XIII INTERNATION FORUM ON THERMOELECTRICITY
| XIII INTERNATION FORUM ON THERMOELECTRICITY | |
3.1. On the achievements in the field of thermoelectricity in EU countries.
ITA Honoured academician Rowe M., NEDO Centre for Thermoelectric Engineering, Cardiff University, Great Britain.
3.2. Current status of research and developments on technology of thermoelectric energy generation in Japan.
ITA academician Kajikawa Ò., Shonan Institute of Technology, Japan.
3.3. On the achievements in the field of thermoelectricity in the USA.
ITA academician Tritt T., Clemson University, Department of Physics and Astronomy, USA.
3.4. On the achievements in the field of thermoelectricity in China.
Chen L., Shanghai Institute of Ceramics, Chinese Academy of Sciences.
3.5. On the progress of thermoelectricity in Israel.
ITA academician Dashevsky Z.M., Ben-Gurion University, Israel.
3.6. Thermoelectricity in Russia: current status and prospects.
ITA Honoured academician Vedernikov M.V., ITA academician Bulat L.P., ITA academician Iordanishvili E.K., ITA academician Pustovalov À.À., ITA associate member Fedorov M.I., A.F.Ioffe Physics and Engineering Institute, RAS; State University of Low-Temperature and Food Technologies; Saint-Petersburg Polytechnic University; Research-Industrial Enterprise "BIAPOS"; A.F.Ioffe Physics and Engineering Institute, RAS, Russia.
3.7. Thermoelectricity in Mexico.
ITA academician Gurevich Yu.G., CINVESTAV, National Polytechnic Institute, Mexico.
3.8. Thermoelectricity in Moldova.
ITA academician Nikolaeva A.A., Institute of Applied Physics, Moldova.
3.9. Thermoelectricity in Spain.
Vian J.G., Mechanical, Energy and Materials Engineering Department Public University of Navarra, Spain.
3.10. Current status of thermoelectricity development in Poland.
ITA academician Filin S.O., West Pomeranian University of Technology, Poland.
3.11. Thermoelectric activities in Montpellier France.
Tedenac J-C., University of Montpellier, France.
3.12. Thermoelectricity in Ukraine.
ITA associate member Mykhailovsky V.Ya., Institute of Thermoelectricity, Ukraine.
3.13. Conferences on thermoelectrics in 2008.
ITA academician Stockholm J., "Marvel Thermoelectrics", France.
4.1. Marlow Industries, Inc. perspective on power generation materials.
ITA academician Sharp J., USA
4.2. Company "KOMATSU" and its activity.
Aoyama I., Japan.
4.3. Research activity on thermoelectric materials in the National Institute for Material Science (NIMS).
Shinohara Y., Japan
National Institute for Materials Science(NIMS) is Japan's sole Independent Administrative Institution(IAI) specializing in materials science. NIMS was established on April 2001 by combining National Research Institute for Metals(NRIM) with National Institute for Research in Inorganic Materials(NIRIM). It is charged with basic research and development of materials science, and to advance the level of expertise in the field. The focused researches are as follows:
1) Nannotechnology-Driven Advanced Materials Research;
2) Advanced Materials Research for Social Needs.
Japan has a strong need against energy and environmental problems. Researches on thermoelectric materials are listed to be one of Advanced Materials Researches for Social Needs. A new NIMS research project on thermoelectric materials has started since last December. The targeted materials are silicides, oxides, borides and polymers for power generation. The details in the project will be presented at XIII International Forum on Thermoelectricity.
4.4. On the activity of Institute of Thermoelectricity.
ITA academician Anatychuk L.I., Ukraine.
4.5. On the activity of company "KRYOTERM".
ITA associate member Baukin V.E., Russia.
4.6. Activities of company "RMT"
ITA associate member Gromov G.G., Russia.
4.7. Activities of company "NORD".
Skipidarov S.Ya., Russia.
4.8. Activity of BSST company.
ITA academician Lon Bell, USA.
4.9. Company "TERMOPRYLAD" and its activity in thermometry.
ITA associate member Huk A.P., Ukraine.
4.10. On the developments and products of company "ALTEC".
Razinkov V.V., Ukraine.
4.11. On the activity of Department of Thermoelectricity in Chernivtsi National University.
ITA academician Luste O.J., Institute of Thermoelectricity, Ukraine.
4.12. On the achievements of company "Module".
ITA associate-member Anukhin A.I., Ukraine.
4.13. On the scientific and production activity of Research-Industrial Enterprise "BIAPOS".
ITA academician Pustovalov A.A., Russia.
4.14. Expertise of development and introduction of thermoelectric devices by State Scientific-Production Enterprise "TERMOKHOLOD" in the market of Ukraine.
Kiselyov Yu.F., Ukraine.
5.1. On the trends and rational areas of thermoelectricity development.
ITA academician Anatychuk L.I., Institute of Thermoelectricity, Ukraine.
5.2. Current status and prospects of nanostructured thermoelectric materials.
ITA academician Baransky P.I., V. Lashkarev Institute of Semiconductor Physics, Ukraine.
5.3. Current developments in the industrial production of thermoelectric cooling modules.
ITA associate member Baukin V.E., Open JSC"KRYOTERM", Russia.
5.4. Ways for further development of micromodules.
ITA associate member Gromov G.G., Closed JSC "RMT", Russia.
5.5. On the achievements in the field of thermoelectric air-conditioning in the world during recent two years. Heat pumps.
ITA academician Stockholm J., Rozver Yu.Yu., "Marvel Thermoelectrics", France; Institute of Thermoelectricity, Ukraine.
5.6. Limited role of thermoelectricity in climate crisis.
ITA academician Vining C., ZT Services, USA.
The climate crisis presents unique and largely unprecedented social, economic, political and technical challenges. The technical challenges, though enormous, may prove the most tractable of all. Among the technical challenges is the development of energy technologies with much reduced environmental impact This note provides an overview of thermoelectric technology, a solid state 'heat engine' capable of converting heat to electricity or alternatively converting electricity into cooling. Such an overview is timely because thermoelectric technology has made significant scientific progress in recent years and its potential to reduce the environmental impact of electrical power generation has been discussed. While the science, technology and business of thermoelectrics has never been stronger than today, the opportunity for a material impact on the climate crisis appears limited. Only a single application, recovery of vehicle waste heat, appears plausible in this respect. And even that application faces stiff barriers.
5.7. On the application of thermoelectricity in medicine.
Kobylyansky R.R., Institute of Thermoelectricity, Ukraine.
It is well-known in medical practice that thermal effect is an important factor in treatment for numerous diseases of human organism. However, the devices used for this purpose for the most part are bulky ones, lacking appropriate temperature control and thermal modes transformation. This problem can be solved by using thermoelectric cooling. Basic research conducted for many years and devoted to the use of thermoelectric cooling in medicine confirm its successful practical application. Thus, one of the prospective trends in thermoelectricity development consists in creation of simple and reliable, small-size and multifunctional medical devices, intended for diagnostics and treatment for different diseases of human organism.
Construction flexibility, reliability, regulation simplicity and possibility of precise temperature control provided favourable conditions for wide practical application of such devices in numerous technical areas. Thermoelectric devices are used in such areas of medicine as cryotherapy, cryosurgery, ophthalmology, traumatology, neurology, neurosurgery, plastic surgery, urology and dermatology. Such a wide practical application is determined by a number of advantages: possibility of developing miniature cooling devices with practically unlimited operating resource; absence of working fluids and gases in cooling systems; independence of cooler parameters on special orientation or attraction field effect; ability to operate under high mechanical overloads; possibility to provide temperature control by altering supply current; speed and high reliability.
