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2004

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Investigation Of Liquid Flow In Microchannels, D. Liu, S V. Garimella Jan 2004

Investigation Of Liquid Flow In Microchannels, D. Liu, S V. Garimella

CTRC Research Publications

Liquid flow in microchannels is investigated both experimentally and numerically in this work. The experiments are carried out in microchannels with hydraulic diameters from 244 to 974 m at Reynolds numbers ranging from 230 to 6500. The pressure drop in these microchannels is measured in situ, and is also determined by correcting global measurements for inlet and exit losses. Onset of turbulence is verified by flow visualization. The experimental measurements of pressure drop are compared to numerical predictions. Results from this work show that conventional theory may be used to successfully predict the flow behavior in microchannels in the range …

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High-Field Quasi-Ballistic Transport In Short Carbon Nanotubes, Ali Javey, Jing Guo, Magnus Paulsson, Qian Wang, Mark S. Lundstrom, Hongjie Dai, David Mann Jan 2004

High-Field Quasi-Ballistic Transport In Short Carbon Nanotubes, Ali Javey, Jing Guo, Magnus Paulsson, Qian Wang, Mark S. Lundstrom, Hongjie Dai, David Mann

Department of Electrical and Computer Engineering Faculty Publications

Single walled carbon nanotubes with Pd Ohmic contacts and lengths ranging from several microns down to 10 nm are investigated by electron transport experiments and theory. The mean-free path (MFP) for acoustic phonon scattering is estimated to be lap ~300  nm, and that for optical phonon scattering is lop ~15  nm. Transport through very short (~10  nm) nanotubes is free of significant acoustic and optical phonon scattering and thus ballistic and quasiballistic at the low- and high-bias voltage limits, respectively. High currents of up to 70   μA can flow through a short nanotube. Possible mechanisms for the eventual electrical breakdown …

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A Three-Dimensional Quantum Simulation Of Silicon Nanowire Transistors With The Effective Mass Approximation, Jing Wang, Eric Polizzi, Mark S. Lundstrom Jan 2004

A Three-Dimensional Quantum Simulation Of Silicon Nanowire Transistors With The Effective Mass Approximation, Jing Wang, Eric Polizzi, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

The silicon nanowire transistor (SNWT) is a promising device structure for future integrated circuits, and simulations will be important for understanding its device physics and assessing its ultimate performance limits. In this work, we present a three-dimensional (3D) quantum mechanical simulation approach to treat various SNWTs within the effective-mass approximation. We begin by assuming ballistic transport, which gives the upper performance limit of the devices. The use of a mode space approach (either coupled or uncoupled) produces high computational efficiency that makes our 3D quantum simulator practical for extensive device simulation and design. Scattering in SNWTs is then treated by …

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Experimental Investigation Of The Thermal Performance Of Piezoelectric Fans, Tolga Acikalin, Sydney M. Wait, S V. Garimella, Arvind Raman Jan 2004

Experimental Investigation Of The Thermal Performance Of Piezoelectric Fans, Tolga Acikalin, Sydney M. Wait, S V. Garimella, Arvind Raman

CTRC Research Publications

Piezoelectric fans are investigated as a cooling technology for the thermal management of electronic devices. Flow visualization experiments are conducted to better understand the physics of fan operation. Prototypes of the fans are built and tested to assess their feasibility and cooling performance and determine optimal locations for the fans. An enclosure the size of a cellular phone and a commercially available laptop computer are used to demonstrate the cooling feasibility of the fans. Piezoelectric fans are found to offer significant localized cooling, exceeding enhancements in convective heat transfer coefficients of 100%, while exhibiting low power consumption, minimal noise, and …

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Analysis Of A Phase Change Energy Storage System For Pulsed Power Dissipation, S Krishnan, S V. Garimella Jan 2004

Analysis Of A Phase Change Energy Storage System For Pulsed Power Dissipation, S Krishnan, S V. Garimella

CTRC Research Publications

The melting of a phase change material in a container of rectangular cross-section with multiple discrete heat sources mounted on one side is investigated for electronics cooling by latent heat energy storage. This numerical study focuses on the thermal management issues that arise when electronic components experience sudden surges in power dissipation. The transient response of the energy storage system to short pulses in power dissipation is studied. Convective cooling using air-cooled heat sinks on the sides of the containment remote from the heat sources provides for heat rejection to ambient air. The analysis is performed under different pulse frequencies. …

