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1
Alexseev, Alexandre Viktorovich. "Micro loop heat pipe evaporator coherent pore structures." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1303.
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Loop heat pipes seem a promising approach for application in modern technologies where such thermal devices as cooling fans and radiators cannot satisfy overall requirements. Even though a loop heat pipe has a big potential to remove the thermal energy from a high heat flux source, the heat removal performance of heat pipes cannot be predicted well since a first principles of evaporation has not been established. An evaporation model based on statistical rate theory has been recently suggested by Ward and developed for a single pore by Oinuma. A loop heat pipe with coherent pore wick structure has been proposed as a design model.
To limit product development risk and to enhance performance assurance, design model features and performance parameters have been carefully reviewed during the concept development phase and have been deliberately selected so as to be well-founded on the limited existing loop heat pipe knowledge base. A first principles evaporation model has been applied for evaporator geometry optimization. A number of iteration calculations have been performed to satisfy design and operating limitations. A set of recommendations for design optimization has been formulated. An optimal model has been found and proposed for manufacture and experimental investigation.
2
Lee, Man. "Design, fabrication and characterization of an integrated micro heat pipe system /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?MECH%202002%20LEE.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 74-77). Also available in electronic version. Access restricted to campus users.
3
Simionescu, Florentina. "Considerations on optimum design of micro heat pipe sinks using water as working fluid." Auburn, Ala., 2006. http://repo.lib.auburn.edu/Send%2012-15-07/SIMIONESCU_FLORENTINA_33.pdf.
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Coughlin, Scott Joseph. "Optimization of the configuration and working fluid for a micro heat pipe thermal control device." Texas A&M University, 2005. http://hdl.handle.net/1969.1/3193.
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Continued development of highly compact and powerful electronic components
has led to the need for a simple and effective method for controlling the thermal
characteristics of these devices. One proposed method for thermal control involves
the use of a micro heat pipe system containing a working fluid with physical properties
having been speciffcally selected such that the heat pipes, as a whole, vary in effective
thermal conductance, thereby providing a level of temperature regulation. To further
explore this possibility, a design scenario with appropriate constraints was established
and a model developed to solve for the effective thermal conductance of individual
heat pipes as a function of evaporator-end temperature. From the results of this
analysis, several working fluids were identified and selected from a list over thirteen
hundred that were initially analyzed. Next, a thermal circuit model was developed
that translated the individual heat pipe operating characteristics into the system as a
whole to determine the system level effects. It was found that none of the prospective
fluids could completely satisfy the established design requirements to regulate the
device temperature over the entire range of operating conditions. This failure to
fully satisfy design requirements was due, in large part, to the highly constrained
nature of problem definition. Several fluids, however, did provide for an improved
level of thermal control when compared to the unmodified design. Suggestions for improvements that may lead to enhanced levels of thermal control are offered as well
as areas that are in need of further research.
5
SHARMA, MONIKA. "THIN FILM EVAPORATION IN THE PORES OF MICRO LOOP HEAT PIPE WITH NON-UNIFORM HEAT FLUX." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1132344889.
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Shuja, Ahmed A. "Material and Processing Development Contributions Toward the Development of a MEMS Based Micro Loop Heat Pipe." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1179501051.
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PONUGOTI, PRIYANKA. "STUDY OF TRANSIENT BEHAVIOR OF THE EVAPORATOR OF THE MICRO LOOP HEAT PIPE AND MODIFICATIONS TO THE EXISTING GLOBAL MODEL." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1152120818.
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SHUJA, AHMED. "DEVELOPMENT OF A MICRO LOOP HEAT PIPE, A NOVEL MEMS SYSTEM BASED ON THE CPS TECHNOLOGY." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054220863.
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ARRAGATTU, PRAVEEN KUMAR. "OPTIMAL SOLUTIONS FOR PRESSURE LOSS AND TEMPERATURE DROP THROUGH THE TOP CAP OF THE EVAPORATOR OF THE MICRO LOOP HEAT PIPE." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1152120112.
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Medis, Praveen S. "Development of Microfluidic Packaging Strategies, with Emphasis on the Development of a MEMS Based Micro Loop Heat Pipe." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1131996727.
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de, Bock Hendrik Pieter Jacobus. "Design and Experimental Validation of a Micro-Nano structured Thermal Ground Plane for high-g environments." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1367937275.
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Zeghari, Kaoutar. "Développement de micro-caloduc pour le bâtiment et l'électronique : modélisation et expérimentation." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMC218.
