Дисертації з теми "Radiative Heat Transfer Rate"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Radiative Heat Transfer Rate".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Wangdhamkoom, Panitan. "Characteristics of multimode heat transfer in a differentially-heated horizontal rectangular duct." Thesis, Curtin University, 2007. http://hdl.handle.net/20.500.11937/1007.
Повний текст джерелаWangdhamkoom, Panitan. "Characteristics of multimode heat transfer in a differentially-heated horizontal rectangular duct." Curtin University of Technology, Department of Mechanical Engineering, 2007. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=17353.
Повний текст джерелаMaheria, Mehulkumar. "Thermal Analysis of Natural Convectiona and Radiation in Porous Fins." Cleveland State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=csu1281982835.
Повний текст джерелаColomer, Rey Guillem. "Numerical methods for radiative heat transfer." Doctoral thesis, Universitat Politècnica de Catalunya, 2006. http://hdl.handle.net/10803/6691.
Повний текст джерелаEn el capítol 1 s'exposa una breu introducció a la transferència d'energia per radiació, i una explicació de les equacions que la governen. Es tracta de l'equació del transport radiatiu, formulada en termes dels coeficients d'absorció i de dispersió, i l'equació de l'energia. També s'indica quan cal tenir en compte aquest fenòmen, i a més a més, es defineixen totes les magnituds i conceptes que s'han utilitzat en aquesta tesi. També es dóna una breu descripció d'algunes simplificacions que es poden fer a les equacions governants.
El mètode de les radiositats s'explica en el capítol 2. També s'hi descriu un procediment numèric que permet calcular els factors de vista en geometries amb simetria cilíndrica, i es presenten resultats obtinguts amb el mètode descrit. Tot i que aquest capítol està una mica deslligat de la resta de la tesi, l'algoritme ideat per tractar geometries tridimensionals amb un temps computacional molt proper al de geometries bidimensionals, sense un increment de memòria apreciable, dóna uns resultats prou bons com per formar part de la tesi.
El mètode de les ordenades discretes (DOM) es detalla en el capítol 3. L'aspecte més important d'aquest mètode es l'elecció del conjunt d'ordenades per integrar l'equació del transport radiatiu. S'enumeren quines propietats han d'acomplir aquests conjunts. S'hi explica amb detall la discretització de la equació del transport radiatiu, tant en coordenades cartesianes com en cilíndriques. Es presenten també alguns resultats ilustratius obtinguts amb aquest mètode.
En el moment en que es vol resoldre un problema real, cal tenir present que el coeficients d'absorció pot dependre bruscament de la longitud d'ona de la radiació. En aquesta tesi s'ha considerat aquesta dependència amb especial interés, en el capítol 4. Aquest interès ha motivat una recerca bibliogràfica sobre la modelització aquesta forta dependència espectral del coeficient d'absorció. Aquesta recerca s'ha dirigit també a l'estudi dels diferents models numèrics existents capaços d'abordar-la, i de resoldre la equació del transport radiatiu en aquestes condicions. Es descriuen diversos mètodes, i, d'aquests, se n'han implementat dos: el mètode de la suma ponderada de gasos grisos (WSGG), i el mètode de la suma de gasos grisos ponderada per línies espectrals (SLW). S'hi presenten també resultats ilustratius.
S'han realitzat multitud de proves en el codi numèric resultant de l'elaboració d'aquesta tesi. Tenint en compte els resultats obtinguts, es pot dir que els objectius proposats a l'inici de la tesi s'han acomplert. Com a demostració de la utilitat del codi resultant, aquest ha estat integrat en un codi de proposit general (DPC), resultat del treball de molts investigadors en els darrers anys.
