Embedded Two-Phase Cooling of Large 3D Compatible Chips With Radial Channels

2015 ◽  
Author(s):  
Mark Schultz ◽  
Fanghao Yang ◽  
Evan Colgan ◽  
Robert Polastre ◽  
Bing Dang ◽  
...  
Keyword(s):  
Heat Fluxes ◽  
Future Generations ◽  
Test Facility ◽  
Coolant Temperature ◽  
Two Phase ◽  
Chip Area ◽  
Power Maps ◽  
Core Areas ◽  
Two Phase Cooling ◽  
Initial Results

Thermal performance for embedded two phase cooling using dielectric coolant (R1234ze) is evaluated on a ∼20 mm × 20 mm large die. The test vehicles incorporate radial expanding channels with embedded pin fields suitable for through-silicon-via (TSV) interconnects of multi-die stacks. Power generating features mimicking those anticipated in future generations of processor chips with 8 cores are included. Initial results show that for the types of power maps anticipated, critical heat fluxes in “core” areas of at least 350 W/cm2 with at least 20 W/cm2 “background” heating in rest of the chip area can be achieved with less than 30 °C temperature rise over the inlet coolant temperature. These heat fluxes are significantly higher than those seen for relatively long parallel channel devices of similar base channel dimensions. Experimental results of flow rate, pressure drop, “device,” and coolant temperature are also provided for these test vehicles along with details of the test facility developed to properly characterize the test vehicles.

Embedded Two-Phase Cooling of Large Three-Dimensional Compatible Chips With Radial Channels

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Mark Schultz ◽  
Fanghao Yang ◽  
Evan Colgan ◽  
Robert Polastre ◽  
Bing Dang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Heat Fluxes ◽  
Test Facility ◽  
Coolant Temperature ◽  
Two Phase ◽  
Chip Area ◽  
Power Maps ◽  
Core Areas ◽  
Two Phase Cooling ◽  
Initial Results

Thermal performance for embedded two-phase cooling using dielectric coolant (R1234ze) is evaluated on a ∼20 mm × 20 mm large die. The test vehicles incorporate radial expanding channels with embedded pin fields suitable for through-silicon-via (TSV) interconnects of multidie stacks. Power generating features mimicking those anticipated in future generations of processor chips with eight cores are included. Initial results show that for the types of power maps anticipated, critical heat fluxes (CHFs) in “core” areas of at least 350 W/cm2 with at least 20 W/cm2 “background” heating in rest of the chip area can be achieved with less than 30 °C temperature rise over the inlet coolant temperature. These heat fluxes are significantly higher than those seen for relatively long parallel channel devices of similar base channel dimensions. Experimental results of flow rate, pressure drop, “device,” and coolant temperature are also provided for these test vehicles along with details of the test facility developed to properly characterize the test vehicles.

CFD Analysis of Flow Boiling in a Silicon Microchannel With Non-Uniform Heat Flux

2015 ◽  
Author(s):  
Daniel Lorenzini ◽  
Yogendra K. Joshi
Keyword(s):  
Flow Boiling ◽  
Heat Fluxes ◽  
Cfd Modeling ◽  
Experimental Investigations ◽  
Uniform Heat Flux ◽  
Substrate Thickness ◽  
Two Phase ◽  
Uniform Heat ◽  
Vof Model ◽  
Power Maps

Boiling systems are capable of dissipating high heat fluxes, and as such have potential applications in thermal management of high power microelectronics. Although there are a number of experimental investigations of flow boiling in small flow passages and several empirical correlations have been proposed, the computational fluid dynamics (CFD) modeling of such systems is much less explored. In the present investigation, a phase-change model representing the heat and mass transfer is coupled with the volume of fluid (VOF) model for the transient analysis of flow boiling. The analyzed domain consists of a silicon microchannel with a finite substrate thickness, subjected to non-uniform heat fluxes at localized regions, providing with a more realistic scenario for the case of microelectronics power maps. The results show the strong effect on the two-phase flow characteristics for these configurations and visualization of the induced flow regimes is presented. Furthermore, discussion about the heat transfer mechanisms, challenges and possible solutions are given in order to provide guidelines for effective cooling of these devices.

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

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.

scholarly journals Embedded Two-Phase Cooling of High Flux Electronics Via Press-Fit and Bonded FEEDS Coolers

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Raphael K. Mandel ◽  
Daniel G. Bae ◽  
Michael M. Ohadi
Keyword(s):  
Experimental Testing ◽  
High Heat ◽  
Heat Fluxes ◽  
Coefficient Of Performance ◽  
System Level ◽  
Pumping Power ◽  
Test Chip ◽  
Two Phase ◽  
Press Fit ◽  
Two Phase Cooling

The increasing heat densities in electronic components and focus on energy efficiency have motivated utilization of embedded two-phase cooling, which reduces system-level thermal resistance and pumping power. To achieve maximum benefit, high heat fluxes and vapor qualities should be achieved simultaneously. While many researchers have achieved heat fluxes in excess of 1 kW/cm2, vapor qualities are often below 10%, requiring a significantly large amount of energy spent on subcooling or pumping power, which minimizes the benefit of using two-phase thermal transport. In this work, we describe our recent work with cooling devices utilizing film evaporation with an enhanced fluid delivery system (FEEDS). The design, calibration, and experimental testing of a press-fit and bonded FEEDS test section are detailed here. Heat transfer and pressure drop performance was characterized and discussed. With the press-fit Si test chip, heat fluxes in excess of 1 kW/cm2 were obtained at vapor qualities approaching 45% and a coefficient of performance (COP) approaching 1400. With the bonded SiC test chip, heat fluxes in excess of 1 kW/cm2 were achieved at a vapor quality of 85% and heat densities approaching 490 W/cm3.

