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Gowreesunker, Baboo Lesh Singh. "Phase change thermal enery storage for the thermal control of large thermally lightweight indoor spaces". Thesis, Brunel University, 2013. http://bura.brunel.ac.uk/handle/2438/7649.
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Energy storage using Phase Change Materials (PCMs) offers the advantage of higher heat capacity at specific temperature ranges, compared to single phase storage. Incorporating PCMs in lightweight buildings can therefore improve the thermal mass, and reduce indoor temperature fluctuations and energy demand. Large atrium buildings, such as Airport terminal spaces, are typically thermally lightweight structures, with large open indoor spaces, large glazed envelopes, high ceilings and non-uniform internal heat gains. The Heating, Ventilation and Air-Conditioning (HVAC) systems constitute a major portion of the overall energy demand of such buildings. This study presented a case study of the energy saving potential of three different PCM systems (PCM floor tiles, PCM glazed envelope and a retrofitted PCM-HX system) in an airport terminal space. A quasi-dynamic coupled TRNSYS®-FLUENT® simulation approach was used to evaluate the energy performance of each PCM system in the space. FLUENT® simulated the indoor air-flow and PCM, whilst TRNSYS® simulated the HVAC system. Two novel PCM models were developed in FLUENT® as part of this study. The first model improved the phase change conduction model by accounting for hysteresis and non-linear enthalpy-temperature relationships, and was developed using data from Differential Scanning Calorimetry tests. This model was validated with data obtained in a custom-built test cell with different ambient and internal conditions. The second model analysed the impact of radiation on the phase change behaviour. It was developed using data from spectrophotometry tests, and was validated with data from a custom-built PCM-glazed unit. These developed phase change models were found to improve the prediction errors with respect to conventional models, and together with the enthalpy-porosity model, they were used to simulate the performance of the PCM systems in the airport terminal for different operating conditions. This study generally portrayed the benefits and flexibility of using the coupled simulation approach in evaluating the building performance with PCMs, and showed that employing PCMs in large, open and thermally lightweight spaces can be beneficial, depending on the configuration and mode of operation of the PCM system. The simulation results showed that the relative energy performance of the PCM systems relies mainly on the type and control of the system, the night recharge strategy, the latent heat capacity of the system, and the internal heat gain schedules. Semi-active systems provide more control flexibility and better energy performance than passive systems, and for the case of the airport terminal, the annual energy demands can be reduced when night ventilation of the PCM systems is not employed. The semi-active PCM-HX-8mm configuration without night ventilation, produced the highest annual energy and CO2 emissions savings of 38% and 23%, respectively, relative to a displacement conditioning (DC) system without PCM systems.
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Nguyen, Van-Tri. "Thermal and thermo-mechanical behavior of energy piles". Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1160/document.
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Le comportement thermique et thermo-mécanique des pieux énergétiques est étudié par plusieurs approches : mesures au laboratoire sur des éprouvettes de sol, modélisation physique en modèle réduit, expérimentations sur pieu en vraie grandeur, et calculs numériques/analytiques. D’abord, la conductivité thermique d’un loess à l’état non saturé est mesurée en fonction de la teneur en eau et de la succion. Les résultats montrent une relation univoque entre la conductivité thermique et la teneur en eau pendant un cycle d’humidification/séchage alors qu’une boucle d’hystérésis est observée pour la relation entre la conductivité thermique et la succion. Deuxièmement, des essais thermiques sont réalisés sur un pieu énergétique expérimental en vraie grandeur pour étudier le transfert thermique à l’échelle réelle. Troisièmement, une solution analytique est proposée pour simuler la conduction thermique d’un pieu énergétique vers le sol environnant pendant un chauffage. Les tâches mentionnées ci-dessus concernant le comportant thermique sont ensuite complétées par des études sur le comportement thermo-mécanique des pieux énergétiques. D’un côté, des expérimentations sont réalisées sur un modèle réduit de pieu installé dans un sable sec ou dans une argile saturée. Trente cycles thermiques, représentant trente cycles annuels, sont appliqués au pieu sous différentes charges axiales en tête. Les résultats montrent un tassement irréversible avec les cycles thermiques ; ce tassement est plus important sous une charge axiale plus grande. De plus, le tassement est plus marqué pendant les premiers cycles thermiques et devient négligeable pour les cycles suivants. De l’autre côté, les travaux expérimentaux sur le modèle réduit de pieu sont complétés par les calculs numériques utilisant la méthode des éléments finis. Cette approche est d’abord validée avec les résultats obtenus sur le pieu modèle avant d’être utilisée pour prédire les résultats des expérimentations en vraie grandeurThe thermal and thermo-mechanical behavior of energy piles is investigated by various approaches: laboratory measurement on small soil samples, physical modeling on small-scale pile, experiments on real-scale pile, and analytical/numerical calculations. First, the thermal conductivity of unsaturated loess is measured simultaneously with moisture content and suction. The results show a unique relationship between thermal conductivity and moisture content during a wetting/drying cycle while a clear hysteresis loop can be observed on the relationship between thermal conductivity and suction. Second, thermal tests are performed on a full-scale experimental energy pile to observe heat transfer at the real scale. Third, an analytical solution is proposed to simulate conductive heat transfer from an energy pile to the surrounding soil during heating. The above-mentioned tasks related to the thermal behavior are then completed by studies on the thermo-mechanical behavior of energy piles. On one hand, experiments are performed on a small-scale pile installed either in dry sand or in saturated clay. Thirty thermal cycles, representing thirty annual cycles, are applied to the pile under various constant pile head loads. The results show irreversible pile head settlement with thermal cycles; the settlement is higher at higher pile head load. In addition, the irreversible thermal settlement is the most significant during the first cycles; it becomes negligible at high number of cycles. On the other hand, the experimental work with small-scale pile is completed with numerical calculations by using the finite element method. This approach is first validated with the results on small-scale pile prior to be used to predict the results of full-scale experiments
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Zhang, Hua. "Saline, thermal and thermal-saline buoyant jets". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21325.pdf.
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Shi, Jun. "On thermal mismatch and thermal gradients and the failure of thermal barrier coatings". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 2.35 Mb., 123 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3221078.
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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.
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Dyer, Kristy Kathleen. "Thermal and Non-Thermal Emission in Supernova Remnants". NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010806-162918.
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Supernova remnants present an excellent opportunity to study the shockacceleration of relativistic particles. X-ray synchrotron emission fromrelativistic electrons should contain important information, butextracting it requires advances in models and observations. I present thefirst test of sophisticated synchrotron models against high resolutionobservations on SN 1006, the first and best example of synchrotron X-rayemission, which has been well observed at radio, X-ray and gamma-raywavelengths. Synchrotron emission can be limited at the highest energies by finite age,radiative losses or electron escape. Earlier calculations suggested thatSN 1006 was escape limited. I adapted an escape-limited synchrotron modelfor XSPEC, and demonstrated that it can account for the dominantlynonthermal integrated spectrum of SN 1006 observed by ASCA-GIS and RXTEwhile constraining the values of the maximum electron energy and otherparameters. Combined with TeV observations, the fits give a mean postshockmagnetic field strength of 9 microgauss and 0.7% of the supernova energyin relativistic electrons. Simultaneous thermal fits gave abundances farabove solar, as might be expected for ejecta but had not previously beenobserved. I created subsets of the escape-limited model to fit spatially resolvedASCA SIS observations. I found only small differences between thenortheast and southwest limbs. A limit of less than 9% was placed on theamount of nonthermal flux elsewhere in the remnant. Important findingsinclude the possibility that rolloff frequency may change across theremnant face, and ruling out cylindrical symmetry for SN 1006 along aNW/SE axis. These models have implications far beyond SN 1006. The only previousmodel available to describe X-ray synchrotron emission was a powerlaw.These new models are superior to powerlaws both for their robustconstraints and because they shed physical insight on the accelerationmechanism. As new instruments increase our spatial and spectral resolutionI predict many more remnants will be found with varying amounts of X-raysynchrotron emission, hidden along with thermal lines and continuum. Theability to separate thermal and nonthermal emission is essential tounderstanding both nonthermal emission as well as the thermal component.
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Rashidian, Mahla. "Thermal degradation study by continuous thermal stability rig". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemisk prosessteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22913.
