Tesis sobre el tema "Thermo Mechanical system"
Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros
Consulte los 50 mejores tesis para su investigación sobre el tema "Thermo Mechanical system".
Junto a cada fuente en la lista de referencias hay un botón "Agregar a la bibliografía". Pulsa este botón, y generaremos automáticamente la referencia bibliográfica para la obra elegida en el estilo de cita que necesites: APA, MLA, Harvard, Vancouver, Chicago, etc.
También puede descargar el texto completo de la publicación académica en formato pdf y leer en línea su resumen siempre que esté disponible en los metadatos.
Explore tesis sobre una amplia variedad de disciplinas y organice su bibliografía correctamente.
Olofsson, Joel. "Thermo-mechanical analysis of cryo-cooled electrode system in COMSOL". Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-353895.
Texto completoElschich, Ahmed. "Thermo-mechanical Fatigue of Electrical Insulation System in Electrical machine". Thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-62579.
Texto completoChang, Gary Carleton University Dissertation Engineering Systems and Computer. "System identification and control of a thermo-mechanical pulping refiner". Ottawa, 1995.
Buscar texto completoKrishnan, Ganesh. "Thermo-mechanical reliability of ultra-thin low-loss system-on-package substrates". Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26474.
Texto completoCommittee Chair: Tummala, Rao; Committee Member: Pucha, Raghuram V.; Committee Member: Wong, C.P. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Christian, Corey D. (Corey Dwight). "Breaking the thermo-mechanical coupling of thermoelectric materials : determining the viability of a thermoelectric generator". Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/121790.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (pages 69-70).
Thermoelectric power generators (TEGs) convert a temperature difference into electricity. This temperature difference can be created from waste heat. Since up to 50% [1] of US industrial energy input is lost as waste heat, an economical means of recovering waste heat and converting it into useful electricity could represent significant energy savings. Coupled with our integrative system design which involves creating application specific thermoelectric arrays, this technology can also help enable low power generation for off-grid needs in the developing world. Although conversion efficiencies as high as 20.9% [2] (heat to electrical energy) have been predicted from simulations of TEGs systems, in practice the efficiencies are typically only a few percent. Moreover, conventional systems often require expensive components to manage heat flow through the system.
As a result of the low efficiency and high system cost, electricity generated by thermoelectric energy harvesting from waste heat is currently not competitive with conventional electricity generation on a dollars-per-watt basis. This realization has led researchers to not only focus on increasing TEG device efficiency limits but to devise cheaper manufacturing processes and methods. A system design constraint that has not been fully investigated is the coupling of thermal and mechanical properties in thermoelectric materials. The extent to which this coupling affects the performance of the TEGs will be studied. This thesis develops an approach for decoupling the thermal and mechanical properties and tests it through a variety of simulations. We propose a mechanically compliant attachment strategy which could be integrated in various waste heat recovery applications.
The strategy involves breaking the thermal and mechanical bond formed by the brittle thermoelectric elements and its substrate. Copper wire, which is more pliable, is then used to connect the thermoelectric element to the substrate. A system analysis was performed for waste heat recovery from a vehicles exhaust pipe. We found that utilizing the proposed strategy should not only lead to increased mechanical compliance but can also lead to cost savings on a dollars-per-watt basis. We found that 84% power retention could be obtained when up to 16x less material is used under most apparent conditions¹.
by Corey D. Christian.
S.M. in Engineering and Management
S.M.inEngineeringandManagement Massachusetts Institute of Technology, System Design and Management Program
Bitadze, Alexander. "Thermo-dynamical measurements for ATLAS Inner Detector (evaporative cooling system)". Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/5186/.
Texto completoPopov, Anton. "Three-dimensional thermo-mechanical modeling of deformation at plate boundaries : case study San Andreas Fault System". Phd thesis, Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2009/3187/.
Texto completoSeit jeher rätselhaft sind die Prozesse, die die Akkretion der Nordamerikanischen Terranen in Richtung der Pazifischen Platte sowie die Wanderung der Plattengrenze der San-Andreas-Verwerfung in Richtung Festland bestimmen. Eine Theorie besagt, dass sich die Pazifische Platte erst abkühlt und den aufsteigenden Mantel im „Slab Window“ fängt und somit die Akkretion der kontinentalen Krustenblöcke bewirkt. Die andere Theorie geht von einer Akkretion durch das Fangen von Teilen der Farallon-Platte (Mikroplatten) aus, die in der inaktiven nordamerikanischen Farallon-Subduktionszone fest stecken. Die quantitative Beurteilung dieser beiden gegensätzlichen Konzepte erfordert eine thermomechanische numerische 3-D-Modellierung. Das dafür benötigte Software Tool steht jedoch der geodynamischen Modellierung derzeit noch nicht zur Verfügung. Das Hauptziel der vorliegenden Arbeit umfasst im Wesentlichen zwei miteinander verbundene Aufgaben. Die erste besteht in der Entwicklung und Erprobung des Finite-Element-Codes, dessen Eigenschaften den hohen Anforderungen an die Ausführung der dreidimensionalen Simulationen lithosphärischer Deformation auf geologischer Zeitskala gerecht werden müssen. Die zweite Aufgabe ist die Anwendung des entwickelten Tools auf die neogenen Deformationen der Kruste und des Mantels entlang der San-Andreas-Verwerfung in Zentral- und Nordkalifornien. Die Modellierung auf geologischer Zeitskala lithosphärischer Deformation bringt für die Software Tools in Bezug auf Konzept und Durchführung zahlreiche Herausforderungen mit sich. Unter anderem gilt es, den Brittle-Ductile-Übergang in einem einzigen Modell sowie die Gesteinsrheologie in einer breiten Spanne unterschiedlicher Temperaturen und Spannungen adäquat darzustellen und die extremen Deformationen der freien Oberfläche und internen Grenzen aufzulösen. Im Rahmen der vorliegenden Arbeit erfolgte die erfolgreiche Entwicklung und Erprobung des neuen Finite-Element-Codes (SLIM3D). Dieser Code beinhaltet eine gekoppelte thermomechanische Behandlung von Deformationsprozessen und ermöglicht eine elasto-visko-plastische Rheologie mit Diffusion, Dislokation, Peierls Kriechmechanismen und Mohr-Coulomb-Plastizität. Der Code verbindet eine Arbitrary Lagrangian-Eulerian kinematische Formulierung mit freien Oberflächen- und Winkler-Randbedingungen. Das entwickelte Modellierungsverfahren wird für die Untersuchung der Aspekte verwendet, die die neogene lithosphärische Deformation in Zentral- und Nordkalifornien beeinflussen. Die Modellanordnung konzentriert sich auf die Interaktion zwischen drei großen tektonischen Elementen in dieser Region: die Nordamerikanische Platte, die Pazifische Platte sowie die Gorda-Platte, die sich in der Mendocino-Triple-Junction treffen. Unter anderem verdeutlicht die Modellierung den Einfluss des Aufsteigens der Asthenosphäre in das sich öffnende „slab window“ der übergelagerten Nordamerikanischen Platte. Die Modelle beziehen auch die angelagerten Überreste der Mikroplatten in der fossilen Farallon-Subduktionszone, die vereinfachte subduzierende Gorda-Platte sowie markante Heterogenitäten der Kruste, wie beispielsweise den „Salinian Block“, mit ein. Die Ergebnisse zeigen, dass die Erwärmung der Mantellithosphäre unter den älteren Störungszonen sowie die Transpression eine Abkühlung im „Slab Window“ als alleinige Begründung für die Ostwärtsbewegung der Plattengrenze nicht zulassen. Aus Sicht der thermomechanischen Modellierung bestätigen die Ergebnisse das geologische Konzept, welches durch das mehrmalige Fangen von Mikroplatten den Hauptgrund für die Wanderung der Plattengrenze der San-Andreas-Verwerfung in Richtung Festland über die letzten 20 Millionen Jahre sieht. Die Überreste der Farallon-Platte, die in der fossilen Subduktionszone gefangen sind, verursachen im Mantel eine wesentlich stärkere Heterogenität als die Abkühlung der Asthenosphäre und stellen somit den effizienteren und direkteren Weg für die Anlagerung der nordamerikanischen Gebiete an die Pazifische Platte dar. Die Modelle demonstrieren, dass ein hoher effektiver Reibungskoeffizient an großen Störungen nicht in der Lage ist, die eindeutigen Zonen der Dehnungslokalisierung in der spröden Kruste vorherzusagen. Die Größe des Reibungskoeffizienten, die sich aus der Modellierung ableitet, beträgt etwa 0,075 und ist damit wesentlich kleiner als die durch unterschiedliche Bohrlochmessungen und Labordaten ermittelten Spannungswerte zwischen 0,6 und 0,8. Daher liefern die in dieser Arbeit präsentierten Ergebnisse der Modelle in der seit langem geführten Debatte über die Stärke von großen Störungen in der San-Andreas-Verwerfung eine zusätzliche unabhängige Begründung der „Weak-Fault“-Hypothese.
