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[en] Thermoelectricity is nowadays at the basis of the development of some interesting innovative and technological solutions either related to HVAC and small power generation systems. Starting from some niche applications for the military sector, the interest in such a technology has been recently extended the more traditional commercial markets related to mainly to refrigeration
[it]La termoelettricita e alla base di soluzioni tecnologiche che di recente hanno mosso l'interesse dei mercati commerciali. Le soluzioni proposte riguardano sia i processi di termoregolazione e di climatizzazione sia la produzione diretta di energia elettrica. A partire da applicazioni strategiche nel settore militare proposte nel passato, oggi ci si orienta verso soluzioni che possano competere anche nei mercati piu tradizionali, in particolare nel settore della refrigerazione
[en] After a brief recall of the basic principles of thermoelectricity, the essential characteristics intervening in the different thermoelectric devices operating modes are defined. Properties of the materials the most used nowadays and performances of the apparatus that they allow to realize are indicated. Advantages and drawbacks of the principal applications in the form of electrical generators, refrigerators and heat pumps are pointed out
[fr]Apres un bref rappel des principes physiques de base de la thermoelectricite, les caracteristiques essentielles qui interviennent dans les differents modes de fonctionnement des dispositifs thermoelectriques sont definies. Les proprietes des materiaux les plus utilises de nos jours et les performances des appareillages qu'ils permettent de realiser sont indiquees. Les avantages et les inconvenients des principales applications sous forme de generateurs electriques, refrigerateurs et pompes de chaleur sont signales
[en] The thermoelectric conversion technology taken up in this report is the method of converting the heat energy from the high temperature exceeding 2000degC to the low temperature of -160degC directly to electric energy mainly by using the solid elements. Concretely, the thermoelectric conversion devices utilizing Seebeck effect, Peltier effect, alkali metal temperature difference cell, the thermoelectronic radiation phenomenon from high temperature electrodes and so on are taken up. The features of these technologies are the flexible dealing of heat sources with temperature level, the wide range of electric power output, easy maintenance and high reliability because of no moving part, calm and harmony with environment and so on. In this report, the purpose of this report, the principle of thermoelectric conversion, the approach to heighten the efficiency of thermoelectric materials, the heightening of the functions in material and processing technologies, the heightening of the functions in device and modularizing technologies, the heightening of the functions in the aspects of systems and uses, the heightening of functions as seen in 12th International Conference on Thermoelectric Conversion, the investigation of the patents, and the expansion of the fields of utilization by hightening functions are described. (K.I.)
[en] In this paper we analyze the thermodynamic efficiency expected for a fully dissipative thermoelectric generator (TEG) operating under stationary conditions at a finite rate. Although a finite-time thermodynamic analysis of TEGs has been aimed at since long time, no complete theory is available yet. The state of the art of theory is reviewed, and a simple expression for the maximum achievable efficiency of TEGs operating under fully irreversible conditions is obtained. This also sets a reference efficiency for forthcoming studies of nonstationary operation of TEGs.
[en] The thermoelectric phenomena, their physical principle and the application thereof in thermoelectric generators are discussed. The requirements placed on the material and the technological problems of the construction of thermoelectric generators are outlined
[en] Highlights: • Crystalline thermoelectric (TE) micro/nanowires are fabricated by a thermal drawing process. • TE fibers are flexible, ultralong, and mechanically stable, while offering high TE properties. • TE generators covered on different curved surfaces provide mW/cm2-level power density. • A wearable TE cooling textile is assembled to achieve a maximum cooling of 5 °C. • TE fibers provide an efficient route to bridge the gap between micro/nanowires and their integrated devices. High-performance flexible thermoelectric devices are increasingly demanded to efficiently convert thermal energy to electricity by covering heat sources with arbitrary and conformal geometries. However, some fundamental limitations still exist, e.g., low output power density, poor mechanical stability, and small cover area, which have largely restricted their studies and applications. Here, we fabricate crystalline thermoelectric micro/nanowires by thermally drawing hermetically sealed high-quality inorganic thermoelectric materials in a flexible fiber-like substrate. The resulting thermoelectric fibers are intrinsically crystalline, highly flexible, ultralong, and mechanically stable, while maintaining high thermoelectric properties as their bulk counterparts. Two types of thermoelectric generators covered on different curved surfaces are constructed to provide mW/cm2-level output power density. Additionally, a wearable two-dimensional cooling textile is assembled to achieve a maximum cooling of 5 °C. This approach works for a broad range of thermoelectric materials, and bridges the gap between high-performance thermoelectric micro/nanowires and their integrated devices for practical applications.
[en] Full text: Cubic half-Heusler (HH) compounds with the chemical formula XYZ with 18 valence electrons are found to be semiconducting and exhibit promising thermoelectric properties. In this work isoelectronic substitution of the X element as well as a combined high mobility electron injection, low energy electron filtering and boundary scattering approach have been employed in order to enhance the efficiency of thermoelectric conversion. Subsequently, thermoelectric converters based on HH compounds were assembled and characterized with respect to their power output in a homemade test rig. (author)