Dissertations / Theses on the topic 'Natural Convection Cooling'
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Worthington, D. R. E. "The cooling of electronic power supplies by natural convection." Thesis, University of Exeter, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380691.
Full textVan, der Westhuizen Pieter Hermanus. "Dynamic modelling of the natural convection water cooling principle / by Pieter v.d. Westhuizen." Thesis, North-West University, 2007. http://hdl.handle.net/10394/1949.
Full textGdhaidh, Farouq Ali S. "Heat transfer characteristics of natural convection within an enclosure using liquid cooling system." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/7824.
Full textGdhaidh, Farouq A. S. "Heat Transfer Characteristics of Natural Convection within an Enclosure Using Liquid Cooling System." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/7824.
Full textMehrtash, Mehdi. "Numerical Investigation Of Natural Convection From Plate Finned Heat Sinks." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613530/index.pdf.
Full textWillson, Thomas D. "A study of natural convection cooling of multiple discrete heat sources in a vertical channel." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23126.
Full textPaje, Rufino A. "Experiments on liquid immersion natural convection cooling of leadless chip carriers mounted on ceramic substrate." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/25932.
Full textBaudoin, Antoine. "Cooling Strategies for Wave Power Conversion Systems." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-306706.
Full textThompson, Ronald G. Jr. "Natural convection heat transfer studies of simulated and actual electronic components using dielectric liquids for immersion cooling." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23978.
Full textTwo experimental studies of the natural convection characteristics of heated protrusions immersed in dielectric liquids were conducted. the first study used a three by three array of simulated 20 pin dual-in-line chips which were made from aluminum blocks with full heaters. The second set of experiments used a three by three array of thermal evaluation devices mounted on an alumina substrate. The devices were 8.9 mm square chips which contained resistors and a type of temperature sensing transistor. Both studies used an insulated Plexiglas enclosure with a top mounted heat exchanger maintained at a constant 10 degrees C. Each array was mounted on a Plexiglass substrate, and spacers were used to vary the horizontal distance from the components to the enclosure wall. Five separate enclosure widths were used, with a maximum spacing of 40 mm. The vertically oriented aluminum blocks were tested with FC-71 and power levels ranging from 0.115 W/chip to 2.9 W/chip. The non-dimensional data obtained was used to develop an empirical correlation which predicts Nusselt number as a function of Rayleigh number and enclosure width. The correlation was accurate to within 4% of the array averaged data, and the maximum uncertainty in the Nusselt number was 7.4%. The actual electronic components were tested with FC-71, FC-43 and FC-75. Power levels ranged from 0.34 W/chip to 1.48 W/chip. Again, the data obtained was used to develop a Nusselt number correlation. In this case a better correlation of the data was achieved using Grashof number and enclosure width. The correlation is accurate to within 2% of the array averaged data. The maximum Nusselt number uncertainty was 4.7%
Gaiser, Alfred O. "Natural convection liquid immersion cooling of high density columns of discrete heat sources in a vertical channel." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/26097.
Full textSESINI, PAULA A. "Analise das instabilidades termo-hidraulicas em um circuito operando em regime de circulacao natural bi-fasico." reponame:Repositório Institucional do IPEN, 1998. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10686.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Bradley, Joseph Matthew. "Natural convection cooling of a three-by-three array of leadless chip carrier packages in a dielectric liquid." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA282298.
Full textThesis advisor(s): Yogendra Joshi. "March 1994." Includes bibliographical references. Also available online.
