Tesi sul tema "Bundle of tubes"
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Mazzone, Robert Walter. "Enhanced condensation of R-113 on a small bundle of horizontal tubes". Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/43769.
Testo completoMabrey, Burlin Davis. "Condensation of refrigerants on small tube bundles". Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/22984.
Testo completoThe construction of an apparatus for the condensation performance testing of a horizontal bundle of four tubes with various refrigerants was completed. The apparatus was instrumented, and data reduction software was developed to provide bundle and single tube condensation data. Two tube bundles were tested, smooth copper tubes and low integral-fin copper-nickel tubes, with two refrigerants, R-114 and R-113. An enhancement ratio of about 2.0 for the overall heat transfer coefficient was demonstrated for the finned tubes over the smooth tubes. Internal contamination, possibly due to a breakdown of the refrigerant molecules when subjected to high temperatures in the boiling chamber, inhibited further meaningful data collection. Recommendations for improvement of the test apparatus are made.
http://archive.org/details/condensationofre00mabr
Lieutenant, United States Navy
Beech, Philip Michael. "Filmwise condensation of high velocity downward flowing steam on a bundle of horizontal tubes". Thesis, Queen Mary, University of London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309675.
Testo completoBazin, Clément. "Numerical and experimental studies of two-phase flows interacting with a bundle of tubes". Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAX106.
Testo completoThe steam generators (SG) in nuclear power plants are made up of bundles of tubes subjected to two-phase water-steam flows. Vibrations related to this interaction can cause damage (fatigue, wear due to friction and shocks) that can lead to serious consequences for nuclear safety.In the context of preventing vibrational risks in SG tubes, experimental studies are conducted using analytical bundles of straight tubes subjected to transverse two-phase flow. In parallel, it is also important to develop a numerical simulation tool to access data and information that are difficult to measure.The goal of this work is to simulate the interaction between a two-phase fluid and a rigid structure (single tube or bundle of tubes) using the NEPTUNE_CFD code. These simulations aim to reproduce the mechanical loading exerted by the fluid on the tubes. The modeling used in this work is based on a two-fluid - three-field model, including a continuous liquid field, a dispersed gas field made up of slightly deformed bubbles, and a dispersed-continuous hybrid field to account for highly deformed bubbles and gas pockets. The first part of this work focused on the validation of the two-phase liquid-turbulence coupling as well as the modification and adaptation of the modeling to better account for the presence of an immersed structure. New models for turbulent dispersion force, source terms of coalescence and break-up, added mass, and the activation criterion of the continuous field were proposed. In the second part of this work, we simulated the two-phase flow around a fixed single tube to extract underlying physics, and identify its limitations and shortcomings. Finally, in the last part of this work, we simulated the interaction of a two-phase flow with a bundle of rigid tubes. The numerical results were compared to experimental measurements. This approach allowed us to justify the relevance of our modeling, find similarities between numerical and experimental results, while also suggesting areas for improvement
Ramadan, Abdulghani. "Numerical And Experimental Investigation Of Forced Filmwise Condensation Over Bundle Of Tubes In The Presence Of Noncondensable Gases". Phd thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607831/index.pdf.
Testo completo#61605
= 1 - 30 m/s) for free stream velocity, (m1,&
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= 0.01 -0.8) for free stream air mass fraction, (d = 12.7 -50.8 mm) for cylinder diameter and (T&
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-Tw =10-40 K) for temperature difference. Results show that
a remarked reduction in the vapor side heat transfer coefficient is noticed when very small amounts of air mass fractions present in the vapor. In addition, it decreases by increasing in the cylinder diameter and the temperature difference. On the other hand, it increases by increasing the free stream velocity (Reynolds number). Average heat transfer coefficient at the middle and the bottom cylinders increases by increasing the angle of inclination, whereas, no significant change is observed for that of the upper cylinder. Although some discrepancies are noticed, the present study results are inline and in a reasonable agreement with the theory and experiment in the literature. Down the bank, a rapid decrease in the vapor side heat transfer coefficient is noticed. It may be resulted from the combined effects of inundation, decrease in the vapor velocity and increase in the non-condensable gas (air) at the bottom cylinders in the bank. Differences between the present study results and the theoretical and the experimental data may be resulted from the errors in the numerical schemes used. These errors include truncation and round off errors, approximations in the numerical differentiation for interfacial fluxes at the vapor-liquid interface, constant properties assumption and approximations in the initial profiles. Mixing and re-circulation in the steam-air mixture at the lower tubes may be the other reasons for these deviations.