5.8. Household thermoelectric cooling equipment - current status and prospects.
ITA academician Filin S.O., West Pomeranian University of Technology, Poland.
5.9. Progress in creation of thermoelectric generators.
ITA associate member Mykhailovsky V.Ya., Institute of Thermoelectricity, Ukraine.
The results of scientific and technological developments of organic fuel-based thermoelectric generator designs are presented. Energy conversion mechanisms in such generators, classification and mathematical description of their physical models are presented, the ways and methods of creation of organic fuel-based thermogenerators, efficiency of which exceeds 6 %, are determined. Specific designs of thermogenerators for different applications with electrical power in the range of tens of milliwatt to hundreds of watt are presented. Their characteristics are described, rational areas and prospective ways for broadening their practical application are determined.
5.10. Thermoelectric generators for conversion of low-grade heat from industry and internal combustion engines, including motor transport.
ITA academician Anatychuk L.I., Institute of Thermoelectricity, Ukraine.
Analysis of existing thermoelectric generators using industrial heat waste and heat from internal combustion engines has been presented. Results of thermoelectric generator development designed for combined operation with diesel engine have been given. Research technique of the device parameters under different operating conditions and results of thermoelectric tests have been presented. Prospects of wide use of such devices in the branches of industry where there is adequate suppliers of heat generation, and in motor transport, have been estimated.
5.11. Current status and prospects for thermoelectric thermometry development.
ITA academician Stadnyk B.I., National University "Lvivska Politekhnika", Ukraine.
5.12. Prospects for development of high-temperature thermoelectric thermometry.
Fedik I.I., Oleinikov P.P., Ulanovsky A.A., Research and Production Association "LUCH", "Obninsk Thermoelectric Company"Ltd., Russia.
Brief historical reference is given on the development of high-temperature thermoelectric thermometry. It is shown that the largest spread in industrial practice has been gained by primary sensing devices with sensing elements made of tungsten-rhenium alloys [1].
In Russia and CIS countries thermal electrodes comprise 5 and 20% of rhenium. In the USA most popular converters include 5 and 26% of rhenium addition in thermal electrodes. Certain spread has been gained by converters with 3% of rhenium in one of the electrodes [2].
Some idea on the nomenclature of tungsten-rhenium converters in China is given by the Internet site of Chinese company Wuxi Guotao Tungsten Rhenium Alloy Factory.
The volume of consumption of thermal electrode alloys in Russia in recent years has been preserved at the level of 100 kg/year.
The basic technological processes and structural peculiarities of measuring means manufactured in Russia are discussed [3-5]. The state of measurement assurance is characterized.
Due to drastically increased interest in developed countries in high-temperature measurements, the working group ¹5 ÒÊ65 ÌÝÊ started activities for international recognition of nominal static characteristics tungsten-rhenium thermocouples. Presentation of thermocouple ÂÐ5/20 was made by director of Obninsk thermoelectric company at the meeting of working group ¹5 ÒÊ65 IEC in Tokyo in May, 2008.
As a result, the Russian side was proposed to prepare samples and conduct control calibration of samples of thermocouple ÂÐ5/20 in metrological centres of Germany, USA and Japan. The results of this work will be discussed at the meeting of working group ¹5 ÒÊ65 IEC, planned for May, 2009 in D.Mendeleyev Research Institute of Metrology (Saint-Petersburg). It would be advisable for specialists from Ukraine to join in this work. The samples of thermocouples for similar works are ready.
Based on the studies of superdispersed hardening of tungsten-rhenium alloys [6], the pilot part of the project "Modernization on the basis of nanotechnologies of production of temperature sensing devices of increased precision and stability for the needs of nuclear industry" [7] has been prepared and launched.
5.13. Thermoelectric renewable power sources.
Mykytyuk P.D., Institute of Thermoelectricity, Ukraine.
The results of theoretical and experimental investigations on developing thermoelectric renewable power sources, converting soil thermal energy into electrical power are presented. The prospects for development and rational areas of application of such power sources are demonstrated.
5.14. Thermoelectric microgenerators. Current status and application prospects.
Strutynska L.T., Institute of Thermoelectricity, Ukraine.
Current status and application prospects of thermoelectric generators, including the organic-fuel-based ones, are analyzed. The ways for improving their efficiency and topical trends of their broad practical application are determined.
5.15. Progress and possibilities of computer design of thermoelectric devices.
ITA academician Luste O.J., Institute of Thermoelectricity, Ukraine.
5.16. Current status and trends in progress of alternating current measurements by thermoelectric signal transducers.
Bodnaruk V.I., Institute of Thermoelectricity, Ukraine.
Based on the comparative analysis of measuring thermoelectric transducers manufactured by different techniques, a brief characteristic of their advantages and otherwise is given, promising lines of theoretical and experimental studies aimed at creation of new up-to-date devices according to current needs are substantiated.
5.17. On the development of thermoelectric material science.
Vykhor L.M., Institute of Thermoelectricity, Ukraine.
6.1. Physics of thermoelectric cooling. Alternative line.
ITA academician Gurevich Yu.G., CINVESTAV, National
Polytechnic Institute, Mexico.
An alternative thermodynamic approach to the physics of thermoelectric cooling in metal-metal, metal n-type semiconductor, and p-n junctions is presented. The heat balance equations with the appropriate boundary conditions are solved to obtain the temperature distributions using the assumption of very strong recombination and linear approximation of the electric current. The temperature distributions are proportional to the difference of the Peltier coefficients and its physical meaning is analyzed for each junction.
Also, a new approach to study the thermoelectric cooling considering the non-equilibrium charge carriers and the quasi-neutrality approximation is presented. The role of recombination rate as the new source of heat in transport phenomena is discussed leading to a new formulation for the heat balance equations.
6.2. Once again on the mathematical bias in thermoelectricity.
ITA academician Iordanishvili E.K., Saint-Petersburg Polytechnic University, Russia.
6.3. Ò
Thermoelectric effects in the inhomogeneous media. 1) the method of local isomorphism in the direct problems of thermoelectricity; 2) two threshold phenomena in thermoelectric composites; 3) the effect of surface composite particle nano-layers on thermoelectric figure-of-merit.
ITA academician Snarskii A.A., National Technical University "Kyiv Polytechnic Institute", Ukraine.
The method of local isomorphism, which makes it possible to reduce complex thermoelectric task to simple single-flow one, for example, to the task of conductivity, is developed. In a number of cases this method allows to reduce essentially the time of calculation of direct problems, which is very important at solving reverse problems in the region of thermodynamic defectoscopy.
The conditions, under which there simultaneously exist two thresholds of flow in thermoelectrically inhomogeneous media in contrast to recently observes cases, are found. Critical behaviour of effective kinetic coefficients near the second threshold of flow is investigated.
The model which makes it possible to consider the influence of surface nano-layers of particles on thermoelectric figure-of-merit of a composite is developed.
6.4. New linear nonequilibrium thermodynamics and thermodynamically phenomenological theory of thermoelectricity.
ITA associate member Mamedov M.M., State University, Turkmenistan.