MACEDO, LUIZ A. "Atuação de um sistema passivo de remoção de calor de emergência de reatores avançados em escoamento bifásico e com alta concentração de não-condensáveis." reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11622.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
Rocha, André Damiani 1977. "Convecção natural em placa nas posições vertical e inclinada contendo elementos protuberantes aquecidos." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263471.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: No presente trabalho o resfriamento por convecção natural de uma placa plana, disposta em um meio infinito, contendo elementos protuberantes aquecidos e distribuídos uniformemente sobre uma das paredes da placa é analisado experimentalmente sob a condição de aquecimento uniforme. A parede oposta da placa de teste é isolada utilizando um aquecedor de proteção que possui as mesmas dimensões da placa de teste. Os testes experimentais utilizam um aparato com placa de fibra de vidro contendo elementos protuberantes de alumínio de seção quadrada, em cujo interior passa uma resistência. A placa de teste é posicionada em uma estrutura de ferro que foi projetada para permitir a variação da inclinação da placa. As trocas de calor por condução, através da placa de fixação dos elementos protuberantes, e por radiação, entre as superfícies das protuberâncias foram consideradas. Testes experimentais foram realizados variando a potência entre 30 e 70W para uma variação angular entre 0° e 60° a partir da posição vertical. Do presente trabalho concluiu-se que foi possível avaliar o número de Nusselt em função do número de Rayleigh para placa protuberante e inclinada através de uma única correlação, desde que a componente da aceleração gravitacional paralela à placa seja utilizada no cálculo do número de Rayleigh modificado
Abstract: In the present work, cooling with natural convection of a plate, disposed in an infinite middle, containing protruding heated elements and distributed evenly on one of the walls of the plate it is analyzed experimentally about the condition of uniform heating. The opposite wall of the test plate is considered isolated using a guard heater that possesses the same dimensions that the test plate. Experimental tests are performed in a apparatus containing fiberglass plates with protruding, square section, aluminum elements. The test plate is positioned in a structure of iron that was projected to allow the angular variation of the plate. The conduction heat transfer through the plate and radiation heat transfer among the surfaces of the protruding were considered. Tests were accomplished varying the power between 30 and 70W for an angular variation between 0° and 60° starting from the vertical position. The investigation shows that it is possible to evaluate Nusselt number as a function of the modified Rayleigh number for inclined and protruding plate through an only correlation, since to component of the gravitational acceleration parallel to the plate it is used in the calculation ofthe modified Rayleigh number
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica
Benedict, Terry J. "An advanced study of natural convection immersion cooling of 3 x 3 array of simulated components in an enclosure filled with dielectric liquid." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/22860.
Full textAn experimental study has been conducted to examine the three dimensional natural convection heat transfer from an array of simulated electronic components immersed in a chamber filled with Fluorinert FC-75, a commercially available dielectric liquid. The top and bottom walls of the chamber were maintained at uniform temperature while all other surfaces were insulated. The simulated components were in the form of a 3 x 3 array of discrete protruding aluminum blocks, each with geometrical dimensions of a 20 Pin Dual-inline-Package. The components were electrically powered resulting in a range of energy dissipation levels from 0.1 to 3.1 watts. Flow visualization in steady state was accomplished using Magnesium particles illuminated by a Helium Neon laser plane. Component surface temperature measurements allowed determination of the heat transfer characteristics. Timewise fluctuations of temperature at several locations were measured with increasing power levels. Keywords: Computer programs, Electronic cooling, Protruding heat sources, Flow visualization, Convective heat transfer, Immersion cooling, Dielectric liquids, Theses. (jhd)
Desai, Chetan Prabhakar. "An experimental and numerical investigation of natural convection in open ended annuli and its application to the cooling of an aircraft brake assembly /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487863429091573.
Full textAytar, Erol. "Natural convection immersion cooling of an array of heated protrusions in an enclosure filled with dielectric liquid : effects of enclosure width and fluid Prandtl number." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28387.
Full textTorres, Edgardo I. "Natural convection cooling of a 3 by 3 array of rectangular protrusions in an enclosure filled with dielectric liquid: effects of boundary conditions and component orientation." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23078.
Full textVerma, Darpan. "Hybrid Solar Energy System with integrated Concentration Photovoltaic Cells and Thermoelectric Devices." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553613351859182.
Full textMatthews, Scott T. "Natural convection immersion cooling of an array of vertically oriented heated protrusions in an enclosure filled with a dielectric liquid : effects of enclosure width, Prandtl number and component orientation." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28388.
Full textBrangeon, Boris. "Contribution à l’étude numérique de la ventilation naturelle dans des cavités ouvertes par la simulation des grandes échelles : application au rafraîchissement passif des bâtiments." Thesis, La Réunion, 2012. http://www.theses.fr/2012LARE0037.
Full textContext: Air-conditioning represents a high-energy expenditure in the sector of the building, which could be reduced drastically through the use of passive cooling systems. In hot and humid climates, the passive cooling of premises is a tried and tested technique ordained around four principles: to minimize the external and internal heat transfers, to bring inertness to the building, to humidify the air, and to ensure a good convection in order to favor convective exchanges. Objective: The description of thermo-convective transfers (estimation of mass flows rate and heat transfers) set in open cavities (rooms with crossing ventilation, solar chimney, outer skin of a double facade,...) is still relatively uncommon and the stakes are high to improve passive systems. The study of these phenomena can be evaluated through computational fluid dynamics. This thesis’s objectives are to achieve precise numerical simulations of airflow inspecific configurations of passive systems in damp tropical climates, in order to improve and deepen our knowledge of natural convection and to begin to give information concerning the choice of numerical boundary conditions to apply to open geometries.Numerical approach: The numerical approach adopted in this work, to study the natural turbulent convection, is the Large-Eddy Simulation. This approach is halfway between a direct numerical simulation and Reynolds-averaged Navier–Stokes equations. Such a technique is advantageous as it leads to a necessary substantial reduction of the number of discretizationpoints compared to the technique of direct simulation requirements, while retaining the dynamic aspect of the flows. Results: The results obtained in this work refer to the study of the dynamic boundary conditions to impose in open geometries with SND and to the application of the LES to different configurations of open cavities with a turbulent flow, in order to characterize temperature and velocity fields and then deduce mass flow rate, enthalpy flow,... The results have been compared either to other numerical results in the framework of national benchmarks (benchmark AmeThand ADNBâti) or to experimental results
Sancet, Aitor. "Study of heat transfer and flow pattern in a multiphase fuel oil circular tank." Thesis, University of Gävle, University of Gävle, Department of Technology and Built Environment, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-4926.