Marcel, Thibaud. "Simulation numérique et modélisation de la turbulence statistique et hybride dans un écoulement de faisceau de tubes à nombre de Reynolds élevé dans le contexte de l'interaction fluide-structure". Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0109/document.
Testo completoThe prediction of fluid-elastic instabilities that develop in a tube bundle is of major importance for the design of modern heat exchangers in nuclear reactors, to prevent accidents associated with such instabilities. The fluid-elastic instabilities, or flutter, cause material fatigue, shocks between beams and damage to the solid walls. These issues are very complex for scientific applications involving the nuclear industry. This work is a collaboration between EDF, CEA and IMFT. It aims to improve the numerical simulation of the fluid-structure interaction in the tube bundle, in particular in the range of critical parameters contribute to the onset of damping negative system and the fluid-elastic instability
Belghazi, Mourad. "Condensation d'un fluide pur et de mélanges zéotropes à l'extérieur d'un faisceau de tubes à surface améliorée". Université Joseph Fourier (Grenoble), 2001. http://www.theses.fr/2001GRE10055.
Testo completoBlanc, Philippe. "Condensation des fluides frigorigènes HFC134a et HFC22 à l'extérieur d'un faisceau de tubes horizontaux améliorés". Université Joseph Fourier (Grenoble ; 1971-2015), 1994. http://www.theses.fr/1994GRE10221.
Testo completoMansur, Sergio Said. "Amélioration des échangeurs thermiques tubulaires par l'utilisation d'inserts hélicoïdaux à l'extérieur des tubes". Grenoble 1, 1993. http://www.theses.fr/1993GRE10192.
Testo completoAdom, Ebenezer. "Investigation of boiling heat transfer on small diameter tubes and tube bundles". Thesis, Heriot-Watt University, 2007. http://hdl.handle.net/10399/2067.
Testo completoOrtega, Del Rosario Maria de los Ángeles. "Système de stockage et transfert d'énergie par chaleur latente adaptable au rafraîchissement d’air en bâtiments : conception et analyse thermique". Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0197/document.
Testo completoThe present work aims to design and study an air-PCM heat exchanger unit as a passive solution for thermal comfort assessment in buildings during summertime, providing tools to ease the design and building integration. The PCM present a large storage capacity per volume unit where by, they can contribute to the reduction of the energy consumption related to cooling applications. Although, theyshow some drawbacks, as a low thermal conductivity in commercial PCM, so a wellthought design of these kind of systems is necessary to achieve adequate thermal performances.The first part of this thesis surveys the existing systems through a literature review,highlighting the geometry relation with the physics and thermal performance. This search provided the bases for the development of an air-PCM unit design, following a problem-solving methodology developed by the I2M laboratory. A keyword matrix was obtained from the physical phenomena and functional analysis of the unit. From this matrix, the patents analysis provided inspiration for the design resulting in a tubebundle air-PCM heat exchanger with vertical tubes aligned perpendicular to the airflow.The development of design and integration in buildings tools was sought through a modeling that can accurately predict the thermal performance of the system.Simplified models are preferred for this task. Nevertheless, they can under predict the actual performance if the physical phenomena involved is not properly accounted. Then, local and global experimental approaches were used to achieve anunderstanding of the physics associated with charging and discharging cycles in theunit. For this, a test bench was installed, measuring temperature and airflow underdifferent in let conditions, accompanied by a visual tracking through digital images.Image and data processing were used to obtain thermal performance indicators and equivalent correlations using known dimensionless numbers for convective conductive heat transfer mechanisms in the PCM.These findings allowed the development of thermal models based on energy balances, that accounted the complexity of phenomena involved in the unit for performance prediction. Finally, the thermal performance of the system was tested intwo buildings applications: as a mobile unit in a PEH house in Gradignan and as anactive façade in a building in Talence
