Review and Projections of Integrated Cooling Systems for Three-Dimensional Integrated Circuits

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Satish G. Kandlikar
Keyword(s):  
Hot Spots ◽  
Heat Dissipation ◽  
Cooling System ◽  
Mechanical Design ◽  
Heat Fluxes ◽  
Electrical Performance ◽  
Channel Height ◽  
Cooling Systems ◽  
3D Ic ◽  
Pressure Drops

In an effort to increase processor speeds, 3D IC architecture is being aggressively pursued by researchers and chip manufacturers. This architecture allows extremely high level of integration with enhanced electrical performance and expanded functionality, and facilitates realization of VLSI and ULSI technologies. However, utilizing the third dimension to provide additional device layers poses thermal challenges due to the increased heat dissipation and complex electrical interconnects among different layers. The conflicting needs of the cooling system requiring larger flow passage dimensions to limit the pressure drop, and the IC architecture necessitating short interconnect distances to reduce signal latency warrant paradigm shifts in both of their design approach. Additional considerations include the effects due to temperature nonuniformity, localized hot spots, complex fluidic connections, and mechanical design. This paper reviews the advances in 3D IC cooling in the last decade and provides a vision for codesigning 3D IC architecture and integrated cooling systems. For heat fluxes of 50–100 W/cm2 on each side of a chip in a 3D IC package, the current single-phase cooling technology is projected to provide adequate cooling, albeit with high pressure drops. For future applications with coolant surface heat fluxes from 100 to 500 W/cm2, significant changes need to be made in both electrical and cooling technologies through a new level of codesign. Effectively mitigating the high temperatures surrounding local hot spots remains a challenging issue. The codesign approach with circuit, software and thermal designers working together is seen as essential. The through silicon vias (TSVs) in the current designs place a stringent limit on the channel height in the cooling layer. It is projected that integration of wireless network on chip architecture could alleviate these height restrictions since the data bandwidth is independent of the communication lengths. Microchannels that are 200 μm or larger in depth are expected to allow dissipation of large heat fluxes with significantly lower pressure drops.

On Development of a Semi-Mechanistic Wall Boiling Model

2013 ◽  
Author(s):  
Saurish Das ◽  
Hemant Punekar
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Thermal Stresses ◽  
Cooling System ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Wall Heat Transfer ◽  
Cooling Systems ◽  
Transfer Phenomenon

In modern cooling systems the requirement of higher performance demands highest possible heat transfer rates, which can be achieved by controlled nucleate boiling. Boiling based cooling systems are gaining attention in several engineering applications as a potential replacement of conventional single-phase cooling system. Although the controlled nucleate boiling enhances the heat transfer, uncontrolled boiling may lead to Dry Out situation, adversely affecting the cooling performance and may also cause mechanical damage due to high thermal stresses. Designing boiling based cooling systems requires a modeling approach based on detailed fundamental understanding of this complex two-phase heat and mass transfer phenomenon. Such models can help analyze different cooling systems, detect potential design flaws and carry out design optimization. In the present work a new semi-mechanistic wall boiling model is developed within commercial CFD solver ANSYS FLUENT. A phase change mechanism and wall heat transfer augmentation due to nucleate boiling are implemented in mixture multiphase flow framework. The phase change phenomenon is modeled using mechanistic evaporation-condensation model. Enhancement of wall heat transfer due to nucleate boiling is captured using 1D empirical correlation, modified for 3D CFD environment. A new method is proposed to calculate the local suppression of nucleate boiling based on the flow velocity, and hence this model can be applied to any complex shaped coolant passage. For different wall superheat, the wall heat fluxes predicted by the present model are validated against experimental data, in which 50-50 volume mixture of aqueous ethylene glycol (a typical anti-freeze coolant mixture) is used as working fluid. The validation study is performed in ducts of different sizes and shapes with different inlet velocities, inlet sub-cooling and operating pressures. The results are in good agreement with the experiments. This model is applied to a typical automobile Exhaust Gas Recirculation (EGR) system to study boiling heat transfer phenomenon and the results are presented.

Layout Based Full Chip Thermal Simulations of Stacked 3D Integrated Circuits

2003 ◽  
Author(s):  
Ashok Raman ◽  
Marek Turowski ◽  
Monte Mar
Keyword(s):  
Integrated Circuits ◽  
Integrated Circuit ◽  
Hot Spots ◽  
Heat Dissipation ◽  
Three Dimensional ◽  
3D Ic ◽  
Localized Heating ◽  
3D Integrated Circuits ◽  
Thermal Simulations

This paper presents full-chip scale detailed thermal simulations of three-dimensional (3D) integrated circuit (IC) stacks. The inter-layer dielectric (ILD) and inter-metal dielectric (IMD) materials inside 3D IC stacks may cause extensive localized heating. The influence of multiple layers of dielectrics on heat trapping inside the 3D stack is analyzed. Different methods to minimize such localized heating are studied. It is shown that the use of thermal vias is very effective in heat dissipation from the hot spots. Comparisons are made between several 3D IC configurations to verify these conclusions.