Full textThis is a thesis work proposed by Sweco System in order to carry out a study related to the heating system of a circular fuel oil storage tank or cistern. The study tank is a 23m diameter and 18m height with a storage capacity of around 7500m3 of Eo5 heavy fuel oil. The content ought to be at a minimum storage temperature of 50ºC so that the fuel oil is fluid enough and operation labors can be adequately performed. In fact, these types of heavy fuel oils have fairly high viscosities at lower temperatures and the heating and pumping system can be compromised at temperatures below the pour point. For this purpose a heating system is installed to maintain the fluid warm. So far the system was operated by an oil burner but there are plans to its replacement by a District Heating-heat exchanger combo. Thereby, tank heating needs, flow and thermal patterns and heat transfer within it are principally studied.
Tank boundaries are studied and their thermal resistances are calculated in order to dimension heat supply capacity. The study implies Finite Elements (Comsol Multiphysics) and Finite Volume (Fluent) analysis to work out some stationary heat transfer by conduction cases on some parts and thermal bridges present on these boundaries. Afterwards both cooling and heating processes of the fuel oil are studied using several strategies: basic models and Computational Fluid Dynamics (CFD). CFD work with Fluent is focused on optimizing inlet and outlet topologies. Understanding the cooling process is sought as well; Fluent CFD transient models are simulated in this way as well. Additionally the effect of filling levels is taken into account leading to a multiphase (fuel oil and air) flow cases where especially heating coupling of both phases is analyzed.
Results show that maximum heat supply needs are around 80kW when the tank temperature is around 60ºC and 70kW when it is around 50ºC. Expectedly the main characteristic of the flow turns out to be the buoyancy driven convective pattern. K-ε turbulence viscous models are applied to both heating and cooling processes showing thermal stratification, especially at the bottom of the tank. Hotter fluid above follows very complex flow patterns. During the heating processes models used predict fairly well mixed and homogenous temperature distribution regardless small stratification at the bottom of the tank. In this way no concrete inlet-outlet configuration shows clear advantages over the rest. Due to the insulation of the tank, low thermal conductivity of the fluid and vast amount of mass present in the tank, the cooling process is slow (fluid average temperature drops around 5.7 ºC from 60ºC in 15 days when the tank is full and ambient temperature is considered to be at -20ºC) and lies somewhere in the middle between the solid rigid and perfect mixture cooling processes. However, due to stratification some parts of the fluid reach minimum admissible temperatures much faster than average temperature does. On the other hand, as expected, air phase acts as an additional thermal resistance; anyhow the cooling process is still faster for lower filling levels than the full one.
El presente proyecto fue propuesto por Sweco Systems para llevar a cabo un estudio relacionado con el sistema de calefacción de una cisterna o tanque de almacenamiento de fuel oil circular. Dicho tanque tiene 23 m de diámetro y 18 m de altura con una capacidad de almacenamiento de alrededor de 7500 m3 de Eo5 fuel oil pesado. El contenido mantenerse a una temperatura mínima de 50 ºC de manera que el fuel oil es suficientemente fluido para que las labores de operación puedan ser ejecutadas adecuadamente. De hecho, estos tipos de fuel oil pesado tienen altas viscosidades a bajas temperaturas y, por tanto, tanto los sistemas de calefacción y como el de bombeo pueden verse comprometidosr a temperaturas por debajo del pour point. Con este fin un sistema de calefacción es instalado para mantener el fluido suficientemente caliente. Hasta el momento, el sistema era operado por un quemador de fuel, sin embargo, hay planes que éste sea sustituido por un combo intercambiador de calor-District Heating. Por lo tanto, principalmente son estudiadas las necesidades de calefacción así como los flujos térmicos y fluidos.