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Transport In Flat Heat Pipes At High Heat Fluxes From Multiple Discrete Sources, U. Vadakkan, S V. Garimella, J. Y. Murthy Jan 2004

Transport In Flat Heat Pipes At High Heat Fluxes From Multiple Discrete Sources, U. Vadakkan, S V. Garimella, J. Y. Murthy

CTRC Research Publications

A three-dimensional model has been developed to analyze the transient and steady-state performance of flat heat pipes subjected to heating with multiple discrete heat sources. Three-dimensional flow and energy equations are solved in the vapor and liquid regions, along with conduction in the wall. Saturated flow models are used for heat transfer and fluid flow through the wick. In the wick region, the analysis uses an equilibrium model for heat transfer and a Brinkman-Forchheimer extended Darcy model for fluid flow. Averaged properties weighted with the porosity are used for the wick analysis. The state equation is used in the vapor …

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Thermal Management Of Transient Power Spikes In Electronics - Phase Change Energy Storage Or Copper Heat Sinks?, S. Krishnan, S V. Garimella Jan 2004

Thermal Management Of Transient Power Spikes In Electronics - Phase Change Energy Storage Or Copper Heat Sinks?, S. Krishnan, S V. Garimella

CTRC Research Publications

A transient thermal analysis is performed to investigate thermal control of power semiconductors using phase change materials, and to compare the performance of this approach to that of copper heat sinks. Both the melting of the phase change material under a transient power spike input, as well as the resolidification process, are considered. Phase change materials of different kinds (paraffin waxes and metallic alloys) are considered, with and without the use of thermal conductivity enhancers. Simple expressions for the melt depth, melting time and temperature distribution are presented in terms of the dimensions of the heat sink and the thermophysical …

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Analysis And Prediction Of Constriction Resistance For Contact Between Rough Engineering Surfaces, A. F. Black, V. Singhal, S V. Garimella Jan 2004

Analysis And Prediction Of Constriction Resistance For Contact Between Rough Engineering Surfaces, A. F. Black, V. Singhal, S V. Garimella

CTRC Research Publications

The constriction resistance of a semi-infinite cylinder terminating in the frustum of a cone in a gaseous environment is analyzed numerically. The variation of constriction resistance with the ratio of contact radius to cylinder radius, the cone angle, and the gas-to-substrate thermal conductivity ratio is investigated. Nonlinear curve fitting is used to develop a comprehensive predictive correlation for the constriction resistance as a function of these parameters. The parameters are investigated over a wide range of values covering the range expected in practical applications. The correlation could be used in conjunction with an appropriate surface deformation model to predict the …

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A Two-Temperature Model For The Analysis Of Passive Thermal Control Systems, S. Krishnan, J. Y. Murthy, S V. Garimella Jan 2004

A Two-Temperature Model For The Analysis Of Passive Thermal Control Systems, S. Krishnan, J. Y. Murthy, S V. Garimella

CTRC Research Publications

Passive control of steady and unsteady thermal loads using effective thermal conductivity enhancers, such as metal foams, internal fins and metal filler particles, is being explored for a variety of electronics applications. The interstices are filled with air, phase change materials, or other fluids. Local thermal equilibrium between the solid filler and the matrix is not ensured in such systems since their thermal diffusivities are frequently very different. The use of a single volume-averaged energy equation for both the phases cannot be justified in such situations. A two-medium approach is used in the present work to account for the local …

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Investigation On The Oil Supply System Of A Scroll Compressor, Micahel M. Cui Jan 2004

Investigation On The Oil Supply System Of A Scroll Compressor, Micahel M. Cui

International Compressor Engineering Conference

No abstract provided.

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Sound Reduction For Copeland Midsize Semi-Hermetic Compressors Using Experimental Methods, Wayne C. Fu Jan 2004

Sound Reduction For Copeland Midsize Semi-Hermetic Compressors Using Experimental Methods, Wayne C. Fu

International Compressor Engineering Conference

No abstract provided.