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

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Sadegh Khalili ◽  
Srikanth Rangarajan ◽  
Vadim Gektin ◽  
Husam Alissa ◽  
Bahgat Sammakia
Keyword(s):  
Information Technology ◽  
Latent Heat ◽  
High Performance ◽  
Cooling System ◽  
Step Change ◽  
Heat Fluxes ◽  
Fluid Distribution ◽  
Two Phase ◽  
Flow Rates ◽  
Two Phase Cooling

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.

Effects of Varying Geometrical Parameters on Boiling From Microfabricated Enhanced Structures

2003 ◽  
Vol 125 (1) ◽  
pp. 103-109 ◽  
Author(s):  
C. Ramaswamy ◽  
Y. Joshi ◽  
W. Nakayama ◽  
W. B. Johnson
Keyword(s):  
Heat Dissipation ◽  
Layer Structure ◽  
Single Layer ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Geometrical Parameters ◽  
Small Range ◽  
Two Phase ◽  
Wall Superheat

The current study involves two-phase cooling from enhanced structures whose dimensions have been changed systematically using microfabrication techniques. The aim is to optimize the dimensions to maximize the heat transfer. The enhanced structure used in this study consists of a stacked network of interconnecting channels making it highly porous. The effect of varying the pore size, pitch and height on the boiling performance was studied, with fluorocarbon FC-72 as the working fluid. While most of the previous studies on the mechanism of enhanced nucleate boiling have focused on a small range of wall superheats (0–4 K), the present study covers a wider range (as high as 30 K). A larger pore and smaller pitch resulted in higher heat dissipation at all heat fluxes. The effect of stacking multiple layers showed a proportional increase in heat dissipation (with additional layers) in a certain range of wall superheat values only. In the wall superheat range 8–13 K, no appreciable difference was observed between a single layer structure and a three layer structure. A fin effect combined with change in the boiling phenomenon within the sub-surface layers is proposed to explain this effect.

scholarly journals Experimental Investigation and Prediction on Pressure Drop during Flow Boiling in Horizontal Microchannels

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 510
Author(s):  
Yan Huang ◽  
Bifen Shu ◽  
Shengnan Zhou ◽  
Qi Shi
Keyword(s):  
Pressure Drop ◽  
Flow Model ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Separated Flow ◽  
Heat Fluxes ◽  
Phase Flow ◽  
Vapor Quality ◽  
Two Phase ◽  
Gas Flux

In this paper, two-phase pressure drop data were obtained for boiling in horizontal rectangular microchannels with a hydraulic diameter of 0.55 mm for R-134a over mass velocities from 790 to 1122, heat fluxes from 0 to 31.08 kW/m2 and vapor qualities from 0 to 0.25. The experimental results show that the Chisholm parameter in the separated flow model relies heavily on the vapor quality, especially in the low vapor quality region (from 0 to 0.1), where the two-phase flow pattern is mainly bubbly and slug flow. Then, the measured pressure drop data are compared with those from six separated flow models. Based on the comparison result, the superficial gas flux is introduced in this paper to consider the comprehensive influence of mass velocity and vapor quality on two-phase flow pressure drop, and a new equation for the Chisholm parameter in the separated flow model is proposed as a function of the superficial gas flux . The mean absolute error (MAE ) of the new flow correlation is 16.82%, which is significantly lower than the other correlations. Moreover, the applicability of the new expression has been verified by the experimental data in other literatures.

Thermal Characterization of Interlayer Microfluidic Cooling of Three-Dimensional Integrated Circuits With Nonuniform Heat Flux

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Yoon Jo Kim ◽  
Yogendra K. Joshi ◽  
Andrei G. Fedorov ◽  
Young-Joon Lee ◽  
Sung-Kyu Lim
Keyword(s):  
Integrated Circuits ◽  
Mass Flow Rate ◽  
Thermal Management ◽  
Mass Flow ◽  
Flow Rate ◽  
Single Phase ◽  
Hot Spot ◽  
Three Dimensional ◽  
Two Phase ◽  
Two Phase Cooling

It is now widely recognized that the three-dimensional (3D) system integration is a key enabling technology to achieve the performance needs of future microprocessor integrated circuits (ICs). To provide modular thermal management in 3D-stacked ICs, the interlayer microfluidic cooling scheme is adopted and analyzed in this study focusing on a single cooling layer performance. The effects of cooling mode (single-phase versus phase-change) and stack/layer geometry on thermal management performance are quantitatively analyzed, and implications on the through-silicon-via scaling and electrical interconnect congestion are discussed. Also, the thermal and hydraulic performance of several two-phase refrigerants is discussed in comparison with single-phase cooling. The results show that the large internal pressure and the pumping pressure drop are significant limiting factors, along with significant mass flow rate maldistribution due to the presence of hot-spots. Nevertheless, two-phase cooling using R123 and R245ca refrigerants yields superior performance to single-phase cooling for the hot-spot fluxes approaching ∼300 W/cm2. In general, a hybrid cooling scheme with a dedicated approach to the hot-spot thermal management should greatly improve the two-phase cooling system performance and reliability by enabling a cooling-load-matched thermal design and by suppressing the mass flow rate maldistribution within the cooling layer.

A Pumped Two-Phase Cooling System for Spacecraft

1983 ◽  
Author(s):  
S. Ollendorf ◽  
F. A. Costello
Keyword(s):  
Cooling System ◽  
Two Phase ◽  
Two Phase Cooling
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