The objective of the work is to confirm the inconsistency of traditional thermodynamic- phenomenological theory of thermoelectricity and the development of its adequate theory on the basis of new linear nonequilibrium thermodynamics. Classical linear nonequilibrium thermodynamics is incorrect due to the incorrectness of traditional interpretation of the law of degradation of energy. Being the thermodynamics of reversible processes, it is called the linear thermodynamics of the irreversible processes. In this connection the traditional thermodynamically phenomenological theory of thermoelectricity based on the classical linear thermodynamics is inconsistent.
The basis of new linear nonequilibrium thermodynamics and its application for describing the thermoelectric effects is presented. Finally, not only adequate, but also more informative thermodynamically phenomenological theory of thermoelectricity is obtained. At the same time, within the limits of this theory, the refined Thomson hypothesis also becomes substantiated.
Moreover, within the framework of a new theory, the necessity in experimental determination of cross coefficients in linear equations is eliminated, since, they are directly determined through the diagonal coefficients. Within the framework of a new theory of thermoelectricity, the Onsager reciprocity relations are derived from the refined Thomson hypothesis.
The adequacy of the proposed new thermodynamically phenomenological theory of thermoelectricity is confirmed by experimental data based on the Onsager and Saxen relations, the Thomson hypothesis in the case of reversible processes.
6.5. Thermoelectricity and thermoelectromagnetism as one of the relevant lines of basic science.
ITA academician Grabov V.M., A.I.Herzen State Pedagogical University, Russia.
In the latter half of ÕÕ century new directions in fundamental physics at the joint of hydrodynamics and thermodynamics, thermodynamics and electrodynamics, especially under the conditions remote from thermodynamic equilibrium, in which the processes of self-organization with the formation of dissipative dynamic and electrodynamic structures are achieved, are rapidly developing. Thermodynamic nonequilibrium is the basis for evolution, including living systems evolution.
New photo-thermoelectric phenomena in the layers of semiconductors, which consist in a significant increase of thermoelectric efficiency of semiconductor materials with nonequilibrium charge carriers excited by external electromagnetic radiation effect, are investigated.
Thermoelectric phenomena in aqueous solutions of ionic compounds, the thermal emf value of which is about 0.6-1.8 mV/K, are investigated, and sign is determined by ions having the highest mobility. A high value of thermal emf is due to considerable growth of ion mobility with temperature.
New thermo-electrokinetic phenomena in viscous electroconducting medium are discovered and investigated. The sign and value of thermo-electrokinetic emf, its dependence on concentration and flow rate in aqueous solutions of a wide range of acids, alkalis and salts, are reliably determined.
The importance of research results on thermoelectric and thermo-electrokinetic phenomena under the conditions removed from thermodynamic equilibrium, the broadening of investigation range on new materials and media are determined by the fact that the environment, the part of the universe accessible for observation is located under essentially nonequilibrium conditions. In this case in the processes of self-organization and natural systems evolution with an increase in the level of complexity, including biological systems, thermo-electrokinetic and thermo-electromagnetic phenomena are of great importance.
6.6. Thermomagnetic phenomena in nanostructures.
Sinyavsky E.P., Institute of Applied Physics, Moldova.
6.7. Peculiarities of thermoelectric properties of intermetallic semiconductors.
6.8. Comparative analysis of a new method for calculation of heat engineering
parameters of a real thermopile.
6.9. On the optimization of p-leg of stage medium-temperature thermoelements.
6.10. Thermoelectric opportunities of quasi-one-dimensional organic crystals of tetrathiotetracene-iodide.
6.11. Peculiarities of thermoelectric properties of single-crystalline Bi nanowires doped with acceptor impurity of different orientation under anisotropic strain.
6.12. Thermoelectric properties of polycrystalline bismuth-antimony solid solutions.
6.13. Phase stability of intermetallic materials for thermoelectricity.
6.14. Bulk nanostructured thermoelectrics based on bismuth telluride.
6.15. Thermoelectric sensors based on GexSi1-x whiskers.
6.16. High-performance materials based on n- and p-type PbTe for thermoelectric applications.
6.17. Development of techniques for manufacturing thermoelectric materials based on bismuth and antimony chalcogenides with regard to RoHS European requirements.
6.18. Extruded materials for low-temperature coolers.
6.19. Materials based on higher manganese silicide.
6.20. Anisotropic thermoelectric materials based on layered tetradimite-like chalkogenides.
6.21. Materials for synthetic transverse thermoelectric devices.
6.22. Thermoelectric elements for sensors of physical and biomedical signals.
6.23. Critical assessment and prediction of coefficients of linear thermal expansion of low-temperature thermoelectric materials.
6.24. On thermoelectric properties of quantum wires.
6.25. Physics and technology of thermoelectric materials based on chalkogenide semiconductors.
6.26. Properties of Bi2Te3 thin films obtained by PLD method.
6.27. Interlayer nanostructures in thermoelectric laminar crystals of Bi2Te3 type (impurity).
6.28. Problems of efficiency increase of thermoelectric generators.
6.29.Some peculiarities of optimization of electric supply modes of thermoelectric coolers as part of photodetectors.
6.30. About test results of RMT company' miniature thermoelectric modules.
6.31. On the promising lines of thermoelectric heat pumps application.
6.32. Thermoelectric properties of some perovskite oxides.
6.33. Special thermoelectric generator for gas industry.
6.34. Ivan Pulyui's contribution to progress in telethermometry (commemorating 164 anniversary of Ivan Pulyui).
ITA academician Stadnyk B.I., Romaka V.A. National University "Lvivska Politekhnika", Ukraine.
The effect of dopants, namely, of transient 4f- è 3d- metals, on the electrokinetic, magnetic, structural and energetic characteristics of intermetallic semiconductors of MgAgAs structural type, is investigated. It is shown that the presence of essential concentrations of impurity centers (10
Rasit Ahiska, Gazi University, Faculty of Technology, Turkey.
In the present study, a new method for searching all exit parameters of the thermoelectric module has been realized. The new method bases on measurement of thermoemf of a working module and comparing the results obtained with those of classical methods. The new method is used for investigation of the values of parameters of a standard thermoelectric module of Melcor with production code of ÑÐ1.0-127-05L. The theoretical results calculated by the means of new and classical methods for the parameters of an actual thermoelectric module have been compared with the experimental results and the advantage of the new method in sense approximation accuracy has been proven.
ITA associate member Terekov A.Ya., Open JSC "Research and Production Enterprise KWANT", Russia.
The service life and efficiency are the fundamental characteristics of thermoelectric generators (TEG), for this purpose the most effective thermoelectric materials based on lead chalcogenides (n- leg) and germanium chalcogenides (p - leg) are used in thermoelements (TE).
To provide maximum efficiency of thermoelements (and TEG, respectively) cascade TE legs with operating temperature along the heat-absorbing side of 600-650°C are used. In p-leg of cascade thermoelements on heat-releasing side semiconductor compound based on (Bi; Sb)2Te3 solid solution, which is found in the direct contact with the semiconductor material based on germanium telluride, is used. The conducted metallographic researches and service life tests showed that the boundary between these materials was not substantially changed at the temperature of 200 - 260°C for 25 years, however, as to the opposite boundary with an upper cascade made of tin telluride, here the diffusion of germanium through the upper cascade to its contact with the commutation tire made of iron, was observed. On the basis of obtained diffusion equations the work on optimization of tin telluride thickness with the purpose of determining preset service life, for example, 5 years, at certain operation temperature range of 450-600°C, was carried out.