Recent Advances in Thermal Modeling of Micro-Evaporators for Cooling of Microprocessors

2007 ◽  
Author(s):  
John R. Thome ◽  
Re´mi Revellin ◽  
Bruno Agostini ◽  
Jung Eung Park
Keyword(s):  
Flow Pattern ◽  
Hot Spots ◽  
Bubble Dynamics ◽  
Flow Boiling ◽  
Heat Fluxes ◽  
Base Temperature ◽  
Two Phase ◽  
Pressure Drops ◽  
Flow Boiling Heat Transfer ◽  
Recent Experimental Work

Cooling of microprocessors using flow boiling of low pressure refrigerants in multi-microchannel evaporator cooling elements is a promising technique for dissipation of footprint heat fluxes of over 300 W/cm2 while maintaining the chip safely below its maximum working temperature, providing a nearly uniform chip base temperature and minimizing energy consumption. The present invited lecture focuses on our recent experimental work and modeling of two-phase flow and boiling in single and multi-microchannels, covering: bubble dynamics, bubble coalescence, flow pattern recognition, diabatic flow pattern map, critical heat flux, hot spots, flow boiling heat transfer and two-phase pressure drops.

The Effectiveness of Data Center Overhead Cooling in Steady and Transient Scenarios: Comparison of Downward Flow to a Cold Aisle Versus Upward Flow From a Hot Aisle

2015 ◽  
Author(s):  
Luis Silva-Llanca ◽  
Marcelo del Valle ◽  
Alfonso Ortega
Keyword(s):  
Energy Efficiency ◽  
Heat Exchanger ◽  
Cooling System ◽  
Control Flow ◽  
Air Cooling ◽  
Upward Flow ◽  
Cooling Systems ◽  
Cooling Effectiveness ◽  
Downward Flow ◽  
Pressure Drops

The most common approach to air cooling of data centers involves the pressurization of the plenum beneath the raised floor and delivery of air flow to racks via perforated floor tiles. This cooling approach is thermodynamically inefficient due in large part to the pressure losses through the tiles. Furthermore, it is difficult to control flow at the aisle and rack level since the flow source is centralized rather than distributed. Distributed cooling systems are more closely coupled to the heat generating racks. In overhead cooling systems, one can distribute flow to distinct aisles by placing the air mover and water cooled heat exchanger directly above an aisle. Two arrangements are possible: (i.) placing the air mover and heat exchanger above the cold aisle and forcing downward flow of cooled air into the cold aisle (Overhead Downward Flow (ODF)), or (ii.) placing the air mover and heat exchanger above the hot aisle and forcing heated air upwards from the hot aisle through the water cooled heat exchanger (Overhead Upward Flow (OUF)). This study focuses on the steady and transient behavior of overhead cooling systems in both ODF and OUF configurations and compares their cooling effectiveness and energy efficiency. The flow and heat transfer inside the servers and heat exchangers are modeled using physics based approaches that result in differential equation based mathematical descriptions. These models are programmed in the MATLAB™ language and embedded within a CFD computational environment (using the commercial code FLUENT™) that computes the steady or instantaneous airflow distribution. The complete computational model is able to simulate the complete flow and thermal field in the airside, the instantaneous temperatures within and pressure drops through the servers, and the instantaneous temperatures within and pressure drops through the overhead cooling system. Instantaneous overall energy consumption (1st Law) and exergy destruction (2nd Law) were used to quantify overall energy efficiency and to identify inefficiencies within the two systems. The server cooling effectiveness, based on an effectiveness-NTU model for the servers, was used to assess the cooling effectiveness of the two overhead cooling approaches.

Alumina Nanofluid for Spray Cooling Enhancement

2007 ◽  
Author(s):  
Aditya Bansal ◽  
Frank Pyrtle
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Dissipation ◽  
Cooling System ◽  
Spray Cooling ◽  
Open Loop ◽  
Heat Fluxes ◽  
Alumina Nanoparticles ◽  
Transfer Enhancement ◽  
Thermal Conductivities

Nanofluids have been demonstrated as promising for heat transfer enhancement in forced convection and boiling applications. The addition of carbon, copper, and other high-thermal-conductivity nanoparticles to water, oil, ethylene glycol, and other fluids has been determined to increase the thermal conductivities of these fluids. The increased effective thermal conductivities of these fluids enhance their abilities to dissipate heat in such applications. The use of nanofluids for spray cooling is an extension of the application of nanofluids for enhancement of heat dissipation. In this investigation, experiments were performed to determine the level of heat transfer enhancement with the addition of alumina nanoparticles to the fluid. Using mass percentages of up to 0.5% alumina nanoparticles suspended in water, heat fluxes and surface temperatures were measured and compared. Compressed nitrogen was used to provide constant spray nozzle pressures to produce full-cone sprays in an open loop spray cooling system. Heat fluxes were measured for single-phase and evaporative spray cooling regimes.