El presente trabajo tiene como objetivo diseñar y estudiar una unidad intercambiador de calor aire-PCM como presentan una solución pasiva al conforttérmico en edificios durante el verano, proporcionando herramientas para facilitar el diseño y la integración en edificios. Los PCM una gran capacidad de almacenamiento por unidad de volumen, por lo que pueden contribuir a la reducción del consumo de energía relacionado con las aplicaciones de refrigeración. Estos materiales presentan algunos inconvenientes en cual su uso, como una baja conductividad térmica, típica en PCM comerciales, por lo es necesario un diseño que tome en cuenta esta problemática para lograr rendimientos térmicos adecuados. La primera parte de esta tesis examina los sistemas existentes a través de unarevisión de la literatura, destacando la relación de geometría con los fenómenos físicos y el rendimiento térmico. Esta búsqueda proporcionó las bases para el desarrollo de un diseño de unidad aire-PCM, siguiendo una metodología de resolución de problemas desarrollada por el laboratorio I2M. Se obtuvo una matrizde palabras clave a partir de los fenómenos físicos y el análisis funcional de launidad. A partir de esta matriz, el análisis de patentes proporcionó inspiración para el diseño que dio como resultado un intercambiador de calor PCM de aire y haz detubos verticales alineados perpendicularmente al flujo de aire.El desarrollo del diseño y la integración en herramientas de edificios se buscó através de un modelo que pudiese predecir con precisión el rendimiento térmico delsistema. Los modelos simplificados son los preferidos para esta tarea. Sin embargo,su poder de predicción puede verse afectada si los fenómenos físicos involucradosno se contabilizan adecuadamente. Es por ello que se utilizaron enfoques experimentales locales y globales para lograr una comprensión de la física asociadacon los ciclos de carga y descarga en la unidad. Se realizó una instalación de unbanco de pruebas, que permitió mediciones de temperatura y flujo de aire en diferentes condiciones de entrada, acompañado de un seguimiento visual a travésde imágenes digitales. El procesamiento de imágenes y datos se utilizó para obtener indicadores de rendimiento térmico y correlaciones a partir de números adimensionales relacionados con mecanismos de transferencia de calor porconvección y conducción en el PCM.Estos hallazgos permitieron el desarrollo de modelos térmicos para la predicción delrendimiento, basados en balances de energía de cada volumen de control.Finalmente, el rendimiento térmico del sistema se probó en dos aplicaciones deedificios: como una unidad móvil en una casa PEH en Gradignan y dentro de una oficina del laboratorio I2M
Havlů, Michal. "Algoritmus automatického výběru vhodného typu zařízení z databáze výměníků tepla". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228730.
Testo completoGidi, Alejandro. "Two-phase flow-induced vibrations in a heated tube bundle". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0031/NQ66267.pdf.
Testo completoAhmad, Hussain Hamed. "Boiling of immiscible systems over tube bundles". Thesis, Heriot-Watt University, 1989. http://hdl.handle.net/10399/966.
Testo completoGorgy, Evraam. "Experimental evaluation of heat transfer impacts of tube pitch on highly enhanced surface tube bundle". Diss., Kansas State University, 2011. http://hdl.handle.net/2097/11995.
Testo completoDepartment of Mechanical and Nuclear Engineering
Steven J. Eckels
The current research presents the experimental investigation of the effect of tube pitch on enhanced tube bundles’ performance. The typical application of this research is flooded refrigerant evaporators. Boosting evaporator’s performance through optimizing tube spacing reduces cost and energy consumption. R-134a with the enhanced tube Turbo BII-HP and R-123 with Turbo BII-LP were used in this study. Three tube pitches were tested P/D 1.167, P/D 1.33, and P/D 1.5. Each tube bundle includes 20 tubes (19.05 mm outer diameter and 1 m long each) constructed in four passes. The test facility’s design allows controlling three variables, heat flux, mass flux, and inlet quality. The type of analysis used is local to one location in the bundle. This was accomplished by measuring the water temperature drop in the four passes. The water-side pressure drop is included in the data analysis. A new method called the EBHT (Enthalpy Based Heat Transfer) was introduced, which uses the water-side pressure drop in performing the heat transfer analysis. The input variables ranges are: 15-55 kg/m².s for mass flux, 5-60 kW/m² for heat flux, and 10-70% for inlet quality. The effect of local heat flux, local quality, and mass flux on the local heat transfer coefficient was investigated. The comparison between the bundle performance and single tube performance was included in the results of each tube bundle. The smallest tube pitch has the lowest performance in both refrigerants, with a significantly lower performance in the case of R-134a. However, the two bigger tube pitches have very similar performance at low heat flux. Moreover, the largest tube pitch performance approaches that of the single tube at medium and high heat fluxes. For the R-123 study, the smallest tube bundle experienced quick decease in performance at high qualities, exhibiting tube enhancement dry-out at certain flow rates and high qualities. The flow pattern effect was demonstrated by the dry-out phenomena. At medium and high heat fluxes, as the tube pitch increases, the performance approaches that of the single tube. All tube bundles experience quick decrease in performance at high qualities. Evidently, P/D 1.33 is the optimum tube pitch for the studied refrigerants and enhanced tubes combinations.