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L'objectif de cette étude est d’introduire un système de transfert thermique passif dont les performances seront optimisées pour réduire l’effet de l’humidité dans les matériaux de construction bio sourcés et particulièrement dans les mélanges en Bauge. La solution étudiée est les caloducs combinant le transfert thermique par changement de phase et une flexibilité d’application que ça soit pour chauffage comme dans notre cas ou pour refroidissement comme il est courant dans le domaine du refroidissement passif. Cette technologie permet la gestion thermique avec toute simplicité, sans encombrement ni consommation de l’énergie. Le caloduc est en effet un dispositif fermé généralement conçu en cuivre ayant une architecture interne permettant la circulation du fluide entre la zone chauffante (évaporateur) et la zone refroidie (condenseur). Différents prototypes expérimentaux ont été construits au laboratoire pour caractériser en premier lieu les propriétés thermiques des mélanges en bauge, étudier le transfert thermique dans différents caloducs poreux et à micro canaux et aussi pour étudier l’application des caloducs dans ces mélanges de bauge en se basant sur une méthode standardisée de caractérisation hydrique des matériaux de construction. Nombreuses études expérimentales sont introduites. L'influence du taux de chargement, type de fluide, type de structure interne, dimensions, géométrie, et aussi la puissance électrique est détaillée et analysée. En parallèle, des modèles mathématiques thermiques et hydrauliques ont été développés pour prédire les performances du caloduc poreux et à micro canaux. Une comparaison avec les résultats expérimentaux est également effectuée permettant une vérification des modèles. Aussi, une étude d’optimisation est introduite en comparant les performances des différents caloducs et en étudiant l’effet d’utilisation des MCPs côté évaporateur et condenseur. Enfin, l’application des caloducs dans les bâtiments est mise en évidence par une étude expérimentale en intégrant les caloducs dans les mélanges en bauge. L’étude est réalisée dans une chambre climatique simulant différents cycles de variation d’humidité afin d’évaluer l’effet du caloduc sur les performances hygrothermiques de ce matériauThe objective of this study is to introduce a passive heat transfer system whose performance will be optimized to reduce the effect of humidity in bio-sourced building materials and particularly in cob mixes. The studied technology is heat pipes combining heat transfer through phase change and flexibility of application whether for heating as in this study or for cooling as it is common in passive cooling application. This solution enables an effective thermal management with easiness, without compaction nor energy consumption. The heat pipe is in fact a closed device generally designed using copper with an internal wick structure allowing the circulation of the fluid between the heating zone (evaporator) and the cooled zone (condenser). Different experimental set ups were built in the laboratory to first characterize the thermal properties of cob mixes, then, to study the heat transfer in different porous and microchannel heat pipes and after to study the application of heat pipes in these cob mixes based on a standardized method for hydrothermal construction materials characterization. Many experimental studies are introduced by investigation the effect of several parameters. The influence of the fill ratio, type of working fluid, and type of internal structure, dimensions, geometry, and the effect of input heat flux are detailed and analyzed. In parallel, thermal and hydraulic mathematical models have been developed to predict the performance of the porous and microchannel heat pipe. A comparison with the experimental results is also carried out allowing a verification of the models. In addition, an optimization study is introduced by comparing the performance of different heat pipes and studying the effect of using PCMs on the evaporator and condenser side. Finally, the application of heat pipes in buildings is evaluated by investigating experimentally the integration of heat pipes in cob mixes. The study is carried out in a climatic chamber simulating different cycles of humidity variation in order to assess the effect of the heat pipe on the hydrothermal performance of this material
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Nadgauda, Omkar Satish Harris Daniel K. "Fabrication, filling, sealing and testing of micro heat pipes." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Fall/Theses/NADGAUDA_OMKAR_39.pdf.
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Parimi, Srinivas. "Coherent Porous Silicon Technology for Micro Loop Heat Pipes and Chromatography." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1147030376.
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Júnior, Ilvandro Luiz Souza Sueth. "Análise teórica-experimental do desempenho térmico de micro tubos de calor." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18147/tde-15022019-142004/.
Full textAbstract:
O objetivo deste trabalho consiste na análise teórica e experimental do desempenho térmico de dois arranjos de micro tubos de calor. Os arranjos diferem entre si pelo material base de fabricação, que são Acrilonitrila Butadieno Estireno (ABS) e latão, pelo número de canais e pelas dimensões. O fluido de trabalho utilizado foi R134a. A literatura indica micro tubos de calor como soluções proeminentes e de destaque para resfriamento de micro sistemas. Estes dispositivos podem ser adaptados a diferentes condições térmicas através da mudança de fluidos de trabalho, geometrias e materiais base do trocador. O estudo teórico foi baseado no modelo de circuitos térmicos proposto no presente trabalho, que visa calcular indicadores de desempenho térmico, sendo condutividade térmica efetiva e resistência térmica equivalente dos micro tubos de calor a partir das temperaturas obtidas experimentalmente. O estudo experimental foi baseado em obter distribuições de temperaturas dos dispositivos propostos sob diferentes condições de trabalho, variando-se a fração de enchimento de fluido de trabalho, inclinação e temperatura do condensador. Os resultados obtidos para o arranjo de micro tubos de calor em latão demonstrou uma razão de aumento de até 1482% na capacidade de transporte de calor, enquanto que o arranjo de micro tubos de calor em ABS apresentou uma razão de aumento de 247%. Os melhores desempenhos de ambos os casos foram observados para ângulos positivos com baixas frações de enchimento.The purpose of this work is the theoretical and experimental study on the thermal performance of two micro heat pipes arrays. The differences between the arrays are the base substrate, which are Acrylonitrile Butadiene Styrene (ABS) and brass, the number of channels and their dimensions. The working fluid used was R134a. Previous works indicate micro heat pipes as prominent solutions for the cooling of micro systems. These devices can be adapted to different thermal conditions by changing the working fluids, geometries and base materials of the heat exchanger. The theoretical study was based on the thermal circuits model presented in this work, that aims on computing thermal performance indicators, such as the effective thermal conductivities and the equivalent thermal resistances of the micro heat pipes from the temperatures obtained experimentally. The experimental study was based on obtaining temperature distributions of the micro heat pipes under different working conditions, by varying the working fluid filling ratio, tilt angle and the temperature of the cooling water at the condenser. The results obtained for the brass micro heat pipe array showed a performance ratio increase up to 1482% in heat transfer capacity, while the ABS micro heat pipe array showed a performance ratio increase of 247%. The best performance for both cases were observed for positive tilt angles with low working fluid filling ratios.
16
Oinuma, Ryoji. "Fundamental study of evaporation model in micron pore." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1239.
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As the demand for high performance small electronic devices has increased, heat removal
from these devices for space use is approaching critical limits. A heat pipe is a promising
device to enhance the heat removal performance due to the phase change phenomena for
space thermal management system. Even though a heat pipe has a big potential to remove
the thermal energy from a high heat flux source, the heat removal performance of heat
pipes cannot be predicted well since the first principle of evaporation has not been
established. The purpose of this study is to establish a method to apply the evaporation
model based on the statistical rate theory for engineering application including
vapor-liquid-structure intermolecular effect. The evaporation model is applied to the heat
pipe performance analysis through a pressure balance and an energy balance in the loop
heat pipe.