Se estudian las fronteras del tanque, y sus respectivas resistencias térmicas son calculadas con el fin de dimensionar la capacidad necesaria de suministro de calor. El estudio implica Elementos Finitos (Comsol Multiphysics) y Volúmenes Finitos (Fluent) para elaborar análisis estacionarios de transferencia de calor por conducción en algunos casos. Existen puentes térmicos en las paredes y su importancia es también anallizada. Posteriormente se estudian tanto los procesos de calentamiento y enfriamiento del fuel oil utilizando diversas estrategias: modelos básicos y Dinámica de Fluidos Computacional (CFD). El trabajo con CFD se centra en la optimización de topologías de entradas y salidas del sistema. También es solicitado entender el proceso de enfriamiento; En este sentido, se simulan modelos CFD transitorios de Fluent. Además, el efecto de los niveles de llenado se tiene en cuenta dando lugar a estudios de flujo multifase (fuel oil y aire), haciendo hincapié en el análisis de acoplamiento de transferencia de calor entre las dos fases.
Los resultados muestran que las necesidades de calefacción máximas son de alrededor de 80kW cuando la temperatura del tanque es de alrededor de 60 º C y 70kW cuando está alrededor de 50 ºC. Como era de esperar, la principal característica de este tipo de flujos es la convección natural resultante de las fuerzas de flotabilidad. Se aplican modelos turbulentos k-ε a los procesos de calentamiento y enfriamiento, mostrando estratificación térmica, sobre todo en la parte inferior de la cisterna. El líquido más caliente que se sitúa encima muestra complejos patrones de flujo. Durante los procesos de calentamiento, los modelos utilizados predicen un buen mezclado y distribución homogénea de la temperatura independientemente de esta pequeña estratificación en la parte inferior de la cisterna. De esta manera, ninguna concreta configuración de entradas-salidas simuladas muestra claras ventajas sobre el resto. Debido al aislamiento de la cisterna, la baja conductividad térmica del fluido y la gran cantidad de masa presente en el tanque el proceso de enfriamiento es lento (la temperatura media del fluido desciende 5.7 º C desde 60 º C en 15 días cuando el tanque está lleno y la temperatura ambiente es de -20 º C) y se encuentra en algún lugar en medio de los procesos de enfriamiento del sólido rígido y perfecta mezcla. Sin embargo, debido a la estratificación, algunas partes el líquido alcanzan la temperatura mínima admisible mucho más rápido que la media de temperatura. Por otra parte, como se esperaba, la fase de aire actúa como una resistencia térmica adicional, de todos modos, el proceso de enfriamiento es aún más rápido para niveles de llenado más bajos que el lleno.
Lee, Chun-Yi, and 李俊毅. "Notebook computers improved natural convection cooling design." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/65180357944626161237.
Full text國立中央大學
機械工程研究所碩士在職專班
100
Notebook''s cooling technology has been needing a continuous development and research. Because the computer inner part cooling technology problem of serious day by day, have to look for to more creatively cooling technology project. Really revising is original of spread heat design imperfection. Understand passionate condition and behavior pattern in the cooling technology for computer system inner part further. Analyze computer system to spread with improvement hot mechanism to make it reach ideal operation temperature. It is currently the mainest work of notebook. This thesis emphasizes in NetBook to spread hot part. The NetBook main distinguishing feature consumes for low achievement, baby size and frivolity. Because NetBook consumes tile count less of characteristic, this text tries the natural convection method of using the calm to carry on spreading heat. We hope to reduce noise and decrease to consume an ability. After testing an existing model, if we use traditional natural convection to spread a hot way and conduct the temperature to the machine hull. It will cause the machine hull lead hot influence user''s impressions. As a result the design modified version natural convection spreads hot system. This system''s using a hot pipe will mainly have fever the heat that the component produces to conduct to the rear of the system. It spread through the rear again hot hole and outside air to carry on hot commutation to reach to spread a hot purpose. It must match with in the base seamy side to post to attach one good hot conductor. Avoid worse part caused of plastic base heat conduction efficiency leading a hot phenomenon. After test by waiting for effect module to carry on an identification. It confirm this modified version natural convection to spread hot system to have a feasibility. This cooling technology can apply a notebook at low watt.
Chai, Chun-Yu, and 翟春郁. "Cooling Analysis of Industrial Personal Computer by Natural Convection." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/95170219318152230108.
