Dissertations / Theses: 'Heat Transmission'

1

Etter, Christy L. "Numerical model of the transient behavior of a copper-water heat pipe." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19972.

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Liang, Haodong. "Fractal Interfaces and Heat Transmission Problems." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-dissertations/124.

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The main portion of my thesis focuses on a 2-dimensional second order heat transmission problem in domains with pre-fractal interfaces. My focus is on the numerical approximation of the solutions. Precisely, I€™m concerned to develop a suitable mesh refinement algorithm that could be adapted to our situation, by taking into account the regularity of the solutions and the geometry of irregular pre-fractal interfaces. I obtain an error estimate between the weak solution and the discrete solution, which indicates an optimal rate of convergence as in the classical case when the solution has H^2-regularity. In addition, numerical simulations are also included, which demonstrates the features of our heat transmission model. Another portion of my thesis focuses on the asymptotic analysis of singular boundary value problems with highly conductive layers of pre-fractal type. My models illustrate the problems of a lower- dimensional highly conductive material intruding into a higher- dimensional material with lower conductivity. I consider a 2D model of Sierpinski pre-fractal layers and 3D models of hierarchical layers. The main results consist in the so-called Mosco-convergence of certain energy functionals, which implies the strong convergence of the solutions and of the spectral resolutions as a byproduct in real applications.

3

Chu, Wun Wai. "Experimental study for the fully-developed single-phase heat transfer and friction factor in micro-fin tube." Thesis, University of Macau, 2011. http://umaclib3.umac.mo/record=b2493619.

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4

Pidgeon, Wesley. "Numerical analysis of heat conduction from a buried heat pipe." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/18393.

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5

Norris, Pamela Marie. "An investigation of coolant passage heat transfer in a diesel engine cylinder head." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/17633.

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6

Roth, Eric. "Transient heat transfer." PDXScholar, 1991. https://pdxscholar.library.pdx.edu/open_access_etds/4264.

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With the advent of the new high Tc superconductors, liquid nitrogen will be one of the preferred cryogens used to cool these materials. Consequently, a more thorough understanding of the heat transfer characteristics of liquid nitrogen is required. In our investigations we examine the transient heating characteristics of liquid nitrogen to states of nucleate and film boiling under different liquid flow conditions. Using a platinum hot wire technique, it is verified that there is a premature transition to film boiling in the transient case at power levels significantly lower than under steady state nucleate boiling conditions. It is also shown that the premature transition can be reduced or eliminated depending on the flow velocity.

7

Baird, James Robert. "Phase change heat transfer in narrow passages." Thesis, Graduate School of Engineering, 2001. http://hdl.handle.net/2123/5130.

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8

Leung, Sharon Shui Yee. "Heat transfer in microchannels : taylor flow." Thesis, The University of Sydney, 2012. http://hdl.handle.net/2123/17835.

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9

Galarraga, Maider. "Heat balance of a historical church- transmission losses." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-17137.

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The structure of old monumental churches differs a lot from contemporary buildings. The structural materials were wood, brick and stone. In order to construct high buildings with huge spans, thick massive walls and many massive columns were needed. Originally these buildings had no heating and for centuries the outdoor temperature determined the indoor climate. As churches are considered historical heritage buildings their renovation should be thoroughly studied. In this thesis the transmission losses of Hamrånge church will be analysed. Hence, the transmission trough walls and windows as well as the heat buffering of materials will be examined. In addition, the effect of possible reformation measurements will be concluded. Finally, this project belongs to a complete study of the church, were not only transmission losses are considered but also air infiltration losses and solar heat gain. That way, a comparison between them will be carried out in order to contribute to attain the objective of the project: possible restoration for church heating system with respect to preservation, energy requirements, thermal comfort and aesthetics.
Church project

10

Norris, Pamela Marie. "An experimental investigation of heat transfer in a diesel engine cylinder head." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/17590.

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11

Patel, Zaheed. "Heat transmission along the surface of dental implant." Thesis, University of the Western Cape, 2009. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5032_1310989960.

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Objectives: Temperature changes along an implant body have not been widely studied. The objectives of this in vitro study were (i) to establish if the temperature of the abutment influences the temperature of the implant surface, (ii) to establish the temperature transmission from abutment to implant body, and (iii) to establish for what abutment temperature the critical time/temperature threshold of 47oC for 1 minute at implant level is reached.