For achieving service life not less than 25 years it is necessary to introduce antidiffusion barrier between germanium telluride and tin telluride, prepared on the basis of the germanium compounds with high-temperature metals. Steady operation of TEG on gas mains and bench measurements of energy characteristics of modules after 15- year resource confirmed the correctness of the materials science solution in the selection of barrier and production technology.
Technical solutions mentioned above make it possible to increase the operation temperature of medium- temperature thermopiles up to 650°C with the efficiency of 10,5-11%.
ITA academician Casian A.I., Technical University, Moldova.
The aim of this paper is to analyse the thermoelectric opportunities of quasi-one-dimensional (Q1D) organic crystals of tetrathiotetracene-iodide, TTT2I3. These crystals have high electrical conductivity and pronounced Q1D properties. It is shown theoretically that in very pure such crystals it is possible to increase simultaneously the electrical conductivity and the thermopower, due to the increase of electronic density of states and to the interference of two more important electron-phonon interactions. The highest calculated until now in such materials value of thermoelectric power factor at room temperature is obtained. The electronic part of thermal conductivity is investigated in detail because it could increase with the increase of electrical conductivity. Some unusual transport properties of these crystals observed experimentally are explained. It is shown theoretically that in really existing crystals of TTT2I3 it is possibly to increase the dimensionless thermoelectric figure of merit ZT up to 1.5 at room temperature, if the carriers concentration is diminished by approximately 2.5 times with respect to the stoichiometric one. Possibilities to further increase ZT in these crystals are discussed.
ITA academician Nikolaeva A.A., Institute of Applied Physics, Moldova.
The objective of this work is to investigate the influence of alloying, orientation and elastic extension on thermoelectric efficiency of bismuth nanowires.
Substantial increase in thermoelectric efficiency in Bi-based nanowires predicted in the works [1,2,3] assumed the C3 orientation along wire axis, that was not practically realized experimentally. In this work for the first time using laser recrystallization method of threads in glass encapsulation, formed by moulding from liquid phase, single-crystalline nanowires of Bi -0,05at%Sn with C3 orientation along the wire, were obtained, which was confirmed by the method of the angular diagrams of transverse magneto-resistance, and with the aid of the Shubnikov-de-Haas oscillations.
It is shown that peculiarities of nonmonotonic dependence of thermal emf s(Ò), ), variation of sign, extremum of positive polarity in Bi nanowires find their theoretical explanation, taking into consideration the scattering on a rough surface and long-wave acoustic phonons [4]. Bi doping with tin impurity shifts the region of positive maximum on s(Ò)
to the region of higher temperatures, which can be considered as the basis of promising production technology of nano-structures with preset properties for thermoelectric applications.
It is established that the change of crystallographic orientation to C3 along the wire axis and Bi -0,05at%Sn wires elastic extension leads to a substantial increase in thermoelectric efficiency in the temperature range of 200-300 K.
The work was supported by Moldavian Grant ¹08.805.05.06A.
ITA associate member Rogacheva E.I., National Technical University "Kharkiv Polytechnic Institute", Ukraine.
The results of works on a comprehensive analysis of low-temperature thermoelectric materials - the polycrystalline bismuth-antimony solid solutions in the composition range of 0 - 15 at.% of antimony conducted at National Technical University "Kharkiv Ppolytechnic Institute", are represented. Microstructure, crystalline structure and microhardness depending on the composition of solid solutions, method of the preparation of models and thermal treatment, are investigated. Temperature (77 - 300 K) and the magnetic field dependences of the galvanomagnetic and thermoelectric properties are obtained, on basis of which the isotherms of properties are built and the boundaries of weak magnetic field for the alloys with different composition at different temperatures are determined. It is shown that the isotherms of properties bear pronounced nonmonotonic nature connected with the qualitative changes in band structure taking place with composition change. The obtained results should be taken into consideration during development and optimization of properties of thermoelectric materials based on bismuth-antimony solid solutions.
Tedenac J-C., University of Montpellier, France.
ITA academician Bulat L.P., Pshenai-Severin D.A., Drabkin I.A., Karatayev V.V., Osvensky V.B., Pivovarov G.I., Tatyanin Ye.V., Bublik V.T., Tabachkova N.Yu. State University for Low-Temperature and Food Technologies, Open JSC "Giredmet", Technological Institute for Superhard and New Carbon Materials, State Technological University Moscow Institute of Steel and Alloys, Russia.
The theoretical prerequisites for an increase of thermoelectric figure-of-merit in the bulk nanostructured thermoelectrics are discussed. A series of samples of nanostructured thermoelectrics is produced by hot pressing nanoparticles at different pressures (from 10 MPa to 9 GPa) and temperatures from room temperature to 500°C, which exceeds corresponding properties of materials obtained by zone melting by 3 times. Preliminary experimental results confirm that in similar nanostructured bulk thermoelectrics figure-of-merit can actually grow in comparison with source materials.
×ëåí-êîðåñïîíäåíò ÌÒÀ Äðóæèí³í À.Î., Îñòðîâñüêèé ².Ï., Êîãóò Þ.Ð., Íàö³îíàëüíèé óí³âåðñèòåò "Ëüâ³âñüêà ïîë³òåõí³êà", Óêðà¿íà.
The investigations on temperature dependences of the Seebeck coefficient of GexSi1-x(0< õ < 0.05) whiskers (0< õ < 0.05) in the temperature range 4.2 550Ê are carried out. The possibility of designing and predicting the characteristics of temperature sensors and temperature difference, valid in low-temperature range (4,2-77 K) and at elevated temperatures (300-550 K) under conditions of external effects (magnetic field, radiation) is demonstrated.
ITA academician Dashevsky Z.M., Ben-Gurion University, Israel.
Lead telluride-based compounds are known for their favorable thermoelectric properties in the temperature range of 600 Ñ. In this work attention is paid to the improvement of thermoelectric efficiency of materials based on PbTe due to functional distribution and use of advantages of indium properties as a doping agent. The technology of obtaining includes the preparation of major alloys with necessary composition, crushing them to appropriate sizes of powder particles, cold pressing, sintering and annealing. It was demonstrated for the first time that dimensionless figure-of-merit ZT for p-type Pb0.5Sn0.5Te with different indium content approached 1 in wide temperature range (50-600 Ñ).
Sokolov Î.B., Skipidarov S.Ya., Duvankov N.I., Kurganov V.A., "NORD" Specialized Design Technological Bureau, Russia.