17
Markos-Gebresilassie, Mulugeta. "Steady liquid flow and liquid-vapor interface shapes in different groove structures in micro heat pipes." Ann Arbor, Mich. : ProQuest, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3258674.
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Thesis (Ph.D. in Applied and Computational Mathematics)--S.M.U., 2007.Title from PDF title page (viewed Mar. 18, 2008). Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1673. Adviser: Vladimir Ajaev. Includes bibliographical references.
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Zaaroura, Ibrahim. "Amélioration du transfert de chaleur et de masse à l'aide de nanofluides auto-réhumidifiants." Thesis, Valenciennes, Université Polytechnique Hauts-de-France, 2020. http://www.theses.fr/2020UPHF0024.
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La gestion thermique est actuellement un enjeu majeur dans de nombreux secteurs industriels. Les dispositifs de transfert de chaleur (comme les caloducs) sont des systèmes intégrés qui utilisent des modes de transfert par convection, évaporation et condensation. L'efficacité de l'échange thermique peut être améliorée en utilisant une nouvelle méthode de nanotechnologie connue sous le nom de nanofluides. Les nanofluides sont des suspensions de particules nanométriques (de 2 à 100 nm) dans les fluides. Cette amélioration est due à l'augmentation significative de la conductivité effective dans la plage de 10 à 50% ainsi qu'à leurs coefficients de transfert de chaleur par convection. Cependant, des limitations liées aux phénomènes de nanoparticules, de sédimentation et d'agrégation apparaissent au cours de différentes phases. Dans ce projet, afin d'optimiser les performances et la stabilité des nanofluides, deux méthodes différentes ont été utilisées: une optique couplée à une méthode de thermographie infrarouge et une méthode acoustique à haute fréquence. La sélection des nanoparticules a été basée sur leurs performances thermiques lors de l'évaporation de gouttelettes sessiles à l'aide d'un système Kruss, dans les mêmes conditions et à des concentrations différentes. Ainsi, des ondes acoustiques haute fréquence, en surface, ont permis d'analyser la stabilité de nanoparticules lors de l’évaporation où ces particules sont en suspension avec des fluides de base tels que l'eau ionisée, des mélanges binaires auto-réhumidifiant (Pour améliorer la circulation des fluides à l'intérieur caloducs grâce à leurs propriétés physiques comme les phénomènes Marangoni thermique, Marangoni de concentration, capillaires ...). Les nanofluides sélectionnés seront utilisés par la suite pour analyser expérimentalement leurs performances sur les dispositifs de transfert de chaleur à boucle de fluide capillaire biphasé et dans les échangeurs de chaleur à micro-canaux en trouvant et en calculant la résistance thermique du système, le coefficient de transfert de chaleur par convection et la température de paroiThermal management is currently a major issue in many sectors of industry. Heat transfer devices (like Heat Pipes, Heat exchangers…) are integrated systems that use transfer modes by convection, evaporation and condensation. The efficiency of heat exchange can be improved by using a new nanotechnology method known as nanofluids. Nanofluids are suspensions of nano-size particles (from 2 to 100nm) in the fluids. This improvement is due to the significant increase in the effective conductivity in the range 10-50% as well as their convective heat transfer coefficients. However, limitations related to the phenomena of nanoparticle, sedimentation and aggregation appear during different phases. In this project, in order to optimize the performance and stability of nanofluids, two different methods were used: an optical one coupled to an infrared thermography method and a high frequency acoustic method. The selection of nanoparticles was based on their thermal performance during evaporation of sessile droplets using a Kruss system, under same conditions and at different concentrations. Thus, high frequency acoustic waves, at the surface, make it possible to analyze the stabilities of nanoparticles during its evaporation where these particles are in suspension with base fluids such as ionized water, self-rewetting binary mixture (To improve the circulation of fluids inside heat pipes thanks to their physical properties like thermal Marangoni, concentration Marangoni, capillary...). The selected nanofluids will be used later to analyze experimentally their performance on two-phase capillary fluid loop heat transfer devices and in micro-channel heat exchangers by finding and calculating the thermal resistance of the system, convection heat transfer coefficient and wall temperature
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Huang, Der-Lin, and 黃德麟. "Novel Micro Heat Pipe." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/07987114127020844061.
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碩士淡江大學
機械工程學系
88
With the development of miniaturized and high power electronic devices in recent years, electronic heat dissipating apparatus have become important. In 1984 T. P. Cotter proposed the ideal of micro heat pipe to solve the problem of heat dissipation on electronic devices. Researches about micro heat pipe involved theoretical analysis and experimental tests were proposed. In this thesis, star groove and plate micro heat pipe were fabricated. Heat transfer performance of micro heat pipe was enhanced due to better capillarity provided by more acute angles and micro gap. Star groove and plate micro heat pipe fabricated by bulk micromachining 4-inch (100) silicon wafers. Finally, micro heat pipe structure was bonded by employed eutectic bonding technique. Testing has been conducted to evaluate the performance over a range of fluid volume, heat fluxes and working angle. We glue heater on the evaporator section of the heat pipe, infuse cold water through a copper pipe in the condenser section, and paste K-type thermocouples on the micro heat pipe in the direction of the length. Then we join the thermocouple to a data acquisition system and adopt Fourier’s Law to calculate effective heat conductivity. The best thermal conductivities of star grooves MHP and plate MHP are 277.9 W/mK and 289.4 W/mK, respectively.
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Ko, Ming-Han, and 柯明翰. "Fabrication of Metallic Micro Heat Pipe Heat Spreaders." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/83456280411049357092.