Amin, Abdullah Al. "MULTISCALE MULTIPHYSICS THERMO-MECHANICAL MODELING OF AN MGB2 BASED CONDUCTION COOLED MRI MAGNET SYSTEM". Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case151385068164148.
Texto completoNgaradoumbe, Nanhornguè Ronel. "Sensitivity analysis applied to fem models for coupled multiphase system". Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3421559.
Texto completoI problemi che accoppiano vari campi della sica sono temi molto attuali nell'ambito dell'ingegneria civile. Il presente lavoro prende in esame modelli multifase per lo studio di calcestruzzi sottoposti ad alte temperature, applicabili per la valutazione della resistenza al fuoco di strutture civili o industriali. Numerosi fenomeni non lineari interessano il comportamento del calcestruzzo quando si considerano temperature elevate; tali fenomeni riguardano non solo la conduzione di calore e la diffusione di vapore, ma anche il trasferimento di calore latente provocato dal cambiamento di fase dell'acqua all'interno dei pori ed il usso d'acqua causato da gradienti di pressione, da effetti capillari, da gradienti del contenuto di acqua adsorbita. Inoltre le alte temperature causano forti cambiamenti microstrutturali e fanno sì che si sviluppino diversi fenomeni sici e chimici interagenti fra di loro, che provocano variazioni signicative della struttura interna e delle proprietà del materiale. Nella modellazione del comportamento igro-termo-meccanico del calcestruzzo, si dovrebbero utilizzare modelli che considerano la complessità e le interazioni dei processi sici descritti in precedenza. L'utilizzo di modelli accoppiati multifase, basati sulla meccanica dei mezzi porosi, si dimostra pertanto uno strumento necessario per una corretta previsione del comportamento igrometrico, termico, chimico e meccanico di tale materiale. Questi modelli sono tuttavia molto complessi e sosticati, perché hanno a che fare con parecchi campi fortemente accoppiati, sono caratterizzati da sistemi accoppiati di equazioni differenziali non lineari e richiedono un gran numero di parametri del materiale. Inoltre, nelle applicazioni di interesse pratico, la soluzione numerica di tali sistemi di equazioni richiede notevoli tempi di calcolo risultando quindi piuttosto costosa. Nasce quindi l'esigenza di ridurre sia l'onere richiesto dalla determinazione sperimentale dei parametri necessari, sia i tempi computazionali. Per poter procedere in questo senso serve quindi un'analisi della sensitività del modello rispetto alla variazione dei suoi parametri, per poter individuare in che modo la soluzione venga inuenzata dalla variazione dei parametri che compaiono nei sistemi di equazioni. Tale analisi rivela quali sono i parametri che controllano il modello e quali sono gli effetti delle loro variazioni, permettendo quindi di individuare i parametri la cui determinazione precisa è essenziale per l'accuratezza dei risultati e distinguerli da quelli la cui determinazione può essere meno precisa o che possono essere reperiti in letteratura. Dopo aver eseguito tale analisi, si potrà procedere ad una semplicazione del modello matematico, con effetti beneci anche sui tempi di calcolo, ed avviare in questo modo un processo di "model reduction". Lo scopo di questa tesi è l'analisi di sensitività di un modello agli elementi finiti (Comes-HTC) per l'analisi del comportamento del calcestruzzo esposto ad alte temperature; l'analisi di sensitività è stata eettuata attraverso la differenziazione automatica (AD). L'applicazione di questa tecnica al codice fem Comes-HTC ha permesso di sviluppare uno strumento eciente per il calcolo dei coecienti di sensitività, attraverso il quale è stato possibile quanticare gli effetti e l'importanza relativa dei parametri del materiale sull'insieme di soluzioni calcolate dal modello. I risultati ottenuti hanno consentito una migliore comprensione dei fenomeni sici descritti dal codice Comes-HTC, evidenziando anche il forte accoppiamento tra il campo igrometrico, termico e meccanico che inuisce sul legame tra le variabili del modello e i parametri del materiale.
Ismail, Dahman y Alexis Andrei. "Thermomechanical stress analysis of the main insulation system of traction electrical machines". Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-20305.
Texto completoMer effektiva tunga fordon utvecklas med högre räckvidd, uppdaterade elektroniska och mekaniska delar. Bränsleeffektiviteten och föroreningen av koldioxid måste vara lägre för att uppnå nya EU-förordningar. Antalet tunga fordon ökar i takt med att den globala befolkningen ökar, detta leder i sin tur till ökad utsläpp av bland annat koldioxid. Genom att ta de elektriska och mekaniska delarna till nästa steg kan de globala utsläppsproblemen minskas massivt. Elektriska maskiner för framdrivning är nästa steg mot en renare framtid. Studiens huvudmål för att undersöka den elektriska maskinens isoleringssystem. Termomekaniska påfrestningar på grund av termisk cykling påverkar de elektriska maskinerna och dess delkomponenter. Genom att använda en FEM-applikation med förenklade modeller av den elektriska maskinen erhålls och diskuteras resultat. Specifikt om 2D-modeller är tillräckliga för att representera en 3D-modell. Hur tillräckligt de olika 2D-modeller kan representera 3D-modellen jämförs och diskuteras i denna studie. Ett fysiskt experiment utförs för att validera och kalibrera FEA-modellerna. Vilken av de mindre frekventa cykler med högre amplitud eller mer frekventa cyckler med lägre amplitud påverkar isoleringssystemet mest har undersökts. Simuleringarna kan göras med antingen, temperatur kopplad förskjutnings analys eller sekventiellt kopplad analys. Temperatur kopplad kopplad förskjutning är den snabbaste metoden att använda i simuleringsmodellerna. En 3D-modell är det bästa sättet att beskriva ett objekt och har därför implementerats. Ytterligare två, 2Dmodeller är framtagna i FEM-miljö för snabbare beräkning och för att undersöka om 2D-modellerna kan representera den tredimensionella geometrin. Samtliga tre modeller har specifika randvillkor för att förenkla modellerna. Känslighetsstudier görs för att bestämma vilken parameter som påverkar de inducerade termomekaniska spänningarna mest. Ett fysiskt experiment har utförsts för att validera och kalibrera simuleringsmodellerna. Resultatet visar att 3D-modellen representerar ett tre dimensonellt objekt bäst. Simuleringsresultat har visat att epoxy, som är en av huvudkomponenterna i isoleringssystemet, är mest kritisk när det gäller att först nå brott- och sträckgräns, följt av pappersisolering och koppar beläggningen. Detta är ett typiskt resultat av alla tre simuleringsmodeller. Slutsatsen visar att vissa 2D-modeller kan presentera 3D-modellen, andra kan inte. Den beroende faktorn beror på ur vilket tvärsnitt man tittar på den elektriska maskinen. Det fysiska experimentet visar liknande resultat jämfört med simuleringen när det gäller belastning vid en lägre temperatur, och avvikelsen blir större när temperaturen ökar. 3D-modellen, är den modell som har den bästa representationen av en riktig elektrisk maskin eftersom den inkluderar normal- och skjuvspänningskomponenter i alla riktningar. Anledningen är att den har bättre randvillkor jämfört med 2Dmodellerna. 2D-modellen i XY-planet har visat liknande resultat som 3D-modellen. En av huvudkomponenterna i isoleringssystemet, epoxy, utsätts för de högsta spänningarna jämfört med dess sträck- och den brottgräns, följt av pappersisolering och koppar beläggning. Känslighetsstudien har kommit fram till att statorns axiella längd inte påverkar spänningsamplituderna. Den mest kritiska parametern som påverkar de termomekaniska spänningarna är temperatur amplituden, materialens CTE och tjockleken på det skarvade skiktet. Alla maximala spänningsamplituder för samtliga tre komponenter är belägna i den fria änden.