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This investigation was done at NTNU and together with Statoil research and development department in Rotvoll, Trondheim to facilitate a new semi dynamic amine thermal degradation rig.This study was an initial attempt to investigate semi dynamic thermal stability rig as an alternative to thermal degradation study. The major purposes are: (1) to study MEA and MDEA thermal degradation by thermal stability rig apparatus which is designed by Statoil. (2) to demonstrate the result differences between the new and conventional experimental method. MEA and MDEA were selected in this study due to have more available literature data in amine based absorption process. The loaded liquid was circulated through the pipe from the cold stream to the hot stream. There is no analytical method was connected to the rig therefore a regular sample was taken every week and sent to SINTEF analytical lab to identify degradation products.Residence time of solution in high temperature zone also was calculated as an important factor in thermal degradation investigation. Different authors have been provided to understand: the background, the experimental set up, the analytical method to describe the degradation products, data interpretation and the mechanism of the degradation.Based on analytical results, it seems that only small portion of MEA and MDEA were degraded. It showed that the elapsed time was not enough to observe degradation in a significant amount. Metal qualification tests showed low metal concentration in solutions and generally very little corrosiveness effect. However, few degradation products were reported in this study the most probably degradation mechanism is estimated similar to suggested degradation pathway by Davis (2009). More works are required in future to better interpret the new thermal stability rig.
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Šumić, Mersiha. "Thermal Performance of a Solarus CPC-Thermal Collector". Thesis, Högskolan Dalarna, Energi och miljöteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:du-14526.
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The aim of this master thesis is an investigation of the thermal performance of a thermal compound parabolic concentrating (CPC) collector from Solarus. The collector consists of two troughs with absorbers which are coated with different types of paint with unknown properties. The lower and upper trough of the collector have been tested individually. In order to accomplish the performance of the two collectors, a thorough literature study in the fields of CPC technology, various test methods, test standards for solar thermal collectors as well as the latest articles relating on the subject were carried out. In addition, the set‐up of the thermal test rig was part of the thesis as well. The thermal performance was tested according to the steady state test method as described in the European standard 12975‐2. Furthermore, the thermal performance of a conventional flat plate collector was carried out for verification of the test method. The CPC‐Thermal collector from Solarus was tested in 2013 and the results showed four times higher values of the heat loss coefficient UL (8.4 W/m²K) than what has been reported for a commercial collector from Solarus. This value was assumed to be too large and it was assumed that the large value was a result of the test method used that time. Therefore, another aim was the comparison of the results achieved in this work with the results from the tests performed in 2013. The results of the thermal performance showed that the optical efficiency of the lower trough of the CPC‐T collector is 77±5% and the corresponding heat loss coefficient UL 4.84±0.20 W/m²K. The upper trough achieved an optical efficiency of 75±6 % and a heat loss coefficient UL of 6.45±0.27 W/m²K. The results of the heat loss coefficients are valid for temperature intervals between 20°C and 80°C. The different absorber paintings have a significant impact on the results, the lower trough performs overall better. The results achieved in this thesis show lower heat loss coefficients UL and higher optical efficiencies compared to the results from 2013.
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Humpheson, Lee. "Thermal inactivation kinetics and thermal physiology of Salmonella". Thesis, University of Surrey, 1997. http://epubs.surrey.ac.uk/844197/.
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Microbial thermal inactivation survivor curves (log10 numbers plotted against time) have long been described as maintaining a strictly linear rate of decline. However, much evidence exists which suggests deviation from log-linear kinetics does occur, and that this is not purely the result of experimental procedure as contended by some authors. Here, the shape of inactivation kinetics in Salmonella enteritidis was investigated. A heat challenge method was developed which, as far as could be ascertained, was free from methodological artefacts influencing the shape of survivor curves. High initial cell densities allied to sensitive enumeration resulted in biphasic survivor curves at 60°C. Tailing survivors accounted for approximately 1 in 105 of the initial population and possessed roughly four times the heat resistance. At temperatures 50 to 65°C, the presence of tailing prevented the use of D-values to accurately describe death rates. However, describing survivor curves using a log-logistic model increased data-fit at all temperatures investigated. The biphasic nature of survivor curves was studied closely between 49 and 60°C. It was observed that the extent of tailing was temperature-dependent; as temperature decreased, linearity increased such that at 51°C, survivor curves had no tailing. Studies using S. typhimurium and S. senftenberg 775W revealed similar kinetics. In these salmonellas, survivor curves demonstrated linearity at 54 and 57°C, respectively. The influences of culture age and growth rate on the shape of 60°C-inactivation curves were also investigated. Batch-cultured S. enteritidis cells of various maturities gave rise to survivor curves of differing heat sensitivities. Exponentially growing cells were shown to be the most heat sensitive, while late-stationary phase cells were the only populations to result in non-tailed survivor curves. Carbon-limited continuously cultivated cells demonstrated similar biphasic inactivation kinetics. Predictably, the slowest dilution rate corresponded to the greatest heat resistance. Starved cells produced linear inactivation kinetics that were virtually identical to those of late-stationary phase batch-cultured cells. That tailing in batch cultures was similar to chemostat populations, indicated that possible differences in growth rates in batch-cultured cells could not account for tailing. Furthermore, growth was necessary for tailing to be observed. Investigations into the cause of tailing revealed that these cells were not genetically distinct from the majority population. Instead, it is believed that tailing cells arise following the expression of heat-shock proteins during heating. Partial inhibition of de novo protein synthesis during heating resulted in much reduced levels of tailing. It is proposed that the temperature of inactivation determines the proportion of cells capable of expressing a heat-shock response, such that the temperature at which linearity is achieved corresponds to the point at which all cells are fully heat-shock protected.
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De, Indrayush. "Thermal characterization of nanostructures using scanning thermal microscopy". Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0563/document.
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La caractérisation thermique est cruciale pour la conception et le développement d'applications critiques dans divers domaines. Elle trouve son utilisation dans la détection de défauts et de points chauds dans la fabrication de semi-conducteurs, l'imagerie sous-sol ainsi que la recherche de transport thermique et de charge à des longueurs inférieures à 100 nm. La capacité de comprendre et de contrôler les propriétés thermiques des nanostructures à un niveau de sous-micron est essentielle pour obtenir les performances souhaitées. Pour atteindre cet objectif, la microscopie thermique à balayage (SThM) est très bien adaptée pour cartographier la conductivité thermique à la surface des matériaux et des appareils à l'échelle nanométrique.SThM est une technique d'imagerie "champ proche". C'est une méthode de contact, la sondeétant en contact avec la surface à une force contrôlée. STHM utilise une structure cantilever identique à celle des sondes utilisées dans un Microscope à Force Atomique (AFM). La principale différence est le fait qu'un capteur thermique est intégré à la pointe de la sonde. En outre, ce capteur peut également être utilisé comme chauffage dans le cas d'éléments thermorésistants tels que Pt ou Pd. Par conséquent, le SThM est le résultat d'un AFM équipé d'une sonde thermique. Cet instrument fournit une résolution sous-micromètre dans la résolution spatiale, c'est-à-dire plus que la résolution des techniques optiques dans la gamme de longueurs d'onde visible. La résolution classique qui est réalisée de nos jours est de l'ordre de moins de 100nanomètres alors que celle obtenue avec la première sonde Wollaston était environ 10 fois plus élevée.Par conséquent, mesurer la température et les propriétés thermiques de la matière à la microscales ont deux objectifs difficiles qui ont monopolisé l'énergie et le temps de nombreux chercheurs partout dans le monde depuis plusieurs décennies. Ces deux objectifs ne sont pas similaires. Tout d'abord, la mesure d'une température dans un domaine dont la dimension caractéristique est inférieure au micromètre semble moins difficile que mesurer la conductivité thermique d'un matériau à cette échelle. [...]The objective of this thesis is to master quantitative aspects when using nearfield thermal microscopy by using the scanning thermal microscopy technique (SThM). We start by taking an in-depth look into the work performed previously by other scientist and research organizations. From there, we understand the progress the SThM probes have made through the decades, understand the probe sensitivity to the range of conductivity of the materials under investigation, verify the resistances encountered when the probe comes in contact with the sampl and the applications of SThM.Then we look into the equipment necessary for performing tests to characterize material thermal properties. The SThM we use is based on atomic force microscope (AFM) with a thermal probe attached at the end. The AFM is described in this work along with the probes we have utilized.For the purpose of our work, we are only using thermoresistive probes that play the role of the heater and the thermometer. These probes allow us to obtain sample temperature and thermalconductivity. We use two different types of thermal probes – 2-point probe and 4-point probe with SiO2 or with Si3N4 cantilever. Both the probes are very similar when it comes to functioning with the major difference being that the 4-point probe doesn’t have current limiters. Then, we present the use of recent heat-resistive probes allowing to reach a spatial resolution of the orde rof 100 nm under atmosphere and of 30 nm under vacuum. These probes can be used in passive mode for measuring the temperature at the surface of a material or component and in activemode for the determination of the thermal properties of these systems. Using thermoresistive probes means that no specialized devices are necessary for operation. Using simple commercialsolutions like simple AC or DC current and Wheatstone bridge are sufficient to provide basic thermal images. In our case we have also utilized other industrial devices and a home madeSThM setup to further improve the quality of measurement and accuracy. All the elements of the experimental setup have been connected using GPIB and that have been remotely controlled from a computer using a code developed under Python language. This code allows to make the frequency dependent measurement as well as the probe calibration. [...]