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碩士淡江大學
機械工程學系
90
Micro heat pipe heat spreader (MHPHS) with a three-layer copper foils was designed to allow separation of the liquid and vapor flow to reduce the viscous shear force. Two wick designs, one using 200μm wide etched radial grooves and the other with 100 mesh copper screens were investigated. The foils were vacuum diffusion bonded to form a 31mm×31mm×2.7mm heat spreader. Thermal performance of the MHHPS was evaluated experimentally in a fan-heat sink CPU test apparatus with a heating area of 13.97mm×13.97mm. The clamping pressure between the spreader and the heat sink was maintained at 13kgf during the test. After the evaluation, the MHPHS with 82% methanol fill rate, radial grooves wicking structure showed the best performance as compared to the other samples. It has lower evaporator temperature with value of 17℃, corresponding to a 30% decrease in thermal resistance at an actual input power of 35W, as compared to the system without MHPHS.
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Huang, Yu-Nien, and 黃玉年. "Fabrication and Test of Silicon Micro Heat Pipe." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/85317641872606859432.
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碩士淡江大學
機械工程學系
87
With the development of miniaturized and high power electronic devices in recent years, electronic heat dissipating apparatus have become important, and accordingly various models have been developed. Micro Heat Pipe, advanced initially by T. P. Cotter in 1984, is a micro heat transfer device designed to transfer heat by high-efficient phase change. Subsequently, most related research gauges numerical analysis to deduce its heat dissipating capacity. However, it has been weak in experimental and capacity tests. In view of that, I posit fabrication and test of silicon micro heat pipe. Applying micro-fabricative technique, I use KOH etchant to etch 54.7° lumbo-equal triangle ditch, 115 μm in width, 24.5mm in length, and 127 in number, in a square area 25.4 mm on (100) a 4-inch silicon wafer. And then I bond it with 7740 glass by Anodic-bonding to complete the structure of a micro heat pipe. Designing a new simple packaging technique, I evacuate a micro heat pipe to a pressure under 4.0 x 10-3 torr and fill it with 12%, 24%, 36%, and 70% volume of methanol as working liquid. In the capacity test, I glue 6mm × 25.4mm heater on the evaporator section of the heat pipe, infuse 16.5℃ cold water through a copper pipe in the condenser section, and paste a K-type thermocouple on the micro heat pipe in the direction of the length. Then I join the thermocouple to a data acquisition system and adopt Fourier''s Law to calculate effective heat conductivity as capacity valuation. In addition, I also deeply discuss and experiment on the working angle vs. effective heat conductivity of the micro heat pipe. From experiments, I obtain that the working temperature of micro heat pipe ranges from 20℃ to 80℃, the greatest dissipating capacity is 6 Watt, and the effective conductivity attains 208W/mk. There is no dry-out phenomenon of the micro heat pipe in any working angles. The results are compared to earlier published data of Duncan and Badran.
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Kao, Cheng-Chun, and 高政群. "Design and Fabrication of the Micro Loop Heat Pipe." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/04273706136085447176.
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卓世傑. "A Research of Powder Sintered type Micro Heat Pipe." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/33567980057604425109.
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碩士國立臺北科技大學
機電整合研究所
88
The purpose of this thesis is to manufacture a micro heat pipe that uses copper powder as wick structure to provide a passive heat transfer design for notebook computers. Consider three effects of powder size, sinter time and sinter temperature, both the porosity and permeability can be measured. We also observe the variety of permeability and conductivity at different porosity. Also this thesis provides a method of manufacturing sinter heat pipe that uses copper powder sintered as wick structure in the laboratory and doing the performance testing on the heat pipe. We found that the operation angle does not have significant influence on the thermal resistance of the heat pipe, which means the capillary force of the wick structure is enough large than the gravitational force, so the thermal resistance not effected by the gravity.
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李偉嵐. "Manufacturing and analysis of flat plate micro heat pipe." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/57292006691765925815.
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Hsu, Chin-Chun, and 許欽淳. "Application of Nanofluids in Fabrication of Micro Loop Heat Pipe." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/47592649691974683658.
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碩士淡江大學
機械與機電工程學系
92
A 60 mm×33 mm×0.8 mm micro loop heat pipe (MLHP), consisting of an evaporator, vapor line, condenser, and two liquid lines, was fabricated and characterized. The wicking structure consists of parallel V-grooves with a hydraulic diameter of 76 m formed using bulk silicon etching. MLHP were realized by bonding a glass wafer onto a silicon substrate, resulting in a transparent cover for two-phase flow observation. Methanol and silver nanofluid were used as the working fluid. The test results showed that silver nanofluid demonstrates a higher heat load performance range (12.96 W~15.13 W) than methanol (4.35 W~6.34 W) with an evaporator area of 1 cm0.8 cm and condenser temperature of 12C. The thermal resistances of methanol and silver nanofluid were 0.84 ℃/W (4.98 W) and 0.89 ℃/W (15.13 W) separately.
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Chiu, Tai-Rong, and 邱泰榮. "Fabrication and Study of Wall Sturctures of Micro Heat Pipe." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/82590200418340916044.