Full text大同大學
機械工程學系(所)
97
In recent years, light, thin, short and small devices were developed and high performance microprocessors were used in industrial personal computer. Thermal design is an important factor in the performance of industrial personal computer. The traditional way of cooling the computer is based mainly on air cooling. With the increased demand for heat dissipation, it must continue to improve the fan speed to ensure the cooling effect. But it will increase air volume and air pressure and then increase the noise. In this situation, heat pipes with water-cooled cooling modules have become a mainstream trend in the market to replace the traditional cooling methods. In this study, an industrial personal computer provided by a company is used for the thermal analysis of natural convection. Through suitable arrangement of heat pipes to obtain a rapid cooling system, the heat generated from CPU and north bridge chip can then be dissipated quickly. Such method is called as RHE（Remote Heat Exchanger）method which can solve the noise problem and also enhance the thermal effect. The software of PHOENICS was used to simulate the heat transfer characteristic in the industrial personal computer. In the present study, the desired parameters of analysis are the number of heat pipe, cooling fin, gravity direction, and opening rate. According to the analysis of 3-D numerical simulation by natural convection on the industrial personal computer, here can get distributions of inner speed and temperature and also find optimal configuration of cooling analysis in the industrial personal computer. Afterward, the lower CPU temperature can be obtained. Based on the overall simulation, temperature will decrease about 20℃ to 30℃ by changing the direction of gravity. Through suitable arrangement of RHE and open rate, the lower CPU temperature is able to get 85.6℃.
Chan, Yin-Yan, and 陳賢仁. "The Comparision of Natural Convection, Air-forced Convection and Water Cooling Method with Heat-Sink." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/44337983935027287957.
Full text國立成功大學
工程科學系專班
94
In recent years, the electronic components are continuously developing towards high performance and shrinking it’s size. But also more higher thermal energy also produced. Using heat sink is always the common heat dissipation method as we know. We usually use two kinds of cooling method with heat sink, that is natural convection and forced-air convection. But, among various cooling methods, water cooling system always have the best performance. The real advantage of water cooling system is that it always with low noise but able to handle much greater wattages from CPU than any air-cooler can. In this article, we try to use water cooling method to compare with these two traditional air cooling methods with the same heat sink. Through the experiments to prove that there will be the same or even more higher heat dissipation rate even when we have a low flowing rate of coolant as we use water cooling method with heat sink. In other words, it’s a new idea if we use heat sink as the internal shape inside a water block . In order to prove this, heat sink had been installed into the water block and carried out an experiments. The experiments results show that during the natural convection under heat generation rate at 15W from the heater and reach the equilibrium stage , the thermal resistance of the system was 1.71℃/W and the chip temperature was 107.1℃. Under forced-air convection at 15W at equilibrium stage and the wind speed at 2.4m/s , the thermal resistance was 1.95℃/W and the chip temperature was 58.8℃. Under water-cooling system at water flowing rate at 400L/hr and 15W at equilibrium stage, the thermal resistance was 0.85℃/W and chip temperature was 39.4℃. At water flowing rate at 100L/hr and 15W at equilibrium stage, the thermal resistance was 0.99℃/W and chip temperature was 43.4℃. Even when the water flowing rate decrease to 100L/hr at 15W in equilibrium stage , thermal resistance is 0.99/℃W and chip temperature was 43.4℃. It means 35% efficiency is higher than the air-forced convection at 15W equilibrium stage will be obtained. Nevertheless, the most important result was even when the water flowing rate decrease from 400L/hr to 100L/hr at 80W, thermal resistance only increased 0.075℃/W. It means the flowing rate of water in this water cooling system was inconspicuous.
Destremau, Axel. "Natural convection cooling of vertical plates in an enclosure : a numerical simulation." Thesis, 1991. http://hdl.handle.net/1957/37096.
Full textDu, Shen-Kuei, and 杜勝貴. "Effects of various substrate openings for electronic cooling under forced and natural convection." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/gp9j77.
Full text國立臺北科技大學
製造科技研究所
99
This study experimentally investigates the heat transfer effects of forced convection and natural convection under under different substrate openings design. A computational fluid dynamics (CFD) model was established and implemented to verify and explain the experimental results and heat transfer behavior. It is found that different opening position will destroy the growth of the boundary layer on substrates to alter the cooling ability for both forced under low Reynolds number and forced convection. Nevertheless, having too many opening may reduce heat conduction and affect the overall heat transfer performance. This study provides future researchers with a guideline on designing and electronic package manufacturing. Under low-Reynolds flow situation, combined natural convection and forced convection will rise up heat transfer for 15%. When there exists only natural convection, heat source with face down performs better heat transfer than with face up. However too many openings will cut down the area of heat conduction and rise up surface temperature. Average of surface temperature for heated source will be reduced by forced convection. Therefore fan is the most important element to affect heat transfer because not only that fluid flows across the board through the openings but also forced convection reduces the thickness of boundary layer and overall improve heat transfer.