CAIVANO, RICCARDO. "Design for Additive Manufacturing: Innovative topology optimisation algorithms to thrive additive manufacturing application". Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2957748.
Texto completoChen, Dongju. "Analysis and identification technology of system errors of large vertical ultra-precision machine tool". Compiègne, 2010. http://www.theses.fr/2010COMP1890.
Texto completoUltra-precision machining technology is an important supporting technology of modern high-technology warfare, which is the development foundation for hightech industries and science and technology, and is the development direction of modern manufacturing science. The semiconductor device supported by ultraprecision machining technology, laid the foundation for the development of electronics and information industry. The development of modern science and technology based on the test, almost all of the test equipment needs the support of ultra-precision machining technology. Now ultra-precision machining has entered the nano-scale, and become an indispensable key means of developing high-tech. Whether the military industry, or civilian industry, all need such advanced machining technology. The research on machining precision of a two-axis large ultra-precision machine tool, analyzing the errors of main components of machine tool by multibody theory, the transfer matrix method, and finite element method. In order to show the comprehensive characterization of workpiece, wavelet method, correlation analysis and power spectral density method are used to analyze the surface topography of workpiece, different from the traditional Fourier transfer method, wavelet method express the comprehensive characterization of the signal in time and frequency domain. Correlation analysis method can estimate the signal in two different processes. Power spectral density method can fully reflect the impact of small-scale waviness of surface morphology on the machined accuracy. For the hydrostatic bearings, the parameters equation of bearings was deduced by the knowledge of fluid mechanics, and the calculated results were compared with other calculations. The mathematical model of spindle system in equilibrium was established according to Newton’s law, based on the the model, the relationship between derivation angle and stiffness of bearing was deduced, and the stiffness in all directions are given. The forced vibration of spindle caused by unbalance during machining process was researched through dynamic model of spindle. Dynamic stiffness and frequency response were deduced according to the axial static stiffness of spindle. Thermal-mechanical model of spindle system was established, the calculation basis of the heat transfer in the spindle system was deuced, and thermal error was analyzed with heat transfer mechanism, the variation of bearing performance at the different conditions under the influence of thermal errors, and the impact on the machining accuracy was analyzed. The coupling error model of guidewaies of machine tool was established with multi-body system theory. For the complex structure of guideway and unloading slide, the pressure distribution of gas film of guideway with double row orifices by gas lubrication theory, and corresponding load capacity and gas stiffness was obtained. The movement frequency with gas film thickness of entire slide system during machining process was showed. The coupling dynamic model of motion and unloading slides was established through corresponding frequency, the dynamic response of slide with the variation of gas film thickness was deduced. Finally, the variation of moving frequency in the whole gas film thickness was obtained. Finally, the measured result of workpiece was processed by wavelet transfer. The rotation error model of spindle was proposed by Weierstrass function, and the correctness and feasibility of this model was verified by comparing with actual test results. The correlation between guideway, spindle system and measured result of workpiece was analyzed, thus the degree of influence of every error on the machining accuracy was deduced. Combained with wavelet method and power spectral density method, the errors of guideway and spindle systems was analyzed in frequency domain, the characteristics of vibration signal of machine tool in frequency domain was extracted, and various error that affect the machining accuracy were identified according to the spectral characteristics
Chen, J. P. "Thermo-mechanical behaviour of heavy-duty disc brake systems". Thesis, Cranfield University, 2001. http://dspace.lib.cranfield.ac.uk/handle/1826/10701.
Texto completoChen, Jing Ping. "Thermo-mechanical behaviour of heavy-duty disc brake systems". Thesis, Cranfield University, 2001. http://dspace.lib.cranfield.ac.uk/handle/1826/10701.
Texto completoREGORDA, ALESSANDRO. "THE THERMO-MECHANICAL EVOLUTION OF THE SUBDUCTION-COLLISION SYSTEMS". Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/481243.
Texto completoLa finalité de ce travail est de développer un modèle thermomécanique 2D pour analyser en détails les effets de la dissipation visqueuse et de l'hydratation du coin de manteau sur l’état thermique et la dynamique dans les zones de subduction. L’état thermique et la dynamique résultant des modèles prenant en compte la dissipation visqueuse et/ou l'hydratation du manteau sont comparés aux modèles le les prenant pas en compte (Marotta and Spalla, 2007), afin d’analyser leurs effets sur la viscosité et sur la vitesse de déformation. Notre nouveau modèle démontre l’activation de la convection du manteau à courte longueur d’onde en fonction de l'hydratation et de la serpentinisation du coin de manteau. Il en résulte un recyclage des croûtes continentales et océaniques subduites. En outre, les effets de la vitesse de subduction sur l’ampleur de la région hydratée ont été analysés. Les évolutions des conditions P-T des marqueurs de crustaux et l'état thermique enregistré dans les différentes portions du complexe de subduction sont utilisés pour avoir une meilleure compréhension de la distribution et de l'évolution, dans le temps et dans l'espace, de conditions métamorphiques caractérisées par des rapports P/T contrastés. Une fois ces modèles établis, les évolutions P-T prédites par les modèles sont comparées aux données métamorphiques naturelles observées dans la chaine varisque, plus particulièrement dans les Alpes et le Massif Central français. Afin de prendre en compte l’exhumation de croûte subduite jusqu’aux niveaux les plus superficiels, le modèle prends en compte le rôle de l'atmosphère et donc des mécanisme d’érosion et de sédimentation. Cette condition induit une limite supérieure libre qui permet à la croûte subduite d’ arriver à la surface. L'analyse des trajets simulés est compatible avec des scénarios impliquant deux cycles de subduction et de collision dans l'évolution orogénique de la chaîne varisque. L'hypothèse de deux subduction successives est en accord avec les modèles géodynamiques proposés par de nombreux auteurs (e.g., Matte 2001; Guillot et al., 2009; Lardeaux 2014). Sur la base de ces résultats, un modèle caractérisé par deux subductions opposées a été mis en œuvre à fin de mieux rendre compte de l'évolution thermo-mécanique de l'orogenèse varisque.
Crain, Kevin Richard. "Mechanical characterization and thermal modeling of a MEMS thermal switch". Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Fall2005/k%5Fcrain%5F120905.pdf.
Texto completoPaspuleti, Suma. "Mechanical and thermal buckling of thin films". Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4302.
Texto completoThe entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 14, 2006) Includes bibliographical references.
De, Simone Silvia. "Induced seismicity in enhanced geothermal systems : assessment of thermo-hydro-mechanical effects". Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/405890.