Pursuant to RoHS (Restriction of Hazardous Substances) and WEE European directives of January 27, 2003, the requirements regarding application of hazardous substances for manufacturing purposes became more severe. A need to abandon use in refrigerating thermoelectric materials of such traditional alloying additives as lead (Pb), cadmium compounds (CdCl2), mercury compounds (Hg2Cl2) etc arose. For this reason, the possibility of producing efficient p- and n-type materials free from toxic alloying additives was investigated. Earlier, in accordance with the technology of producing thermoelectric materials by means of hot extrusion developed and adopted by SCTB NORD, the p-type material had a traditional formula (Bi2Te3)26(Sb2Te3)74. It was alloyed using lead (Pb). An attempt to replace lead with tin (Sn) or germanium (Ge) was made. Replacement of Pb with Sn resulted in efficiency (Z) reduced by 20%, replacement of Pb with Ge resulted in efficiency reduced by 10%. However, a strong hardening effect of germanium was observed - more than two-fold under compression test. Investigation of the dependence of Z upon the (Bi2Te3)x(Sb2Te3)1-x formula in the range of x = 0 to 0.60 showed that there was a formula with x=0.19 to 0.22 requiring no alloying additives. Such a formula allows for stable producing of material with high efficiency values for the temperature range of 300±50K (Z =3.3x10-3 K-1 at 20°Ñ). That very formula was adopted for production as the main p-type material. As for the temperature range of 100 to 250K, it is reasonable to apply the unalloyed (Bi2Te3)x(Sb2Se3)y(Sb2Te3)1-x-y formula where x = 0.22 to 0.30 and y = 0.01 to 0.05. Specific x and y values are determined experimentally for each batch of the feed materials. As for the n-type material, the dependence of Z upon the (Bi2Se3)x(Bi2Te3)1-x was researched in the range of õ = 0 to 0.60. It was the (Bi2Se3)6(Bi2Te3)94 formula which proved to have the highest efficiency in the range of 100 to 350 K. Previously, alloying using CdCl2 was applied for optimization of properties, while now it is established that optimization of properties is possible without halogens as well, by means of certain processing methods only (crushing time, excessive Bi). In such a case, high efficiency values (Z = 2.9x10-3 K-1 at 20°Ñ) are achieved. This technology, along with the technology allowing usage of halogene compounds with elements not prohibited by RoHS (CHI3, C2C16, C6Br6), is implemented for production.
Ivanova L.D., Zemskov V.S., Granatkina Yu.V., Sokolov O.B., Skipidarov S.Ya., A.Baikov Institute for Metallurgy and Material Science, "NORD" Specialized Design Technological Bureau, Russia.
Materials based on bismuth and antimony chalcogenide solid solutions have been investigated. P- and n-type conduction extruded materials have been obtained with different charge carrier concentration (coefficient of thermopower was changed from 160 to 315 mKW/K at room temperature). Microstructure and thermoelectric properties of these metals have been studied in the temperature range of 100-300 K. It was established that plastic deformation took place in alloys under the extrusion that resulted in formation of recrystallized fine-grained polyhedral structure with grains from 2 to 20 mkm. Character of Seebeck coefficients, electric and thermal conduction change on temperature has been estimated. It was established that theory explaining mechanisms of carrier scattering in the above materials developed for alloys received by the direct crystallization methods covered materials received by extrusion. With decreasing of charge carrier concentration it was observed a thermopower coefficient maximum value shift to the region of lower temperatures.
Prototypes of micromodules have been produced and their characteristics: maximum temperature difference, optimal currents, resistances and thermoelectric efficiency coefficients have been investigated in the temperature range of 100-300K. Comparison of experimental characteristics of modules and calculated values obtained according to the program considering temperature dependences of legs material properties has been conducted.
Ivanova L.D., A.Baikov Institute for Metallurgy and Material Science, Russia.
Higher manganese silicide based materials with p-type conductivity have high thermoelectric effectiveness at temperature range 600 - 1200 K. The results of the investigation of single crystals doping of higher silicide manganese Ñr, Fe, Ge and Re obtained by Czochralski method are presented. There are effective distribution coefficients of these impurities determined and their influence on the microstructure and anisotropy of higher manganese silicide thermoelectric properties studied.
The method of production of higher manganese silicide based thermoelectric materials that were obtained by hot pressing was developed. The possibility of material pressing temperature decrease is shown by adding deoxidizing impurity and by using ultrasonic vibration during pressing process. Average quantity of thermoelectric efficiency factor of higher manganese silicide samples, doped by rhenium and obtained by hot pressing comes to ~ 0.7 x 10 -3 K -1 in the range 800 - 1300 K.
ITA academician Zemskov V.S., Shelimova L.E., Zhitinskaya M.A., A. Baikov Institute for Metallurgy and Material Science, Russia
Ternary layered tetradimite-like compounds in quasi-binary systems ÀIVBVI - AV2BVI3 (AIV - Ge, Sn, Pb: AV - Bi, Sb; BVI - Se, Te) ]
are of interest as thermoelectric materials (TE) with conductivity of n - and p-type. The compounds of PbBi4Te7 are of interest as thermoelectric materials (TE) with conductivity of n - and p-type. The compounds of PbBi4Te7 (n-type) belong to the large group of layered tetradimite-like chalcogenides with complex crystalline structures and low lattice thermal conductivity. The structure of ternary compounds is multiple sandwiches of different type with ordered alternation in the direction of hexagonal c-axis. The connection between the sandwiches is achieved by weak Van der Waals forces. Measurements of transport tensors: electrical conductivity s11, s33, thermal conductivity ê11, ê33, Seebeck effect S11, S33 and Hall effect R123, R321 (11- along the plane of cleavage face 33- in the direction of trigonal axis) were carried out on high-quality single crystals of ternary layered compounds of PbSb2Te3, PbBi4Te7 in the temperature range of 85-350 K. Essential anisotropy of thermoelectric properties is discovered. Experimental results on the measurements of Seebeck coefficient and electrical conductivity for PbSb2Te4 can be connected with peculiarities of energy spectrum of charge carriers.
Honoured ITA academician Goldsmid J., Australia.
The ideal synthetic transverse thermoelement is a composite made from two materials that themselves form a conventional thermocouple with a high figure of merit and simultaneously have very different values for the ratio of the thermal conductivity to the electrical resistivity. These two criteria can be met at low temperatures using a superconductor as one of the components but it is difficult to find a suitable pair of materials at ordinary temperatures. Previously, a reduction of the conventional figure of merit has been accepted in selecting metal-semiconductor or semimetal-semiconductor composites. However, it has recently been shown that a reduction in density of one of the components allows both criteria to be satisfied. These developments are reviewed and the paper also discusses the arrangement of the components. A layered structure is not the only form that a synthetic anisotropic element can take. For example, by using thin film technology, a transverse thermoelement can be formed in a single process. Also, an anisotropic material can be made by using embedded wires of one component in a matrix of the other. If this approach is adopted, the result may be a nanostructured synthetic transverse thermoelement.
ITA academician Hotra Z.Yu., National University "Lvivska Politekhnika", Ukraine.
Shtern Yu.I., Pavlova L.M., Mironov P.E., Moscow State Institute of Electronic Engineering (Technical University), Russia.
In operating thermoelectric cooling devices (ÒCD) large temperature gradients are created (more than 40K/mm), and in thermoelectric generators they are even larger. Due to stringent temperature conditions, mechanical strength of TCD should be sufficiently high.
Stability of mechanical characteristics is primarily determined by the proximity of the values of coefficients of thermal linear expansion of materials used in TCD designs. Between the structural elements of TCD with a view to reduce thermal loss, the intermediate layers of paste or glue with a relatively high thermal conductivity are deposited, damping, moreover, mechanical stresses caused by the difference in coefficients of thermal linear expansion. However, these intermediate layers further contribute to thermal resistance, hence a technological problem related to the necessity to optimize the thickness of intermediate layers to minimum critical value. The positive effect of reducing the thickness of intermediate layers is also the increase in the speed of response of thermoelectric device. Thus, requirements to the degree of compatibility between coefficients of thermal linear expansion of TCD materials should be rather stringent.