Lin, Dah Wei, and 林大巍. "The Material Structure Change Problem of Arbitrary Shape Body in Natural Convection Cooling." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/81725763056721639277.
Full textFlorio, Laurie Ann. "Investigation of static and dynamic enhancement of laminar natural convection cooling of electronics." Thesis, 2005. http://library1.njit.edu/etd/fromwebvoyage.cfm?id=njit-etd2005-025.
Full textChoi, Yeon Suk Van Sciver Steven W. "Cryogenic cooling system by natural convection of subcooled liquid nitrogen for HTS transformers." 2004. http://etd.lib.fsu.edu/theses/available/etd-07092004-105303.
Full textAdvisor: Dr. Steven W. Van Sciver, Florida State University, College of Engineering, Dept. of Mechanical Engineering. Title and description from dissertation home page (viewed Sept. 22, 2004). Includes bibliographical references.
Gdhaidh, Farouq A. S., Khalid Hussain, and Hong Sheng Qi. "Numerical Study of Conjugate Natural Convection Heat Transfer Using One Phase Liquid Cooling." 2014. http://hdl.handle.net/10454/10636.
Full textA numerical study in 3-D is performed using water as a cooling fluid to investigate the one phase natural convection heat transfer within enclosure. A heat source representing a computer CPU mounted on one vertical wall of a rectangular enclosure is simulated while a heat sink is installed on the opposite vertical wall of the enclosure. The air flow inside the computer compartment is created by using an exhaust fan, and the flow is assumed to be turbulent. The applied power considered ranges from 15 40 W. In order to determine the thermal behaviour of the cooling system, the effect of the heat input and the dimension of the enclosure are investigated. The results illustrate that as the size of the enclosure increase the chip temperature declined. However the drop in the temperature is very small when the width increased more than 50 mm. When the enclosure was filled with water the temperature was reduced by 38%. Also the cooling system maintains the maximum chip temperature at 71.5 C when the heat input of 40 W was assumed and this is within the current recommended computer electronic chips temperature of no more than 85 degrees C.
Tseng, Yung-Shin, and 曾永信. "Enhancement of Thermal Characteristics for Electronic Cooling under Natural Convection through Substrate with Apertures." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/12516104807297242838.
Full text國立清華大學
工程與系統科學系
95
In this study, a CFD model has been developed to interpret and validate the experimental results originating from a concept of enhancing heat dissipation from a substrate with flow inducing openings. Through parametric study as a part of the preliminary research, the practicability and the influence of parameters of this previously unnoticed cooing concept has been discussed. Results indicate that the openings will have a destructive effect on the growth of the boundary layer occurring on the lower surface of the substrate; and hence improve the cooling ability of a configured module without using any additional active heat dissipation measures. More improvement investigations further indicate that the cooling ability of the opening can be augmented through the design rules such as a control of the opening rate to reduce the conduction resistance, an enhancement of net heat transfer ability through a distribution analysis of Nu numbers, etc. Finally, by combining a guide aperture on the shell board and unsymmetrical arrangement design, some adverse phenomena or effects (e.g., the limit of aperture ratio and an obstruct flow within the upper channel) have been obviously improves as found in this study. The concept of opening not only improves 15% in heat dissipation the best original design, but also eliminates some difficulties in finding an appropriate thermal solution such as the manufacturing cost and the design flexibility. Moreover, results show that thermal radiation is an important cooling mechanism as a part of electronic cooling modes, but it is usually overlooked by most researches with an incorrect judgment. A reasonable diagnosis method was also developed in order to verify the issues under investigation. This method would provide future designers with a qualitative understanding of the importance of thermal radiation.
Knight, Daniel L. "Natural convection liquid immersion cooling of a column of discrete heat sources in a vertical channel." Thesis, 1988. http://hdl.handle.net/10945/23323.
Full textHo, Po-Ching, and 何柏慶. "Experimental Study on Natural Convection Heat Transfer of Indirect Water Cooling System in a Semicircular Tunnel." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/36892807398499978848.