Aquesta esmentada integració permet la resolució de problemes combinats de transferència de calor, analitzats en els capítols 5 i 6, on la radiació s'acobla amb la transferència de calor per convecció. La influència de la radiació en la transferència total de calor s'estudia en el capítol 5, publicat a la International Journal of Heat and Mass Transfer, volum 47 (núm. 2), pàg. 257-269, 2004. En el capítol 6, s'analitza l'efecte d'alguns paràmetres del mètode SLW en un problema combinat de transferència de calor. Aquest capítol s'ha enviat a la revista Journal of Quantitative Spectroscopy and Radiative Transfer, per què en consideri la publicació.
The main objective of the present thesis is to study the energy transfer by means of radiation. Therefore, the basic phenomenology of radiative heat transfer has been studied. However, considering the nature of the equation that describes such energy transfer, this work is focussed on the numerical methods which will allow us to take radiation into account, for both transparent and participating media. Being this the first effort within the CTTC ("Centre Tecnològic de Transferència de Calor") research group on this subject, it is limited to simple cartesian and cylindrical geometries.
For this purpose, chapter 1 contains an introduction to radiative energy transfer and the basic equations that govern radiative transfer are discussed. These are the radiative transfer equation, formulated in terms of the absorption and scattering coefficients, and the energy equation. It is also given a discussion on when this mode of energy transfer should be considered. In this chapter are also defined all of the magnitudes and concepts used throughout this work. It ends with a brief description of some approximate methods to take radiation into account.
The Radiosity Irradiosity Method is introduced in chapter 2. In this chapter it is also described a numerical method to calculate the view factors for axial symmetric geometries. The main results obtained in such geometries are also presented. Although a little disconnected from the rest of the present thesis, the algorithm used to handle "de facto"' three dimensional geometries with computation time just a little longer than two dimensional cases, with no additional memory consumption, is considered worthy enough to be included in this work.
In chapter 3, the Discrete Ordinates Method (DOM) is detailed. The fundamental aspect of this method is the choice of an ordinate set to integrate the radiative transfer equation. The characterization of such valuable ordinate sets is laid out properly. The discretization of the radiative transfer equation is explained in etail. The direct solution procedure is also outlined. Finally, illustrative results obtained with the DOM under several conditions are presented.
In the moment we wish to solve real problems, we face the fact that the absorption and scattering coefficients depend strongly on radiation wavelength. In the present thesis, special emphasis has been placed on studying the radiative properties of real gases in chapter 4. This interest resulted on a bibliographical research on how the wavenumber dependence of the absorption coefficient is modeled and estimated. Furthermore, this bibliographical research was focussed also on numerical models able to handle such wavenumber dependence. Several methods are discussed, and two of them, namely the Weighted Sum of Gray Gases (WSGG) and the Spectral Line Weighted sum of gray gases (SLW), have been implemented to perform non gray calculations. Some significant results are shown.
Plenty of tests have been performed to the numerical code that resulted from the elaboration of this thesis. According to the results obtained, the objectives proposed in this thesis have been satisfied. As a demonstration of the usefulness of the implemented code, it has been succesfully integrated to a general purpose computational fluid dynamics code (DPC), fruit of the effort of many researchers during many years.
Results of the above integration lead to the resolution of combined heat transfer problems, that are analyzed in chapters 5 and 6, where radiative heat transfer is coupled to convection heat transfer. The effect of radiation on the total heat transfer is studied in chapter 5, which has been published as International Journal of Heat and Mass Transfer, volume 47 (issue 2), pages 257--269, year 2004. In chapter 6, the impact of some parameters of the SLW model on a combined heat transfer problem is analyzed. This chapter has been submitted for publication at the Journal of Quantitative Spectroscopy and Radiative Transfer.
Ramamoorthy, Babila. "Numerical simulation of radiative heat transfer." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2009r/ramamoorthy.pdf.
Повний текст джерелаQuintero, de la Garza Rodrigo Javier 1974. "Spheroidization of iron powders by radiative heat transfer." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85328.
Повний текст джерелаIncludes bibliographical references (leaves 45-46).
by Rodrigo Javier Quintero de la Garza.
S.M.
Dai, Jin. "Near-Field Radiative Heat Transfer between Plasmonic Nanostructures." Doctoral thesis, KTH, Optik och Fotonik, OFO, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-195653.