McIlwain, Stuart Russell. "Improved prediction methods for finned tube bundle heat exchangers in crossflow". Thesis, University of Strathclyde, 2003. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21526.
Testo completoNelson, Peter Jonathan. "Boiling the immiscible water/n - nonane system from a tube bundle". Thesis, Heriot-Watt University, 1986. http://hdl.handle.net/10399/1060.
Testo completoOmar, Hossin. "Numerical Simulations of Fluidelastic Instability in Tube Bundles". Thesis, University of New Brunswick, 2010. http://hdl.handle.net/1882/1089.
Testo completoScoones, David John. "Boiling on plain and low-finned tube bundles". Thesis, Heriot-Watt University, 1986. http://hdl.handle.net/10399/2134.
Testo completoAndrews, Patrick Rowan. "Boiling on in-line and staggered tube bundles". Thesis, Heriot-Watt University, 1985. http://hdl.handle.net/10399/1608.
Testo completoTeixidó, Roman Miguel. "A cotangent bundle Hamiltonian tube theorem and its applications in reduction theory". Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/288376.
Testo completoEl model de Marle-Guillemin-Sternberg (MGS) és una eina extremadament important per la teoria de les accions Hamiltonianes en varietats simplèctiques. Ha estat utilitzada per provar molts resultats te tipus local tant en geometria simplèctica com en la teoria de sistemes Hamiltonians simètrics. Proporciona un model per un entorn tubular de una òrbita de la acció de forma que fica en forma normal tant l'acció del grup com l'estructura simplèctica. El principal problema del model MGS és que no és explícit. Només es poden provar la seva existència i les seves propietats principals. Per altra banda, en el cas de que la varietat sigui un fibrat cotangent la el model MGS no respecta la fibració natural. En la primera part de la tesis construïm un model MGS especialment adaptat a la geometria dels fibrats cotangents. Aquest model generalitza els resultats obtinguts per T. Schmah per òrbites amb moment completament isotròpic. Addicionalment, la nostra construcció és explicita excepte per la integració d'una equació diferencial sobre el grup G. Aquesta equació pot ser solucionada de forma explícita per els grups SO(3) o SL(2), per tant podem donar explícitament coordenades simplèctiques per a accions arbitraries d'aquests grups sobre qualsevol fibrat cotangent. En la segona part de la tesis apliquem aquest model MGS cotangent per descriure l'estructura de les reduccions simplèctiques de fibrats cotangents. Mostrem que la projecció sobre la base de una fulla de moment és un espai estratificat de Whitney. També podem refinar l'estratificació de l'espai simplèctic reduït de forma que cadascuna de les peces és un espai fibrat. Demostrem que cadascuna d'aquestes peces està dotada d'una forma pre-simplèctica de rang constant i que sempre hi ha una única peça que es oberta i densa en l'espai reduït. A més aquesta peca maximal és simlpectomorfa a un subfibrat vectorial de un cert fibrat cotangent.
Chilman, Scott V. "Nucleate boiling characteristics of R-113 in a small enhanced tube bundle". Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28404.
Testo completoCastiglia, Davide. "Fluid flow and heat transfer in unconventional tube bundle arrangements in crossflow". Thesis, King's College London (University of London), 2002. https://kclpure.kcl.ac.uk/portal/en/theses/fluid-flow-and-heat-transfer-in-unconventional-tube-bundle-arrangements-in-crossflow(19f17b5f-6ea1-4f6c-9168-8e809d2495f7).html.
Testo completoShire, Neil Frank. "Heat transfer and hydrodynamics of boiling over tube bundles". Thesis, Heriot-Watt University, 1995. http://hdl.handle.net/10399/769.