Full text國立臺灣大學
機械工程學研究所
95
In the large underground cables tunnel, the part of the electric energy carried by the cables will dissipate and transform into heat. Therefore, an effective cooling system is demanded to take the heat away for decreasing the air temperature in the tunnel as well as keeping a safe and pleasant environment. In this work a semicircular tunnel were used as the main body to simulate the underground tunnel, within which an electrical heater could generate heat. Four PE water tubes were set to perform indirect water cooling. The air temperature distribution in the tunnel, the temperature change on the water tubes and the heater were all measured and analyzed. Both the non-dimensional variables Nusselt number, Nu, and Rayleigh number, Ra, were also calculated. The effect of the cold water flow rate（8LPM, 12LPM and 16LPM）, number of cold water tube（four and single）, the relative positions of the single heater and cold water tubes, and the surface temperature of the heater（from 100℃ to 250℃）were discussed. The whole study was conducted for the Rayleigh number between 4.41 x 104 and 8.19 x 104. In the experiment of four cold water tubes, the result shows that the larger the flow rate of cold water is, the larger the axial temperature gradient in the front section of the tunnel gets. However, the uniform air temperature in axial direction was obtained when the flow rate of cold water getting smaller. By the temperature distribution profile, a local relative high and low temperature area near the upper-right and lower-right of the semicircular wall of the tunnel can be found. In each cross-section in the axial direction, is maximized and minimized with the water flow rate at 16LPM and 8LPM, respectively, while rises in accordance with the increasing water flow rate. In the study of single heater and cold water tube, the tunnel temperature rises sharply at first and becomes uneven with increasing surface temperature of heater. rises to 5.2x104 from 4.7x104 when the surface temperature of heater is increased from 100℃ to 150℃. However, a large change in Rayleigh number（from 4.7 x 104 to 5.2 x 104） only makes small change in （from 10.1 to 10.3）. If the surface temperature of heater is raised to the range of 200℃ and 250℃, increases obviously. In addition, highest and can be obtained by arranging the cold water tube directly above the heater.
Hsu, Chen-Yuan, and 許哲綸. "Air Cooling Characteristics of Vertical Rectangular Fins Attached to A Transceiver Unit by Laminar Natural Convection." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/35304008812959552180.
Full text南台科技大學
機械工程系
94
This study aims at the evaluation of air cooling characteristics of vertical rectangular fins attached to a transceiver unit of the cellular base transceiver station (BTS) by laminar natural convection. The objective is to analyze the efficiency and performance of the transceiver unit’s fins in peak and off-peak hours under different heating rate. The study items include (I) The influence of the rectangular fin surface along the height air flows on heat-transfer coefficient, (II) Simulation of temperature field using three-dimensional finite element analysis by commercial software PDE Toolbox, (III) Comparison of the fin’s temperature distribution measured and simulated, (IV) Optimal design regarding fin thickness to fin efficiency (V) The best combinations for fin thickness and height, (VI) Analysis of optimal fin-to-fin spacing. The simulation of temperature distribution conducted by PDE Toolbox was based on fin’s geometrical model firstly and then different base temperatures in peak and off-peak hours were introduced as boundary conditions ; the heat-transfer coefficient adopted from literature around the fin exhibits that a decreasing trend with the increase of fin surface and an increasing heat-transfer coefficient with relatively higher base temperature. The simulation showed that an increasing temperature of fin along the air-flow direction. This result is in good agreement with theory of natural convection. and experiment. Then analyzing each parameter depends upon the fin efficiency and performance from several mathematical models in literature. The result shows that (1) the influence of fin efficiency is not much more obvious with fin thickness 2mm or 4mm; (2) under fixed heat-transfer coefficient, the fin thickness is as the proportion of the fin height; (3) in the range of laminar flow, the optimal spacing for fins was evaluated smaller than original design from maker. It indicates that fin spacing is allowed to smaller for better cooling effect.
Pamuk, Turgay, and Matthew D. Kelleher. "Natural convection immersion cooling of an array of simulated chips in an enclosure filled with dielectric liquid." Thesis, 1987. http://hdl.handle.net/10945/22377.
Full textPark, Sung-kwan. "Numerical analysis of liquid cooling by natural convection for heated protusions simulating vertical plate-mounted electronic components facing an opposing plate." Thesis, 1993. http://hdl.handle.net/1957/36488.
Full textYang, Hong-Huei, and 楊鴻輝. "Experimental Study on Natural Convection Heat Transfer of Indirect Water Cooling System with Single Linear Heat Source in a Circular Tunnel." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/52172077491193031459.