Thermoelements being a component of TCD design, are exposed to mechanical stresses in the course of assembly and operation. Mechanical strength of materials used for the manufacture of thermoelements (bismuth telluride based solid solutions), as compared to materials of other elements (metals and ceramics) is considerably lower, so it is a limiting factor for a change in TCD design. In connection with the foregoing, the availability of reliable data on thermal expansion of thermoelectric materials in a wide temperature range, including low temperatures, is a prerequisite in the design of TCD.
Analysis of the literature shows that investigations of thermal expansion of low-temperature thermoelectric materials of n- and ð-type in the range from 150 to 450 K are rather scarce or lacking at all. Anisotropic character of thermal expansion for all studied low-temperature thermoelectric materials was established. Thermal expansion of Bi2Te3 compound in the temperature range above 300 K has been studied in more detail by several techniques. At lower than room temperatures, temperature dependences of coefficients of thermal linear expansion of bismuth telluride have been obtained only in two papers and there is a marked difference between them. For Bi2Se3 compound coefficient of thermal linear expansion along crystallographic directions, parallel and perpendicular to cleavage planes (a and a), was studied on polycrystalline samples in the temperature range of 300 - 930 K, and for Sb2Te3 compound coefficients of thermal linear expansion were studied in a narrow temperature range from 300 to 400 K. Information on coefficients of thermal linear expansion of solid solutions Bi2Te3 - Bi2Se3 and Bi2Te3 - Sb2Te3 are fragmentary and scattered in different sources. The presence of interaction between the components does not enable to use for these systems the additivity rule in the calculation of coefficients of thermal linear expansion of solid solutions based on the data of pure components.
In this connection, the present paper deals with critical analysis and choice of the recommended values of coefficients of thermal linear expansion of low-temperature thermoelectric materials by joint processing of the literary data by least-squares method and on the basis mutual agreement of temperature dependences of volumetric coefficients of thermal expansion and heat capacities. Thermodynamic procedure for calculation of coefficients of thermal linear expansion for solid solutions Bi2Te3 - Bi2Se3 and Bi2Te3 - Sb2Te3 is proposed.
Honoured ITA academician Vedernikov M.V., A.F.Ioffe Physics and Engineering Institute, Russia.
Theoretical idea on the possibility of gigantic increase of thermoelectric figure of merit in low-dimensional nanostructures has attracted considerable interest in thermoelectric studies during recent 15 years. Several papers experimentally demonstrated thin-film structures with ZT = 2,5-3. However, higher figures cannot be obtained for the time being. In the analysis of the problem it is useful to recollect that in the theory of condensed state as far back as since the 1960-s an original approach to study of energy structure of single-dimensional objects ("quantum wires") - the Luttinger liquid theory has been developed. The paper summarizes the results of experimental research on a series of transport properties of quantum wires in A.Ioffe Physics and Engineering Institute. They agree with the Luttinger liquid theory.
ITA academician Freik D.M., V.Stephanyk Pre-Carpathian National University, Ukraine.
Virt I.S., Shkumbatyuk T.P., Kurylo I.V., Rudyi I.O., Lynnyk L.F., TeterkinV.V., I.Franko Drohobych State Pedagogical University, National University "Lvivska Politekhnika", V.Lashkarev Institute for Semiconductor Physics of NASU, Ukraine.
Semiconductor compounds of V2VI3 type are rather widely used as materials for thermoelectric devices due to their high coefficient of thermoelectric conversion - ZÒ. In particular,
Bi2Te3
is known to be the best thermoelectric material. With the existing tendency to miniaturization of thermoelectric devices, alongside with studying the properties of the bulk samples, it is also necessary to study the properties of thin films of these materials.
This paper provides the results of studies on Bi2Te3 thin films doped with acceptor and donor impurities, as well as structures on their basis. The respectively synthesized Bi2Te3
ingots were used as targets for their subsequent evaporation-deposition by pulsed Nd:YAG laser (PLD method). Thin films were grown onto heated 200 -300 °C substrates: glass, sapphire or silicon. Film thicknesses, depending on growth conditions, made from 30 to 3000 nm. Measurement of electric resistivity, study on surface morphology and structural analysis of the resulting films were performed. Electron diffraction (RHEED), X-ray radiation (XRD), transmission electron microscopy (TEM) were used. Crystalline indices were identified and parameters of crystal lattice of rhombohedral structure of films on different substrates were determined. Average grain size of films texture was assessed with different film thicknesses.
Kahramanov K.Sh., Scientific and Production Association "SELEN", Azerbaijan.
ITA academician Sabo E.P., Abkhasia.
Due to the advent of new space programs (Lunar, Martian and Deep Space) the demand for thermoelectric generators (TEG) with higher efficiency, specific power and service life resumed. The results of test and operation analysis of earlier constructed TEGs are presented in the report. It is shown that potential of well-known thermoelectric materials is not realized completely, main reasons are material structural peculiarities and low mechanical properties. The ways to problem solution of TEG efficiency improvement, connected with thermopile construction changes and production techniques of thermoelement legs and their commutations, are determined. Positive results of preliminary tests on producing ring thermopiles, improvement of material mechanical properties by means of their fine-grained crystal structure formation and thermal stress reduction in commutation bridges using plasma, ion-plasma and thermoreactive technologies during their formation, are presented.
ITA associate-member Arakelov G.A., Scientific and Production Association "Orion".
ITA associate member Volkov Ì.P., Close JSC "RMT", Russia.
ITA academician Lobunets Yu.M., Institute of Thermoelectricity, Ukraine.
On the basis of the analysis of generalized model of thermoelectric heat pump (THP), basic conditions under which thermoelectric method of energy conversion is able to provide competitiveness of the equipment for domestic heating and air-conditioning system are determined. One of possible diagrams for heat recovery in ventilation systems is examined; its technical and economic analysis is carried out. Basic requirements to such systems and basic tasks for the development of this direction of THP application are formulated.
Klyndyuk A.I., Chizhova Å.À. , Sazanovich N.V., Krasutskaya N.S., Belarussian State Technological University, Belarus.
Results of research on electric conductivity and thermoEMF of ceramics based on laminated perovskite-like oxides (LnBa)(Me'Me'')O5+s (Ln=ÐÂÅ, Ìå', Me"=Fe, Co, Cu) (i), as well as perovskite barium-strontium Ba1-xSrxPb1.1O3+s(ii).
are presented.
It is found that (i) compounds are p-type semiconductors, whose conduction with increasing temperature is changed for metal, which is due to release of "loosely-coupled" oxygen from the samples. The (ii) phases are n-type conductors, whose conduction changes from metal to semiconductor with increasing degree of strontium substitution for barium.
Based on the results of research on electrophysical properties, parameters of electric current transport in studied materials were determined and the values of their power factor were calculated.
Comparison of power factor values of (i) phases with the literary data allows concluding that laminated perovskite-like oxides can be considered as the basis for search and elaboration of new thermoelectric materials efficient at elevated temperatures.
It is established that introduction of excess lead to (ii) phases leads to a considerable increase of their power factor. Thus, the method used in this paper for self-doping of perovskite oxides by creating cation nonstoichiometry therein can be considered as a promising way for enhancement of their thermoelectric figure of merit.