Testo completoBalabani, Stavroula. "An experimental investigation of the crossflow over tube bundles". Thesis, King's College London (University of London), 1996. https://kclpure.kcl.ac.uk/portal/en/theses/an-experimental-investigation-of-the-crossflow-over-tube-bundles(27c20ab8-798a-4a07-b1cd-b31fbd77578e).html.
Testo completoMacIver, Alasdair. "The application of enhanced surfaces to boiling over tube bundles". Thesis, Heriot-Watt University, 1993. http://hdl.handle.net/10399/1472.
Testo completoPenner, Lloyd Alan. "Two-dimensional flow predictions in a tube bundle using orthogonal and non-orthogonal grids". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq23452.pdf.
Testo completoHaas, Russell E. "Nucleate pool boiling of R-114/oil mixtures in a small enhanced tube bundle". Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23733.
Testo completoAngula, Ester. "Numerical performance evaluation of a delugeable flat bare tube air-cooled steam condenser bundle". Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97151.
Testo completoENGLISH ABSTRACT: In this study, one and two-dimensional models are developed for the evaluation of the thermal performance of a delugeable flat tube bundle to be incorporated in the second stage of an induced draft hybrid (dry/wet) dephlegmator (HDWD) of a direct air-cooled steam condenser (ACSC). Both models are presented by a set of differential equations. The one-dimensional model is analysed analytically by using three methods of analysis which are: Poppe, Merkel, and heat and mass transfer analogy. The two-dimensional model is analysed numerically by means of heat and mass transfer analogy method of analysis whereby, the governing differential equations are discretised into algebraic equations using linear upwind differencing scheme. The two-dimensional model’s accuracy is verified through a comparison of the two dimensional solutions to one dimensional solutions. Satisfactory correlation between the one and two-dimensional results is reached. However, there is a slight discrepancy in the solutions, which is mainly due to the assumptions made in one-dimensional model. The effect of tube height, tube pitch, tube width, deluge water mass flow rate, frontal air velocity, steam, and air operating conditions on the heat transfer rate and air-side pressure drop for both wet and dry operating modes are investigated. The long tube height, large tube width, small tube pitch, and high frontal air velocity are found to increase the tube bundle’s performance. However, this performance is associated with a high airside pressure drop. The performance of the deluged flat tube bundle is found to be less sensitive to the changes in the deluge water mass flow rate and air operating conditions. Furthermore, the best configuration of a delugeable flat tube bundle is identified through a comparison to round tube bundle presented by Anderson (2014). The performance of the round tube bundle is found to be around 2 times, and 1.5 times of that of flat tube bundle, when both bundles operate as an evaporative and dry air-cooled condenser respectively.
AFRIKAANSE OPSOMMING: In hierdie studie is een en twee-dimensionele modelle ontwikkel vir die evaluering van die termiese prestasie van 'n benatbare plat buis bundel in die tweede stadium van 'n geïnduseerde ontwerp hibriede (droë / nat ) deflegmator van 'n direkte lugverkoelde stoom kondensator. Beide modelle is aangebied deur 'n stel van differensiaalvergelykings. Die een-dimensionele model is analities ontleed deur die gebruik van drie metodes van analise wat: Poppe, Merkel, en die hitte en massa-oordrag analogie. Die twee-dimensionele model is numeries ontleed deur middel van hitte en massa-oordrag analogie metode van analise waardeur , die regerende differensiaalvergelykings gediskretiseer in algebraïese vergelykings met behulp van lineêre windop differensievorming skema. Die tweedimensionele model se akkuraatheid is geverifieer deur 'n vergelyking van die twee dimensionele oplossings te een dimensionele oplossings. Bevredigende korrelasie tussen die een en twee-dimensionele resultate bereik word. Maar daar is 'n effense verskil in die oplossings, wat is hoofsaaklik te wyte aan die aannames wat gemaak in een-dimensional model. Die effek van buis hoogte, buis toonhoogte, buis breedte, vloed water massa-vloeitempo, frontale lug snelheid, stoom, en in die lug werktoestande op die hitte oordrag snelheid en lug - kant drukval vir beide nat en droë maatskappy modi word ondersoek. Die lang buis hoogte, groot buis breedte, klein buisie toonhoogte, en 'n hoë frontale lug snelheid gevind die buis bundel se prestasie te verhoog. Tog is hierdie prestasie wat verband hou met 'n hoë lug - kant drukval. Die prestasie van die oorstroom plat buis bundel gevind word minder sensitief vir die veranderinge in die vloed water massa-vloeitempo en lug werktoestande. Verder is die beste opset van 'n benatbare plat buis bundel geïdentifiseer deur 'n vergelyking met ronde buis bundel aangebied deur Anderson (2014). Die prestasie van die ronde buis bundel gevind word om 2 keer, en 1.5 keer van daardie plat buis bundel , wanneer beide bundels funksioneer as 'n damp en droë lugverkoelde kondensor onderskeidelik.
