Author: Brian V. Borgmeyer
Publisher:
ISBN:
Category : Electronic apparatus and appliances
Languages : en
Pages : 174
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Book Description
As the conventional heat sinks meet their heat transport limit, the pulsating heat pipe as one of advanced phase-change heat transfer devices will present the next generation of electronics cooling. An experimental and theoretical study was conducted regarding the motion of the liquid and vapor slugs within a pulsating heat pipe. A pulsating heat pipe with non-circular channels was investigated to determine the effect of operating parameters such as working fluid, tilted angle, filled liquid ratio, and heat flux level. The mathematical model theoretically solved for the position and velocity of the liquid and vapor slugs using the modified governing equations for a mechanical forced damped system. For comparison, experimental investigations quantified the position and velocity of the liquid-vapor interface through the use of a high speed camera. The mathematical and experimental investigations explored the effect of the various parameters on fluid motion. Experimental data obtained from the high speed camera did not show good relation to the mathematical model developed, however, the effects of each parameter seen in the model related to experimental observations.
Author: Tyler Baxter Duncan
Publisher:
ISBN:
Category : Microcomputers
Languages : en
Pages : 150
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Book Description
The current investigation is to develop a high heat flux heat pipe that is intended to dissipate a minimum of 80 W/cm 2 . In order to accomplish this task, a "tower" heat pipe will be developed. In this heat pipe, a vertical tube with an enhanced internal surface of capillary grooves will be used to promote condensation and direct fluid flow. The flat end surfaces will have a wick structure of sintered particles to ensure even wetting of the evaporative region and provide optimal conditions for thin film evaporation. A mathematical model will be developed to predict the heat transfer performance of this "tower" heat pipe. The investigation will result in a better understanding of heat transport capability occurring in a highly efficient heat pipe.
Author: Hongbin Ma
Publisher: Springer
ISBN: 1493925040
Category : Science
Languages : en
Pages : 441
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Book Description
This book presents the fundamental fluid flow and heat transfer principles occurring in oscillating heat pipes and also provides updated developments and recent innovations in research and applications of heat pipes. Starting with fundamental presentation of heat pipes, the focus is on oscillating motions and its heat transfer enhancement in a two-phase heat transfer system. The book covers thermodynamic analysis, interfacial phenomenon, thin film evaporation, theoretical models of oscillating motion and heat transfer of single phase and two-phase flows, primary factors affecting oscillating motions and heat transfer, neutron imaging study of oscillating motions in an oscillating heat pipes, and nanofluid’s effect on the heat transfer performance in oscillating heat pipes. The importance of thermally-excited oscillating motion combined with phase change heat transfer to a wide variety of applications is emphasized. This book is an essential resource and learning tool for senior undergraduate, graduate students, practicing engineers, researchers, and scientists working in the area of heat pipes. This book also · Includes detailed descriptions on how an oscillating heat pipe is fabricated, tested, and utilized · Covers fundamentals of oscillating flow and heat transfer in an oscillating heat pipe · Provides general presentation of conventional heat pipes
Author: Uzoma Cornelius Mmeje
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Pulsating heat pipes (PHPs) have been studied since the 1990s and are potential replacements for copper thermal buses or standard heat pipes. Currently there is not a well-defined process for PHP design for a particular heat load or application. This is partially because of the number of variables that affect the performance of a PHP. PHP's that operate using cryogenic fluids have been studied even less than those that operate at near room temperature and higher. In this work we endeavor to expand the understanding of the performance and behavior of cryogenic PHPs including conductance and maximum heat load capacity (load at dry out) with respect to operating temperature, fill ratio and working fluid properties. This study focuses on exploring the operating regions not previously explored in cryogenic pulsating heat pipes at UW Madison. An experimental device (pulsating heat pipe) has been built, consisting of a single evaporator and a single condenser separated by an adiabatic length. The main purpose of this study is to characterize the effective conductivity of the device for a range of condenser temperatures and increase the heat load until dry-out is achieved. This test procedure was conducted for a range of fill ratios. The data were analyzed to obtain optimal parameters that can be used in the design of a pulsating heat pipe using Nitrogen as a working fluid. The second purpose of this experimental study was to explore dry-out phenomena. Because the PHP is a cryogenic device it is non-optical, so the flow pattern cannot be visually observed, but some information about near dry-out behavior can be obtained from the temperature fluctuations observed in the condenser, evaporator, and adiabatic sections. Additional experiments with Argon and a mixture (Air) as the working fluid were run. The results of these studies and the Nitrogen results are compared with respect to conductance and dry-out behavior.
