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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: Hongbin Ma
Publisher: Springer
ISBN: 1493925040
Category : Science
Languages : en
Pages : 441
Get Book Here
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: Fritz Laun (Thermal aerospace engineer)
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 21
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Book Description
With ever increasing technological advances in electronics, modern computer components continue to produce higher power densities that present a challenge to thermal management. A radial flat-plate oscillating heat pipe (RFP-OHP) heat spreader is investigated to study the effect of central heating on the heat transport capability in an OHP. The investigated OHP has dimensions of 100 mm x 100 mm x 2.5 mm with central heating using a 30 mm x 30 mm heater. Experimental results show that when heat is added to the center section of one side of the radial flat-plate OHP, and when heat is removed from the whole surface of another side of the heat pipe, the startup power for the oscillating motion increases. In addition, the spacer effect on the heat transport capability including the startup is investigated experimentally. The spacer added between the cooling block and OHP could lower the startup power for oscillatory motion. When compared to a copper slab of the same dimensions in the same test configuration, the temperature difference for the OHP with and without the additional copper spacer was reduced by a maximum of 46 and 25%, respectively, at a power input of 525 W and a heat flux of 58 W/cm2.
Author: Christopher Smoot
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 62
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Book Description
A new disc oscillating heat pipe has been developed and tested for use in high heat flux applications with a localized heat source. The results show that the heat pipe offers a significant improvement in performance over a copper disc when charged with water or acetone. Despite the improvement, the heat pipe displayed some unexpected behavior. The heat pipe required far more power input to achieve startup than expected, given the heat pipe's small size, and the heat pipe demonstrated much smaller temperature oscillation amplitude than expected. To investigate this behavior, two additional oscillating heat pipes were constructed to test the effect of heat conduction through the adiabatic section of the heat pipe. The results clearly demonstrated that the presence of heat conduction through the adiabatic section of a heat pipe required far more power to startup, between 25 and 275 W additional power depending on the working fluid, condenser temperature, and orientation. The presence of heat conduction through the adiabatic section also demonstrated reduced oscillation amplitude. It was also found that the presence of heat conduction through the adiabatic section of an oscillating heat pipe resulted in better performance than a heat pipe without conduction through the adiabatic section.
Author: Corey A. Wilson
Publisher:
ISBN:
Category : Diamonds
Languages : en
Pages :
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Book Description
An experimental investigation was conducted of oscillating heat pipes (OHP) charged with diamond nanofluid. By combining the high thermal conductivity of nanofluids with the high heat transport rate of OHPs, a new type of heat pipe was developed. The diamond nanofluid used in this experiment was a combination of 5-50 nm diamond nanoparticles and a base fluid of high performance liquid chromatography (HPLC) grade water. The nanofluid thermal conductivity was found to be 1.00 W/m-K this is a 67% increase compared to HPLC grade water. It was shown that the OHP thermal resistance decreased from 0.75 °C/W with HPLC grade water to 0.49 °C/W with diamond nanofluid at an operating temperature of 20 °C and a heat load of 50 W, which is a 34% improvement in thermal resistance. Also by increasing the temperature, the OHP performance increased substantially. However, the difference between the nanofluid and the base fluid at higher temperatures was less significant. Even so, a thermal resistance of 0.03 °C/W was achieved at 336 W and with an operating temperature of 70 °C. Fluid frequency and amplitude were observed, via neutron radiography, to increase at increased temperatures and increased heat flux. Also, for the same heat flux and operating temperature, the water OHP had a slightly higher frequency and amplitude than the nanofluid OHP. Both of these trends matched the temperature trends observed with the thermocouples.
Author: Shibin Liang
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages :
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Book Description
A mathematical model describing the oscillation characteristics of slug flow in a capillary tube is presented. The model considers the vapor bubble as the gas spring for the oscillating motions in a capillary tube including effects of capillary force, gas spring constant, dimensions, gravitational force, and initial pressure distribution of the working fluid. Numerical results indicate that the isentropic bulk modulus generates stronger oscillations than the isothermal bulk modulus. While it demonstrates that the capillary tube diameter, bubble size, and unit cell numbers determine the oscillation, the capillary force, gravitational force, and initial pressure distribution of the working fluid significantly affect the frequency and amplitude of oscillating motion in the capillary tube. An experimental study of a five-turn closed loop oscillating heat pipe has been conducted. The oscillating heat pipes charged with HPLC grade water, acetone and ethanol have been tested respectively. In a vertical orientation, the oscillating motion of the slug flow in the oscillating heat pipe has been observed.
Author: Mustafa Nezih Kaya
Publisher:
ISBN:
Category :
Languages : en
Pages : 46
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Book Description
In this research, we quantify the parametric effects (number of turns, inclination angle, and filling ratio) on different designs of closed loop oscillating heat pipes (CLOHPs). Experiments were conducted on a CLOHP. Tubes were heated and cooled by constant temperature in wind tunnels, and n-pentane was used as the working fluid. The effects of number of turns were investigated to prove the less gravity effect when the number of turns increases. Inclination angle effects were investigated to verify inclination angle decreases the affects of gravitational force. Tubes were charged to 0 and to 70 percent of total volume of tubes with n-pentane to demonstrate optimum heat transfer between condenser and evaporation sections. The importance of this work is in presenting design parameters to obtain lower energy consumption compare with previous known designs. Results indicate that 9 turns, 90-degree inclination angle, and charging 70 percent are the most effective design parameters.
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:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
In this research, we quantify the parametric effects (number of turns, inclination angle, and filling ratio) on different designs of closed loop oscillating heat pipes (CLOHPs). Experiments were conducted on a CLOHP, which is made of copper tube with 1.65-mm inner diameter. Tubes are heated and cooled by constant temperature in wind tunnels, and n-pentane was used as the working fluid. The numbers of turns used were 5, 7, and 9. The effects of number of turns were investigated in order to prove the less gravity effect when the number of turns increases. Inclination angles used were 75, 82.5, and 90-degree. Inclination angle effects were investigated to verify that inclination angle decreases the affects of gravitational force. The tubes were charged to 0 and to 70 percent of total volume of tubes with n-pentane to demonstrate optimum heat transfer between condenser and evaporation sections. The importance of this work is in presenting design parameters to obtain lower energy consumption in comparison to previous known designs. Results indicate that 9 turns, 90-degree inclination angle, and charging 70 percent n-pentane of tubes were the most effective design parameters.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 42
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Book Description
Operation requirements of oscillating heat pipes (OHPs) were proposed. Based on the requirements, OHPs with acetone and nonflammable fluorocarbon fluids, FC-72 and FC-75, as the working fluid were developed. The OHPs had 40 tubing turns formed from a copper tubing with an inner diameter of 1.75 mm and a total length of 18.61 m. The OHPs were formed in the shape of a planer array that was 256-min wide and 446mm high. There were two condensers on both outer sides and one evaporator in the middle of the OHPs. Thermal performance tests were conducted at various operating temperatures and heat rates. The working fluid fill ratio was varied The OHPs with acetone and FC-72 exhibited their highest heat transport performance in excess of 2000 W without dryout. This is the first time that such a performance was demonstrated. The gravitational acceleration did not have noticeable influence on the performance of the OHPs. The thermal performances of the fluorocarbon OHPs were compared with the case of the acetone OHP.
Author: O. J. Foust
Publisher: Routledge
ISBN:
Category : Liquid metals
Languages : en
Pages : 352
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Book Description