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碩士國立海洋大學
機械與輪機工程學系
91
【Abstract】 As the MEMS technology is getting mature and its applications become diverse, people could miniaturize many products successfully. Heat pipe is one of the most popular components to diffuse heat in notebook computers. Micro heat pipes (MHP) seem to be an important research topic in the future. The purposes of this thesis are making several kinds of wall structures of MHP by the MEMS technology and exploring the feasibility of these wall structures for possibly improving the performance of MHP later on. First, in this experiment we design several straight and network channels as wall structures of MHP. For the straight channels, there are V-type, trapezioid type and U-type. For the network channels, there are four types, namely, array rectangular blocks, staggered rectangular blocks, array type of diamond blocks and staggered diamond blocks. Next, all the wall structures are fabricated by bulk micromachining (1 0 0) - 4 inch silicon wafers. Then the difficulties encountered in fabrication are identified and resolved. Finally the flowrates for various wall structures are tested and abilities for transporting the working fluids are compared. It was found in this study that dry ectching by Inductive Coupling Plasma Etching ( ICP ) yields the most satisfactory result in fabrication. As for the tests of flowrates, the wall structure of staggered diamond blocks performs better than and others. It was shown in this study that the wall structures of MHP can be well fabricated by MEMS technology. Further studies in this field are highly recommended.
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Yu, Hung-Jen, and 尤宏仁. "Fabrication of Micro Loop Heat Pipe with Porous Silicon Wick Structure." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/91493681890983675370.
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碩士淡江大學
機械與機電工程學系
91
A micro loop heat pipe(MLHP)with porous silicon wick structure has been fabricated and characterized. Porous silicon was fabricated by anodic electrochemical etching on a 11mm×10mm wafer area, had a pore diameter of 4μm, pore pitch of 10μm and wick porosity of 8.15％. The evaporator was realized by bonding a 7740 glass wafer to the silicon substrate. Transparent tygon tube was used as vapor line、liquid line for two phase flow visualization. The condenser with a 3mm×40mm copper tube was maintained the temperature to 16℃ by pumping flow of cooling water. Water was used as the working fluid. MLHP started up when heat load is at 6 W and had a thermal resistance of 0.27℃/W.
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Chen, Wen-Tung, and 陳文棟. "Investigation of the thermal performance of flat micro-grooves heat pipe." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/25200152829341531942.
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碩士國立中央大學
光電科學研究所
95
The high power LED possesses of high brightness, environmental protection, and energy saving. But owing to the heat effect, this LED would be reduced life time and efficiency, and result in the wavelength shift. The general heat sink cannot diffuse heat effectively for the small size LED. Therefore, using the main characteristic of two-phase changed of heat pipe can achieve the heat diffusion and reduce the junction temperature of LED. The cylinder heat pipe is not convenient for contacting with the flat heat source. Thus flat heat pipe is used to increase contact area and to decrease the contact resistance between heat source and heat pipe. The flat heat pipes not only increase the fill of working fluid, but also use more grooves to transport liquid back to hot point. In this case, we fabricated different shape grooves flat heat pipes, radial grooves heat pipe and parallel grooves heat pipe, to observe the heat transportation of heat pipes. The heat transfer of radial heat pipe starts from the center to edge by vaporizing working fluid to enhance diffusing area. But the radial heat pipe has no significant effect in reducing the temperature of heat source. The main reason is that the temperature of heat pipe is controlled by cold point, thus the working fluid cannot boil. The heat transport of parallel heat pipe starts from edge to edge, so that the diffusion area of parallel heat pipe can be enlarged. In parallel case, the working fluid can boil under different liquid fills and incline angles, thus the thermal resistance is reduced effectively. The reducing thermal resistance of 30% fill is better than 63% fill, and 30% fill is no limited by gravity force.
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Lin, Tsung-Yin, and 林宗穎. "A Micro Heat Pipe Chip Integrated with Micro Heater and In-situ Temperature Sensor Array." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/91852002684429364681.
Full textAbstract:
碩士國立臺灣大學
應用力學研究所
93
Due to the improvement of semiconductor manufacturing techniques, the quantities and densities of electric components on a single chip increase quickly. The heat dissipated of miniaturized make chips to be operated in higher temperature which will decrease not only the speed of electric components but also the stability of the chips. Taking the CPU, “Intel Pentium 4 Processor Extreme Edition on 0.13 Micron Process in the 775-land Package” published in 2004 for example, its thermal design power can reach about 109.6 Watt. To remove heat generated inside an operating chip becomes more and more important from now on. The most popular electric cooling devices are fins and fans now, but those devices face the critical point of the ability to transfer heat from local hot spot. In 2004 Intel slows down their new products of CPU, and can not find a suitable device to provide cooling is one of the reasons. Heat pipe is one of the well known cooling devices, and some of them have been integrated with Notebook cooling module. Since Cotter suggest that Micro Heat Pipe could a new electric cooling device in the future, experiments and researches are proposed at the past 20 years. However, the research about how the working fluid inside micro heat pipes still have a lot of issues to be worked out. In this experiment I fabricate micro heat pipe chip using surface machining and bulk machining of MEMS manufacturing. The the channel of micro heat pipe is 150μm in width, and 15mm in length. This is the first time to fabricate a micro heat pipe chip integrated with micro heater and In-situ micro temperature sensor array. I hope that this research can promote the development of the electric cooling industry. There are four subjects in this experiment: First, integrated micro heater and micro heat pipe and micro temperature sensors in one single chip; Second, combining the glass chip and silicon chip using anodic bonding and epoxy pasting; Third, filling working fluid in a convenient way; Fourth, analyzing the behavior of the micro heat pipe under different applied works. I use micro heater to simulate hot spot, and use micro heat pipe as a cooling device to find out the performance of this design. Chip_0 which no working fluid is filled burned out when 800mW is applied on the heater; however, Chip_1 and Chip_2 which is filled several working fluids can work when 1W is applied on the heater. Then, gravity and heat sink are use to improve the performance of the micro heat pipe, and both of them are workable. Although the maximum thermal conductivity of Chip_1 and Chip_2 are about 8.333 and 4.545 W/mK, but they improve the maximum thermal conductivity about 3 to 5times than Chip_0.
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Lin, Che-Hsing, and 林哲興. "A Study of Liquid-Vapor Interface Interaction in a Micro Heat Pipe." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/pf9399.