Повний текст джерелаQC 20161111
Luo, Gang. "A cloud fraction and radiative transfer model." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/25753.
Повний текст джерелаSafdari, Mohammad Saeed. "Characterization of Pyrolysis Products from Fast Pyrolysis of Live and Dead Vegetation." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/8807.
Повний текст джерелаEnd, Thomas [Verfasser]. "Optimal Control of Nonlocal Radiative Heat Transfer / Thomas End." München : Verlag Dr. Hut, 2012. http://d-nb.info/1021072893/34.
Повний текст джерелаBakeer, Muna. "Radiative heat transfer in gallium arsenide lec crystal pullers." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29916.
Повний текст джерелаApplied Science, Faculty of
Mechanical Engineering, Department of
Graduate
Luan, Wenqi. "Radiative and total heat transfer in circulating fluidized beds." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25101.pdf.
Повний текст джерелаTorpey, Mark R. "A study of radiative heat transfer through foam insulation." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14661.
Повний текст джерелаMbiock, Aristide. "Radiative heat transfer in furnaces : elliptic boundary value problem." Rouen, 1997. http://www.theses.fr/1997ROUEA002.
Повний текст джерелаZhang, Yufang. "Coupled convective heat transfer and radiative energy transfer in turbulent boundary layers." Phd thesis, Ecole Centrale Paris, 2013. http://tel.archives-ouvertes.fr/tel-00969159.
Повний текст джерелаGlockling, James L. D. "Heat and mass transfer in specific aerosol systems." Thesis, London South Bank University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303937.
Повний текст джерелаBasu, Soumyadipta. "Near-field radiative energy transfer at nanometer distances." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31777.
Повний текст джерелаCommittee Chair: Zhang, Zhuomin; Committee Member: Citrin, David; Committee Member: Hesketh, Peter; Committee Member: Joshi, Yogendra; Committee Member: Peterson, Andrew. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Nouri, Nima. "Radiative Conductivity Analysis Of Low-Density Fibrous Materials." UKnowledge, 2015. https://uknowledge.uky.edu/me_etds/66.
Повний текст джерелаKhan, Yasir Urfat. "Modelling of spectral effects in radiative heat transfer in furnaces." Thesis, Coventry University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337097.
Повний текст джерелаTong, Jonathan Kien-Kwok. "Photonic engineering of near- and far-field radiative heat transfer." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104127.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 181-195).
Radiative heat transfer is the process by which two objects exchange thermal energy through the emission and absorption of electromagnetic waves. It is one of nature's key fundamental processes and is ubiquitous in all facets of daily life from the light we receive from the Sun to the heat we feel when we place our hands near a fire. Fundamentally, radiative heat transfer is governed by the photonic dispersion, which describes all the electromagnetic states that can exist within a system. It can be modified by the material, the shape, and the environment. In this thesis, morphological effects are used to modify the photonic dispersion in order to explore alternative methods to spectrally shape, tune, and enhance radiative heat transfer from the near-field to the far-field regimes. We start by investigating the application of thin-film morphologies to different types of materials in the near-field regime using a rigorous fluctuational electrodynamics formalism. For thin-film semiconductors, trapped waveguide modes are formed, which simultaneously enhance radiative transfer at high frequencies where these modes are resonant and suppress radiative transfer at low frequencies where no modes are supported. This spectrally selective behavior is applied to a theoretical thermophotovoltaics (TPV) system where it is predicted the energy conversion efficiency can be improved. In contrast, thin-films of metals supporting surface plasmon polariton (SPP) modes will exhibit the opposite effect where the hybridization of SPP modes on both sides of the film will lead to a spectrally broadened resonant mode that can enhance near-field radiative transfer by over an order of magnitude across the infrared wavelength range. In order to observe these morphological spectral effects, suitable experimental techniques are needed that are capable of characterizing the spectral properties of near-field radiative heat transfer. To this end, we developed an experimental technique that consists of using a high index prism in an inverse Otto configuration to bridge the momentum mismatch between evanescent near-field radiative modes and propagation in free space in conjunction with a Fourier transform infrared (FTIR) spectrometer. Preliminary experimental results indicate that this method can be used to measure quantitative, gap-dependent near-field radiative heat transfer spectrally. While utilizing near-field radiative transfer remains a technologically challenging regime for practical application, morphological effects can still be used to modify the optical properties of materials in the far-field regime. As an example, we use polyethylene fibers to design an infrared transparent, visibly opaque fabric (ITVOF), which can provide personal cooling by allowing thermal radiation emitted by the human body to directly transmit to the surrounding environments while remaining visible opaque to the human eye.