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Controling The Noise Radiation Of Hermetic Compressors By Means Of Minimization Of Power Flow Through Discharge Pipes Using Genetic Algorithms, Andrey R. Dasilva, Arcanjo Lenzi, Edmar Baars Jan 2004

Controling The Noise Radiation Of Hermetic Compressors By Means Of Minimization Of Power Flow Through Discharge Pipes Using Genetic Algorithms, Andrey R. Dasilva, Arcanjo Lenzi, Edmar Baars

International Compressor Engineering Conference

No abstract provided.

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Design Of Flapper Valves For A Co2 Commercial Refrigeration Compressor, Douglas A. Collings, Thomas J. Weadock Jan 2004

Design Of Flapper Valves For A Co2 Commercial Refrigeration Compressor, Douglas A. Collings, Thomas J. Weadock

International Compressor Engineering Conference

No abstract provided.

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Optimizing Chest Compression To Rescue Ventilation Ratios During One-Rescuer Cpr By Professionals And Lay Persons: Children Are Not Just Little Adults, Charles F. Babbs, Vinay Nadkarni Jan 2004

Optimizing Chest Compression To Rescue Ventilation Ratios During One-Rescuer Cpr By Professionals And Lay Persons: Children Are Not Just Little Adults, Charles F. Babbs, Vinay Nadkarni

Weldon School of Biomedical Engineering Faculty Publications

Objective: To estimate the optimum ratio of chest compressions to ventilations for onerescuer CPR that maximizes systemic oxygen delivery in children. Method: Equations describing oxygen delivery and blood flow during CPR as functions of the number of compressions and the number of ventilations delivered over time were adapted from the former work of Babbs and Kern. These equations were solved explicitly as a function of body weight, using scaling algorithms based upon principles of developmental anatomy and physiology. Results: The optimal compression to ventilation (C/V) ratios for infants and younger children increase sharply as a function of body weight. Optimal …

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Two-Stage Rolling Piston Carbon Dioxide Compressor, Nelik Dreiman, Rick Bunch, Yun Horn Hwang, Reinhard Radermacher Jan 2004

Two-Stage Rolling Piston Carbon Dioxide Compressor, Nelik Dreiman, Rick Bunch, Yun Horn Hwang, Reinhard Radermacher

International Compressor Engineering Conference

No abstract provided.

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Thermal And Fluid Dynamic Behavior Of Trans-Critical Carbon Dioxide Hermetic Reciprocating Compressors: Numerical Analysis, Carlos D. Perã©Z Segarra, Joaquim Rigola, Assensi Oliva Jan 2004

Thermal And Fluid Dynamic Behavior Of Trans-Critical Carbon Dioxide Hermetic Reciprocating Compressors: Numerical Analysis, Carlos D. Perã©Z Segarra, Joaquim Rigola, Assensi Oliva

International Compressor Engineering Conference

No abstract provided.

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Dynamic Analysis Of Multibody Systems For Reciprocating Compressor Of Household Refrigerator, Yong Yeoun Kim, Hyung Eun Im, Won Gul Hwang, Il Kyo Oh Jan 2004

Dynamic Analysis Of Multibody Systems For Reciprocating Compressor Of Household Refrigerator, Yong Yeoun Kim, Hyung Eun Im, Won Gul Hwang, Il Kyo Oh

International Compressor Engineering Conference

No abstract provided.

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The Performance Optimization Of Rolling Piston Compressors Based On Cfd Simulation, Wei Geng, Chun Hui Liu, Yan Zhen Wang Jan 2004

The Performance Optimization Of Rolling Piston Compressors Based On Cfd Simulation, Wei Geng, Chun Hui Liu, Yan Zhen Wang

International Compressor Engineering Conference

No abstract provided.

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Measurement Of Contact Conditions Between Swashplate And Shoe In The Automotive Swashplate Compressor, Tadashi Yanagisawa, Mitsuhiro Fukuta, Hiroyasu Takahashi, Hisashi Suzuki, Taizo Sato Jan 2004

Measurement Of Contact Conditions Between Swashplate And Shoe In The Automotive Swashplate Compressor, Tadashi Yanagisawa, Mitsuhiro Fukuta, Hiroyasu Takahashi, Hisashi Suzuki, Taizo Sato

International Compressor Engineering Conference

No abstract provided.