Texto completoLa micro-sismicitat induïda per operacions relacionades amb els Sistemes Geotèrmics Estimulats ha originat un gran interès científic, no només pel risc i la preocupació que comporta, sinó també perquè la relació entre la injecció de fluids i l'activitat sísmica no s'entén completament. Aquesta tesi pretén avançar en la comprensió dels processos hidro-termo-mecànics (THM) que causen aquesta sismicitat, per poder explicar-la i gestionar-la. En primer lloc, hem investigat l'acoblament hidro-mecànic (HM) i el seu efecte sobre les pressions. En Hidrologia Subterrània clàssica l'emmagatzematge especifico expressa la capacitat de l'aqüífer de deformar-se després d'una variació de pressió. Malgrat això, la sobrepressió generada per la injecció exerceix una força que deforma tot l'aqüífer, depenent de la seva geometria i de les formacions adjacents. Per això, l'emmagatzematge no es pot expressar amb un sol paràmetre, sinó que depèn de la resposta poro-elàstica de tot l'aqüífer, per la qual cosa diem que l'emmagatzematge específic és "no-local", cosa que vam mostrar mitjançant solucions analítiques de la resposta transitòria al problema HM de la injecció en aqüífers de dimensió finita, amb geometria tant unidimensional com cilíndrica. Seguidament, hem considerat una injecció no isoterma i comparat els efectes de l'acoblament hidro-mecànic (HM) i termo-mecànic (TM). Hem obtingut expressions analítiques per a les tensions i els desplaçaments induïts a llarg termini per la pertorbació hidràulica i tèrmica, en el cas de dominis unidireccional i radial. Per a això, hem considerat flux estacionari i desenvolupat una solució analítica senzilla per al transport de calor en règim transitori, la qual cosa ens ha permès calcular la resposta poro i termo-elàstica i en particular la sensibilitat de les tensions a les condicions mecàniques en el contorn exterior. A continuació, hem desenvolupat simulacions HM i THM acoblades de la injecció d'aigua freda en un sistema format per una falla embeguda en una roca intacta, a fi d'analitzar les variacions de l'estabilitat mecànica durant la injecció. Les simulacions HM mostren que l'estabilitat de les fractures depèn de la seva orientació i del tensor de tensions inicial. Concloem que la reducció de temperatura provoca prop del pou una forta pertorbació de les tensions, que pot induir sismes en fractures orientades críticament, especialment quan la tensió màxima actua perpendicularment a la fractura. Finalment, hem estudiat els mecanismes que poden induir sismes quan s'atura la injecció de fluids en sistemes geotèrmics profunds (sismicitat post-injecció). A més de l'efecte directe de l'augment de la pressió, hem considerat l'efecte tèrmic a causa del refredament i la redistribució de tensions generada pel moviment de cisalla que ocorre durant la injecció en fractures favorablement orientades. Aquests efectes s'han analitzat tant per separat com superposats. Dels resultats podem deduir que la sismicitat post-injecció pot ocórrer al llarg de fractures que eren inicialment estables i es desestabilitzen durant la injecció, a causa de les tensions tèrmiques i a les induïdes per la cisalla, però es mantenen estables gràcies a les forces de pressió. Posteriorment, aquestes fractures trenquen quan s'interromp la injecció, ja que les pressions es dissipen ràpidament. Això suggereix que la sismicitat post-injecció pot atenuar-se amb una reducció lenta del cabal d'injecció.
Khadivipanah, Peiman. "Modelling thermo-mechanical response of metal canister disposed in engineered barrier systems". Doctoral thesis, Universitat Politècnica de Catalunya, 2022. http://hdl.handle.net/10803/673618.
Texto completoEl principal objetivo de esta tesis es describir e implementar una ecuación constitutiva dependiente de la velocidad (viscoplástica) para un contenedor a base de cobre usando una única variable de estado interna y usarlo para modelar esquemas de almacenamiento sujetos a condiciones de cizallamiento. Para ello se considera el modelo de Bodner y Partom (BP) (Bodner & Partom, 1975). Para evaluar la respuesta del cobre a las variaciones en la velocidad de deformación a lo largo de un rango de temperatura, este modelo utiliza ecuaciones constitutivas viscoplásticas basadas en una única variable de estado interno que es una función del trabajo plástico. El modelo constitutivo de BP se ha implementado en programa de ordenador CODE_BRIGHT (DIT-UPC, 2021; Olivella et al., 1994; Olivella et al., 1996). La ecuación constitutiva se verifica con los resultados existentes y su validación se lleva a cabo evaluando la capacidad para reproducir experimentos. Para la verificación, se simuló la respuesta tensión-deformación de una barra en condiciones de tracción uniaxial a velocidad constante con CODE_BRIGHT y se compararon los resultados con la solución obtenida de Stealth Finite Difference Code y las soluciones semi-analíticas. Además, se analiza la reacción de un contenedor instalado dentro de una barrera de ingeniería, que sufre hidratación e hinchazón hasta que alcanza la saturación completa antes del cizallamiento. El modelo elasto-viscoplástico implementado realmente representa el comportamiento del contenedor en condiciones de plastidad. Aunque el contenedor es muy rígido y resistente en comparación con los componentes de arcilla donde se colocará, las deformaciones por cizallamiento que ocurren en el sistema de barrera de ingeniería (EBS) tendrán un impacto en el contenedor (Börgesson, 1986). Por último, el contenedor de combustible nuclear gastado se podrá analizar en condiciones extremas, ya que es un sistema de larga duración y debe resistir todo tipo de condiciones ambientales, por ejemplo, terremotos y glaciaciones. Después de la implementación y verificación del modelo en CODE BRIGHT, este programa se ha utilizado para modelar las pruebas de cizallamiento en 2D y 3D. En la escala Mock-up y Full-scale en modelos 2D y 3D, se ha llevado a cabo una comparación entre el método de tensiones totales (solo análisis mecánico) y el método de tensiones efectivas (análisis hidromecánico). Los resultados experimentales de una prueba de cizallamiento canister en arcilla (Börgesson, 1986) se han comparado con los resultados del modelo numérico utilizando CODE BRIGHT. El análisis de sensibilidad sobre la viscosidad para los cálculos de tensión total y la permeabilidad para los cálculos de tensión efectiva se han realizado en la escala Mock-up y Full-scale. En la prueba de cizalla de contenedor-arcilla, se ha realizado un análisis de sensibilidad de la malla y también una comparación entre el método que actualiza la malla con los desplazamientos (método Lagrangiano) y el método de malla fija. Finalmente, en dos y tres dimensiones, se ha realizado la simulación de ensayos de cizallamiento contenedor-arcilla basados en el impacto de la presencia de una discontinuidad (la discontinuidad está en la roca y por ello hay cizallamiento en el sistema), así como análisis de sensibilidad de parámetros. y malla en análisis mecánico e hidromecánico acoplado
Enginyeria civil
Aldubyan, Mohammad Hasan. "Thermo-Economic Study of Hybrid Photovoltaic-Thermal (PVT) Solar Collectors Combined with Borehole Thermal Energy Storage Systems". University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1493243575479443.
Texto completoHuang, Yi Ph D. Massachusetts Institute of Technology. "Spectral engineering for solar-thermal and thermal-radiative systems". Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127052.
Texto completoCataloged from the official PDF of thesis.
Includes bibliographical references (pages 224-239).
Increasing energy efficiency for power generation and reduction of energy consumption are two important venues to address the energy supply and global warming challenges we face today. Radiation from the sun and terrestrial heat sources can be harvested for power generation. It is also an important heat transfer channel, with which one can control in order to regulate the temperature of objects. In this thesis, we focus on strategies to harvest and control solar and thermal radiation, with the goals (1) to improve power generation efficiency using solar and thermal photovoltaics and (2) to reduce the energy consumption used to maintain human comfort in built environments. Solar radiation, as one of the most abundant energy sources on Earth, is now harvested by photovoltaics around the world. While solar photovoltaics already has reached considerable efficiencies, there is still room for improvement.
One fundamental limit in solar photovoltaics is the discard of photons with energy smaller than the material bandgap. Another challenge for solar PVs, due to the intermittent nature of solar power, is the lack of low-cost electricity storage systems that provide electricity on-demand. Solar thermal systems, on the other hand, can dispatch energy on-demand due to low-cost of thermal storage systems. Hybrid systems that combine solar PV and solar thermal systems can potentially harvest solar energy at higher efficiency and provide more dispatchable sources of energy. In the first part of my thesis, we designed and experimentally tested a spectral-selective, thermally-conductive component to be used in such hybrid solar-PV thermal system.