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Li, Yifan Li. "NANOSCALE THERMAL CHARACTERIZATION BY SCANNING THERMAL MICROSCOPY (STHM)". University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron159057422807603.
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Dong, Shuhong. "Effects of Thermal Gradient and Cyclic Oxidation on the Delamination and Lifetime of High Temperature Protective Coatings". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38334.
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Thermal barrier coatings have been widely used to provide thermal protection to components in the hot section of gas turbines. This research focuses on two influencing factors on coating behavior: thermal gradient and cyclic oxidation.
The delamination mechanics under thermal gradient is analyzed, taking thermally grown oxide into consideration. Coatings experience thermal gradients at different stages during actual service flight. One is due to engine power shut down when landing and the other due to internal cooling of the substrate. Thermally grown oxide (TGO) also acts as a critical factor in delamination mechanics. The induced stress gradient and corresponding energy release rate for interface delamination and shallower delamination are presented. Mechanism maps that explain the criteria for preventing delamination from developing and propagating are established. Three cooling trajectories are envisaged to analyze the variation in the possibility of delamination.
Multilayer coatings used in components of the hot section of aero turbine engines also experience cyclic temperature variation during flight cycles. As experiment conditions vary and coating performance is improved, the time required to run through the test of coating failure can be both time-consuming and prohibitive. Therefore, protocols providing prediction of quantified coating behavior are in demand to shorten life-time tests. Curves of mass change are obtained from quantifying scale growth and loss by different models such as Cyclic Oxidation Spall Program (COSP). A modification is made by combining COSP and a mechanic based model to obtain critical parameters for lifetime prediction from short time experiment. The time for coatings to reach peak temperature during cycling is discovered to influence prominently on modeling results. Predictions for several coating compositions and cycling conditions are consistent with the data from the existing experiments of the coating system.
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Wiles, Robert Donald. "The thermal and thermo-oxidative degradation of polyethylene terephthalate". Thesis, Manchester Metropolitan University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320298.
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Mao, Guofeng. "Thermal bridges". Doctoral thesis, KTH, Byggnader och installationer, 1997. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2609.
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Zhyzha, M., Алла Миколаївна Дядечко, Алла Николаевна Дядечко i Alla Mykolaivna Diadechko. "Thermal imagers". Thesis, Сумський державний університет, 2013. http://essuir.sumdu.edu.ua/handle/123456789/31088.
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There is no need to remind of the importance of a technical process in our lives. Humanity has already accustomed to the modern devices and equipment and we cannot imagine how we lived without it. The development of technology finds applications in life, medicine, education, industry and business. But one has to remember that each device may have both positive and negative impact on human health.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/31088
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Karayacoubian, Paul. "Effective Thermal Conductivity of Composite Fluidic Thermal Interface Materials". Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2881.
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Thermally enhanced greases made of dispersions of small conductive particles suspended in fluidic polymers can offer significant advantages when used as a thermal interface material (TIM) in microelectronics cooling applications. A fundamental problem which remains to be addressed is how to predict the effective thermal conductivity of these materials, an important parameter in establishing the bulk resistance to heat flow through the TIM. The following study presents the application of two simple theorems for establishing bounds on the effective thermal conductivity of such inhomogeneous media. These theorems are applied to the development of models which are the geometric means of the upper and lower bounds for effective thermal conductivity of base fluids into which are suspended particles of various geometries.
Numerical work indicates that the models show generally good agreement for the various geometric dispersions, in particular for particles with low to moderate aspect ratios. The numerical results approach the lower bound as the conductivity ratio is increased. An important observation is that orienting the particles in the direction of heat flow leads to substantial enhancment in the thermal conductivity of the base fluid. Clustering leads to a small enhancement in effective thermal conductivity beyond that which is predicted for systems composed of regular arrays of particles. Although significant enhancement is possible if the clusters are large, in reality, clustering to the extent that solid agglomerates span large distances is unlikely since such clusters would settle out of the fluid.
In addition, experimental work available in the literature indicates that the agreement between the selected experimental data and the geometric mean of the upper and lower bounds for a sphere in a unit cell are in excellent agreement, even for particles which are irregular in shape.
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Yam, Chi-wai, i 任志偉. "Effect of internal thermal mass on building thermal performance". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B27770631.
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Carmody, Rachel Naomi. "Energetic Consequences of Thermal and Non-Thermal Food Processing". Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10608.
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All human societies process their food extensively by thermal and non-thermal means. This feature distinguishes us from other species, and may even be compulsory given that humans are biologically committed to an energy-rich diet that is easy to chew and digest. Yet the energetic consequences of food processing remain largely unknown. This dissertation tests the fundamental hypothesis that thermal and non-thermal processing lead to biologically relevant increases in energy gain from protein-rich meat and starch-rich tubers, two major caloric resources for modern and ancestral humans that present divergent structural and macronutrient profiles. The energetic consequences of food processing are evaluated using three indices of energy gain, each of which account for costs not currently captured by conventional biochemical assessments of dietary energy value. Chapter 2 investigates the effects of cooking and pounding on net energy gain as indexed by changes in body mass, controlling for differences in food intake and activity level. Chapter 3 examines the effect of cooking and pounding on diet-induced thermogenesis, the metabolic cost of food digestion. Chapter 4 considers the effort required to engage in food processing, arguing that the advantageous ratio of benefit to cost has likely had important effects on human life history. By each of these definitions of energy gain, food processing is shown to have substantial energetic significance. Overall, energetic gains due to thermal processing exceeded those of non-thermal processing, consistent with recent proposals that the adoption of cooking had a particularly important influence on human biology. Gains due to food processing were observed in both meat and tuber substrates, supporting a transformative role for habitual food processing in the evolution and maintenance of the human energy budget.Human Evolutionary Biology
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Huang, 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.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, May, 2020Cataloged 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
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BARBARINO, GIULIANA. "Thermal properties of graphene and graphene-based thermal diodes". Doctoral thesis, Università degli Studi di Cagliari, 2016. http://hdl.handle.net/11584/266670.
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In the perspective of manipulating and controlling heat fluxes, graphene
represents a promising material revealing an unusually high thermal
conductivity �. However, both experimental and theoretical previous
works lack of a strict thermal conductivity value, estimating results
in the range 89-5000 W m-1 K-1. In this scenario, I address graphene
thermal transport properties by means of molecular dynamics simulations
using the novel "approach to equilibrium molecular dynamics"
(AEMD) technique.
The first issue is to offer some insight on the active debate about
graphene thermal conductivity extrapolation for infinite sample. To
this aim, I perform unbiased (i.e. with no a priori guess) direct atomistic
simulations aimed at estimating thermal conductivity in samples
with increasing size up to the unprecedented value of 0.1 mm. The
results provide evidence that thermal conductivity in graphene is definitely
upper limited, in samples long enough to allow a diffusive
transport regime for both single and collective phonon excitations.
Another important issue is to characterize at atomistic level the experimental
techniques used to estimate graphene thermal conductivity.
Some of these use laser source to provide heat. For these reasons,
I deal with the characterization of the transient response to a
pulsed laser focused on a circular graphene sample. In order to reproduce
the laser effect on the sample, the K - A01
and
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Otiaba, Kenny C. "Thermal and thermo-mechanical performance of voided lead-free solder thermal interface materials for chip-scale packaged power device". Thesis, University of Greenwich, 2013. http://gala.gre.ac.uk/11391/.