ITA associate member Smolyar G.O., Kozub L.S., Lozbin D.V., State Enterprise
Central Design Bureau "ARSENAL", Ukraine.
Specialists of ITE NASU in the frame of Contract ¹033 of 01.0408 have finished the works on special electrogenerator demonstration sample creation on the base of thermoelectric and eddy effects (TEG).
Development of an experimental sample of TEG-14/06 preceded to the works on TEG that confirmed the feasibility of characteristics required by the gas industry on reliability, safety and durability of special equipment included into an average statistical gas distributing station (GDS). Necessity for electric power increase realized by electric generator (from 14 to 30… 50 W/min) at simultaneous gas consumption value decrease via the generator as well as mass/dimension characteristics and metal consuming constructions has been established.
Under TEG's development by authors:
It was realized a circuit of electric generation by thermoelectric modules (TM) of required electric power with the use of two staged eddy tube electric unit that provided the conduction of the main technical and economic characteristics;
it was created a mathematical model of an electric generator ensuring the possibility of the structure calculation and characteristics of the device units with the given parameters;
it was made a special stand ensuring the possibility of air supply to the TEG with parameters similar to the real operation conditions;
as a result of the sample half natural tests made on the base of sealed TM (ITE NASU development and production, it was established the possibility of electric power obtaining about 40 W in dc circuit with voltage up to 24V on the electrogenerator sample of 40 kg and gas consumption of 0.3 nm3/h. The TU project has been prepared and the search of possible application spheres of thermoelectric electrogenerators use with eddy tube energy conversion of compressed gas has been done.
Shenderovsky V.A., Rokytsky A., Institute of Physics, Ukraine.
7.1. Mathematical model of thermoelectric generator with a vortex tube as a source of heat.
Lozbin D.V. State Enterprise Central Design Bureau "ARSENAL", Ukraine.
The operating principle and the results of the full-scale tests of thermoelectric generator TEG -14/06 with a vortex tube as a source of heat (further TEG-VT), meant for autonomous electric power supply of CCGC at GDS, are presented in (1). Tests showed that TEG -14/06 provided the required electric power supply for statistical GDS; however, the need for generator improvement to increase generator electrical power (from 14 to 30… 50 W - min) with simultaneous reduction of gas flow through the generator, is established.
The full-scale realization of TEG-VT design variants and conducting the larger volume of tests on natural gas under the conditions of GDS and even in compressed air is combined with the large technical and organizational complexities, and significant financial costs. Therefore the analysis of generator construction diagrams should be carried out on mathematical models.
Three variants of TEG- VT with one-stage gas expansion and diagrams with two-stage gas expansion in vortex tube block are examined in reports.
Mathematical model includes the equation of heat balance on thermoelectric module joints, the equation of heat balance in heat exchangers, empirical equations for the values of temperature effects in vortex pipes. As a result of the solution of combined equations, limiting analytical expressions for the optimum parameter ratios of a vortex pipe and the system of thermoelectric modules (TEM), are obtained.
It is shown that the power (up to 27 V in direct-current circuit of 1.5 A) generated by TEG-VT is sufficient to provide electric power supply of CCGC at GDS. Temperature difference (60… 90 °C) formed by the vortex tube heat generator makes it possible to use effective and relatively cheap TEMs based on
Bi2Te3 - Bi2Se3.
solid solutions.
The efficiency of use of examined generator circuits for different operating conditions at GDS is analyzed.
The use of one-stage generators is shown to be favourable at drops of pressure of
Ðâõ/Ðâèõ < 8,
with large pressure differentials the two-stage diagram of expansion makes it possible to considerably increase temperature differential on the joints of thermoelectric modules resulting in output electrical power increase.
7.2. Ìàthematical models and inverse problems of theory of elasticity and chemical bond in low-symmetry crystals of cadmium antimonide and zinc antimonide.
Hutsul I.V., ITA academician Manyk O.N., Manyk Ò.Î., Chernivtsi National University, Ukraine.
During the study of solid-phase conversion processes, structural changes in alloys during their heating above critical temperature and cooling down to subcritical temperature are of special interest. It gives the possibility to approach molecular-kinetic laws of the formation of crystalline processes of melting and crystallization with relation to chemical bonds.
Theoretical concepts used for the analysis of these processes and being semi-phenomenological based on ontological method are known. As the result at present time there is no definite microscope theory on disordered systems. Making up the principles of this theory revealed the need for expanding the basis of existing theoretical developments by the quantitative calculations, realized by the method of chemical bonds theory. Such synthesis makes it possible to improve classical diagrams of the use of different methods and approaches for problem solution of materials science with the purpose of search for operating practices of obtaining materials with predetermined properties.
In this connection, the objective of this work are comprehensive analysis of the dynamics of chemical bond formation in the crystals of cadmium and zinc antimonide solid solutions using the methods of the theory of oscillations, theory of elasticity and molecular models.
The obtained results of characteristic frequencies investigations on the basis of the calculations of microscopic theory force constants made it possible not only to explain "the fine structure" of the processes of melting and crystallization in solid solutions of CdSb - ZnSb, but also to refine operating practices of the synthesis of new materials with the predetermined properties by setting the conditions of formation (overheating and supercooling temperature range) of those chemical bonds, which are responsible for the appearance of constant properties.
The results obtained can be used for the development of operating practices of the synthesis of new materials on basis of solid solutions
7.3. Thermoelectric coefficient and chemical potential as important features of crystals to determine their inherent parameters.
ITA academician Budjak Ya.S., National University "Lvivska Politekhnika", Ukraine.
Thermoelectric coefficient and chemical potential are important features of semiconductor crystals, which have wide application in contemporary solid-state electronics. As a rule, for this application it is necessary to know different crystalline parameters, which can be determined according to the analysis of experimental measurements of different crystalline properties. The work shows how it is possible to calculate inherent extrinsic crystalline parameters using experimental measurements of kinetic crystalline properties including thermoelectric coefficient.
7.4. Thermoelectric generator for telemetry systems.
ITA associate-member Mykhailovsky V.Ya., Ludchak I.Yu. , Institute of Thermoelectricity, Ukraine.
Investigation results and results of developing thermoelectric generator for supply of autonomous systems of the telemetry of gas-distributing stations are presented. The results of simulation and optimization of its basic energy parameters are given. Construction is described and the results of experimental studies on generator are given.
7.5. On the nanodimensional anisotropy of CdSb and ZnSb thermoelectric materials.
Mikhalchenko V.P. Institute of Thermoelectricity, Ukraine.
To conduct quantitative assessments of dimensional boundary value L below which essential differences in physical properties of nanocrystals in comparison with macroscopic objects are manifested, it is proposed to determine the value
Lxi=230Teta-1/2xi,
,where -
Q
is X-ray characteristic Debye temperature. Anisotropy of Lx is illustrated regarding to nanocrystals of p-type CdSb and ZnSb (rhombic syngony, space group
D152h)used in thermoelectric instrument engineering. Differences in
Lxi make it possible to unambiguously define the directions along which the physical properties of nanoparticles differ more significantly from those of respective macroscopic crystals. The questions on dimensional dependences
Q , mean-square displacement, function of spectral distribution of oscillation frequencies , as well as the questions on nanoparticle habitus (pattern) are briefly discussed. Physical argumentation in favour of estimations on
Lxi according to both gnosiological and applied meaning is presented.