The component can direct part of the solar spectrum to the photovoltaics and to absorb the rest of the spectrum for use in a thermal system, thereby harvesting the entire solar spectrum with an energy conversion efficiency close to 23%, and with over 40% dispatchable electricity generated from thermal energy. The photovoltaic energy conversion efficiency can also improve by recycling photons with energy smaller than the material bandgap. In a thermo-photovoltaic system, low-energy photons can be designed to reflect back to the radiation source, and therefore energy carried by these photons can be re-used. Thermo-photovoltaic devices also showed great potential to provide low-cost, dispatachable electricity when combined with high-temperature thermal storage systems and concentrated solar power. In the second part of my thesis, we have designed and optimized a practical, crystalline-Si based thermo-photovoltaic cell to be fabricated on double-side polished wafers.
The Si-based TPV cell, combined with a 2300K gray radiator, can potentially reach 40% energy conversion efficiency. We have evaluated and optimized the Si-TPV performance with comprehensive considerations of components in the photovoltaic cell, including doping and junction depth, front and back surface field, passivation layer, back reflector, front metallization, as well as tolerance to roughness introduced in fabrication. Experimental tests have been conducted on doped Si samples with back reflectors, and identified potential pathways to further reduce optical and electrical losses. The maturity of the Si PV technologies and its relatively low cost points to great promise of high-efficiency thermo-photovoltaic devices for high-temperature thermal energy storage. Thermal radiation is also integral to the regulation of heat balance and temperatures of human body. Spaces in built environments are typically kept at near-ambient temperatures for human thermal comfort.
However, heating and cooling of spaces consume 40% of the total energy used in the US. Instead of regulating temperature in vast spaces, local regulation of heat near human bodies can potentially save large amounts of energy. In the third part of my thesis, we study the use of fabrics to regulate skin temperatures of the human body by controlling the input and output radiation channels of the human skin, an important yet largely under-studied channel for body temperature regulation. We then propose desired spectral properties of fabrics for both heating and cooling purposes, and in both indoor and outdoor environments. Finally, we investigate via both simulation and experiments, how morphology and material of polymer-based fabrics can be used to achieve the desired spectral properties.
by Yi Huang.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Mechanical Engineering
McEuen, Scott Jacob. "Thermal analysis of biochemical systems". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81702.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (p. 109-112).
Scientists, both academic and industrial, develop two main types of drugs: 1) small molecule drugs, which are usually chemically synthesized and are taken orally and 2) large molecule, biotherapeutic, or protein-based drugs, which are often synthesized via ribosome transcription in bacteria cells and are injected. Historically, the majority of drug development, revenue, and products has come from small molecule drugs. However, recently biotherapeutic drugs have become more common due to their increased potency and specificity (the ability to chemically bond to the targeted protein of interest). Researchers now estimate that as much as 50% of current drug development activities (pre-market approval) are focused on these protein-based drugs. There are several well-documented steps necessary in the development of a new large molecule drug. One critical element during the end of the biotherapeutic drug discovery phase and the beginning of the manufacturing phase is known as preformulation or formulation development. During this stage scientists systematically test the effects of adding various excipients (non-protein additives added to enhance the protein stability, solubility, activity of the drug, etc.) to the potential large molecule drug. Differential scanning calorimetry (DSC) is a common technique used to perform these formulation studies. In a classic DSC experiment, a protein is heated from 20-80°C and the heat absorbed while the protein unfolds is measured. Many researchers prefer the use of a DSC instrument because of its label-free nature, meaning that no fluorescent or radio-labeled tag is necessary to perform the measurement. The heat absorbed during the unfolding event(s) is directly measured. However, current commercial DSC instruments suffer from high protein consumption (especially when compared to other labeled techniques), low sensitivity, and slow throughput. The aim of this thesis is to address two of the three areas mentioned above: high protein consumption and slow throughput. Since many formulation development studies are performed at therapeutic or high protein concentrations, one can reduce the experimental cell volume and thereby reduce the amount of protein material consumed. However, since there is less sample, less heat is produced. While in the literature there are several heat transfer models that describe how a DSC instrument literature there are several heat transfer models that describe how a DSC instrument functions, there are surprisingly few heat transfer models that detail how ambient temperature disturbances impact the thermal measurement. To better describe this behavior, a simplified state-space thermal model was created to predict the disturbance rejection of a custom DSC instrument. This model was verified experimentally using linear stochastic system identification techniques. To reduce sample throughput, the prototype calorimeter cell was made from disposable materials. Because the majority of protein systems are thermodynamically irreversible, at elevated temperatures the protein solution often aggregates and needs to be cleaned before a subsequent experiment can be run. This cleaning process constitutes a significant portion of the overall time to run an experiment. This thesis documents a fully functional DSC instrument that, while not completely disposable, has been designed, built, and tested with disposable microfluidic materials. Future work would then solve the technical hurdles of repeatably loading disposable microfluidic cells into the DSC instrument.
by Scott Jacob McEuen.
Ph.D.
Barnat, Samed. "Etude prédictive de fiabilité de nouveaux concepts d’assemblage pour des « system-in-package » hétérogènes". Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14243/document.
Texto completoThis thesis project is a study of the predictive reliability of new microelectronic package concepts such as "system in package" SiP. The objective is to develop a reliable predictive methodology adapted to the new assembly concepts to optimize and to predict the performance at the design phase. Then, the methodology is applied to concrete projects. This methodology of predictive reliability involves the use of experimental studies, thermomechanical simulations and statistical analysis to process the data and assess the reliability and risks of failure. The use of simulation tools for electronic components is well suited to assist in the evaluation of the most fragile areas, the setting up of design rules and the determination of the most influential parameters with a reduction in the setup time market for a reliable and optimized performance. Studies on silicon strength are conducted with two tests: ball on ring test and on three-point bend test show that the grinding and the thickness influence the variation of the stress and deflection of the silicon at break. With the three points bend test, the onset of crack is linked to defects in sawing and grinding zone. However, with the ball on ring test, only the surface quality influences the initiation of cracks. The ball on ring test is well suited for evaluating the quality of the silicon surface. Chemical techniques of stress release, such as wet etching and plasma etching, improve significantly the strength of silicon samples. These tests on silicon dies are used to characterize the breakdown of silicon under bending test and to complete the simulation results. We have demonstrated in this work, the need and the usefulness of the virtual prototyping of electronic components and the use of a predictive methodology in assessing reliability
Ebinger, Cynthia Joan. "Thermal and mechanical development of the East African Rift System". Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/53531.
Texto completo"May 1988."
Includes bibliographical references (p. 163-169).
The deep basins, uplifted flanks, and volcanoes of the Western and Kenya rift systems have developed along the western and eastern margins of the 1300 km-wide East African plateau. Structural patterns deduced from field, Landsat, and geophysical studies in the Western rift reveal a series of asymmetric basins bounded by approximately 100 kmlong segments of the border fault system. These basins are linked by oblique-slip and strike-slip faults cross-cutting the rift valley. Faults bounding the Kenya and Western rift valleys delineate two north-south-trending, 40-75 km wide zones of crustal extension, and little or no crustal thinning has occurred beneath the uplifted flanks or the central plateau. In the Western rift, volcanism in Late Miocene time began prior to or concurrent with basinal subsidence, followed by rift flank uplift. Individual extensional basins developed diachronously, and basinal propagation may give rise to the along-axis segmentation of the rift valley. The coherence between gravity and topography data indicates that the mechanical lithosphere beneath the two rift valleys has been weakened relative to the central plateau and adjacent cratonic regions. Gravity and topography data at wavelengths corresponding to the overcompensated East African plateau can be explained by density variations within the upper mantle that are dynamically maintained.
by Cynthia J. Ebinger.
Ph.D.
Singh, Naveen Chandra Lall Pradeep. "Thermo-mechanical reliability models for life prediction of area array electronics in extreme environments". Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/master's/SINGH_NAVEEN_54.pdf.
Texto completoBracey, Marcus J. "Dynamic Modeling of Thermal Management System with Exergy Based Optimization". Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1503682474459341.
Texto completoPhan, Long N. 1976. "Automated rapid thermal imaging systems technology". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/75664.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (p. 266-276).