12

Janzen, Isaiah. "Modeling of Heat Treating Processes for Transmission Gears." Digital WPI, 2009. https://digitalcommons.wpi.edu/etd-theses/1123.

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"The effects of heat treating process parameters on the microstructure, residual stress, and distortion of a vacuum carburized, quenched and cold treated ring gear made of Pyrowear 53 has been determined using Abaqus and DANTE software. The data from these finite element method simulations was compared to measured values from physical testing. It was found that the heat treating process of the ring gear could be simulated and provide similar results to the measured and specified values for hardness, carbon content, and distortion. The simulations and distortion in this paper provide a detailed view of the mass transfer, heat transfer, and stress that occur during heat treating. These simulations suggest nonuniform cooling of a ring gear leads to greater distortion than uniform cooling. Simulations compared the retained austenite and hardness in ring gears that were oil quenched and high pressure gas quenched."

13

Lam, Calisto. "Design and validation a full scale experimental chamber with interior convective heat transfer." Thesis, University of Macau, 2010. http://umaclib3.umac.mo/record=b2494143.

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14

Cheng, Wui-wai Mechanical &amp Manufacturing Engineering Faculty of Engineering UNSW. "Enhancing the heat transfer performance of compact heat exchangers by minimizing the contact resistance between fins and tubes." Awarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering, 2006. http://handle.unsw.edu.au/1959.4/24952.

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Thermal contact resistance or, its reciprocal, thermal contact conductance is an important parameter in a wide range of thermal phenomena. It plays a significant role in heat transfer applications such as electronic packaging and nuclear reactors. This parameter also appears in fin-tube heat exchangers; however, it is often neglected in the performance calculations of heat exchangers. This thesis project explores the means by which the heat transfer performance of a finned tube heat exchanger may be enhanced. It includes experimental studies and finite element analysis investigating the effects of expansion bullets and coatings on the thermal contact conductance. An apparatus has been designed and fabricated for the experimental part of the work. A finite element model established the fintube configuration to be used in the design and manufacture of the apparatus. The apparatus was specially made for measuring thermal contact conductance directly in a finned-tube heat exchanger both in vacuum and in gaseous environment. The experiments were done on hexagon shaped specimens with a single fin connecting seven tubes. Sixteen type-T thermocouples have been used to measure temperatures at several locations on the specimen. A full-scale quarter-fin model was chosen for a second finite element analysis. The model simulates the actual specimen and predicts the temperatures. The finite element analyses have been used to validate the experimental results. The experimental results from the bare contact specimens, assembled with different sizes of expansion bullet, show that while higher expansions enhance the thermal contact conductance, the effect of interstitial gas such as nitrogen is beneficial for all specimens expanded with the 9.42 mm size bullet. Applying a coating material with high thermal conductivity is also an effective way to enhance the thermal contact conductance. The results show that the highly conductive plating materials, such as zinc, tin, silver and gold, enhance the thermal contact conductance. The presence of interstitial gas such as nitrogen also results in higher heat transfer rates and higher thermal contact conductance compared to those obtained in vacuum.

15

Bockwoldt, Todd S. "Induced convective enhancement of the critical heat flux for partially heated surfaces in pool boiling." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/13094.

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16

Hendrix, Walter Adrian. "An analysis of body force effects on transient and steady-state performance on heat pipes." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/16678.

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17

Boo, Joon-Hong. "Transient analysis of heat pipe radiators for space station applications." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/19553.

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18

Cassel, Stanley David. "The effect of increasing length on the overall conductance and capacitance of long heat pipes." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/19589.

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19

Remley, Timothy J. "Single-phase heat transfer in a trapezoidal channel." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/22212.

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20

Horn, Thomas J. "Comparison of heat flux standards for calibrating heat flux gages at elevated temperatures and high heat flux levels." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06162009-063032/.

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21

Boulares, Jihed. "Numerical and experimental study of the performance of a drop-shaped pin fin heat exchanger." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FBoulares.pdf.

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Thesis (Mechanical Engineer and M.S. in Mechanical Engineering)--Naval Postgraduate School, June 2003.
Thesis advisor(s): Ashok Gopinath. Includes bibliographical references (p. 73-74). Also available online.

22

Halvorson, Peter Joseph. "On the heat transfer characteristics of spray cooling." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/17365.

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23

Wu, Richard Lap. "Heat transfer in circulating fluidized beds." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/31037.