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The need to maximise thermal performance of electronic devices coupled with the continuing trends on miniaturization of electronic packages require innovative package designs for power devices and modules such as Electronic Control Unit (ECU). Chip scale packaging (CSP) technology offer promising solution for packaging power electronics. This is as a result of the technology’s relatively improved thermal performance and inherent size advantage. In CSP technology, heat removal from the device could be enhanced through the backside of the chip. Heat dissipating units such as heat spreader and/or heat sink can be attached to the backside (reverse side) of the heat generating silicon die (via TIM) in an effort to improve the surface area available for heat dissipation. TIMs are used to mechanically couple the heat generating chip to a heat sinking device and more crucially to enhance thermal transfer across the interface. Extensive review shows that solder thermal interface materials (STIMs) apparently offer better thermal performance than comparable state-of-the-art commercial polymer-based TIMs and thus a preferable choice in packaging power devices. Nonetheless, voiding remains a major reliability concern of STIMs. This is coupled with the fact that solder joints are generally prone to fatigue failures under thermal cyclic loading. Unfortunately, the occurrence of solder voids is almost unavoidable during manufacturing process and is even predominant in lead (Pb)-free solder joints. The impacts of these voids on the thermal and mechanical performance of solder joints are not clearly understood and scarcely available in literature especially with regards to STIMs (large area solder joints). Hence, this work aims to investigate STIM and the influence of voids on the thermo-mechanical and thermal performance of STIM. As previous results suggest that factors such as the location, configuration (spatial arrangement) and size of voids play vital roles on the exact effect of voids, extensive three dimensional (3D) finite element modelling is employed to elucidate the precise effect of these void features on a Pb-free STIM selected after thermo-mechanical fatigue test of standard Pb-free solder alloys. Finite element analysis (FEA) results show that solder voids configuration, size and location are all vital parameters in evaluating the mechanical and thermal impacts of voids. Depending on the location, configuration and size of voids; solder voids can either influence the initiation or propagation of damage in the STIM layer or the location of hot spot on the heat generating chip. Experimental techniques are further employed to compare and correlate levels of voiding and shear strength for representative Pb-free solders. Experimental results also suggest that void size, location and configuration may have an influence on the mechanical durability of solder joints. The findings of this research work would be of interest to electronic packaging engineers especially in the automotive sector and have been disseminated through publications in peer reviewed journals and presentations in international conferences.
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Taherian, Ali Reza. "Thermal softening kinetics and textural quality of thermally processed vegetables". Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23301.
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Dry Romano beans (Phaseolus vulgaris) were soaked and cooked at temperatures ranging from 70 to 100$ sp circ$C for different time intervals. The rate of texture softening associated with each temperature was found to be consistent with two simultaneous pseudo first-order kinetic mechanisms 1 and 2. Approximately 40% of the firmness of Romano beans was lost by the rapid softening mechanism 1. The remaining firmness loss was characterized by mechanism 2 which was found to be much slower ($ sim$1/50th of the former). The temperature dependence indicator (z value) of reaction rate constants were 30 and 24 C$ sp circ$, respectively for mechanisms 1 and 2 with associated activation energies of 82 kJ/mole and 103 kJ/mole, respectively.Turnip (Brassica napobbrassica) and beet roots (B. Vulgaris L.) were cooked at temperatures ranging from 70 to 100$ sp circ$C for different time intervals. Three textural properties (firmness, springiness, and stiffness) were found to follow the same trend of apparent first order kinetic theory with two substrates. Temperature dependence of softening (z value) was found to be within 27 and 35 C$ sp circ ,$ with activation energies in the range of 93 and 60 kJ/mole.
Cylindrical turnip, beet root pieces and Romano beans were packed in thin profile plastic containers and cylindrical metal cans and thermally processed in the static and rotational modes. Through heat penetration testing, process times were adjusted to give an equivalent lethality of 10 min for each product. Thin profile packed vegetables, in all cases, were found to have a firmer and stiffer texture. On the other hand, for rotational processing, the result showed no significant improvement in textural properties (firmness, springiness and stiffness) over the still counterparts. It was found that previously determined kinetic data could be used to estimate texture retention.
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Mejuto, Carlos. "Improved lumped parameter thermal modelling of synchronous generators". Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4612.
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Within the existing available mix of numerical and analytical thermal analysis options, lumped parameter thermal modelling is selected as the operational backbone to develop an improved novel synchronous generator thermal modelling package. The objective is for the creation of a user friendly quick feedback tool, which can serve as a means to make quick machine design thermal calculations and answer customer queries quickly and reliably. Furthermore, thermally improved generator designs will allow for inevitable operational losses to be channelled away from the machine more efficiently. As a result, machine component temperatures will be reduced, allowing lower generator thermal ratings. The end result will be smaller, longer lasting, more efficient generators, with the ability to be adapted with greater ease to particular applications. With the contribution of selected numerical analysis techniques, mainly finite element analysis for the distribution of iron losses, the MySolver thermal modelling package is developed and presented in this thesis. It is this combination of numerical and analytical tools that improves synchronous generator thermal modelling accuracy, but ultimately it is the lumped parameter nature of the thermal models developed that makes MySolver succeed as a reliable quick feedback electrical machine thermal design tool, validated using experimental results for a wide range of operating conditions. The initial part of the thesis analyses the electrical machine thermal modelling techniques available today, indicating advantages and disadvantages associated with each one, and providing a rationale for the selection of lumped parameter modelling to be used by MySolver. The development of the synchronous generator lumped parameter thermal models is detailed, with examples on its construction presented. Subsequently, finite element analysis is utilised to predict the distribution of machine iron losses across the rotor and stator laminations, with the findings applied to MySolver. Furthermore, a study is performed into the lumped parameter discretisation level needed to effectively represent machine windings. MySolver is experimentally verified using experimental data from a fully instrumented synchronous generator and this data is also used to obtain further insight into the temperature distribution within the generator. In the final part results are evaluated and the use of MySolver for modelling and optimising electrical machines is discussed. Finally, appropriate conclusions on the work presented are drawn.
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Mustapha, Lateef Abimbola, i Lateef Abimbola Mustapha. "Thermo-Mechanical Characterization and Interfacial Thermal Resistance Studies of Chemically Modified Carbon Nanotube Thermal Interface Material - Experimental and Mechanistic Approaches". Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625379.
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Effective application of thermal interface materials (TIM) sandwiched between silicon and a heat spreader in a microelectronic package for improved heat dissipation is studied through thermal and mechanical characterization of high thermally conductive carbon nanotubes (CNTs) integrated into eutectic gallium indium liquid metal (LM) wetting matrix. Thermal conductivity data from Infrared microscopy tool reveals the dependence of experimental factors such as matrix types, TIM contacting interfaces, orientation of CNTs and wetting of CNTs in the matrix on the thermal behavior of TIM composite.
Observed generalized trend on LM-CNT TIM shows progressive decrease in effective thermal conductivity with increasing CNT volume fractions. Further thermal characterizations LM-CNT TIM however show over 2x increase in effective thermal conductivity over conventional polymer TIMs (i.e. TIM from silicone oil matrix) but fails to meet 10x improvement expected.
Poor wetting of CNT with LM matrix is hypothesized to hinder thermal improvement of LM-CNT TIM composite. Thus, wetting enhancement technique through electro-wetting and liquid crystal (LC) based matrix proposed to enhance CNT-CNT contact in LM-CNT TIM results in thermal conductivity improvement of 40 to 50% with introduction of voltage gradient of 2 to 24 volts on LM-CNT TIM sample with 0.1 to 1 percent CNT volume fractions over non voltage LM-CNT TIM test samples.
Key findings through this study show that voltage tests on LC- CNT TIM can cause increased CNT-CNT networks resulting in 5x increase in thermal conductivity over non voltage LC-CNT TIM and over 2x improvement over silicone-CNT TIMs. Validation of LM wetting of CNT hypothesis further shows that wetting and interface adhesion mechanisms are not the only factors required to improve thermal performance of LM-CNT TIM. Anisotropic characteristic of thermal conductivity of randomly dispersed CNTs is a major factor causing lower thermal performance of LM-CNTs TIM composite. Other factors resulting in LM-CNT TIM decreasing thermal conductivity with increasing CNT loading are (i) Lack of CNT-CNT network due to large difference in surface tension and mass density between CNTs and LM in TIM composite (ii) Structural stability of MWCNT and small MFP of phonons in ~5um MWCNTs compared to the system resulted in phonon scattering with reduced heat flow (iii) CNT percolation threshold limit not reached owing to thermal shielding due to CNT tube interfacial thermal resistance.