Full textAbstract:
碩士中原大學
機械工程研究所
92
The present study modifies Cotter’s model for predicting the maximum heat transport capacity and discusses the performance of a single V-shaped microgroove of the Micro heat pipe. A cylindrical coordinate system is used to analyze the correlated between the liquid flow velocity and vapor flow direction, which will affect the behavior of liquid surface and liquid flow velocity, and to obtain the relating volumetric flow-rate in the single microgroove. Then, in order to include the frictional effect of the liquid-vapor interaction into the Cotter’s model, a dimensionless liquid flow shape factor, , which is defined by the volumetric flow-rate, is introduced to predict the maximum heat transport capacity. Introduce a dimensionless number , represent the strength of the friction effect of the vapor-liquid interface flow, into the correlated relation between vapor flow and liquid flow in the analytical process. The results indicated that as value increases, the liquid flow influenced by the vapor flow also increases, which is obviously resulting the reducing values of . The predicted maximum heat transport capacity agrees well with Babin’s experimental of a copper-water micro heat pipe data for the case of and contact angle . In a triangular micro heat pipe, the results indicated that maximum heat transport capacity and increases with increasing contact angle .
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Huang, Hung-Sen, and 黃泓森. "The Effect of Angle of V-Shaped Channels on the Heat Flux in a Micro Heat Pipe." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/x9h595.
Full textAbstract:
碩士中原大學
機械工程研究所
93
The present study modifies Cotter’s model for predicting the maximum heat transport capacity and discusses the performance of a single V-shaped microgroove of the Micro heat pipe. A cylindrical coordinate system is used to analyze the correlated between the liquid flow velocity and vapor flow direction, which will affect the behavior of liquid surface and liquid flow velocity, and to obtain the relating volumetric flow-rate in the single microgroove. Then, in order to include the frictional effect of the liquid-vapor interaction into the Cotter’s model, a dimensionless liquid flow shape factor, , which is defined by the volumetric flow-rate, is introduced to predict the maximum heat transport capacity. The equation shows the effect of channel angle to solve the channel number of cylinder heat pipe and cross-sectional area. The heat pipe could get the optimum channel angle as 2ψ= , channel number =30. It shows that the max heat transfer flux effected by channel angle is bigger than the effect by contact angleα.
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Huang, Yung-Huai, and 黃詠淮. "A Study on Liquid Flows in a Triangular Groove of a Micro Heat Pipe." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/58084373253190632456.
Full textAbstract:
碩士中原大學
機械工程研究所
94
The present study modifies Cotter’s model to predict the maximum heat transport capacity and to obtain the equation by the geometric shape of a single V-shaped microgroove of the micro heat pipe. The product of friction factor and Reynolds number correlated between the channel-half angle and contact angle is used to analyze the dimensionless liquid flow shape factor, and to find its optimal design. The effects of both the contact angle, , and the product of friction factor and Reynolds number, , on the dimensionless liquid flow shape factor , are minial when the channel-half angle is less than 5 degree, i.e., . A higher dimensionless liquid flow shape factor, , is obtained at the low product of friction factor and Reynolds number. The results indicate that the optimal design of the dimensionless liquid flow shape factor is reached when contact angle, , and channel-half angle, .
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Chen, Wan-Ling, and 陳宛伶. "Study on The Hydroforming of Radial Micro-channels for Flat Heat Pipe and Thermal Performance Testing." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/61767381359510370482.
Full textAbstract:
碩士國立交通大學
機械工程系所
103
In this study, a high-pressure hydroforming apparatus with a maximum working pressure of 250MPa was used to fabricate the wick structures for the flat heat pipe. Copper sheets (C1100) with a thickness of 0.15 mm were tested in the hydroforming experiment. At the same time, finite element analysis (Abaqus/Explicit) was used to analyze the hydroforming process numerically. A finite element model of sheet metal hydroforming was based on material properties gotten from material testing, and conditions of hydroforming. And this research compared the results of simulation and hydroforming experiment to verify the accuracy of the finite element model. After that, this finite element model was used to predict the formability of radial micro-channels to decide experiment parameters of hydroforming. A radial flat heat pipe was assembled with hydroformed radial micro-channels and filled with water as working fluid in vacuum environment. Then, thermal performance experiments were conducted by using different amount of working fluid, and subsequently this radial flat heat pipe was also used on cooling LED practically.
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陳偉今. "The Excimer Laser and The Inductively Coupled Plasma Etching in the Development of Micro Chip Heat Pipe." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/41941324728977379745.
Full textAbstract:
碩士國立臺北科技大學
機電整合研究所
89
This thesis is to propose the chip type heat pipe design and manufacture. In the manufacture process make use both the Excimer Laser and Inductively Coupled Plasma (ICP) etching technology. It is the first time to combine these two technique and applying to etch micro channel in Si wafer. The triangle and rectangle micro channel in this thesis. The dimensions of triangle micro channel is designed an isosceles triangle with width 40μm , included 60 angle. The dimensions of rectangle micro channel is designed 40μm×10μm and 20μm×155μm. In the first step, we construct three type of Micro channel Structure in the photo resist by Excimer laser. We construct the mask have 400μm width, 30°to90°isosceles triangle、400μm×100μm and 200μm×1550μm rectangle. We find the optimal etching parameter for the 60°triangle channel by using the different angle triangle which exposed different laser power in the mask. We get the optimal parameter is 90°isosceles triangle、200mJ laser power、dragging 5.5mm/min for the 40μm width、0.4312μm depth in the AZ 1500. The shape etched by ICP, we can get near 60°triangle micro channel structure. The 20μm×1.669μm rectangle structure also can be constructed by this method. The ICP will transfer the shape of photo resist to the Si wafer by selection ratio(80:1). We find the grass-like structure in the triangle channel. It could be generated by the inclined plane in photo resist, which result from different absorb by plasma. We find the grass-like’s phenomenon in the first time during the combined Excimer Laser and ICP process. In the future, the different angle of triangle channel will be deviced by using in the MEMS or bio chip. We hope this thesis could be referenced in this research.