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Cycle Analysis And Turbo Compressor Sizing With Ketone C6f As Working Fluid For Water-Cooled Chiller Applications, Bruce P. Biederman, Jarso Mulugeta, Lili Zhang, Joost J. Brasz Jan 2004

Cycle Analysis And Turbo Compressor Sizing With Ketone C6f As Working Fluid For Water-Cooled Chiller Applications, Bruce P. Biederman, Jarso Mulugeta, Lili Zhang, Joost J. Brasz

International Compressor Engineering Conference

No abstract provided.

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Modeling And Simulation Of The Suction Process In A Multi-Cylinder Automotive Compressor, Jeong Il Park, Douglas E. Adams, Yoshinobu Ichikawa, Jacob Bayyouk Jan 2004

Modeling And Simulation Of The Suction Process In A Multi-Cylinder Automotive Compressor, Jeong Il Park, Douglas E. Adams, Yoshinobu Ichikawa, Jacob Bayyouk

International Compressor Engineering Conference

No abstract provided.

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Simulation Of A Virtual Compressor's Vibration, Mirko Della Libera, Alberto Pezzutto, Maurizio Lamantia, Gianluca Buligan Jan 2004

Simulation Of A Virtual Compressor's Vibration, Mirko Della Libera, Alberto Pezzutto, Maurizio Lamantia, Gianluca Buligan

International Compressor Engineering Conference

No abstract provided.

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Analysis Of Structural Mistuning Effects On Bladed Disc Vibrations Including Aerodynamic Damping, Yoon S. Choi, Dana A. Gottfried, Sanford Fleeter Jan 2004

Analysis Of Structural Mistuning Effects On Bladed Disc Vibrations Including Aerodynamic Damping, Yoon S. Choi, Dana A. Gottfried, Sanford Fleeter

International Compressor Engineering Conference

No abstract provided.

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Turbo Water Chiller With Water As Refrigerant, Eberhard Wobst, Nikolai Kalitzin, Rainer Apley Jan 2004

Turbo Water Chiller With Water As Refrigerant, Eberhard Wobst, Nikolai Kalitzin, Rainer Apley

International Compressor Engineering Conference

No abstract provided.

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Development Of A Hermetic Rotary Carbon Dioxide Compressor, Zer Kai Yap, David K. Haller Jan 2004

Development Of A Hermetic Rotary Carbon Dioxide Compressor, Zer Kai Yap, David K. Haller

International Compressor Engineering Conference

No abstract provided.

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Conceptual Design Study Of A Supersonic Compressor Applied To Refrigerant Compression Cycles, Shawn P. Lawlor, Paul M. Brown, Steven G. Mackin Jan 2004

Conceptual Design Study Of A Supersonic Compressor Applied To Refrigerant Compression Cycles, Shawn P. Lawlor, Paul M. Brown, Steven G. Mackin

International Compressor Engineering Conference

No abstract provided.

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Optimization Of Scroll Compressor Involute Height With Machining Considerations, Brian Vanderkooy Jan 2004

Optimization Of Scroll Compressor Involute Height With Machining Considerations, Brian Vanderkooy

International Compressor Engineering Conference

No abstract provided.

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A Transcritical Co2 Turbine-Compressor, Lance Hays, Joost J. Brasz Jan 2004

A Transcritical Co2 Turbine-Compressor, Lance Hays, Joost J. Brasz

International Compressor Engineering Conference

No abstract provided.

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Optimization Of Scroll Compressor Performance With Manufacturing Capability And Reliability Constraints, Jack Sauls Jan 2004

Optimization Of Scroll Compressor Performance With Manufacturing Capability And Reliability Constraints, Jack Sauls

International Compressor Engineering Conference

No abstract provided.

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Introduction Of Transcritical Refrigeration Cycle Utilizing Co2 As Working Fluid, Haruhisa Yamasaki, Masaji Yamanaka, Kenzo Matsumoto, Gaku Shimada Jan 2004

Introduction Of Transcritical Refrigeration Cycle Utilizing Co2 As Working Fluid, Haruhisa Yamasaki, Masaji Yamanaka, Kenzo Matsumoto, Gaku Shimada

International Compressor Engineering Conference

No abstract provided.

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