by Jonathan Kien-Kwok Tong.
Ph. D.
Vujičić, Mile R. "Finite element modelling and experimental validation in radiative heat transfer." Thesis, Swansea University, 2006. https://cronfa.swan.ac.uk/Record/cronfa42640.
Повний текст джерелаCoyle, Carolyn Patricia. "Advancing radiative heat transfer modeling in high-temperature liquid-salts." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/129113.
Повний текст джерелаCataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 125-133).
Nuclear and solar-thermal communities are investigating the use of high Prandtl number liquid-salts in energy generation systems, including fluoride salt-cooled high-temperature reactors (FHRs), molten salt reactors (MSRs), fusion devices, and concentrated solar power plants. The temperature distribution in the coolant salts can be affected by participating media radiative heat transfer, due to the high temperature operation and their semitransparent nature. Computational fluid dynamics (CFD) becomes a valuable tool to model the complex 3-dimensional nature of the heat transfer, especially in regions where temperature-dependent material corrosion drives the need for accurate local temperature predictions. Correctly modeling radiative heat transfer in CFD requires well-characterized liquid-salt optical properties, which are not yet known. Additionally, current CFD approaches can become computationally too expensive for practical use when spectral effects need to be resolved.
A lower cost approach, capable of still resolving the coupled convective-radiative heat transfer is therefore needed. In this thesis, an experimental apparatus for measuring the spectral absorption coefficients of 46.5%LiF:11.5%NaF:42%KF (FLiNaK) and 50%NaCl:50%KCl is designed and validated to have high-measurement accuracy in the transmissive and multiphonon absorption regions where radiative emissions peak. A high-fidelity CFD methodology is then developed to model participating media radiative heat transfer. The approach defines a consistent, spectral banding procedure that captures non-gray absorption behavior at reasonable computational cost. The methodology is applied to CFD simulations of a twisted elliptical tube heat exchanger geometry, where local, 3-dimensional effects are especially significant.
A matrix of simulation results comparing FLiNaK and 66.6%LiF:33.4%BeF2 (FLiBe) coolants provides a quantitative assessment of the thermal radiation contributions to the overall heat transfer. Laminar flows, expected in accident scenarios, experience the strongest effect, where lower average wall temperatures and enhanced temperature uniformity result in an effective Nusselt number increase of up to 11%. Turbulent flows see a reduction in maximum local wall temperatures up to 25'C, which could have a notable impact on reducing corrosion effects. The observed trends demonstrate the larger impact of radiation effects in FLiBe simulations due to larger absorption in BeF2. This suggests thermal radiation may be more dominant in MSRs, where dissolved fuel and impurities increase absorption.
The method proposed to include the effects of thermal radiation in CFD analysis can support a more effective and accurate design of high temperature systems and components, providing increased safety margins for operation.
by Carolyn Patricia Coyle.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Nuclear Science and Engineering
Goncalves, Dos santos Rogério. "Large Eddy simulations of turbulent combustion including radiative heat transfer." Châtenay-Malabry, Ecole centrale de Paris, 2008. http://www.theses.fr/2008ECAP1052.