Sadikin, Azmahani. "An experimental study of two-phase flow in idealised tube bundles". Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2898.
Testo completoLi, Fang. "Heat Transfer in a High-pressure Gas-solid Fluidized Bed with Horizontal Tube Bundle and Continuous Addition of Fines". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38002.
Testo completoCui, Xingdong. "Prediction of critical heat flux in bundles using tube look-up table". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0002/MQ28415.pdf.
Testo completoKanizawa, Fábio Toshio. "Estudo teórico e experimental sobre padrões de escoamento, fração de vazio e perda de pressão durante escoamento bifásico água-ar cruzado ascendente externo a banco de tubos". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18147/tde-30032015-080832/.
Testo completoThe present thesis concerns a theoretical and experimental study of external two-phase flows across tube bundles. Initially, a comprehensive literature review covering flow patterns, void fraction and pressure drop for single and two-phase flows across tubes bundle is presented. The review also describes predictive methods for these parameters. A comparison of these methods reveals reasonable disagreement among their predictions, indicating the absence of generalized methods. Subsequently, the apparatus and instrumentation designed and built to obtain the experimental data are described. The experimental apparatus comprises the test section, a water loop, air compression and conditioning systems, and sets for fluid flow injections and conditioning. The test section is a normal triangular tube bundle, with 19.1 mm OD tubes, 381 mm long and transversal pitch of 24 mm. The experiments were performed for air-water upward vertical flow, for superficial liquid and gas velocities ranging from 0.020 to 1.500 m/s and 0.10 to 10.00 m/s, respectively. Innovative techniques to evaluate the void fraction within the bundle were developed based on capacitive and optical methods. The flow patterns were identified subjectively and objectively by k-means clustering method, using as clustering parameters the pressure drop and the capacitive signals. Bubbles, dispersed bubbles, large bubbles, churn, intermittent and annular flow patterns were identified subjectively. The data groups identified by the objective method are representative of the flow patterns. Void fraction measurements were obtained for bubbly flow using both techniques (optical and capacitive). The void fraction data based on the optical method had its experimental range limited due to changes in the flow characteristics caused by the addition of the fluorescent dye Rhodamine B. The experimental results indicate that the void fraction increases with increasing the superficial velocities of both phases. In general, the void fraction predictive methods available in the literature capture the trends of the experimental results only for reduced liquid flow rates. According to the experimental results, the frictional pressure drop increases asymptotically with increasing the flow rates of both phases. None of the predictive methods from literature evaluated in the present study predicted satisfactorily the experimental results. Methods for prediction of flow patterns, void fraction and frictional pressure drop parcel were also developed in the present study. These methods provided reasonable predictions of the experimental results obtained in the present study, and also from the literature for air and water flows across tube bundles.
Schlup, Jason. "Two phase flow visualization in evaporator tube bundles using experimental and numerical techniques". Thesis, Kansas State University, 2013. http://hdl.handle.net/2097/16237.
