Experimental Investigation of Design Parameters on Oscillating Heat Pipe (OHP) Based Waste Heat Recovery System PDF Download
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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: 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:
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: Govinda Mahajan
Publisher:
ISBN:
Category :
Languages : en
Pages : 104
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Book Description
The development and implementation of technologies that improves Heating Ventilation & Air Conditioning (HVAC) system efficiency, including unique waste heat recovery methods, are sought while considering financial constraints and benefits. Recent studies have found that through the use of advanced waste heat recovery systems, it is possible to reduce building’s energy consumption by 30%. Oscillating heat pipes (OHP) exists as a serpentine-arranged capillary tube, possesses a desirable aerodynamic form factor, and provides for relatively high heat transfer rates via cyclic evaporation and condensation of an encapsulated working fluid with no internal wicking structure required. In last two decades, it has been extensively investigated for its potential application in thermal management of electronic devices. This dissertation focuses on the application of OHP in waste heat recovery systems. To achieve the goal, first a feasibility study is conducted by experimentally assessing a nine turn copper-made bare tube OHP in a typical HVAC ducting system with adjacent air streams at different temperatures. Second, for a prescribed temperature difference and volumetric flow rate of air, a multi-row finned OHP based Heat Recovery Ventilator (OHP-HRV) is designed and analyzed for the task of pre-conditioning the intake air. Additionally, the energy and cost savings analysis is performed specifically for the designed OHP-HRV system and potential cost benefits are demonstrated for various geographical regions within the United States. Finally, an atypically long finned OHP is experimentally investigated (F-OHP) under above prescribed operating condition. Helical fins are added to capillary size OHP tubes at a rate of 12 fins per inch (12 FPI), thereby increasing the heat transfer area by 433%. The coupled effect of fins and oscillation on the thermal performance of F-OHP is examined. Also, F-OHP’s thermal performance is compared with that of bare tube OHP of similar dimension and operating under similar condition. It was determined that OHP can be an effective waste heat recovery device in terms of operational cost, manufacturability, thermal and aerodynamic performance. Moreover, it was also determined that OHP-HRV can significantly reduce energy consumption of a commercial building, especially in the winter operation.
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: Omar Talal Ibrahim
Publisher:
ISBN:
Category :
Languages : en
Pages : 81
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Book Description
Passive and compact heat dissipation systems are and will remain vital for the successful operation of modern electronic systems. Oscillating heat pipes (OHPs) have been a part of this research area since their inception due to their ability to passively manage high heat fluxes. In the current investigation, different designs of tubular, flat plate, and multiple layer oscillating heat pipes are studied by using different operating parameters to investigate the operating limitations of each design. Furthermore, selective laser melting was demonstrated as a new OHP manufacturing technique and was used to create a compact multiple layer flat plate OHP. A 7-turn tubular oscillating heat pipe (T-OHP) was created and tested experimentally with three working fluids (water, acetone, and n-pentane) and different orientations (horizontal, vertical top heating, and vertical bottom heating). For vertical, TOHP was tested with the condenser at 0°, 45° and 90° bend angle from the y-axis (achieved by bending the OHP in the adiabatic) in both bottom and top heating modes. The results show that T-OHP thermal performance depends on the bend angle, working fluid, and orientation. Another design of L-shape closed loop square microchannel (750 x 750 microns) copper heat pipe was fabricated from copper to create a thermal connector with thermal resistance
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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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: 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: 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: 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: Aaron A. Hathaway
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 45
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Book Description
An experimental investigation on oscillating heat pipes with uneven turns was conducted in order to determine the effect of short turns on the heat transport capability. The shorter turns do not go through both the evaporating and condensing sections; the short turns were placed only in the evaporating section. The design of the OHP consists of 14 long turns which run from the evaporator to the condenser and 6 short turns were placed only on the evaporating section. An extensive experimental investigation on the effects of the input power, tilted angle, condensing temperature, and charging ratio was conducted. Experimental results show that for all test conditions, the OHP functions very well and it can transport an input power up to 1200 W and can reach a thermal resistance of 0.028. From the experimental results of tilted angle effect, it can be found that the heat pipe is almost independent of the tilted angle. Most importantly, it is shown that with a number of short turns placed on the evaporating section, the OHP can operate efficiently without the assistance of the gravitational force. In other words, the heat pipe developed herein can operate at a condition of the heating section on the top and the cooling section on the bottom with a distance of 18.5 cm from the center of the evaporator section the center of the condensing section. In addition, the results show that the heat transfer performance depends on the operating temperature and charging ratio. When the operating temperature increases, the heat transfer performance of the OHP investigated herein significantly increase. WC/o.