Author: Amir Faghri
Publisher: Global Digital Press
ISBN: 1560323833
Category : Science
Languages : en
Pages : 32
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Book Description
Presents basic and advanced techniques in the analytical and numerical modeling of various heat pipe systems under a variety of operating conditions and limitations. It describes the variety of complex and coupled processes of heat and mass transfer in heat pipes. The book consists of fourteen chapters, two appendices, and over 400 illustrations, along with numerous references and a wide variety of technical data on heat pipes.
Author: Chiang Yi Wai
Publisher:
ISBN: 9780494400562
Category :
Languages : en
Pages : 164
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Book Description
Pulsating heat pipes (PHPs) have emerged as possible cooling devices for high heat flux electronics. In this study, an optimum PHP design is investigated. The PHPs were constructed of multiport extruded aluminum tubing. Several parameters were varied for this purpose: type of working fluid, the fluid fill ratio, the heat pipe orientation, and the PHP dimensions. Addition of diamond nanoparticles to the working fluid was also tested. It was found that the optimum fluid fill ratio depends on the PHP structure, with 50% and 20% being the best values for the 35-port and 26-port PHPs, respectively. Also, the 35-port design was able to dissipate a higher power input of 80W, versus 60W for the 26-port case. In the vertical orientation the PHP delivered better performance compared to the horizontal case. Acetone outperformed ethanol only at low power inputs. The nanoparticle addition slightly improved the PHP performance.
Author: David Reay
Publisher: Butterworth-Heinemann
ISBN: 0080982794
Category : Technology & Engineering
Languages : en
Pages : 280
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Book Description
Heat Pipes, Sixth Edition, takes a highly practical approach to the design and selection of heat pipes, making it an essential guide for practicing engineers and an ideal text for postgraduate students.This new edition has been revised to include new information on the underlying theory of heat pipes and heat transfer, and features fully updated applications, new data sections, and updated chapters on design and electronics cooling. The book is a useful reference for those with experience and an accessible introduction for those approaching the topic for the first time. Contains all information required to design and manufacture a heat pipe Suitable for use as a professional reference and graduate text Revised with greater coverage of key electronic cooling applications
Author: Anjun Jiao
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages :
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Book Description
The heat pipe, as one of the most efficient heat transport devices, is a peerless choice in the electronic cooling field. In order to better understand the heat transfer mechanisms of the heat pipe, a heat transfer model, which considers the effects of the surface condition, disjoining pressure, gravity force, and contact angle on the thin film profile, heat flux distribution, has been developed. The theoretical analyses showed that the heat transfer in the evaporator could be divided into three templates: CASE I, II, and III with increasing the heat load input. In order to verify the theoretical analysis, experimental investigations of a grooved heat pipe with micro trapezoid wicks, a miniature loop heat pipe with a copper sintered-layer flat evaporator, and a flat heat pipe with the wire core wicks were conducted, respectively. Comparison of the experimental data with theoretical results showed that the model can be used to predict the temperature response in evaporator at low heat load but is invalid at high heat load. The thin film evaporation heat transfer model is successful to address the heat transfer in a cell during the freezing process. In order to obtain ultra-high cooling rate and uniform temperature profiles at cryogenic temperature, one cryogenic oscillating heat pipe with the liquid nitrogen as its working fluid has been developed and experimentally studied. Experimental results showed that its heat transport capability reached 380W with 0, 49 C Ave e c T [delta] = at charged ratio of 48 percent. At steady state, the amplitude temperature response in evaporator was smaller than that of condenser while the temperature response kept the same frequency in both evaporator and condenser. The [delta]T amplitude between evaporator and condenser decreased with increasing the heat load.
Author: Yaxiong Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 536
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Book Description
Author: P. J. Marto
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 68
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Book Description