While mixture analytical models employed are able to predict thermal behaviors consistent with CNT-CNT network and CNT- polymer matrix contact phenomenon, these models are not equipped to predict thermo-chemical attributes of CNTs in LM-CNT TIM. Extent of LM-CNT wetting and LM-solid surface interfacial contact impacts on interfacial thermal resistance are investigated through LM contact angle, XPS/AES and SEM-EDX analyses on Au/Ni and Ni coated copper surfaces. Contact angle measurements in the range of 120o at both 55oC and 125oC show non wetting of LM on CNT, Au and Ni surfaces. Interface reactive wetting elemental composition of 21 days aged LM on Au/Ni and Ni surfaces reveals Ga dissolution in Au and Ni diffusion of ~0.32um in Au which are not present for similar analysis of 1 day LM on Au/Ni surface. Formation of Au-Ni-Ga IMC and IMC-oxide iono-covalency occurrence at the interface causes reduction in surface tension and reduction in interfacial contact resistance.
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Rafiei, A. "Understanding the thermo-mechanical behaviour of thermal piles in sand". Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1544011/.
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Thermal piles are piled foundations that can be used both to extract heat at shallow depth from the ground and to transfer load from the structure to the ground. Despite an increased number of applications of thermal piles in recent years, knowledge of the thermo-mechanical behaviour of thermal piles is still limited. The literature reveals that additional thermal loading results in considerable induced axial load and stress along the pile, that can lead to a reduction in safety factor down to 1. Also, there are inconsistencies in the literature regarding the thermo-elastic/plastic, reversible/irreversible response of thermal piles and also on the effects of cyclic thermal loading on the side shear friction at the soil–pile interface. Moreover, the framework proposed in the Thermal Pile Standard (Ground Source Heat Pump Association, 2012) has not been tested for various soils conditions. In this study, the effect of thermo-mechanical loading on the mechanical performance of thermal piles and the soil–pile interface is investigated. A 1g laboratory model was developed using a stainless steel model pile embedded in medium-dense, dry sand. Strain and temperature along the pile were monitored using multiplexed fibre Bragg grating sensors. A 2D finite difference heat transfer model was developed in Matlab, predicting the temperature profiles within the soil. Findings from the numerical model were used to design the location of the temperature sensors in the soil. Laboratory tests were divided into five scenarios, involving both shaft resisting and shaft and base resisting piles. It was found that under thermo-mechanical loading, up to 68.4% of the maximum induced load was transferred to the pile toe for the shaft resisting pile, compared to virtually none under mechanical loading. It was further found that the level of restraint caused by medium-dense sand with a relative density of 57% was rather limited in the absence of surcharge load and the degree of freedom varied between 0.97 and 1.0. Moreover, it was found that the location of the null point shifts during each heating/cooling period. For a shaft and base resisting pile heated up to 50°C, the maximum induced thermal load was found to be 90% of the ultimate capacity of the pile. The maximum induced stress remained below the BS 8004:1986 (British Standards Institution, 1986) recommendations. Irreversible settlements were observed for both types of pile. The load threshold, where the limit to thermo-elastic behaviour was observed, was found to be up to 18% of the ultimate pile capacity, while this value was up to 31% in the case of shaft and base resisting pile. Despite an increase in the side friction during heating periods (up to 32% compared to the friction under ultimate state mechanical loading), the subsequent cooling periods seemed to reduce the friction level, and cyclic skin friction degradation and accumulation of pile settlement were observed in the heating and cooling cycles. The results also show deviations from the proposed framework for a model pile in sand mainly due to a variable friction angle at the soil–pile interface.
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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.
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Green, Craig Elkton. "Composite thermal capacitors for transient thermal management of multicore microprocessors". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44772.
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While 3D stacked multi-processor technology offers the potential for significant computing advantages, these architectures also face the significant challenge of small, localized hotspots with very large heat fluxes due to the placement of asymmetric cores, heterogeneous devices and performance driven layouts. In this thesis, a new thermal management solution is introduced that seeks to maximize the performance of microprocessors with dynamically managed power profiles. To mitigate the non-uniformities in chip temperature profiles resulting from the dynamic power maps, solid-liquid phase change materials (PCMs) with an embedded heat spreader network are strategically positioned near localized hotspots, resulting in a large increase in the local thermal capacitance in these problematic areas.
Theoretical analysis shows that the increase in local thermal capacitance results in an almost twenty-fold increase in the time that a thermally constrained core can operate before a power gating or core migration event is required. Coupled to the PCMs are solid state coolers (SSCs) that serve as a means for fast regeneration of the PCMs during the cool down periods associated with throttling events. Using this combined PCM/SSC approach allows for devices that operate with the desirable combination of low throttling frequency and large overall core duty cycles, thus maximizing computational throughput. The impact of the thermophysical properties of the PCM on the device operating characteristics has been investigated from first principles in order to better inform the PCM selection or design process.
Complementary to the theoretical characterization of the proposed thermal solution, a prototype device called a "Composite Thermal Capacitor (CTC)" that monolithically integrates micro heaters, PCMs and a spreader matrix into a Si test chip was fabricated and tested to validate the efficacy of the concept. A prototype CTC was shown to increase allowable device operating times by over 7X and address heat fluxes of up to ~395 W/cm2. Various methods for regenerating the CTC have been investigated, including air, liquid, and solid state cooling, and operational duty cycles of over 60% have been demonstrated.
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Tang, Xiaoli Dong Jianjun. "Theoretical study of thermal properties and thermal conductivities of crystals". Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Physics/Dissertation/Tang_Xiaoli_9.pdf.
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Nasrollahi, Nazanin. "Thermal environments and occupant thermal comfort in Iranian office buildings". Thesis, Cardiff University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445202.
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Broadbent, Alison. "The thermal and non-thermal radio emission from the galaxy". Thesis, Durham University, 1989. http://etheses.dur.ac.uk/6548/.
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It is shown that a detailed correlation exists between IRAS 60 µm band emission from the galactic disc and radio continuum emission measured at a similar angular resolution at 11 and 6 cm. The emission at these short radio wavelengths is predominantly from thermal bremsstrahlung in regions of ionized gas and so the strong correlation, which holds for the diffuse, extended emission as well as the discrete, compact sources, indicates that an important contribution to the 60 µm emission is associated with HII regions. Isolation of this component of the 60 µm infrared emission has involved the estimation of the zodiacal light contamination and detailed modelling of the HI-associated dust emission. The residual 60 µm emission can then be used as a tracer of radio thermal emission. On the small scale this enabled a search for new supernova remnant candidates in the 11 cm survey of Reich et al. and the 6 cm survey of Haynes et al. close to the inner Galactic Plane. On the large scale we have separated the thermal and non-thermal emission of the 408 MHz all-sky survey of Haslam et al. from the whole of the Galactic Plane and within ~ 8º of the plane. From the thermal galactic emission we have been able to estimate the average infrared excess, the total 60 µm luminosity and total mass of HII in the Galaxy. The clearer picture obtained of the non-thermal emission of the Galaxy has allowed us to improve upon previous attempts at modelling the synchrotron emission in terms of the cosmic ray electron distribution and magnetic field variation modulated by the galactic spiral structure.
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Alammar, Ahmed Ali Ghulfus. "Enhancing thermal performance of heat pipe based solar thermal collector". Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8207/.
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In this work, a CFD model was developed to simulate the flow and phase-change process inside the Two-Phase Closed Thermosyphon (TPCT). This was carried out to investigate the effect of fill ratio and inclination angle on the thermal performance of the TPCT, and to visualise the phase change characteristics under the influence of the inclination and different fill ratios. Also, the surface wettability in terms of the contact angle was investigated to report their effect on the thermal characteristics of the TPCT and to visualise the phase-change characteristics inside the TPCT for different contact angles using Fluent Ansys. Furthermore, the effect of different parameters on the geyser boiling in the TPCT was investigated experimentally. Consequently, the influence of geyser effect on the TPCT thermal characteristics was examined under the effect of various liquid charges and inclination angles at a broad range of heat inputs. Finally, advanced manufacturing technique using wire Electrical Discharge Machining (EDM) was employed to introduce a surface roughness in the TPCT internal wall, thereby enhancing the thermal performance of the TPCT. This was achieved by comparing its thermal performance with a plain TPCT at two different initial sub-atmospheric pressures (3 and 30 kPa) and different heat loads.
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Samba, Ahmadou. "Battery electrical vehicles analysis of thermal modelling and thermal management". Caen, 2015. http://www.theses.fr/2015CAEN2003.
