of a Passive Two-Phase Cooling System for Datacenters

10.1115/1.0003525v ◽

2021 ◽

Author(s):

Jackson Braz Marcinichen ◽

Raffaele Luca Amalfi ◽

Filippo Cataldo ◽

John Richard Thome

Keyword(s):

Experimental Validation ◽

Cooling System ◽

Two Phase ◽

Two Phase Cooling

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On Efficient Passive Cooling of Control Rod Drivers

Volume 2: Plant Systems, Construction, Structures and Components; Next Generation Reactors and Advanced Reactors ◽

10.1115/icone21-16449 ◽

2013 ◽

Author(s):

A. N. Gershuni ◽

A. P. Nishchik ◽

V. G. Razumovskiy ◽

I. L. Pioro

Keyword(s):

Heat Transfer ◽

Natural Convection ◽

High Performance ◽

Cooling System ◽

Vertical Channel ◽

Passive Cooling ◽

Primary Circuit ◽

Two Phase ◽

Primary Coolant ◽

Control Rod

Experimental research of natural convection and the ways of its suppression in an annular vertical channel to simulate the conditions of cooling the control rod drivers of the reactor protection system (RPS) in its so-called wet design, where the drivers are cooled by primary circuit water supplied due to the system that includes branched pipelines, valves, pump, heat exchanger, etc., is reported. Reliability of the drivers depends upon their temperature ensured by operation of an active multi-element cooling system. Its replacement by an available passive cooling system is possible only under significant suppression of natural convection in control rod channel filled with primary coolant. The methods of suppression of natural convection proposed in the work have demonstrated the possibility both of minimization of axial heat transfer and of almost complete elimination of temperature non-uniformity and oscillation inside the channel under the conditions of free travel of moving element (control rod) in it. The obtained results widen the possibilities of substitution of the active systems of cooling the RPS drivers by reliable passive systems, such as high-performance heat-transfer systems of evaporation-condensation type with heat pipes or two-phase thermosyphons as heat-transferring elements.

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