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Lee, Chun-Lin, and 李俊霖. "Investigation of the Polymer Based V-shaped Microchannels and the Application on the Flexible Micro Heat Pipe." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/81569894539405486894.
Full textAbstract:
碩士國立臺灣大學
機械工程學研究所
97
This work presents the investigations of the V-shaped microchannels and its application on the flexible micro heat pipe. The V-shaped microchannel structure is fabricated by polyurethane (PU) from pattern transfer. The lithography and orientation dependent etching is applied to silicon substrate to fabricate the mold with conjugated V-shape grooves. The whole flexible micro heat pipe is composed of PU structure, and the microchannel structure is applied to the micro heat pipe as the wick section. In addition, the aluminum plates with cubic structure are embedded in the micro heat pipe to increase the heat transfer ability at the condenser and evaporator. The design of the cubic structure could increase the contact area which enhanced the bonding with the polyurethane structure. To find the adequate working fluid, the contact angle of different fluids are measured and capillary test are applied. And the different criterions are also utilized. The methanol is chosen as the adequate working fluid. And the capillary evaporation is applied to the V-shaped microchannel structure with methanol as the testing fluid to measure the dry-out length under different tilting angles.
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Hou, Dong-Fu, and 侯東甫. "Fabrication of Micro Loop Heat Pipes." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/36985316143478654087.
Full textAbstract:
碩士淡江大學
機械工程學系
90
A 60mm×33mm×0.8mm micro loop heat pipe (MLHP), consisting of evaporator, vapor line, condenser, and two liquid lines, has been fabricated and characterized. The wicking structure consists of parallel V-grooves with hydraulic diameter of 47μm, 67μm and 83μm were formed by bulk silicon etching. MLHP were realized by bonding a glass wafer to the silicon substrate, resulting in a transparent cover for two phase flow visualization. Water and methanol were used as the working fluid. The test results showed that water demonstrate a wider heat load performance range (3.3W~12.96W) than methanol (1.2W~5.85W) with an evaporator area of 1cm2 and condenser temperature of 17℃. The best thermal resistance is 0.106 ℃/W, 64 times higher than the one without fluid filling. The smaller diameter grooves caused liquid capillarity to increase and presented an enhancement of transfer capacity. It was observed that the presence of non-condensable gases might affect the reliability of the MLHP and reduce their performance significantly.
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Chen, Hong-Chih, and 陳泓志. "Fabrication of Micro Radial Grooved Heat Pipes." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/00814751154715676468.
Full textAbstract:
碩士淡江大學
機械工程學系
89
Due to the semiconductor industries have developed continuously in recent years, the heat dissipating of the miniaturized and high power electronic devices have become more important. Since the T. P. Cotter proposed the idea of micro heat pipe (MHP) to solve the heat dissipative problem in 1984, the researches that related to micro heat pipe theoretical analysis and experimental tests were continually presented. In this thesis, a new concept was applied into the plate MHPs. As a consequence, Micro radial grooved heat pipes were designed to separate the liquid and vapor flow to reduce the viscous shear force. A 5x5 cm2 MHP arrays was fabricated by using photolithography, wet bulk micromachining, and eutectic bonding techniques on 4-inch (100) silicon wafers. An experimental test facility was undertaken to evaluate the performance of wafers with three kinds of different filled volumes and different input powers. We glued heater below the evaporator section, infuse cold water through a square copper heat exchanger above the heat pipe and paste 15 K-type thermocouples on both side of MHP structure to record the variation of surface temperatures. After the evaluation, the MHP with 70% filled volume has the better performance as compared to the other samples on condition that maximum power input is 27.403W(22.64W/cm2). The maximum surface temperature is 67℃ that is reductions of 27.1% than the plain silicon wafer, the maximum temperature difference is 47℃ that is reductions of 32.9% than the plain silicon wafer, and the temperature difference between the top and bottom side of the evaporator section is only 12.5℃ that is reductions of 78% than the plain silicon wafer.
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Ho, Kun-Lin, and 何昆霖. "A study on flow and heat transfer of micro heat pipes." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/sxv89p.
Full textAbstract:
碩士國立高雄應用科技大學
機械與精密工程研究所
102
This study fabricated micro flat heat pipes, whose exterior dimension and working fluid was 40 mm × 35 mm × 1.5 mm and deionized water, respectively, with different channel designs. Before anodic bonding with a glass wafer, the microchannel was fabricated by ICP-RIE etching on a silicon wafer through a photolithography process. Two different types of microchannel were designed. One exhibited tapered channels, whose channel had widest and narrowest size of 0.3 mm and 0.1 mm, respectively, the other exhibited discontinuous channels having channel width of 0.3 mm. Those micro flat heat pipes filled in ratio of 40% were tested with various orientations and input powers and were visualized to investigate the fluid flow and thermal performance of those heat pipes. The results showed that the phenomenon of condensed liquid returning from condensing region to evaporating region was very different between both channel designs. The micro flat heat pipe having tapered channels exhibited an enhanced capillary force to successfully drive the condensed liquid from the condensing region to the evaporating region even when its evaporator was held in a higher place than the condenser. However, the discontinuous channels caused failure in returning the condensed liquid because of the large pitch between two pieces of channel. As the input power was 22 W, the thermal resistance of the heat pipe having convergin channel was 2.08 K/W.
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Kuo, Po-hsuan, and 郭伯軒. "Numerical Analysis of the Heat Transfer Characteristics of Micro Heat Pipes." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/10918793389012710404.