Full text臺灣大學
機械工程學研究所
98
Natural convection heat transfer in a circular enclosure has been developed for a long time. One of many applications is cooling system of underground cable tunnels. For Taiwan, We lack for experiences of building underground cable tunnels. We need more literatures to provide a lot of information for structuring underground cable tunnels. In underground cable tunnels, a part of electric energy is dissipated by electrical cable so the cooling-water system is needed. In this research the circular tunnel made of concrete was used to simulate underground cable tunnels. Tube-shaped heater was simulated electrical cables. Five pipes made of stainless structured indirect cooling water system. The purpose of this research is to optimize cooling efficiency. The effect of the position of cooling water pipes(A,B,C,D,E), the angle of the heat source(30°,60°,90°,120°), the power of the heat source(1300, 975, and 650 W), the flow rate of the cooling water(4, 8, 12, and 15LPM), the number of the cooling water pipes were discussed. T-type Thermocouples installed on cross section of downstream section of underground cable tunnel to measure air temperature. In the experiment of single pipe of cooling water, the smallest distance between single pipe of cooling water and heater was the highest efficiency but local relative high temperature was higher than any other case. When the position of single pipe of cooling water is fixed, the power of heater didn’t influence the distribution of temperature of air significantly. The average Temperature profile was like a parabolic line when the flow rate of cooling water increased from 4 LPM to 15 LPM and strong fluctuations of temperature of air occurred on the section of entrance of the tunnel as the flow rate of cooling water more than 12 LPM. The level of heat source was lower then the temperature of air was more uniform. In the experiment of number of pipes of cooling water, the result shows that more pipes of cooling water were activity then the temperature of cross section of the tunnel is lower due to increase the total area of cooling water pipes. The best layout is that Multi-pipes are arranged on the top of the tunnel and heater is the same but below the pipes.
Huang, Ci-Ming, and 黃啟銘. "Natural Convection Heat Transfer Characteristics and cooling Performance Enhancement for a Module with Block Heat Sources in a Three Dimensional Cabinet." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/sm6btd.
Full text國立虎尾科技大學
航空與電子科技研究所
97
This study aims to investigate natural convection heat transfer characteristics and cooling performance enhancement for a module with block heat sources in a three dimensional cabinet. The major objective of this study has two aspects. First, efforts are performed to examine the influences of thermal interaction between the fluids inside and outside the cabinet on the flow structure, temperature distribution and Nu number. Second, air vents are proposed to construct in the three dimensional cabinet wall, attentions are paid to conduct the enhancement of cooling performance of the block heat sources. The numerical computation domain covers the cabinet and surrounding area, the temperature and heat flux on the cabinet surface are not previously known and have to be found in the solution processes, In addition, in order to verify the numerical simulation, this study has set up an experimental system. The difference in surface temperature of block between the numerical and experimental data is within 11.1％~22.5％. The maximum difference in hot spot temperatures of the blocks for the situations with and without consideration of thermal interaction can be up to 24.5 % as Pr = 0.7, 104≦Ra≦106, 100≦Kbf = Kpf = Kwf = 1000 and Kff = 8000. When air vents are constructed in the cabinet wall, the hot spot temperature can be reduced by 30.5 %. In addition, when fin is constructed on the back side of the board for the ventilated cabinet, the hot spot temperature can be reduced by 52 %.
Chiu, Zone-Pin, and 邱琮評. "Natural Convective Heat Transfer Characteristics and Cooling Performance Enhancement for a Module with Arrays of Block Heat Sources in the Three Dimensional Cabinets." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/qz9qt3.
Full text國立虎尾科技大學
航空與電子科技研究所
98
The study aims to investigate the natural convective heat transfer characteristics and cooling performance enhancement for a module mounted with arrays of discrete block heat sources in a three dimensional cabinet. The major objective of this study has three aspects. First, efforts are performed to investigate the influence of thermal interaction between the streams inside and outside the cabinet on the natural convective heat transfer characteristics for the heat source module. Second, attention is given to investigate the cooling performance enhancement of the module for different fin shape and configuration. Finally, the cooling performance enhancement of the module by constructing air vents in cabinet wall is conducted. The numerical simulation is rigorously performed in this study. Owing to the consideration of the thermal interaction between streams inside and outside the cabinet, the numerical computation domain covers the cabinet and its surrounding area. In addition, an experimental system is set up to verify the results of numerical simulation. The difference in surface temperature of block heat source between the numerical and experimental data is within 0.01％~7.5％. The result show that the maximum difference in hot spot temperatures of the blocks for the situations with and without consideration of thermal interaction for the closed cabinet can be up to 22.9 % as Pr = 0.7, 104≦Ra≦106, Kbf = Kpf = Kwf = 100 and Kff = 8000. The heat transfer characteristics increase with higher fin. The hot spot temperature can be reduced by 29.6% for fin height Fz = 0.3. For the ventilated cabinet with the heat source module mounted with fin, the hot spot temperature can be reduced by 48.6 %. In addition, variation of hot spot temperature is within 3% for the module position 0.2≦C3≦0.6.