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Heat transfer in circulating fluidized beds was studied in both a 7.3 m high, 152 x 152 mm square, pilot-scale combustor and a 9.3 m high, 152 mm ID transparent cold model unit. Results were obtained for particles of mean size 171-299 µm at superficial gas velocities from 4 to 9.5 m/s and for solids circulation rates up to 70 kg/m².s. For the combustor, results obtained by using membrane walls and a vertical tube as heat transfer surfaces show a strong influence of the cross-sectional area-averaged suspension density on time-averaged, length-averaged suspension-to-surface heat transfer coefficient. The influence of superficial gas velocity is found to be small. Radiation becomes significant at suspension temperatures higher than 400 C and at low suspension densities. Heat transfer coefficients were also found to vary with the lateral position of the tube. The vertical length of heat transfer surface is shown to be an important parameter, allowing seemingly discrepant published results to be reconciled. For the cold model unit, sudden and dramatic peaks in instantaneous heat transfer coefficients were measured using an instantaneous heat transfer probe. Simultaneous heat transfer and capacitance measurements suggest that these peaks are caused by the arrivals of particle strands at the heat transfer surface. Two-probe heat transfer measurements suggest the existence of a characteristic residence length for the strands at the wall in this column. A proposed heat transfer model, based on an overall core-annulus flow structure in the riser, and periodic formation, movement along the wall, and disintegration of strands in the annulus, gives reasonable agreement with a wide range of published data. It accounts successfully for the effects of heat transfer surface length and particle sizes. However, the effect of the heat transfer surface configuration on the flow pattern of particles must also be taken into account to give improved agreement with experimental data.
Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate

24

Worm, Steven Lee. "Experimental measurement of heat transfer phenomena in a solid adsorbent." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/16487.

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25

Finch, Anthony Terrell. "The electrohydrodynamic (EHD) enhancement of convection and boiling in a shell-and-tube heat exchanger." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/16643.

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26

Trautman, Mark A. "The manipulation of instabilities in a natural convection boundary layer along a heated, inclined plate." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/16872.

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27

Adams, Thomas M. "Turbulent convection in microchannels." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19421.

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28

Fuller, Timothy Alan. "An analytical study of the performance characteristics of solid/vapor adsorption heat pumps." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/16961.

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29

Williams, Winifred Elizabeth. "HEAT TRANSFER IN THE MICROCIRCULATION." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275277.

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30

Heng, Stephen Fook-Geow. "Experimental and theoretical thermal analysis of microelectronic devices." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/16694.

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31

Stromberger, Jöerg H. "An experimental investigation of electrohydrodynamic (EHD) enhancement of boiling heat transfer." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/17050.

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32

Stowe, Robert Alan. "Heat transfer from a circular cylinder subject to an oscillating crossflow as in a stirling engine regenerator." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26741.

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An experiment was designed and carried out on the fundamental, but poorly understood problem of oscillating flow past a single, transverse, circular cylinder. This is an approximation of the flow about a single element in a matrix-type regenerator used in Stirling-cycle engines. The experimental rig was designed and built to allow tests to be carried out for the wide range of fluid flow parameters characteristic of various Stirling engines. The influence of these parameters on convective heat transfer rates was measured so the approximate effects of these same parameters on a Stirling engine regenerator could be determined. The main conclusion from the experiment was that average Nusselt numbers, based on test-cylinder diameter and subject to flow conditions similar to those found in Stirling engine regenerators, were 40 to 80% higher than those predicted by a steady flow correlation, for a given Reynolds number. This may be due to the high levels of turbulence generated near the test-cylinder. A secondary conclusion is that the compression and expansion of the working fluid due to a 90 degree phase angle difference between the motion of the pistons raises convective heat transfer rates from the test-cylinder substantially over the 180 degree phase angle, or "sloshing" motion case.
Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate

33

Morello, Gerry F. "Temperature and heat transfer studies in a water immersion retort." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/28556.