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L’avancée de la recherche sur les batteries a conduit à une utilisation massive des batteries Lithium-ion de grande capacité dans les véhicules électriques. De tels designs, en grand format, ont l'avantage de réduire le nombre de cellules interconnectées dans les packs de batteries. Dans les applications de transport, le temps de recharge des batteries constitue un frein au développement des véhicules électriques. L'augmentation du courant de charge peut soumettre à la batterie à des situations très critiques et peut ainsi entrainer une augmentation considérable de sa température. En long terme, ces phénomènes peuvent conduire à la réduction de sa durée de vie ainsi que ses performances et dans certains cas à l’emballement thermique. Afin d’éviter de telles situations, il est nécessaire d’optimiser la gestion thermique de manière à maintenir la batterie dans une gamme de températures de fonctionnement sûre. Ceci passe par la mise en place d’un modèle thermique capable de prédire la température d’une cellule et d’un pack de batterie à différentes conditions de fonctionnement et ensuite proposer différentes stratégies de refroidissements. Compte tenu de la forme et des dimensions du type de batterie utilisé (batterie « pouch ») un modèle électro-thermique est développé afin de prédire la distribution de température de la cellule, ce modèle nécessite moins de paramètres d'entrée et possède une grande précision. En outre, un nouvel outil d'estimation des paramètres thermiques a été développé. Le comportement thermique de la batterie, soumise à des conditions de fonctionnements extrêmes, a été étudié avec ce modèle. De ces résultats, on remarque que la cellule de batterie présente une distribution thermique non-uniforme lorsque celle-ci est parcourue par des courants de grandes amplitudes. Ce constat nous amène à étudier le design des batteries de type « pouch » afin d’élire celle qui présente une distribution thermique et électrique plus uniformes. Pour se faire un modèle 3D électrochimique-thermique a été développé. Enfin, différentes stratégies de gestion thermique des batteries telles que: le refroidissement actif par liquide et passif utilisant un matériau à changement de phase (liquide-solide à changement de phase) incorporé dans une mousse d'aluminium, ont été étudiées puis comparés en appliquant un cycle de conduite, provenant d’un véhicule tout électrique de la gamme Peugeot. L'objectif principal est de réduire la complexité, le poids, le volume, le coût et également de maintenir à un haut niveau de sureté de fonctionnement du module de batterieAdvanced research on rechargeable Lithium-ion batteries has allowed for large format and high-energy batteries to be largely used in Battery Electric Vehicles (BEVs). For transportation applications, beside limitations of driving range, long charging time is still considered as an important barrier for a wide use of BEVs. The increase of the charging current amplitude may however subject the battery to stressful situations and can significantly increase the temperature of the battery. These phenomena reduce the battery’s lifetime and performances and in worst-case scenario, thermal runaway can occur. To avoid this, there is a need for an optimized thermal management in order to keep the battery in a safe and beneficial range of operating conditions. Firstly, in this PhD dissertation a two-dimensional electrical-thermal model has been developed to predict the cell temperature distribution over the surface of the battery. This model requires less input parameters and still has high accuracy. In addition, a novel estimation tool has been developed for estimation of the thermal model parameters. Furthermore, the thermal behavior of the proposed battery has been investigated at different environmental conditions as well as during the abuse conditions for assessment of thermal stability of the battery. Taking into account the harsh thermal distribution, an advanced three-dimensional electrochemical-thermal model has been developed in order to investigate the impact of the cell design on the thermal, voltage and current distributions in order to avoid high non-homogenous distribution. The developed model allows us to optimize the cell design, in order to achieve the longest lifetime and high performances of battery cell. Finally, different thermal management strategies such as liquid cooling and passive cooling using phase change material embedded in an aluminium-foam (liquid-solid phase change) have been investigated and compared in depth by applying real BEV drive cycles. The main objective of this study is to decrease the complexity, the weight, the volume and the cost and to maintain high safety according to the best strategy
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Xu, Zheng. "Thermal Performance Comparison of Three Integrated Thermal Solar Roof Collectors". Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35859.
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The integrated solar roof collector system can bring the house year-round energy saving benefit. In heating season, part of the space heating and preheating domestic hot water demand can be met by this integrated system. In the cooling season, cooling load reduction and preheating domestic hot water can be achieved by operating this system. The traditional solar thermal system is an add-on system rather than integrated, which increases the cost-benefit ratio. The current system is integrated with the roof structure. Except for the energy collecting benefit, it will reduce the material cost, labor cost and construction period.
The objectives of this research is to estimate the energy performance of three collector configurations including space heating saving, and preheat hot water saving. This study also compares energy performance for the three collectors on two types of evaluated houses in Roanoke, Virginia.Master of Science
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Jensma, Madeline R. "THERMAL MODELING AND TESTING OF THE BLUE THERMAL VACUUM CHAMBER". DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2151.
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The Blue Thermal Vacuum Chamber (TVAC) located in the Space Environments Laboratory at California Polytechnic State University, San Luis Obispo (Cal Poly), may be used for thermal vacuum testing of test articles that fit with in the semi cylindrical test section that has a radius of approximately 18 cm and a length of 61 cm. The potential test articles include CubeSat systems and subsystem. The Blue TVAC can also be used for educational and research purposes. The goal of this thesis project is to develop a thermal model of the Blue TVAC to predict and analyze the thermal response of the chamber. Thermal vacuum testing is conducted to verify the repeatability of a test and validate the thermal model. Thermal vacuum tests were conducted according to the ISO Standard 19683 to measure the temperature at various points in the chamber. This data was used to determine the thermal response of the chamber and the distribution of heat within the chamber. After conducting a total of fifteen thermal vacuum tests, eleven without a test article and four with a test article, a repeatable testing procedure was written to ensure that results from such tests are consistent. A thermal model was developed using Thermal Desktop to predict the temperature distribution within the chamber during the cooling phase, cold soak phase, heating phase, and hot soak phase of a thermal vacuum test. The simulations of the empty thermal vacuum test predict the platen temperature in the Blue TVAC with a thermal uncertainty margin of less than 10℃. The simulations of the thermal vacuum test with a 3U CubeSat mass model predict the platen temperature in the Blue TVAC with a thermal uncertainty margin of less than 30℃. These simulations can predict the mass model temperature with a thermal uncertainty margin of less than 15℃. The thermal model can v be used to analyze how future changes to the Blue TVAC may affect the thermal distribution in the chamber. Finally, recommendations are made to further improve the performance and repeatability of the Blue TVAC as well as the thermal model with specific instruction for implementing changes and verifying potential improvements.
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Shi, Qi. "PREDICTION OF THERMAL DISTORTION AND THERMAL FATIGUE IN SHOT SLEEVES". The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1034967167.
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Vuppala, Archana. "Thermal and thermal stress analyses of the state-changing tooling". abstract and full text PDF (free order & download UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1460787.
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Kuryliw, Erik Adam. "Analyzing the thermal annealing behavior of laser thermal processed silicon". [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0000979.
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Fredi, Giulia. "Multifunctional polymer composites for thermal energy storage and thermal management". Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/265328.
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Thermal energy storage (TES) consists in storing heat for a later use, thereby reducing the gap between energy availability and demand. The most diffused materials for TES are the organic solid-liquid phase change materials (PCMs), such as paraffin waxes, which accumulate and release a high amount of latent heat through a solid-liquid phase change, at a nearly constant temperature. To avoid leakage and loss of material, PCMs are either encapsulated in inert shells or shape-stabilized with porous materials or a nanofiller network. Generally, TES systems are only a supplementary component added to the main structure of a device, but this could unacceptably rise weight and volume of the device itself. In the applications where weight saving and thermal management are both important (e.g. automotive, portable electronics), it would be beneficial to embed the heat storage/management in the structural components.
The aim of this thesis is to develop polymer composites that combine a polymer matrix, a PCM and a reinforcing agent, to reach a good balance of mechanical and TES properties. Since this research topic lacks a systematic investigation in the scientific literature, a wide range of polymer/PCM/reinforcement combinations were studied in this thesis, to highlight the effect of PCM introduction in a broad range of matrix/reinforcement combinations and to identify the best candidates and the key properties and parameters, in order to set guidelines for the design of these materials.