Повний текст джерелаThe combustion is one of the principal ways to produced energy used nowadays, it is also a complex phenomenon, where the turbulent flow, chemical reactions, different phases and different heat transfer phenomena can interact. Better understanding of these interactions is essential to improve the actual combustion system and to developed the new ones. The goal of this thesis is to study the interaction of the turbulent combustion with the thermal radiation by the use of three-dimensional numerical simulation. For that, using a computational tool named CORBA, a code for the combustion Large Eddy Simulation (LES) was coupled with a radiative heat transfer code. This technique allows the exchange of information between the two codes without big changes in their structure, then it is possible to take advantages of the different characteristic time from each phenomenon in a high performance parallel computational environment. In a first time, two-dimensional simulation of a turbulent propane/air premixed flame stabilized downstream a triangular flame holder has been realised. After the changing of the twodimensional radiation code for another three-dimensional one, the same configuration was simulated in 3D. A mesh with more than 4. 7 millions cells for the combustion code (AVBP) and more than 3. 3 millions cells for the radiation code (DOMASIUM) are used. Results show a changing in the temperature and species fields, as well as in the flame dynamics when the thermal radiation was taken into account, with a minor intensity in the three-dimensional simulations. This method, also, shows that it is possible to perform 3D complex simulations in a industrial acceptable time
Lussange, Johann A. "The Casimir energy and radiative heat transfer between nanostructured surfaces." Paris 6, 2012. http://www.theses.fr/2012PA066244.
Повний текст джерелаMorales, Rebellon Juan Carlos. "Radiation exchange within enclosures of diffuse gray surfaces : the inverse problem /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
Повний текст джерелаStröhle, Jochen [Verfasser]. "Spectral Modelling of Radiative Heat Transfer in Industrial Furnaces / Jochen Ströhle." Aachen : Shaker, 2004. http://d-nb.info/1172612382/34.
Повний текст джерелаIp, Samuel Chun Hung. "Study of radiative heat transfer in porous media for sintering applications /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?MECH%202002%20IP.
Повний текст джерелаIncludes bibliographical references (leaves 82-85). Also available in electronic version. Access restricted to campus users.
Clements, Alastair Greenman. "Modelling mercury oxidation and radiative heat transfer in oxy-coal environments." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/12594/.
Повний текст джерелаCui, Xiaoming. "Discontinuous finite/boundary element method for radiative heat transfer with application in laser cancer therapy." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Dissertations/Fall2005/x%5Fcui%5F121805.pdf.
Повний текст джерелаLiu, Yan. "Modelling of radiation in laminar flames." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319826.
Повний текст джерелаFu, Ceji. "Radiative Properties of Emerging Materials and Radiation Heat Transfer at the Nanoscale." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4941.
Повний текст джерелаSinger, Farah. "Influence of the nonlocal effects on the near-field radiative heat transfer." Thesis, Poitiers, 2014. http://www.theses.fr/2014POIT2338.
Повний текст джерелаIn this thesis, we study the validity of few nonlocal models of the dielectric permittivity in the calculation of the radiative heat transfer coefficient (RHTC) between two semi-infinite parallel dielectric planes separated by a vacuum gap of width d.In past theoretical studies, it has been shown that upon considering a local model of the dielectric permittivity, near field radiative heat transfer (NFRHT) between two dielectric materials follows a 1/d2 law when d is of the order or less than few hundreds of nanometers. This nonphysical diverging increase has been the bottleneck of the local model. Overwhelming efforts have been deployed in order to come up with a new model in which the nonlocal effects of the dielectric permittivity are taken into account. To the best of our knowledge, no nonlocal correction to the NFRHT has been addressed in the past in the case of dielectrics. In the case of metals however, an important and complete work has been performed using the Lindhard-Mermin nonlocal dielectric permittivity model.Our work focuses on studying four different nonlocal models of the dielectric permittivity and on using them in the calculation of the RHTC between two solid semi-infinite parallel planes of 6H-SiC. We show that the RHTC saturates as the separation distance d tend to zero. The distance at which saturation starts to take place depends on key parameters involved in each model
English, Justin. "HEAT TRANSFER CHARACTERISTICS IN WILDLAND FUELBEDS." UKnowledge, 2014. http://uknowledge.uky.edu/me_etds/52.
