Thèse de doctorat : Physique : Metz : 1999. / 1999METZ038S. 102 ref.

Thèse de doctorat : Spectrochimie, molécules, solides, réactivité : Lille 1 : 2000. / Résumé en français et en anglais. Bibliogr. en fin de chapitres.

Thèse doctorat : Energétique et Thermique : Villeurbanne, INSA : 2008. / Titre provenant de l'écran-titre. Bibliogr. p. 165-170.

Thesis (Ph.D)--Psychology, Georgia Institute of Technology, 2010. / Committee Chair: Walker, Bruce N.; Committee Member: Corballis, Paul M.; Committee Member: Corso, Gregory M.; Committee Member: Folds, Dennis J.; Committee Member: Houtsma, Adrianus J. M. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Inorganic salts are very promising as high-temperature heat transfer fluids and thermal storage media in solar thermal power production. The dual-tank molten salt storage system, for example, has been demonstrated to be effective for continuous operation in solar power tower plants. In this particular storage regime, however, much of the thermal storage potential of the salts is ignored. Most inorganic salts are characterized by high heats of fusion, so their use as phase-change materials (PCMs) allows for substantially higher energy storage density than their use as sensible heat storage alone. For instance, use of molten sodium-potassium eutectic salt over a temperature range of 260 to 560°C (the approximate operating parameters of a proposed utility-scale storage system) allows for a volumetric energy storage density of 212 kWhth/m3, whereas the use of pure sodium nitrate (T_m = 307°C) over the same temperature range (utilizing both sensible and latent heat) yields a storage density of 347 kWhth/m3. The main downside to these media is their relatively low thermal conductivity (typically on the order of 1 W/m-K). While low conductivity is not as much an issue with heat transfer fluids, which, owing to convective heat transfer, are not as reliant on conduction as a heat transfer mode, it can become important for PCM storage strategies, in which transient charging behavior will necessarily involve heating the solid-phase material up to and through the process of melting. This investigation seeks to develop new methods of improving heat transfer in inorganic salt latent heat thermal energy storage (TES) media, such as sodium / potassium nitrates and chlorides. These methods include two basic strategies: first, inclusion of conductivity-enhancing additives, and second, incorporation of infrared absorptive additives in otherwise transparent media. Also, in the process, a group of chloride based salts for use as sensible storage media and/or heat transfer fluids has been developed, based on relevant cost and thermophysical properties data. For direct conductivity enhancement, the idea is simple: a PCM with low conductivity can be enhanced by incorporation of nanoparticulate additives at low concentration (~5 wt %). This concept has been explored extensively with lower temperature heat transfer fluids such as water, ethylene glycol, etc. (e.g., nanofluids), as well as with many lower temperature PCMs, such as paraffin wax. Extension of the concept to high temperature inorganic salt thermal storage media brings new challenges—most importantly, material compatibility. Also, maintenance of the additive distribution can be more difficult. Promising results were obtained in both these regards with nitrate salt systems. The second heat transfer enhancement strategy examined here is more novel in principle: increasing the infrared absorption of a semitransparent salt PCM (e.g., NaCl) with a suitable additive can theoretically enhance radiative heat transfer (for sufficiently high temperatures), thereby compensating for low thermal conductivity. Here again, material compatibility and maintenance of additive dispersion become the focus, but in very different ways, owing to the higher temperatures of application (>600°C) and the much lower concentration of additives required (~0.5 wt %). Promising results have been obtained in this case, as well, in terms of demonstrably greater infrared absorptance with inclusion of additives.

This work focuses on the development of a reliable numerical model for investigating the bone-conduction of sound in the human head. The main challenge of the problem is the lack of fundamental knowledge regarding the transmission of acoustic energy through non-airborne pathways to the cochlea. I employed a fully coupled model based on the acoustic/elastic interaction problem with a detailed resolution of the cochlea region and its interface with the skull and the air pathways. The problem was simulated via hp-finite element approximation, employing a hybrid mesh (tetrahedral, prismatic and pyramidal elements) to better capture the geometrical features of the head. The numerical results thus obtained provide an insight into this fundamental, long standing research problem. / text

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Bakalauro darbe nagrinėjama nehomogeninė šilumos laidumo lygtis. Darbo tikslas rasti lygties bendruosius sprendinius, kurie tenkintų duotąją pradinę ir kraštines sąlygas. Ieškant sprendinių mišrusis uždavinys nehomogeninei lygčiai su nehomogenine pradine sąlyga suvestas į du mišriuosius uždavinius - homogeninei lygčiai su nehomogenine pradine sąlyga ir nehomogeninei lygčiai su homogenine pradine sąlyga. Remdamiesi gautais šių uždavinių sprendiniais, gavome mišriojo uždavinio nehomogeninei šilumos laidumo lygčiai sprendinius. / There was analyzed non-homogeneous heat conduction equation in the bachelor work. This work objective is to find equation general solutions, which have to fulfill of the given initial and boundaries conditions. The mixed problem to non-homogeneous equation with non-homogeneous initial was piece together in two mixed problems – to homogeneous equation with non-homogeneous initial and to non-homogeneous equation with homogeneous initial when we were searching solutions. Based on the obtained these solutions, we got solutions of the mixed problem to non-homogeneous heat conduction equation.

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