A major source of energy savings occurs on the thermal envelop of buildings, which amounts to approximately 10% of annual energy usage in the United States. To pursue these savings, energy auditors use closed loop energy auditing processes that include infrared thermography inspection as an important tool to assess deficiencies and identify hot thermal gradients. This process is prohibitively expensive and time consuming. I propose fundamentally changing this approach by designing, developing, and deploying an Automated Rapid Thermal Imaging Systems Technology (ARTIST) which is capable of street level drive-by scanning in real-time. I am doing for thermal imaging what Google Earth did for visual imaging. I am mapping the world's temperature, window by window, house by house, street by street, city by city, and country by country. In doing so, I will be able to provide detailed information on where and how we are wasting energy, providing the information needed for sound economic and environmental energy policies and identifying what corrective measures can and should be taken. The fundamental contributions of this thesis relates to the ARTIST. This thesis will focus on the following topics: * Multi-camera synthetic aperture imaging system * 3D Radiometry * Non-radiometric infrared camera calibration techniques * Image enhancement algorithms - Hyper Resolution o Kinetic Super Resolution - Thermal Signature Identification - Low-Light Signal-to-Noise Enhancement using KSR
by Long N. Phan.
Ph.D.
Siefert, Nicholas S. "Experimental and Thermo-Economic Analysis of Catalytic Gasification and Fuel Cell Power Systems". Research Showcase @ CMU, 2013. http://repository.cmu.edu/dissertations/255.
Texto completoLambert, Adrien Pascal. "Thermal-mechanical analysis of system-level electronic packages for space applications". Thesis, Montana State University, 2012. http://etd.lib.montana.edu/etd/2012/lambert/LambertA1212.pdf.
Texto completoKelley, Leah C. (Leah Camille). "The design and control of a thermal management system for a photovoltaic reverse osmosis system". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67620.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (p. 86-90).
Reverse osmosis (RO) is a well-known process for desalinating seawater and brackish groundwater. Desalination is energy-intensive, so using photovoltaic (PV) panels to power the process is an attractive environmentally friendly concept, especially for community-scale systems. Increasing the system efficiency will lower the total cost of water produced, making the systems more economically competitive for a greater number of geographic locations. The thermal behaviors of PV panels and RO systems are complementary and can be exploited to improve photovoltaic reverse osmosis (PVRO) system efficiency. For a given level of solar radiation, a PV panel produces more electrical power at lower panel temperatures. For a given applied pressure, the flow of clean water across an RO membrane increases with increasing temperature. By using the RO feed water to cool the PV panels and warming the water in the process, more electrical power can be produced and higher flow rates of clean water across the RO membrane can be achieved, increasing total daily water production. The ability to cool the PV panels permits the use of low-cost, flat-plate concentrating mirrors, which further increase electrical power and clean water production. This thesis develops a thermal management system to improve the performance of a small-scale PVRO. Preliminary case studies show that the thermal exploitation concept is feasible and that a 50% increase in the total daily clean water production of a PVRO system is achievable, with an active thermal controller. A thermal controller is proposed that optimizes the PVRO system performance by minimizing the temperature of the solar panel and maximizing the temperature of the RO feed water. The control system uses a solar panel-mounted heat exchanger, circulator pump and servo valves to maximize water production while operating within the temperature limits of both the solar panel and the reverse osmosis membrane. Preliminary controller simulations show that it can successfully manage the temperatures of both the solar panel and RO feed water. The thermal management concept was experimentally validated on a small-scale, 300 L/day PVRO system. A 57% increase in clean water production was achieved using thermal management and solar concentrating mirrors, which agrees well with simulated performance predictions.
by Leah C. Kelley.
S.M.
Thoms, Matthew W. "Adsorption at the nanoparticle interface for increased thermal capacity in solar thermal systems". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74946.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (p. 86-88).
In concentrated solar power (CSP) systems, high temperature heat transfer fluids (HTFs) are responsible for collecting energy from the sun at the solar receiver and transporting it to the turbine where steam is produced and electricity is generated. Unfortunately, many high temperature HTFs have poor thermal properties that inhibit this process, including specific heat capacities which are half that of water. In an effort to enhance the effective heat capacity of these high temperature HTFs and thus increase the efficiency of the CSP systems, adsorption energy at the liquid-solid interface was investigated as a mechanism for increased thermal capacity. Solid ceramic nanoparticles were dispersed in several molten salts at 1-2% by mass with diameters ranging from 5 nm to 15 nm to provide a significant available surface area for adsorption at the particle-molten salt interface. After successful nanofluid synthesis, differential scanning calorimetry (DSC) was used to measure anomalous deviations from the expected heat capacity and enthalpy of fusion values in the nanofluids. The variation in the sensible and latent heat values was determined to be dependent on the presence of sub-100 nm particles and attributed to a layer of salt that remains adsorbed to the surface of the nanoparticles after the bulk of the salt has melted. The adsorbed salt layer is expected to desorb at a higher temperature, providing an increased effective thermal capacity in the vicinity of this desorption temperature. A thermal analysis technique utilizing DSC was proposed to approximate the thickness of the adsorbed layer at the liquid-solid interface, a value that has previously only been obtained using simulation or transmission electron microscopy. More specifically, the adsorbed layer of LiNO3 on Al2O3 particles was determined to be 5.3-7.1 nm thick, similar to the 1-3 nm layers that have been observed in literature for simple, monatomic fluids. The results provide new insight into the nature of adsorption at the liquid-solid interface in more complex fluid and particle systems that can be harnessed for enhanced thermal capacity in HTFs.
by Matthew W. Thoms.
S.M.
Hatzenbuehler, Mark A. "Modeling of jet vane heat-transfer characteristics and simulation of thermal response". Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23314.
Texto completoThe development of a dynamic computational model capable of predicting, with the requisite design certainty, the transient thermal response of jet vane thrust control systems has been undertaken. The modeling and simulation procedures utilized are based on the concept that the thermal processes associated with jet vane operation can be put into a transfer function form commonly found in the discipline of automatic controls. Well established system identification methods are employed to formulate and verify the relationships between the various gains and frequencies of the transfer function model and experimental data provided by Naval Weapons Center, China Lake.
http://archive.org/details/modelingofjetvan00hatz
Lieutenant, United States Navy
Ghavam-Nasiri, Ali. "Thermo-Hydro-Mechanical Behaviour of Composite Geosynthetic Lining Systems under High Temperature and Low Pressure". Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17782.
Texto completoFoley, Brian S. B. (Brian M. ). Massachusetts Institute of Technology. "Solar thermal collector system modeling and testing for novel solar cooker". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92179.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (page 22).
Solar cookers are aimed at reducing pollution and desertification in the developing world. However, they are often disregarded as they do not give users the ability to cook after daylight hours. The Wilson solar cooker is a solar cooker designed to address this problem by converting solar energy and storing that energy as heat in the form of molten salt (lithium nitrate). This thesis involved research, modeling, and experimentation for the solar collection system of the cooker. This thesis looked at prior research on glazing, Fresnel lenses, and absorber surface treatments to identify and evaluate elements for use in the collection system. Borosilicate glass, with a thermal conductivity of 1.005 W/mK and a solar transmittance of 0.91, and flat black paint, with absorptivity 0.96 and emissivity 0.88 were identified as potential elements for use in first trials. Experimentation was performed on copper and aluminum samples with various surface treatments powered by various Fresnel lenses to evaluate the relative efficiency of these treatments. A novel treatment method, machining a conical hole into the sample, was found to improve efficiency on untreated samples, but inferior to flat black paint. Modeling predicted that the minimum collection area for an acrylic Fresnel lens off-number 1.2 was 0.60 m² for and 0.65 m² for the proposed collector without and with glazing, respectively. A recommendation of collection area 1 m² was proposed to account for unexpected losses due to manufacturing errors, positioning errors, and environmental variation. This thesis also analyzed a proposal for a novel solar collector, a polished aluminum cone. Modeling and efficiency testing showed the cone to be inadequate for the radiation collection needed for the solar cooker.
by Brian Foley.