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Temperature and heat transfer studies in a pilot-scale water immersion retort were performed. The temperature study investigated the temperature distribution and stability of the retort during the cook period. The investigation of heat transfer uniformity within the retort was based on heating and cooling parameters calculated from the heat penetration curves of food-simulating teflon transducers. The uniformity of sterilizing conditions within the retort was determined from process lethalities calculated for the transducers. Variable retort operating conditions consisted of two retort temperatures (115 and 125°C) and three weir heights (29.2, 31.2 and 34.6 cm). Mean standard deviations of thermocouple readings indicating temperature distribution during the cook period ranged from 0.19 to 0.22 C°. Slight temperature gradients were found between the upper and lower water channels and between the entrance and exit regions of water channels. The coldest locations (the exit regions of water channels 1 and 2) averaged approximately 0.6 C° lower than the hottest locations (the entrance and exit region of water channel 11 and the exit region of water channel 10). Mean standard deviations of thermocouple readings indicating temperature stability during the cook period ranged from 0.10 to 0.20 C°. Temperature stability was uniform between all water channels, except channel 11, which was less stable. The entrance and exit regions of water channels displayed similar stability. The existence of heat transfer variability within the water immersion retort was indicated. A retort temperature of 125°C produced smaller fh and fc values than 115°C. Variations in weir height influenced the distribution of fh values between trays. Weir height 2 (31.2 cm) exhibited uniform values between all trays. Weir height 1 (29.2 cm) exhibited uniform fh values between all trays, except for a significantly larger value for the very top tray. Although weir height 3 (34.6 cm) created the most variability between tray levels, weir height 1 displayed the widest range of fh values. More variability in fc values between trays was shown during the cool period. Weir height 2 displayed the most uniform fc values between trays, however, the range of fc values between trays was similar for all three weir heights. Within trays, a gradient of fh and fc values was found between the entrance, exit and middle positions, with the smallest values found in the entrance positions. In comparison, the largest fh values were found in the exit and middle positions of trays 1 and 10. The largest fc values were found in the middle positions of trays 1 and 3 and the middle and exit positions of tray 10. Weir heights 1 and 2 produced smaller jh values than weir height 3, variations in weir height had no influence on jc values. A gradient of jh values between tray levels was shown, with smaller values associated with upper trays and larger values with lower trays. Smaller jh and jc values were associated with the entrance positions of trays than with the middle and exit positions. A comparison with steam processing indicated larger fh values for the water immersion process and larger fc values for the cooling method used with the steam process. Calculation of process lethalities indicated variability of sterilizing conditions within the retort. Larger Fo values were associated with upper trays than with lower trays. Within trays, larger Fo values were found in the tray entrance positions than the middle and exit positions. The largest Fo values were exhibited in the entrance positions of the middle to upper trays, while the smallest values were found in the middle and exit positions of the bottom trays. Retort pressure studies indicated pressure stability during the cook period, however, during the initial minutes of the cool period, a significant pressure drop occurred, which the retort corrected. Pressure stability was maintained once the target pressure was re-established.
Land and Food Systems, Faculty of
Graduate

34

Wright, Sean. "The exergy of thermal radiation and its relevance in solar energy conversion." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0010/NQ52779.pdf.

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35

Thompson, Matthew Roger. "Thermal management of integrated circuits using synthetic jet technology." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/17108.

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36

Morrison, John William. "Auxiliary cooling in heat pipe cooled hypersonic wings." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/17113.

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37

Wang, Jianwei. "An experimental investigation of droplet impact cooling at controlled surface temperatures." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/17329.

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38

Brani, David M. "Improved method for determining radiation intensity using total gas emissivities." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/17811.

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39

Sismanis, Panagiotis G. 1959. "An experimental technique to measure convection in liquid metals /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63217.

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40

McClelland, Elizabeth A. "Heat and mass transfer in an axisymmetric sudden expansion." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/16462.

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41

Moss, Roger W. "The effects of turbulence length scale on heat transfer." Thesis, University of Oxford, 1992. http://ora.ox.ac.uk/objects/uuid:da82e72d-f91b-4fd7-a773-539cba4681e4.

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The second used a pre-heated flat plate in a transient wind tunnel to determine heat transfer rates with freestream turbulence generated by a number of parallel bar grids. Both liquid crystals and thin film gauges were used for heat-flux studies. A correlation has been derived that defines the heat transfer enhancement in terms of turbulence intensity and integral scale, as well as extending the conclusions of previous workers to apply at high intensities and with severe anisotropy.

42

Sun, Yaojun. "Heat transfer in molten core/concrete interaction systems." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/17105.

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43

Santiago, Fabio 1985. "Utilização do método da integral dupla em problemas de condução de calor unidimensional em regime transitório." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263430.