Testo completoDepartment of Mechanical and Nuclear Engineering
Steven Eckels and Mohammad Hosni
This research presents results from experimental and numerical investigations of two-phase flow pattern analysis in a staggered tube bundle. Shell-side boiling tube bundles are used in a variety of industries from nuclear power plants to industrial evaporators. Fluid flow patterns in tube bundles affect pressure drop, boiling characteristics, and tube vibration. R-134a was the working fluid in both the experimental and computational fluid dynamics (CFD) analysis for this research. Smooth and enhanced staggered tube bundles were studied experimentally using a 1.167 pitch to diameter ratio. The experimental tube bundles and CFD geometry consist of 20 tubes with five tubes per pass. High speed video was recorded during the experimental bundle boiling. Bundle conditions ranged in mass fluxes from 10-35 kg/m[superscript]2.s and inlet qualities from 0-70% with a fixed heat flux. Classification of the flow patterns from these videos was performed using flow pattern definitions from literature. Examples of smooth and enhanced bundle boiling high speed videos are given through still images. The flow patterns are plotted and compared with an existing flow pattern map. Good agreement was found for the enhanced tube bundle while large discrepancies exist for the smooth tube bundle. The CFD simulations were performed without heat transfer with non-symmetrical boundary conditions at the side walls, simulating rectangular bundles used in this and other research. The two-phase volume of fluid method was used to construct vapor interfaces and measure vapor volume fraction. A probability density function technique was applied to the results to determine flow patterns from the simulations using statistical parameters. Flow patterns were plotted on an adiabatic flow pattern map from literature and excellent agreement is found between the two. The agreement between simulation results and experimental data from literature emphasizes the use of numerical techniques for tube bundle design.
Liang, Chunlei. "Large eddy simulation of the turbulent flow and heat transfer in tube bundles". Thesis, King's College London (University of London), 2005. https://kclpure.kcl.ac.uk/portal/en/theses/large-eddy-simulation-of-the-turbulent-flow-and-heat-transfer-in-tube-bundles(73e0ff53-1135-4620-bb66-7eb3d091a7a6).html.
Testo completoTuma, Juergen. "The enhancement of heat transfer to gases in longitudinal flow in tube bundles". Thesis, University of Brighton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280462.
Testo completoAlmeshaal, Mohammed Abdulrahman. "An experimental and numerical study of two-phase flow in horizontal tube bundles". Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2900.
Testo completoWu, Tzu-Yu. "Design of Confocal Microendscopy for Fallopian Tube Imaging and Detection of Esophageal Cancer". Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/347227.
Testo completoBahaidarah, Haitham M. S. "A numerical study of heat and momentum transfer over a bank of flat tubes". Texas A&M University, 2004. http://hdl.handle.net/1969.1/2782.
Testo completoAhlinder, Stefan. "On modelling of compact tube bundle heat exchangers as porous media for recuperated gas turbine engine applications". [S.l.] : [s.n.], 2006. http://se6.kobv.de:8000/btu/volltexte/2006/15.
Testo completoAhlinder, Stefan [Verfasser]. "On Modelling of Compact Tube Bundle Heat Exchangers as Porous Media for Recuperated Gas Turbine Engine Applications / Stefan Ahlinder". Aachen : Shaker, 2006. http://d-nb.info/1170538037/34.
Testo completoMusa, Mohd Nor. "Condensation of a binary vapour of immiscible liquids on a horizontal tube bundle under the influence of vapour shear". Thesis, Heriot-Watt University, 1987. http://hdl.handle.net/10399/1046.
Testo completoBeccacece, Lorenzo. "Electromagnetic interaction between multi-walled carbon nanotube bundles". Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS268.
Testo completoThe use of 1D and 2D materials in electronic devices is a matter of interest for the scientific and industrial communities. Thanks to their unique properties, the researchers want to reach the device miniaturization. The carbon nanotubes are part of the 1D materials. After the study of the state of the art on this material and on its integration in electronic devices, we defined new research issues on the matter. The work performed in this Ph.D. covered the synthesis, characterization, modeling and integration of vertically aligned multi-walled carbon nanotube (VAMWCNT) bundles, in microwave devices. The goal was to have a better comprehension of the electrical behavior of the synthetized material in the microwave spectrum, and to test the electromagnetic interaction between two large VAMWCNT bundles. This subject has never been previously explored. Advanced characterizations have been achieved on the material, to determine their quality and properties. Two equivalent electrical models, implemented with numerical experiments, were proposed to have the frequency-dependent behavior of the complex electrical impedance. The characterization results were used as feedback to validate and also to improve the models. A clean room fabrication process was optimized, in order to synthetize the VAMWCNT bundles directly on the metallic lines of the devices, and to study the impact of the synthesis. Finally, a microwave device was designed to study the electromagnetic coupling between two large VAMWCNT bundles. The measurements permitted to observe an effect which can be attributed to their capacitive and magnetic coupling
Akcasayar, Nezih. "Nucleate pool boiling performance of finned and high flux tube bundles in R-114/oil mixtures". Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/27168.