S.B.
Algareu, Abdulmaged Omer. "Development of reflective low concentrated photovoltaic/thermal system". Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7674/.
Texto completoSweetland, Matthew 1970. "Design of thermal control systems for testing of electronics". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8927.
Texto completoIncludes bibliographical references (p. 239-242).
In the electronic component manufacturing industry, most components are subjected to a full functional test before they are sold. Depending on the type of components, these functional tests may be performed at room temperature, at cold temperature, or at high temperature (-50C to 1600C) depending on the type of component and intended market. The thermal management of these components during testing forms two basic issues that need to be addressed. The first issue is the heating or cooling of devices to the desired temperature prior to being tested, and the second issue concerns temperature control during the actual functional test. This thesis covers the design, modeling and testing of two prototype systems. One system uses a low cost IR heating system to preheat bulk devices to a target temperature, prior to the actual functional test. Theory shows that the limits on temperature ramp rates are imposed by the device package configuration and carrier configuration. The results from the prototype system show that the IR heating chamber is an effective low cost, low volume system for uniformly heating a wide range of device and carrier types. The second prototype system uses high performance jet impingement coupled with laser heating to actively control the temperature of a high power density device during a functional test. Experimental results from the prototype system are presented and design guidelines for future systems are developed. The theory for temperature control is developed and the effects of package design and test sequence design on the temperature control limits are studied.
by Matthew Sweetland.
Ph.D.
Rao, Sachit Srinivasa. "Sliding mode control in mechanical, electrical and thermal distributed processes". Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1164817694.
Texto completoChoi, Joon Ho. "CoBi: Bio-Sensing Building Mechanical System Controls for Sustainably Enhancing Individual Thermal Comfort". Research Showcase @ CMU, 2010. http://repository.cmu.edu/dissertations/33.
Texto completoDiBartolomeo, Franklin. "HIGH SPEED CONTINUOUS THERMAL CURING MICROFABRICATION SYSTEM". UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_theses/105.
Texto completoMoody, Seth S. "Development of Dynamic Thermal Performance Metrics For Eco-roof Systems". Thesis, Portland State University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1535587.
Texto completoIn order to obtain credit for an eco-roof in building energy load calculations the steady state and time-varying thermal properties (thermal mass with evapotranspiration) must be fully understood. The following study presents results of experimentation and modeling in an effort to develop dynamic thermal mass performance metrics for eco-roof systems. The work is focused on understanding the thermal parameters (foliage & soil) of an eco-roof, further validation of the EnergyPlus Green Roof Module and development of a standardized metric for assessing the time-varying thermal benefits of eco-roof systems that can be applied across building types and climate zones.
Eco-roof foliage, soil and weather parameters were continuously collected at the Green Roof Integrated PhotoVoltaic (GRIPV) project from 01/20/2011 to 08/28/2011. The parameters were used to develop an EnergyPlus eco-roof validation model. The validated eco-roof model was then used to estimate the Dynamic Benefit for Massive System (DBMS) in 4 climate-locations: Portland Oregon, Chicago Illinois, Atlanta Georgia and Houston Texas.
GRIPV30 (GRIPV soil with 30% soil organic matter) was compared to 12 previously tested eco-roof soils. GRIPV30 reduced dry soil conductivity by 50%, increased field capacity by 21% and reduced dry soil mass per unit volume by 60%. GRIPV30 soil had low conductivity at all moisture contents and high heat capacity at moderate and high moisture content. The characteristics of the GRIPV30 soil make it a good choice for moisture retention and reduction of heat flux, improved thermal mass (heat storage) when integrating an eco-roof with a building.
Eco-roof model validation was performed with constant seasonal moisture driven soil properties and resulted in acceptable measured - modeled eco-roof temperature validation. LAI has a large impact on how the Green Roof Module calculates the eco-roof energy balance with a higher impact on daytime (measured - modeled) soil temperature differential and most significant during summer.
DBMS modeling found the mild climates of Atlanta Georgia and Houston Texas with eco-roof annual DBMS of 1.03, 3% performance improvement above the standard building, based on cooling, heating and fan energy consumption. The Chicago Illinois climate with severe winter and mild spring/summer/fall has an annual DBMS of 1.01. The moderate Portland Oregon climate has a below standard DBMS of 0.97.
Lenert, Andrej. "Tuning energy transport in solar thermal systems using nanostructured materials". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92164.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (pages 137-146).
Solar thermal energy conversion can harness the entire solar spectrum and theoretically achieve very high efficiencies while interfacing with thermal storage or back-up systems for dispatchable power generation. Nanostructured materials allow us to tune the spectral properties and heat transfer behavior to enable such systems. However, under high temperature conditions, thermal management, system optimization and minimization of parasitic losses are necessary to achieve competitive solar power generation. This thesis seeks to achieve spectral control and thermal management through manipulation of nanostructured materials. First, this thesis presents the design and development of a nanophotonic solar thermophotovoltaic (STPV) that harnesses the full spectrum of the sun, in a solid-state and scalable way. Through device optimization and control over spectral properties at high temperatures (~1300 K), a device that is 3 times more efficient than previous STPVs is demonstrated. To achieve this result, a framework was developed to identify which parts of the spectrum are critical and to guide the design of nanostructured absorbers and emitters for STPVs. The work elucidated the relative importance of spectral properties depending on the operating regime and device geometry. Carbon nanotubes and a silicon/silicon dioxide photonic crystal were used to target critical properties in the high solar concentration regime; and two-dimensional metallic photonic crystals were used to target critical properties in the low solar concentration regime. A versatile experimental platform was developed to interchangeably test different STPV components without sacrificing experimental control. In addition to demonstrating significant improvements in STPV efficiency, an experimental procedure to quantify the energy conversion and loss mechanisms helped improve and validate STPV models. Using these validated models, this thesis presents a scaled-up device that can achieve 20% efficiencies in the near term. With potential integration of thermal-based storage, such a technology can supply power efficiently and on-demand, which will have significant implications for adoption of STPVs. Second, the thesis shifts focus away from solid-state systems to thermal-fluid systems. A new figure of merit was proposed to capture the thermal storage, heat transfer and pumping power requirements for a heat transfer fluid is a solar thermal system. Existing and emerging fluids were evaluated based on the new metric as well as practical issues. Finally, sub-micron phase change material (PCM) suspensions are investigated for simultaneous enhancement of local heat transfer and thermal storage capacity in solar thermal systems. A physical model was developed to explain the local heat transfer characteristics of a flowing PCM suspension undergoing melting. A mechanism for enhancement of heat transfer through.control over the distribution of PCM particles inside a channel was discovered and explained. Together, this thesis makes significant contributions towards improving our understanding of the role and the effective use of nanostructured materials in solar thermal systems.
by Andrej Lenert.
Ph. D.
Lizarraga-García, Enrique. "Optimal operation and design of solar-thermal energy storage systems". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74925.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (p. 99-105).