The thesis in divided in eight Chapters. Chapter I and II provide the introduction and the theoretical background, while Chapter III details the experimental techniques applied on the prepared composites. The results and discussion are then described in Chapters IV-VII. Chapter IV presents the results of PCM-containing composites having a thermoplastic matrix. First, polyamide 12 (PA12) was melt-compounded with either a microencapsulated paraffin (MC) or a paraffin powder shape-stabilized with carbon nanotubes (ParCNT), and these mixtures were used as matrices to produce thermoplastic laminates with a glass fiber fabric via hot-pressing. MC was proven more suitable to be combined with PA12 than ParCNT, due to the higher thermal resistance. However, also the MC were considerably damaged by melt compounding and the two hot-pressing steps, which caused paraffin leakage and degradation, as demonstrated by the relative enthalpy lower than 100 %. Additionally, the PCM introduction decreased the mechanical properties of PA12 and the tensile strength of the laminates, but for the laminates containing MC the elastic modulus and the strain at break were not negatively affected by the PCM. Higher TES properties were achieved with the production of a semi-structural composite that combined PA12, MC and discontinuous carbon fibers. For example, the composite with 50 wt% of MC and 20 wt% of milled carbon fibers exhibited a total melting enthalpy of 60.4 J/g and an increase in elastic modulus of 42 % compared to the neat PA. However, the high melt viscosity and shear stresses developed during processing were still responsible for a not negligible PCM degradation, as also evidenced by dynamic rheological tests. Further increases in the mechanical and TES properties were achieved by using a reactive thermoplastic matrix, which could be processed as a thermosetting polymer and required considerably milder processing conditions that did not cause PCM degradation. MC was combined with an acrylic thermoplastic resin and the mixtures were used as matrices to produce laminates with a bidirectional carbon fabric, and for these laminates the melting enthalpy increased with the PCM weight fraction and reached 66.8 J/g. On the other hand, the increased PCM fraction caused a rise in the matrix viscosity and so a decrease in the fiber volume fraction in the final composite, thereby reducing the elastic modulus and flexural strength. Dynamic-mechanical investigation evidenced the PCM melting as a decreasing step in ’; its amplitude showed a linear trend with the melting enthalpy, and it was almost completely recovered during cooling, as evidenced by cyclic DMA tests.
Chapter V presents the results of PCM-containing thermosetting composites. A further comparison between MC and ParCNT was performed in a thermosetting epoxy matrix. First, ParCNT was mixed with epoxy and the mixtures were used as matrices to produce laminates with a bidirectional carbon fiber fabric. ParCNT kept its thermal properties also in the laminates, and the melting enthalpy was 80-90 % of the expected enthalpy. Therefore, ParCNT performed better in thermosetting than in thermoplastic matrices due to the milder processing conditions, but the surrounding matrix still partially hindered the melting-crystallization process. Therefore, epoxy was combined with MC, but the not optimal adhesion between the matrix and the MC shell caused a considerable decrease in mechanical strength, as also demonstrated by the fitting with the Nicolais-Narkis and Pukanszky models, both of which evidenced scarce adhesion and considerable interphase weakness. However, the Halpin-Tsai and Lewis-Nielsen models of the elastic modulus evidenced that at low deformations the interfacial interaction is good, and this also agrees with the data of thermal conductivity, which resulted in excellent agreement with the Pal model calculated considering no gaps at the interface. These epoxy/MC mixtures were then reinforced with either continuous or discontinuous carbon fibers, and their characterization confirmed that the processing conditions of an epoxy composite are mild enough to preserve the integrity of the microcapsules and their TES capability. For continuous fiber composites, the increase in the MC fraction impaired the mechanical properties mostly because of the decrease in the final fiber volume fraction and because the MC phase tends to concentrate in the interlaminar region, thereby lowering the interlaminar shear strength. On the other hand, a small amount of MC enhanced the mode I interlaminar fracture toughness (Gic increases of up to 48 % compared to the neat epoxy/carbon laminate), as the MC introduced other energy dissipation mechanisms such as the debonding, crack deflection, crack pinning and micro-cracking, which added up to the fiber bridging.
Chapter VI introduces a fully biodegradable TES composite with a thermoplastic starch matrix, reinforced with thin wood laminae and containing poly(ethylene glycol) as the PCM. The wood laminae successfully acted as a multifunctional reinforcement as they also stabilized PEG in their inner pores (up to 11 wt% of the whole laminate) and prevent its leakage. Moreover PEG was proven to increase the stiffness and strength of the laminate, thereby making the mechanical and TES properties synergistic and not parasitic.
Finally, Chapter VII focused on PCM microcapsules. The synthesis of micro- and nano-capsules with an organosilica shell via a sol-gel approach clarified that the confinement in small domains and the interaction with the shell wall modified the crystallization behavior of the encapsulated PCM, as also evidenced by NMR and XRD studies and confirmed by DSC results. In the second part of Chapter VII, a coating of polydpamine (PDA) deposited onto the commercial microcapsules MC. The resulting PDA coating was proven effective to enhance the interfacial adhesion with an epoxy matrix, as evidenced by SEM micrographs. XPS demonstrated that the PDA layer was able to react with oxirane groups, thereby evidencing the possibility of forming covalent bond with the epoxy matrix during the curing step.
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Fredi, Giulia. "Multifunctional polymer composites for thermal energy storage and thermal management". Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/265328.
Pełny tekst źródłaStreszczenie:
Thermal energy storage (TES) consists in storing heat for a later use, thereby reducing the gap between energy availability and demand. The most diffused materials for TES are the organic solid-liquid phase change materials (PCMs), such as paraffin waxes, which accumulate and release a high amount of latent heat through a solid-liquid phase change, at a nearly constant temperature. To avoid leakage and loss of material, PCMs are either encapsulated in inert shells or shape-stabilized with porous materials or a nanofiller network. Generally, TES systems are only a supplementary component added to the main structure of a device, but this could unacceptably rise weight and volume of the device itself. In the applications where weight saving and thermal management are both important (e.g. automotive, portable electronics), it would be beneficial to embed the heat storage/management in the structural components.
The aim of this thesis is to develop polymer composites that combine a polymer matrix, a PCM and a reinforcing agent, to reach a good balance of mechanical and TES properties. Since this research topic lacks a systematic investigation in the scientific literature, a wide range of polymer/PCM/reinforcement combinations were studied in this thesis, to highlight the effect of PCM introduction in a broad range of matrix/reinforcement combinations and to identify the best candidates and the key properties and parameters, in order to set guidelines for the design of these materials.
The thesis in divided in eight Chapters. Chapter I and II provide the introduction and the theoretical background, while Chapter III details the experimental techniques applied on the prepared composites. The results and discussion are then described in Chapters IV-VII. Chapter IV presents the results of PCM-containing composites having a thermoplastic matrix. First, polyamide 12 (PA12) was melt-compounded with either a microencapsulated paraffin (MC) or a paraffin powder shape-stabilized with carbon nanotubes (ParCNT), and these mixtures were used as matrices to produce thermoplastic laminates with a glass fiber fabric via hot-pressing. MC was proven more suitable to be combined with PA12 than ParCNT, due to the higher thermal resistance. However, also the MC were considerably damaged by melt compounding and the two hot-pressing steps, which caused paraffin leakage and degradation, as demonstrated by the relative enthalpy lower than 100 %. Additionally, the PCM introduction decreased the mechanical properties of PA12 and the tensile strength of the laminates, but for the laminates containing MC the elastic modulus and the strain at break were not negatively affected by the PCM. Higher TES properties were achieved with the production of a semi-structural composite that combined PA12, MC and discontinuous carbon fibers. For example, the composite with 50 wt% of MC and 20 wt% of milled carbon fibers exhibited a total melting enthalpy of 60.4 J/g and an increase in elastic modulus of 42 % compared to the neat PA. However, the high melt viscosity and shear stresses developed during processing were still responsible for a not negligible PCM degradation, as also evidenced by dynamic rheological tests. Further increases in the mechanical and TES properties were achieved by using a reactive thermoplastic matrix, which could be processed as a thermosetting polymer and required considerably milder processing conditions that did not cause PCM degradation. MC was combined with an acrylic thermoplastic resin and the mixtures were used as matrices to produce laminates with a bidirectional carbon fabric, and for these laminates the melting enthalpy increased with the PCM weight fraction and reached 66.8 J/g. On the other hand, the increased PCM fraction caused a rise in the matrix viscosity and so a decrease in the fiber volume fraction in the final composite, thereby reducing the elastic modulus and flexural strength. Dynamic-mechanical investigation evidenced the PCM melting as a decreasing step in ’; its amplitude showed a linear trend with the melting enthalpy, and it was almost completely recovered during cooling, as evidenced by cyclic DMA tests.