Повний текст джерелаKo, Min Seok. "Numerical simulation of three-dimensional combined convective radiative heat transfer in rectangular channels." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2542.
Повний текст джерелаErfurth, Jens [Verfasser]. "Radiative Heat Transfer in Coal-Fired Furnaces and Oxycoal Retrofit Considerations / Jens Erfurth." Aachen : Shaker, 2012. http://d-nb.info/1069048372/34.
Повний текст джерелаRehfeldt, Sebastian [Verfasser], and Günter [Akademischer Betreuer] Scheffnecht. "Radiative heat transfer in oxy-fuel steam generators / Sebastian Rehfeldt ; Betreuer: Günter Scheffnecht." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2016. http://d-nb.info/1118507487/34.
Повний текст джерелаHenson, Jonathan Charles. "Numerical simulation of spark ignition engines with special emphasis on radiative heat transfer." Thesis, Loughborough University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297589.
Повний текст джерелаShapiro, Michael Jay. "An experimental investigation of the thermal conductivity of thin-wall hollow ceramic spheres." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/8667.
Повний текст джерелаLan, Chao-ho. "Radiative combined-mode heat transfer in a multi-dimensional participating medium using spectral methods /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004312.
Повний текст джерелаMaag, Gilles. "Monte Carlo radiative heat transfer analysis of a CH₄ flow laden with carbon particles." Zürich : ETH, Eidgenössische Technische Hochschule Zürich, Institute of Energy Technology, 2006. http://e-collection.ethbib.ethz.ch/show?type=dipl&nr=283.
Повний текст джерелаWarude, Anand. "Analysis of glass mold to enhance rate of heat transfer." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000618.
Повний текст джерелаSavur, Mehmet Koray. "A numerical study of combined convective and radiative heat transfer in a rocket engine combustion chamber." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Dec%5FSavur.pdf.
Повний текст джерелаPhillips, Bren Andrew. "Nano-engineering the boiling surface for optimal heat transfer rate and critical heat flux." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/76536.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (p. 130-133).
The effects on pool boiling characteristics such as critical heat flux and the heat transfer coefficient of different surface characteristics such as surface wettability, roughness, morphology, and porosity are not well understood. Layer-by-layer nanoparticle coatings were used to modify the surface of a sapphire heater to control the surface roughness, the layer thickness, and the surface chemistry. The surface was then tested in a water boiling test at atmospheric pressure while imaging the surface with high speed infrared thermography yielding a 2D time dependent temperature profile. The critical heat flux and heat transfer coefficient were enhanced by over 100% by optimizing the surface parameters. It was found that particle size of the nanoparticles in coating, the coating thickness, and the wettability of the surface have a large impact on CHF and the heat transfer coefficient. Surfaces were also patterned with hydrophobic "islands" within a hydrophilic "sea" by coupling the Layer-by-layer nanoparticle coatings with an ultraviolet ozone technique that patterned the wettability of the surface. The patterning was an attempt to increase the nucleation site density with hydrophobic dots while still maintaining a large hydrophilic region to allow for rewetting of the surface during the ebullition cycle and thus maintaining a high critical heat flux. The patterned surfaces exhibited similar critical heat fluxes and heat transfer coefficients to the surfaces that were only modified with layer-by-layer nanoparticle coatings. However, the patterned surfaces also exhibited highly preferential nucleation from the hydrophobic regions demonstrating an ability to control the nucleation site layout of a surface and opening an avenue for further study.
by Bren Andrew Phillips.
S.M.
Okyay, Gizem. "Impact of the morphology of soot aggregates on their radiative properties and the subsequent radiative heat transfer through sooty gaseous mixtures." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC031/document.