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Orientador: Luiz Fernando Milanez
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-21T01:50:40Z (GMT). No. of bitstreams: 1 Santiago_Fabio_M.pdf: 8778625 bytes, checksum: 682efcdc5efb8549b7c4dbd3564ef87e (MD5) Previous issue date: 2012
Resumo: O objetivo deste trabalho é utilizar o método da integral dupla na obtenção de soluções analíticas aproximadas para problemas de condução térmica unidimensional em regime transitório. Sendo o método da integral dupla um refinamento do amplamente utilizado método da integral simples, também conhecido Karman-Pohlhausen para a camada limite ou método de Goodman para mudança de fase, inicialmente foi proposto um minucioso estudo do capítulo Application of Integral Methods to Transient Nonlinear Heat transfer, cujo objetivo era compreender o funcionamento deste método, assim como selecionar os problemas apresentados neste trabalho. Posteriormente realizou-se o estudo do artigo primordial de aplicação do método da integral dupla publicado por Volkov, bem como dos principais trabalhos envolvendo o método da integral dupla. Ao todo foram selecionados seis casos do trabalho original de Goodman, os quais foram resolvidos com o uso do método da integral dupla para perfis quadrático e cúbico. A escolha de perfis polinomiais se justifica uma vez que estes são de fácil manipulação diante das operações de diferenciação e integração comum os métodos integrais, além disso, o uso de perfis de grau distinto tem como objetivo mostrar a influência da variação deste na obtenção de melhores aproximações. De modo a convalidar os resultados apresentados pelo método da integral dupla, estes foram comparados com as soluções analíticas exatas presente na literatura assim como, com as soluções aproximadas apresentadas por Goodman e com a solução numérica obtida pelo método de volumes de controles. Os resultados obtidos neste trabalho revelam o melhor desempenho do método da integral dupla quando comparado com os resultados obtidos por Goodman em seu trabalho anteriormente citado
Abstract: The objective of this work is to use the method of the double integral to obtain approximate analytical solutions for one-dimensional heat conduction problems in the transitional regime. As the method of a double integral refinement of the widely used simple integral method, also known Karman-Pohlhausen for the boundary layer or the Goodman method for phase change, was initially proposed a thorough study of Chapter Application of Integral Methods to Transient Nonlinear Heat transfer, the objective of which was to understand the functioning of this method as well as selecting the problems presented in this paper. Subsequently we carried out the study of the primary article of the method of the double integral posted by Volkov as well as major works involving the method of double integral. In all six cases were selected from the original work of Goodman, which were solved using the method of the double integral for quadratic and cubic profiles. The choice of polynomial profiles is justified as they are easy to handle before the operations of common differentiation and integration methods, moreover, the use of profiles of different degree is intended to show the influence of the variation in obtaining better approximations. In order to validate the results presented by the method of the double integral, they were compared with the exact analytical solutions in the literature as well as with the approximate solutions presented by Goodman and the numerical solution obtained from a volume control. The present results show the improved performance of the method of the double integral compared with the results obtained by Goodman in their work cited above
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica

44

Matelli, José Alexandre. "Uso de analogias como recurso didático na disciplina de transmissão de calor /." Guaratinguetá, 2018. http://hdl.handle.net/11449/190884.

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Banca: Álvaro de Souza Dutra
Banca: Messias Borges da Silva
Banca: Estaner Claro Romão
Banca: Carlos Alberto Moreira dos Santos
Bancs: Durval Rodrigues Junior
Resumo: Disserta-se nessa tese sobre o uso de analogias como recurso didático na disciplina de transmissão de calor. A aplicação de analogias no ensino é revisada na literatura, de modo que se estabeleça um referencial teórico que justifique este uso. Assim, propõe-se que a analogia possa ser interpretada como um mediador simbólico de Vigotski. Usos de analogias adaptadas ou desenvolvidas em sala de aula pelo autor da presente tese são apresentados. As impressões do autor acerca da receptividade dos alunos ao recurso são discutidas, bem como alguns casos de interação com os alunos são apresentados
Abstract: The use of analogies as a didactic resource in the discipline of heat transfer is discussed in this thesis. The application of analogies in teaching is reviewed in the literature, so that a theoretical framework that justifies the use of analogies can be established. Thus, it is proposed that the analogy can be interpreted as a Vigotski's symbolic mediation. Uses of analogies either adapted or developed in the classroom by the author of this thesis are presented. The impressions of the author about the students' receptivity to the resource are discussed, as well as some cases of interaction with the students are presented

45

Roth, Eric. "Nucleation and Heat Transfer in Liquid Nitrogen." PDXScholar, 1993. https://pdxscholar.library.pdx.edu/open_access_etds/1370.