Chapter V presents the results of PCM-containing thermosetting composites. A further comparison between MC and ParCNT was performed in a thermosetting epoxy matrix. First, ParCNT was mixed with epoxy and the mixtures were used as matrices to produce laminates with a bidirectional carbon fiber fabric. ParCNT kept its thermal properties also in the laminates, and the melting enthalpy was 80-90 % of the expected enthalpy. Therefore, ParCNT performed better in thermosetting than in thermoplastic matrices due to the milder processing conditions, but the surrounding matrix still partially hindered the melting-crystallization process. Therefore, epoxy was combined with MC, but the not optimal adhesion between the matrix and the MC shell caused a considerable decrease in mechanical strength, as also demonstrated by the fitting with the Nicolais-Narkis and Pukanszky models, both of which evidenced scarce adhesion and considerable interphase weakness. However, the Halpin-Tsai and Lewis-Nielsen models of the elastic modulus evidenced that at low deformations the interfacial interaction is good, and this also agrees with the data of thermal conductivity, which resulted in excellent agreement with the Pal model calculated considering no gaps at the interface. These epoxy/MC mixtures were then reinforced with either continuous or discontinuous carbon fibers, and their characterization confirmed that the processing conditions of an epoxy composite are mild enough to preserve the integrity of the microcapsules and their TES capability. For continuous fiber composites, the increase in the MC fraction impaired the mechanical properties mostly because of the decrease in the final fiber volume fraction and because the MC phase tends to concentrate in the interlaminar region, thereby lowering the interlaminar shear strength. On the other hand, a small amount of MC enhanced the mode I interlaminar fracture toughness (Gic increases of up to 48 % compared to the neat epoxy/carbon laminate), as the MC introduced other energy dissipation mechanisms such as the debonding, crack deflection, crack pinning and micro-cracking, which added up to the fiber bridging.
Chapter VI introduces a fully biodegradable TES composite with a thermoplastic starch matrix, reinforced with thin wood laminae and containing poly(ethylene glycol) as the PCM. The wood laminae successfully acted as a multifunctional reinforcement as they also stabilized PEG in their inner pores (up to 11 wt% of the whole laminate) and prevent its leakage. Moreover PEG was proven to increase the stiffness and strength of the laminate, thereby making the mechanical and TES properties synergistic and not parasitic.
Finally, Chapter VII focused on PCM microcapsules. The synthesis of micro- and nano-capsules with an organosilica shell via a sol-gel approach clarified that the confinement in small domains and the interaction with the shell wall modified the crystallization behavior of the encapsulated PCM, as also evidenced by NMR and XRD studies and confirmed by DSC results. In the second part of Chapter VII, a coating of polydpamine (PDA) deposited onto the commercial microcapsules MC. The resulting PDA coating was proven effective to enhance the interfacial adhesion with an epoxy matrix, as evidenced by SEM micrographs. XPS demonstrated that the PDA layer was able to react with oxirane groups, thereby evidencing the possibility of forming covalent bond with the epoxy matrix during the curing step.
40
Mavromatidis, Pavlos. "Microwave thermal spraying". Thesis, University of Liverpool, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422101.
Pełny tekst źródła
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Huynh, Kien Khanh. "Human Thermal Comfort". MSSTATE, 2001. http://sun.library.msstate.edu/ETD-db/theses/available/etd-04092001-135104/.
Pełny tekst źródłaStreszczenie:
The purpose of this research is to investigate human comfort criteria under steady-state conditions as a function of ambient air temperature, mean radiant temperature, relative humidity, air velocity, level of activity, and clothing insulation. Since the current ASHRAE Standard 55-1994 is for sedentary activity, this study will consider relative humidity (20% to 65%), dry bulb temperature (73 oF to 82 oF), air velocity (30 fpm and 50 fpm), and sedentary-to-moderate activity. The mean radiant temperature will be taken to be the same as the ambient air temperature. The experimental results collected at the Kansas State University Environmental Test Chamber are compared with the Fanger (1982) thermal comfort model and with ASHRAE Standard 55-1994. The experimental study results agreed well with ASHARE Standard 55-1994 for 1-met activity level (sedentary), and the thermal comfort for 1-met activity level was predicted with reasonable accuracy by Fanger?s (1982) Model. For 2.3 met activity level, the experimental results did not agree with ASHRAE Standard 55-1994 or the Fanger Model predictions.
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Loo, Fook Leong. "Polarimetric thermal imaging". Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion.exe/07Mar%5FLoo.pdf.
Pełny tekst źródłaStreszczenie:
Thesis (M.S. in Electronic Warfare System Engineering)--Naval Postgraduate School, March 2007.Thesis Advisor(s): Alfred W. Cooper. "March 2007." Includes bibliographical references (p. 101-102). Also available in print.
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Tardieu, Giliane. "Thermal conductivity prediction". Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/10014.
Pełny tekst źródła
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Ruffoni, Matthew Paul. "Thermal differential EXAFS". Thesis, University of Warwick, 2006. http://wrap.warwick.ac.uk/59702/.
Pełny tekst źródłaStreszczenie:
Differential EXAFS (DiffEXAFS) is a new and novel technique for the study of small atomic strains. It relies on examining tiny differences in x-ray absorption spectra - taken under high-stability, low-noise conditions - generated by unit modulation of some sample bulk parameter. Initial experiments conducted by Pettifer et al. [64] to measure the magnetostriction of FeCo, revealed a sensitivity to atomic displacements of the order of one femtometre (10−15m). This was two orders of magnitude more sensitive than thought possible, based on conventional EXAFS techniques [16] [2]. The mandate for this thesis was to extend DiffEXAFS to the case of samples undergoing temperature modulation - to develop Thermal Differential EXAFS - and in doing so, demonstrate that DiffEXAFS is a generally applicable technique for studying small atomic strains. Topics covered here include the nature of Thermal DiffEXAFS signals, the design, manufacture, and characterisation of apparatus for Thermal DiffEXAFS experiments, and new analysis techniques developed to extract information from DiffEXAFS data. Thermal expansion coefficients have been determined for Fe and SrF2, for temperature modulation of the order of one Kelvin, proving the viability of the technique. Numerically, these were a Fe = (11.6±0.4)×10−6K−1 and a SrF2 = (19±2)×10−6K−1 respectively, which agreed with published values [52] [74]. In these measurements sensitivity to mean atomic displacements of about 0.3 femtometres was achieved. The more interesting case of thermally induced phase transitions has also been studied, with DiffEXAFS measurements taken through the Martensitic phase transition of the Heusler alloy Ni2MnGa. These revealed a hardening of the lattice as the transition was approached in the Martensite phase, agreeing with published trends [93][56], and an accompanying lattice contraction not seen previously.
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Weir, I. J. M. "The thermal lens". Thesis, University of Strathclyde, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372116.
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Zhang, L. "Modelling thermal regenerators". Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385828.
Pełny tekst źródła
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Schmidt, Aaron Jerome 1979. "Contact thermal lithography". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/27116.
Pełny tekst źródłaStreszczenie:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (p. 65-67).
Contact thermal lithography is a method for fabricating microscale patterns using heat transfer. In contrast to photolithography, where the minimum achievable feature size is proportional to the wavelength of light used in the exposure process, thermal lithography is limited by a thermal diffusion length scale and the geometry of the situation. In this thesis the basic principles of thermal lithography are presented. A traditional chrome-glass photomask is brought into contact with a wafer coated with a thermally sensitive polymer. The mask-wafer combination is flashed briefly with high intensity light, causing the chrome features heat up and conduct heat locally to the polymer, transferring a pattern. Analytic and finite element models are presented to analyze the heating process and select appropriate geometries and heating times. In addition, an experimental version of a contact thermal lithography system has been constructed and tested. Early results from this system are presented, along with plans for future development.
by Aaron Jerome Schmidt.
S.M.
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Klett, Sven. "Creating Thermal Solutions". Technische Universität Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A21506.
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Redesign einer Halbleiterklammer mittels Topologieoptimierung und integrierter FEM Rechnung.
Optimierung mittels Inspire von solidThinking. Halbleiterklammer zur Sicherstellung der Kühlung von IGBT Bausteinen in Hochstromapplikationen.
Optimierung unter der Restriktion verfügbarer Fertigungsverfahren.
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Дядечко, Алла Миколаївна, Алла Николаевна Дядечко, Alla Mykolaivna Diadechko i O. Shcherbakov. "Thermal anemometers measurements". Thesis, Вид-во СумДУ, 2009. http://essuir.sumdu.edu.ua/handle/123456789/16886.
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Міхно, Світлана Василівна, Свитлана Васильевна Михно, Svitlana Vasylivna Mikhno i A. Trokhimenko. "Solar thermal collector". Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/13475.
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A solar thermal collector is a solar collector designed to collect heat by absorbing sunlight. The actuality of sun collectors today is unquestionable. They allow to heat dwellings, industrial, commercial buildings, and also to provide a hot water-supply in them.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/13475