Повний текст джерелаSoot and its characterization are of interest to researchers from various domains such as combustion diagnostics, numerical combustion, atmospheric optics, environmental and health applications. In this study, the main interest is on the radiative properties of soot aggregates issued directly from combustion flames in order to determine the effect of the presence of soot on the radiative heat transfer in the simulation of high temperature industrial applications involving gas combustion. Current studies modeling the radiative heat transfer through sooty gaseous media consider only the absorption as the main phenomenon of material-radiation interaction. Generalized correlations are used to determine the radiative properties of soot: these radiative properties are either computed over numerically generated aggregate morphologies or simply as a function of the soot average size, the fractal dimension and the volume fraction. However, the material-radiation interaction is susceptible to be more complex and morphology dependent at the aggregate level because of multiple scattering when the size of the object reaches the order of magnitude of the incident radiation wavelengths.In our work, we investigate the possibility to establish a computational methodology and workflow, starting from the definition of a realistic soot morphology up to the computation of the radiative heat transfer. To that end, observations of soot issued from propane/air, methane/air and methane/oxygen flames are performed using Scanning Electron Microscopy (SEM). SEM tomography is applied for the first time on soot issued from a propane/air flame, combined with Transmission Electron Microscopy (TEM) observations. 2D and 3D fractal analysis techniques are used to investigate the fractal properties of virtual (numerically generated) soot clusters and also of the tomography reconstructed objects. The radiative properties of soot are then computed using our in-house developed DDA (Discrete Dipole Approximation) code. Special attention is paid to the DDA modeling of soot because of the high complex extinction index of the material, and to the directional integration numerical methods because direction-averaged radiative properties are required for the subsequent radiative heat transfer simulations. The morphology and the radiative properties of the realistic morphology are compared to the ones of representative soot aggregates numerically generated by a DLCCA (Diffusion Limited Cluster-Cluster Aggregation) algorithm. The similarities and discrepancies on the radiative properties are investigated, and the differences between representative virtual aggregates on the one hand and the tomography reconstructed object on the other hand in terms of radiative properties are highlighted. Finally the effect of the presence and of the morphology of soot on the radiative heat transfer within a sooty gaseous mixture in a 1D isothermal parallel plate configuration is investigated by the resolution of the radiative transfer equation using DOM (Discrete Ordinates Method)
Zhang, Chang. "Radiative Heat Transfer in Free-Standing Silicon Nitridemembranes in the Application of Thermal Radiation Sensing." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41409.
Повний текст джерелаJohnson, Dennis R. "Analysis and synthesis of radiative heat transfer in longitudinal fins in free space and non-free space." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA236942.
Повний текст джерелаThesis Advisor(s): Kraus, Allan D. Second Reader: Brown, Sue. "June 1990." Description based on signature page. DTIC Identifier(s): Radiators (heating and cooling), radiative transfer, heat transfer (radiation). Author(s) subject terms: Radiative heat transfer, longitudinal fins, free space and non-free space. Includes bibliographical references (p. 147-148). Also available online.
Avila, Matías. "Nonlinear subgrid finite element models for low Mach number flows coupled with radiative heat transfer." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/285809.