Testo completoThe heat transfer characteristics of pure R-114 and R-114/oil mixtures during nucleate pool boiling from a small bundle of finned and High Flux tubes were measured. The bundles had 5 instrumented and 10 additional heated tubes of 15.8 mm outside diameter which were arranged in an equilateral triangular pitch of 19.1 mm giving a pitch-to-diameter ratio of 1.2. Pure refrigerant with York-C lubrication oil mass con-centrations of 1, 2, 3, 6 and 10% was used. All experiments were performed at 2.2C corresponding to a pressure slightly below atmospheric. Data sets were taken using decreasing heat flux only in order to avoid the boiling hysterisis phenomenon. An enhancement in heat-transfer performance of the finned tube bundle due to oil applications was observed. The enhancement increased with up to 3% oil concentration over all heat flux ranges. Further oil additions showed better performances than pure R-114 at high heat flux levels but poorer performance was obtained at lower heat fluxes. High flux tube experiments indicated that the heat transfer performance of the bundle was approximately 2.5 times better than the finned tube bundle performance for pure R-114. No positive performance enhancement was observed from the High Flux tube bundle due to oil addition. The performance immediately degraded with 1% oil and stayed almost constant with 2% and 3% oil additions. A decrease of performance became significant at high heat flux levels with oil concentrations of 6% and 10%. The performance of these two tube bundles was compared to smooth tube operation.
Anderson, Carl Lee. "Nucleate pool boiling performance of smooth and finned tube bundles in R-113 and R-114/oil mixtures". Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/27169.
Testo completoEraydin, Hakan. "Nucleate pool boiling performance of small High Flux and Turbo-B tube bundles in R-114/oil mixtures". Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA241936.
Testo completoThesis Advisor(s): Marto, Paul J. ; Memory, Steve. "December 1990." Description based on title screen as viewed on March 30, 2010. DTIC Identifier(s): Pool Boiling. Author(s) subject terms: Heat Transfer, Pool Boiling. Includes bibliographical references (p. 102-104). Also available in print.
Chýlek, Martin. "Tok látek v nestandardních procesních a energetických zařízeních". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-377756.
Testo completoKubíček, Ondřej. "Návrh ohříváku topné vody pro vyvedení tepla z teplárny o výkonu 5,5 MW". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232145.
Testo completoPomarède, Marie. "Investigation et application des méthodes d'ordre réduit pour les calculs d'écoulements dans les faisceaux tubulaires d'échangeurs de chaleur". Thesis, La Rochelle, 2012. http://www.theses.fr/2012LAROS355/document.
Testo completoThe objective of this thesis is to study the ability of model reduction for investigations of flow-induced vibrations in heat exchangers tube bundle systems.These mechanisms are a cause of major concern because heat exchangers are key elements of nuclear power plants and on-board stoke-holds.In a first part, we give a recall on heat exchangers functioning and on vi-bratory problems to which they are prone. Then, complete calculations leaded with the CFD numerical code Code_Saturne are carried out, first for the flow around a single circular cylinder (fixed then elastically mounted) and then for the case of a tube bundle system submitted to cross-flow. Reduced-order method POD is ap-plied to the flow resolution with fixed structures. The obtained results show the efficiency of this technique for such configurations, using stabilization methods for the dynamical system resolution in the tube-bundle case.Multiphase-POD, which is a method enabling the adaptation of POD to fluid-structure interactions, is applied. Large displacements of a single cylinder elastically mounted under cross-flow, corresponding to the lock-in phenomenon,are well reproduced with this reduction technique. In the same way, large displace-ments of a confined moving tube in a bundle are shown to be faithfully recon-structed.Finally, the use of model reduction is extended to parametric studies. First,we propose to use the method which consists in projecting Navier-Stokes equations for several values of the Reynolds number on to a unique POD basis. The resultsobtained confirm the fact that POD predictability is limited to a range of parameter values. Then, a basis interpolation method, constructed using Grassmann mani-folds and allowing the construction of a POD basis from other pre-calculated basis,is applied to basic cases
Volná, Kateřina. "Vliv zanášení svazku trubek v kotli na jeho životnost". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-377757.
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