Compact Modeling of Fractal Tree-Shaped Microchannel Liquid Cooling Systems

2011 ◽  
Author(s):  
Cheng Chen ◽  
Emad Samadiani ◽  
Bahgat Sammakia
Keyword(s):  
Flow Rate ◽  
Cooling System ◽  
Maximum Flow ◽  
Heat Fluxes ◽  
Compact Model ◽  
Temperature Fields ◽  
Compact Modeling ◽  
Liquid Cooling ◽  
Cooling Systems ◽  
Full Field

Demands for higher computational speed and miniaturization have already resulted in extremely high heat fluxes in microprocessors. Fractal tree-shaped microchannel liquid cooling systems are novel heat transfer enhancement systems to keep the temperature of the microprocessors in a safe range. Due to the complexity of these systems, their full field numerical modeling for simulation of the flow and temperature fields is too time consuming and costly, particularly to be used within iterative optimization algorithms. In this paper, a quick but still accurate compact modeling approach based on Flow Network Modeling (FNM) is introduced for analysis of the flow filed in fractal microchannel liquid cooling systems. The compact method is applied to a representative fractal microchannel cooling system and the obtained velocity and flow rate distribution are validated against a full Computational Fluid Dynamics (CFD)-based model for three different designs. The compact model shows good agreement with the CFD results and robustness on different designs, while requiring much less computational capability and time. Afterwards, the compact model is used for optimization of the geometry of the fractal cooling system to achieve maximum flow rate and uniform flow distribution among the channels for a fixed pressure drop.

scholarly journals Performance improvement of an industrial control enclosure cooling system

2021 ◽  
pp. 177-177
Author(s):  
Wei-Ming Chiang ◽  
Fu-Jen Wang ◽  
K Kusnandar
Keyword(s):  
Heat Dissipation ◽  
Cfd Simulation ◽  
Cooling System ◽  
Flow Distribution ◽  
Field Measurements ◽  
Critical Issue ◽  
Industrial Control ◽  
Cooling Systems ◽  
Auxiliary Circulation ◽  
Air Vent

Following the trend of high-accuracy machining, thermal management of industrial control enclosures become a critical issue. Therefore, a well-designed enclosure cooling system is essential to manage the heat generation inside the enclosure. In this study, to improve the performance of cooling system and the air flow distribution inside the enclosure, computational fluid dynamics (CFD) simulation has been used to evaluate the application of using the auxiliary circulation fan and air baffler. Furthermore, this study also investigates the layout design for both supply air vent and return air vent arrangement by two types of commercialized cooling systems through field measurements. The simulation results show the short circulation of airflow is improved when the air baffler is installed. It also shows that the auxiliary circulation fan is suggested. Besides, air baffler is used to enhance the temperature distribution. The experimental results reveal the upper supply vent arrangement will cause the short circulation of airflow slightly. And, the auxiliary circulation fans can improve the heat dissipation of cooling systems. There is no short circulation of airflow for the lower supply vent arrangement, but the supply air cannot be distributed smoothly by the auxiliary circulation fans because the shape of the air baffler is not properly designed.

scholarly journals Improving the cooling systems of automotive engines and methods for monitoring their condition

2021 ◽  
pp. 41-44
Author(s):  
E.P. Parlyuk ◽  
Keyword(s):  
Mathematical Model ◽  
Heat Exchanger ◽  
Heat Dissipation ◽  
Cooling System ◽  
Quantitative Relationship ◽  
Thermal Processes ◽  
Structural Diagram ◽  
Cooling Systems ◽  
Automotive Engines ◽  
Machine Operation

It has been established that the cooling system of modern tractors and trucks can include 5 to 7 independent cooling circuits. A structural diagram of a modular cooling system for automotive engines and a mathematical model of thermal processes in a heat exchanger of the modular cooling system during machine operation are proposed. It is shown that the development of an algorithm for predicting and monitoring the state of the modular cooling system is possible based on a quantitative relationship between the rate of decrease in heat dissipation capacity and the duration of machine operation.

Assessment of thermal behavior of a cooling system to reduce thermal fatigue cracks in aluminum injection molds

2020 ◽  
pp. 75-86
Author(s):  
Sergio Antonio Camargo ◽  
Lauro Correa Romeiro ◽  
Carlos Alberto Mendes Moraes
Keyword(s):  
Thermal Fatigue ◽  
Cooling System ◽  
Fatigue Cracks ◽  
Cooling Water ◽  
Thermal Conditions ◽  
Thermal Gradients ◽  
Ansys Software ◽  
Cooling Systems ◽  
Thermal Fatigue Cracks ◽  
Number Of Cycles

The present article aimed to test changes in cooling water temperatures of males, present in aluminum injection molds, to reduce failures due to thermal fatigue. In order to carry out this work, cooling systems were studied, including their geometries, thermal gradients and the expected theoretical durability in relation to fatigue failure. The cooling system tests were developed with the aid of simulations in the ANSYS software and with fatigue calculations, using the method of Goodman. The study of the cooling system included its geometries, flow and temperature of this fluid. The results pointed to a significant increase in fatigue life of the mold component for the thermal conditions that were proposed, with a significant increase in the number of cycles, to happen failures due to thermal fatigue.

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.

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