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With the advent of the new" high Tc superconductors as well as the increasing use of cryo-cooled conventional electronics, liquid nitrogen will be one of the preferred cryogens used to cool these materials. Consequently, a more thorough understanding of the heat transfer characteristics of liquid nitrogen is required. In these investigations the transient heating characteristics of liquid nitrogen to states of nucleate and film boiling under different liquid flow conditions are examined. Using a metal hot wire/plate technique, it is verified that there is a premature transition to film boiling in the transient case at power levels as much as 30 percent lower than under steady state nucleate boiling conditions. It is also shown that the premature transition can be reduced or eliminated depending on the flow velocity The second part of this research analyses the nucleation (boiling) process from a dynamical systems point of view. By observing how the boiling system variables evolve and fluctuate over time, it is hoped that physical insight and predictive information can be gained. One goal is to discover some indicator or signature in the data that anticipates the transition from nucleate boiling to film/boiling. Some of the important variables that make up the boiling system are the temperature of the heater and the heat flux through the heater surface into the liquid nitrogen. Results, gained by plotting the systemâ€™s trajectory in the heat flux-temperature plane, are that on average the system follows a counterclockwise trajectory. A physical model is constructed that explains this behavior. Also, as the applied heater power approaches levels at which the transition to film is known to occur, the area per unit time swept out in the heat flux-temperature plane is seen to reach a maximum. This could be of practical interest as the threshold to film boiling can be anticipated and possibly prevented.

46

Zaerr, Jon Benjamin 1963. "Development and evaluation of a dynamic phantom using four independently perfused in vitro kidneys as a tool for investigating hyperthermia systems." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/291341.

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Abstract:

A dynamic phantom for use in investigating hyperthermia heating systems has been designed, constructed, and tested. A computer controlled the flow rate of 80% Ethanol to each of 4 preserved in vitro canine kidneys which acted as the phantom material. The flow rates were regulated with stepper motor controlled valves and measured with flow meters by the computer. This provided a flexible system for adjusting the perfusion as desired. The system was tested with step and ramp changes in perfusion under constant power ultrasound and with a temperature controlled perfusion algorithm, all of which yielded repeatable results. The dynamic phantom developed in this work shows potential for expediting investigations of hyperthermia controllers, temporal blood flow patterns, and inverse problems. Its computer based nature gives it great flexibility which would lend itself well to automated testing procedures.

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Chow, Bosco. "Heat transfer and pressure drop in fixed beds of wood chips." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25085.

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Abstract:

Heat transfer from a flowing gas to a fixed bed of dried Dougas-fir wood chips has been studied by a transient method. Hot air at about 130°C flowed upward through 0.2 m dia x 1 m deep beds of commercially prepared wood chips which had been screened for thickness. Four different wood chip sizes were used, which varied in mean thickness from 2.44 to 7.26 mm. The thickest chips were 18.4 mm wide x 36.3 mm long. Gas temperatures were measured at a number of axial positions as the bed temperature rose from its initial temperature of about 20°C. Heat transfer coefficients were calculated by fitting the air temperature profiles to a transient mathemical model for plug flow of gas through a bed of slab-shaped particles with finite internal thermal resistance. The heat transfer model was solved analytically using an approach pioneered by Amundson (10) for fixed beds of spherical particles and based on Rosen's (6,7) function. This solution has not appeared elsewhere in the literature, and is shown to converge to that of Anzelius (1) if the Biot number for the particle approaches zero. Experiments were done at a series of air velocities with four wood-chip thicknesses and with spherical catalyst particles to provide a check on the technique. The effect on heating rate of 30% by volume steam in the incoming air was investigated. For selected experiments, solid temperatures within the wood chips were measured. A correlation of the heat transfer coefficients is presented. Pressure drop was measured as a function of air velocity for different sizes of wood chips at room temperature and the results are compared with predictions of the Ergun equation.
Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate

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Sawyer, Mikel Louis. "High intensity heat transfer to a stream of monodispersed water droplets." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/17991.

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Coneybeer, Robert T. "Transient thermal models for substation transmission components." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/17686.

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Dempsey, Brian Paul 1958. "LOW PECLET NUMBER HEAT TRANSFER IN A LAMINAR TUBE FLOW SUBJECTED TO AXIALLY VARYING WALL HEAT FLUX." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/275506.

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Dissertations / Theses on the topic 'Heat Transmission'

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