Full textAbstract:
碩士國立成功大學
機械工程學系碩博士班
95
Micro heat pipes can be used in an electronic chip to render its temperature distribution more uniform. In this thesis, based on the Young-Laplace equation and conservation laws for mass, momentum, and energy transport, we construct a one-dimensional thermofluid model for analyzing the steady-state flow and heat transfer characteristics of micro heat pipes consisting of V-shaped micro grooves. The model is then used to calculate the flow and evaporation/condensation of the working fluid in a micro heat pipe, and to calculate the critical heat input beyond which the heat pipe would dry out. It is found that the critical heat input can be increased by increasing the surface tension coefficient, thermal conductivity and density of the working fluid, but decreased if the viscosity of the working fluid increases. Moreover, the equivalent thermal conductivity of a micro heat pipe increases with the convection heat transfer coefficients on the liquid-substrate and liquid-vapor interfaces. We have also found that, for the case studied in this thesis, the critical heat input obtains a maximum when the apex angle of the grooves is around 33 degrees.
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Lin, Chen-Chuan, and 林振銓. "Characterization of Flow-Pattern and Heat Transfer of Micro Flat Heat Pipes." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/94352073607007849438.
Full textAbstract:
碩士國立高雄應用科技大學
機械與精密工程研究所
101
The thermal performance of Si-based micro flat heat pipes (FHPs) fabricated by using the micro fabrication process technology was investigated in this study. A total of three FHPs, including the supporting structure of plate fin, pin fin, and pin fin array, were tested and compared. The overall size of each FHP is 40 mm × 35 mm × 1.5 mm. The FHPs charged with distilled water were tested at several heating powers with various orientations. Both visual observation and temperature response measurement of the present FHPs at various conditions were performed. The results indicated that the heat transfer performance was strongly related to the arrangement of the wick structures. The lower the flow resistance in vapor space resulted in the lower thermal resistance of FHPs. The thermal resistance for the FHPs with supporting structure of pin fin array showed the least thermal resistance of 1.85 K/W at the heating power of 18 W, followed by the pin fin, and plate fin. In addition to examine heat transfer performance, the thermal resistance of the FHPs can be reduced as much as 16.67% and 44.78% compared to the standard copper and aluminum plates. In addition, in order to examine the effect of hydrophilic micro channels, a SiO2 film was coated on the surface of the micro channels. The results showed that the FHP having hydrophilic micro channels reduced thermal resistance effectively due to higher capillary force.
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Wang, Hong-Kai, and 王泓凱. "Fabrication and Experiment of Flat-Plate Micro Heat Pipes." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/68383391918914260887.
Full textAbstract:
碩士國立高雄應用科技大學
機械與精密工程研究所
99
Due to the advance of the fabrication technique of electronic chips, electronic chip is becoming more powerful in function and smaller in size. Well thermal management of electronic chips to maintain stable reliability and to reduce failure risk becomes more and more important. In this study, LED attached to several commonly used substrates, including FR4, MCPCB, and ceramic substrates, with a heat sink were numerically investigated their thermal resistances. Results showed that FR4 substrate contributed 96% thermal resistance to the total thermal resistance of the LED. However, the percentage of the thermal resistance from substrate could be reduced to 19% when the ceramic substrate (AlN) was used instead of FR4. Compared the thermal resistance between ceramic substrate (AlN) and heat pipe substrate, it was found that the thermal resistance could further be decreased by 15% when heat pipe substrate was used. Besides, flat-plate micro heat pipe experiment setup with distinctive design for working fluid charge, which allows heat pipe specimens to test with different charge ratio during the measurement, has also been established. Compared with the solid specimen with flat heat pipe specimens, it was found that the effective thermal conductivity of the flat heat pipe was lower than of the solid specimen at less power. Higher effective thermal conductivity of the flat heat pipe than that of the solid specimen could be obtained at higher power. Further increasing the power resulted in a less effective thermal conductivity than the solid specimen. The reason for above phenomena is because our flat heat pipe could not reach a desired vacuum so that the heat pipe could not be effectively performed until a higher power was provided. However, further increasing the power resulted in dry out of the heat pipe and leading to an inferior performance again.
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Hong-JieTsai and 蔡宏杰. "Asymptotic Analysis and Numerical Computation of the Performance of Micro Heat pipes Under Different Heat Transfer Conditions." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/65912887014259318501.
Full textAbstract:
碩士國立成功大學
機械工程學系碩博士班
98
Micro heat pipes can be used to facilitate heat removal from electronic chips and render the temperature distribution thereon more uniform. In this work, we construct a one-dimensional model, which accounts for the mass, momentum, and energy balance in a micro heat pipe, and use it to calculate the performance characteristics of the heat pipe. As it turns out, the temperature and flow fields in a micro heat pipe usually would develop boundary-layer structures. Perturbation analysis therefore is carried out to resolve such structures, and to obtain asymptotic solutions for the temperature and flow fields. Moreover, numerical computations are carried out to explore the system parameter regime in which the asymptotic results are invalidated. The results indicate that, as the apex angle of the micro channel in the heat pipe increases, the critical heat input (causing dry-out of the micro heat pipe) increases first because of the increased amount of working liquid filled in the heat pipe. But if the apex angle exceeds a particular value, the critical heat input would start to decrease, because the corresponding decrease in the meniscus curvature of the working liquid would reduce the capillary force that drives the working liquid flow. Meanwhile, the critical heat input increases with decreasing heat-pipe length and with increasing micro-channel depth. The effects of various external heat transfer conditions on the performance of heat pipes also are examined, and it is concluded that the heat transport in a micro heat pipe mainly is through the phase change of the working liquid, rather than through conduction. Key words : micro heat pipe