Повний текст джерелаLa descripción general del movimiento de un flujo implica la solución de las ecuaciones de Navier-Stokes compresibles, un problema de muy compleja estructura matemática. Estas ecuaciones proporcinan una descripción detallada de cualquier problema en mecánica de fluidos, que puede presentar distintos mecanismos no lineales que interactúan entre si. En función de la física del problema que se esté considerando, pueden derivarse modelos simplificados de las ecuaciones de Navier-Stokes mediante analisis dimensional, que ignoran algunos fenómenos físicos. Por otro lado, la transferencia de calor por radiación puede interactuar con el movimiento de un fluido, e ignorar sus efectos puede tener consecuencias importantes en las predicciones del flujo. Problemas donde hay fuego implican la evaluacion del efecto del calor por radiación. El presente trabajo está dirigido a flujos a bajo número de Mach térmicamente acoplados, donde el calor por radiación afecta al flujo. Debido a la complejidad del problema matemático, la solución numérica es muy complicada. A pesar de las diferencia en el tratamiento de la incompresibilidad, las ecuaciones de flujo a bajo número de Mach poseen una estructura matemática similar a la de flujo incompresible, en el sentido que la presión mecánica se determina a partir de la ecuación de conservación de la masa. En consecuencia poseen el mismo tipo de inestabilidades numéricas, que son el problema de condiciones de compatibilidad entre los espacios de elementos finitos de velocidad y presión, y las inestabilidades debidas a flujos con convección dominante. Estas inestabilidades pueden evitarse mediante técnicas de estabilización numérica. Muchos métodos de estabilización utilizados hoy día se basan en el método de multiscalas variacionales, donde el espacio funcional de la solucion se divide en un espacio discreto y resolubre y un espacio infinito de subscalas. El modelado de las subescalas y su influencia modifican el problema discreto proporcionando estabilidad. La calidad de la aproximación numérica final (precisión, eficiencia) depende del modelo particular de subescalas. En este trabajo se extienden estas técnicas de estabilización a problemas no lineales y acoplados. Las características que distinguen a nuestra aproximación son considerar las subsecalas como transitorias y mantener la división de escalas en todos los términos no lineales que aparecen en las ecuaciones de elementros finitos y en las del modelo de subescalas. La primera característica permite obtener mayor precisión y mejor estabilidad en la solución, la segunda característica permite obtener esquemas donde las propiedades se conservan globalmente, y mayor precisión del método. El hecho de mantener la división de escalas en todos los términos no lineales está intimamemte relacionado con el modelado de turbulencia en flujos térmicamente acoplados desde un punto de vista estrictamente numérico. La capacidad de simulación de flujo turbulento es una medida de la habilidad de modelar el efecto de las estructuras de escala fina sobre las estructuras de escala gruesa. Se muestra en esta tesis el desempeño del método para de predecir flujo turbulento. La ecuación de transporte de radiación también se aproxima numéricamente en el marco de multiscala variacional. El diseño y análisis de este método se presenta en detalle en esta tesis
Coetsee, Theresa. "Non-isothermal reaction of iron ore-coal mixtures." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-07092008-142912/.
Повний текст джерелаPaul, Sreebash Chandra. "Large eddy simulation of a fuel-rich turbulent non-premixed reacting flow with radiative heat transfer." Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/203/.
Повний текст джерелаHua, Yulong. "Modelling and simulation of circulating fluidized bed combustors : solid segregation, radiative heat transfer and coal combustion." Perpignan, 2004. http://www.theses.fr/2004PERP0570.
Повний текст джерелаL'objectif de ce travail est de développer un modèle mathématique global d'une chaudière à lit fluidisé circulant (LFC) à partir des théories les plus récentes et des résultats expérimentaux issus de la bibliographie. Un modèle hydrodynamique basé sur une approche semi-empirique est développé pour estimer localement la distribution de taille de particules dans le LFC. Une structure de flux solide de type cœur/anneau est appliquée dans le modèle, et la population de particules est discrétisée en plusieurs groupes de différentes tailles. Il montre que les particules les plus grosses se regroupent près des parois et que le diamètre moyen décroît avec la hauteur dans la chaudière, et cette tendance est encore plus forte dans la zone de projections. Un modèle à trois dimensions est développé pour calculer le coefficient de transfert de chaleur par rayonnement dans la zone diluée supérieure des chaudières à LFC. L'équation de transfert radiatif est résolue par la méthode des ordonnées discrètes. La théorie de Mie est appliquée pour calculer les efficacités d'absorption et de diffusion des particules présentes dans le LFC. Le modèle traite de l'influence des propriétés des particules (distribution de taille, propriétés optiques, composition des la phase solide) sur le coefficient de transfert de chaleur par rayonnement. Les résultats de la simulation montrent que les propriétés des particules ont une influence importante sur les échanges radiatifs dans les chaudières à LFC. Un modèle de combustion de charbon combiné au modèle hydrodynamique est développé