The present thesis focuses on the optimal operation and design of solar-thermal energy storage systems. First, optimization of time-variable operation to maximize revenue through selling and purchasing electricity to/from the grid is presented for a thermal energy storage system. Time-variable electricity prices and electricity buy-back from the grid to re-charge the energy storage is considered. The concentrated solar power on demand (CSPonD) concept, in which a salt pond receives solar energy, stores thermal energy, and delivers thermal energy to the power cycle is considered. Electric heaters are added to the CSPonD concept, allowing for periods of electricity buy-back from the grid to re-charge the energy storage. System-level models are developed and optimization of the design and operation is performed with local solvers. Three main case studies are considered: the first case study investigates the optimization of time-variable operation without electrical heating under time-invariant electricity price; the second case study optimizes the operation under time-variant electricity price without electric heaters; the third case study optimizes the operation under time-variant electricity price allowing charging of the pond using the grid electricity. The first case study reflects the time-invariant tariff model, whereas the second and third case studies consider a time-of-use feed-in-tariff. Two hourly price profiles are considered in order to assess the influence of it on the optimal design and operation of the thermal energy storage. The first electricity profile consists of a price profile that fluctuates moderately, and the second price profile fluctuates highly, including negative prices. The results show significant increase in the revenue when adding electric heaters. Under the moderately fluctuating electricity price, the use of heaters increases the revenue significantly, compared to the same case with no electric heaters considered. Under the highly fluctuating electricity price, the use of heaters more than doubles the revenue, compared to the same case with no electric heaters considered. Also, the performance analysis of a regenerative thermal energy storage system with enhancement heat transfer structures is presented. In a regenerative thermal storage system, thermal energy is transferred from a hot heat transfer fluid to the storage unit core elements during charge, and from the core elements to the cold heat transfer fluid during discharge. Herein, concrete as the solid storage material, nitrate solar salt as the heat transfer fluid, and aluminum plates as the heat transfer structures is considered. The discharge process from uniform initial temperature is studied with different configurations (pure concrete and concrete enhanced by transfer structures), operation strategies (laminar versus turbulent flow regimes), and dimensions. Results show a significant decrease in the cost of the thermal energy storage system when heat transfer structures are added, as well as a better performance in terms of discharge efficiency and discharge time period. The amount of solar salt needed for this configuration is approximately one fourth that required for a nitrate two-tank system operating with the same temperature difference.
by Enrique Lizarraga-García.
S.M.
Lee, Heon Ju 1977. "Thermal stability of nano-structured selective emitters for thermophotovoltaic systems". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78173.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (p. 97-103).
A fundamental challenge in solar-thermal-electrical energy conversion is the thermal stability of materials and devices at high operational temperatures. This study focuses on the thermal stability of tungsten selective emitters for thermophotovoltaic (TPV) systems which are anticipated to enhance the conversion efficiency. Selective emitters, 2-D photonic crystals, are periodic micro/nano-scale structures that are designed to affect the motion of photons at certain wavelengths. The structured patterns, however, lose their structural integrity at high temperatures, which disrupt the tight tolerances required for spectral control of the thermal emitters. Through analytical studies and experimental observations, the failure modes of tungsten 2-D photonic crystal are indentified. There were four major mechanisms of thermal degradation by which micro/nano-scale structures change their geometry when heated: grain growth and recrystallization, oxidation, surface diffusion, and evaporation. A novel idea of flat surface tungsten photonic crystal (FSTPC) was proposed and was validated by theoretical modeling and by experiments. Pre-annealing or using single crystalline tungsten will prevent the grain growth. A thin layer of diffusion barrier will prevent oxidation and/or evaporation and maintain the optical performance. By filling in the micro/nano-scale cavities with a damascened IR transparent ceramic, the surface of the emitter will have negligible second derivative of the curvature, and thus eliminates the surface diffusion even at high temperatures. Accelerated tests on silicon-based 2-D photonic crystal show that the micro/nano-scale structures on the silicon surface survive for at least 100 hours at 400 °C, homologous temperature of 0.4, which is equivalent temperature of 1200 °C for tungsten. Based on a scale-accelerated failure model, the life time of the Flat Surface Tungsten Photonic Crystal (FSTPC) is estimated to be at least 40 years at 800 °C.
by Heon Ju Lee.
Ph.D.
Pfahnl, Andreas Carl. "Design of a thermal control system for an IC test-in-tray handler". Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/41026.
Texto completoGraham, Matthew R. (Matthew Ryan) 1976. "Detection of DNA polymorphisms in thermal gradients via a scanning laser confocal system". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/89327.
Texto completoDinh, Toan Khac. "Thermoresistive Effect for Advanced Thermal-Based Sensors". Thesis, Griffith University, 2017. http://hdl.handle.net/10072/365574.
Texto completoThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
Full Text
Greenhut, Andrew David. "Modeling and analysis of hybrid geothermal-solar thermal energy conversion systems". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/58087.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (p. 116-118).
Innovative solar-geothermal hybrid energy conversion systems were developed for low enthalpy geothermal resources augmented with solar energy. The goal is to find cost-effective hybrid power cycles that take advantage of the potential synergies of solar thermal and geothermal resources. One aspect is to determine the hybrid configuration that yields the highest annualized electricity generation. The levelized cost of electricity (LCOE) is estimated using equipment costing rules of thumb developed from Aspen HTFS and Aspen ICARUS software and from other sources. Detailed models for the hybrid solar-geothermal system were developed using Aspen Plus and Aspen Dynamics. Turbine flexibility relative to vapor flow rate, temperature and pressure variations was analyzed. In one scenario, a parametric steady-state study was carried out to examine the performance over the range of conditions resulting from diurnal and seasonal variations. The results of the diurnal and seasonal parametric studies were grossly weighted to approximate a typical year in Nevada, and these results led to an estimate of the annualized electricity generation. In another scenario, a dynamic model was selected from possible "greenfield" hybrid systems and used to examine the transient performance for a typical January day and a typical July day in Nevada. The dynamic model approximates the thermal inertial of the heat exchangers and the working fluids in the exchangers, solar collectors, piping and storage tanks. The dynamic model is driven with forcing functions for solar input and ambient temperature to approximate the typical winter and summer days.
(cont.) In all cases, solar energy was found to come at a higher cost per kW capacity than geothermal when the cost of geothermal wells was not considered. However, including well costs had an effect of evening out the levelized cost of electricity. Model complexity increased as more solar heat was added to existing geothermal systems, which suggests that moving a higher exergy heat source down to a lower exergy heat source is difficult, especially given the transient nature of the solar resource. The models developed in this thesis demonstrate the design decisions and complex dynamic behavior inherent in this type of hybrid system.
by Andrew David Greenhut.
S.M.
Meroueh, Laureen. "Electrically charged thermal energy storage systems for grid-level electricity storage". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115660.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (pages 155-171).
Unlike most other commodities, electricity produced at any given time must match the electricity being consumed or the stability of the electric grid is jeopardized. Electricity demand changes throughout the day result in required generation ramp-ups that strain power plants, reduce cycle efficiency and increase CO2 emissions. This problem is exacerbated when renewable sources such as wind and solar are integrated into the grid, due to their intermittency. A change in methods of energy production globally that allows synergistic coupling of renewable and fossil fuels is needed. Currently, pumped hydroelectric and compressed air energy storage are the two most common methods of storage, but are highly geographic dependent systems and thus of limited applicability. There exists a strong demand for grid-scale energy storage that are cost-effective and without geographic constraints. In this thesis, storage systems that are charged by electricity and discharged to produce electricity at times of high demand, are theoretically evaluated. Various types of storage such as chemical, thermal, and mechanical, are reviewed to determine the most ideal method for grid-level energy storage. Thermal energy storage systems using phase change materials are most attractive on a cost and energy density basis. Two system designs are evaluated that can couple to both existing and future power plants since they are electrically charged, via joule heating for example, and later discharged to produce electricity using the plant's turbomachinery. Described within is a novel system in which silicon is used as the storage medium and energy release is predominantly through radiative heat transfer. Another design based on the eutectic alloy Al0.88 Si0.12 and other sensible energy storage materials is also evaluated. As an example, the energy storage systems are coupled to a power plant operating according to a supercritical Rankin cycle, and their performance is compared to that of a boiler. Additionally, system cost is compared to existing storage technologies. Although storing electricity as heat and back to electricity is thermodynamically unfavorable, we present an analysis to show that this approach can be cost competitive and provides a segue from fossil fuels to renewable energy.
by Laureen Meroueh.
S.M.
Ajja, Rameshwar. "Numerical heat transfer analysis of carbon-based foams for use in thermal protection system". FIU Digital Commons, 2006. http://digitalcommons.fiu.edu/etd/1179.
Texto completoCrane, Bryan Lee 1976. "DNA mutation detection via fluorescence imaging in a spatial thermal gradient, capillary electrophoresis system". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/88874.
Texto completo"February 2001."
Includes bibliographical references (leaves 122-126).
by Bryan Lee Crane.
S.M.