7.6. Spiral zone-inhomogeneous thermoelements.
Kuz' R.V., Institute of Thermoelectricity, Ukraine.
Three-measurable physical and computer model of SZITis developed. Temperature, current and potential distributions in SZIT are obtained, and stress and efficiency of SZIT in the mode of power generation are calculated. Optimization of SZIT geometric design is carried out by means of computer simulation aiming to achieve maximum efficiency.
Efficiency of SZIT is confirmed by the results of experimental studies and tests.
7.7. Absolute method for determination of parameters of thermoelectric cooling modules.
Demyanyuk D.D., Institute of Thermoelectricity, Ukraine.
Presently the problem of qualitative and precise determination of parameters of TEMO is topical. Application of absolute method of measuring TEMO parameters which is quite simple and reliable makes it possible to solve this problem. This method gives the possibility to determine basic parameters of thermoelectric cooling modules with high accuracy: optimum current and voltage, maximum temperature difference and cooling efficiency.
7.8. Double- and three-layered transverse-type composite thermoelements.
Nitsovych O.V., Institute of Thermoelectricity, Ukraine.
Computer model for new types of thermoelements, namely double- and three-layered thermoelements, with periodically shaped surface, which gives the possibility to find temperature, current density, electric potential distributions in thermoelement working medium and to determine its efficiency and transverse thermal emf relative to temperature gradient, is developed. Optimization of geometry and transverse thermal emf of thermoelements is carried out.
The results of the computer optimization of two-layered transverse thermoelements with shaped surface are experimentally confirmed. The results of computer simulation are shown to be more precise and do not exceed the limits of error of physical experiment. By means of computer simulation of short-circuited thermoelements with metallic shorting strips covering semiconductor layer it is possible to increase initial transverse emf by 2 - 6 times.
7.9. Doping of Bi2Te3 -based solid solutions with electroactive impurities (Pb, TeI2).
Kopyl A.I., Institute of Thermoelectricity, Ukraine.
The results of experimental investigations of thermal emf and electrical conductivity dependences of solid solutions based on
Bi2Te3
compound grown by vertical zone melting technique on doping level of the initial synthesized ingots are given. It is established that increase in the ratio of quantity of carriers formed by impurities (Pb, the I) and other defects including anti-structural ones contributes to increase of
a2s
decreases thermal degradation of material at operating temperatures of generator hot junction about ~650 K. It is also established that during the process of doping of
ð-(Bi2Òe3)0.25 (Sb2Òe3)0.72 (Sb2Se3)0.33
with lead in quantities exceeding 0,6% mass the process of saturation is observed.
The use of such material for thermoelectric generators development made it possible to increase module efficiency by 18%.
7.10. Method for non-invasive control of thermoelectric material parameters.
Ascheulov A.A., Buchkovsky I.A., Velichuk D.D., Institute of Thermoelectricity, Ukraine.
The possibilities of original method for the eddy-current control of basic parameters of thermoelectric materials are shown. Previous experimental results carried out using eddy-current sensors indicate the prospect of this direction.
7.11. Computer simulation of processes of bulk distribution of eddy Foucault currents in thermoelectric media.
Ascheulov A.A., Velichuk D.D., Institute of Thermoelectricity, Ukraine
Investigations on the possibility of simulation of distribution of eddy Foucault currents in thermoelectric media for the case of symmetrical nature of current which flows through the measuring oscillatory circuit are carried out on the basis of C.
7.12. Vehicular thermoelectric air-conditioner under extreme conditions.
Rozver Yu.Yu. , Institute of Thermoelectricity, Ukraine.
Ñomparative analysis of compression and thermoelectric conditioners under extreme operation has been given. Results of vehicle thermoelectric conditioner design development intended for operation under elevated temperatures and the study of its parameters and characteristics have been presented.
7.13. Transverse short-circuited thermoelement under electric power generation mode.
Kobylyansky R.R., Institute of Thermoelectricity, Ukraine.
Short-circuited thermoelements have definite advantages in comparison with other cross-type thermoelements since they can have larger efficiency value, high initial voltage and reliability under some conditions. Investigations of short-circuited thermoelements by computer simulation have been given. Distributions of currents, potential and temperature in such elements that enable to determine electric and energy parameter dependences on shorting conductor material, their number, cross-section area and orientation with respect to temperature gradient have been obtained. Optimal conditions for achievement of maximum thermal power and efficiency value have been defined.
7.14. Computer research on power characteristics of spiral rectangular anisotropic thermoelement.
Prybyla A.V., Institute of Thermoelectricity, Ukraine.
Special computer model of a helical rectangular anisotropic thermoelement (HRAT) that enables to study HRAT energy characteristics and physical fields within the thermoelement on the themal energy and current generation mode and the heat pump mode has been created.
The localized eddy thermoelectric currents (LETC) effect in the HRAT's loop operating body has been discovered.
Assessment procedure of the material kinetic coefficient temperature dependences has been developed. Comparison of HRAT efficiency obtained by the computer simulation and approximate analytic formula has been fulfilled. It was stated that error in HRAT efficiency comparison with the help of approximate analytic formulas became considerable and reached 50% at temperature gradient increase.
Recommendations were worked out for making a sensitive detector on the base of HRAT. Volt/watt sensitivity of the proposed structure was 15% higher.
Parameters and electric outlet terminals optimization that enables to reach the HTAT efficiency improvement 12% higher has been made.
7.15. Electric conductivity anisotropy measurements on discs.
Lysko V.V. Institute of Thermoelectricity, Ukraine.
Development results for the measurement method of electric conductivity tensor component ? on thermoelectric material thin discs have been presented. Electric potential distribution in thermoelectric material discs on material conduction values and its anisotropy under two current modes have been found with the help of computer simulation. According to the obtained dependences calibrating curves for the electric conduction tensor component determination on the measured voltages between probes placed on discs edges have been plotted.
Given results present the base for the measurement unit development which enables measurements of all electric conduction tensor components on discs.
7.16. Use of catalysts for heat and electricity generation.
Strutynska L.T., Institute of Thermoelectricity, Ukraine.
Investigation results of the heating catalytic elements for gaining of ecological heat and heat catalytic sources included into thermoelectric generators for electric energy generation have been presented. It was shown that the main way for the use of total catalytic oxidation of gas and liquid fuel are heating elements and heating systems for domestic and quarters, radio electronic equipment, devices for direct conversion of thermal energy into electric one. The most promising is the catalysts use for the microgenerator on organic fuel development
7.17. Domestic use of thermoelectricity.
Shevadzutsky A.O., Institute of Thermoelectricity, Ukraine.
Thermoelectricity application in private life has vast but not totally used potentialities. Thermoelectric energy converters due to their usability, reliability, long life, capability of simple combination with many equipment and systems, maintenance-free may be introduced in wide application. Now from all approaches of thermoelectricity in private life that which can be introduced into wide use and characterized by the most variety applications is thermoelectric cooling and thermoelectric energy generation
Thermoelectric energy generation enable to increase heating system efficiency due to heat losses recuperation, enable to make self-contained heating systems producing energy for automatics supply; to develop heat and energy generators; to develop devices of daily use that use for operation heat of human body (wristwatches); to use for supply of different low-powered energy consumers and even to find alternative to chemical sources of current. Though efficiency of current thermoelectric generators if not large, they find successful application for the development of many domestic appliances that may have large total efficiency (heat and energy generators); to develop absolutely self-contained heating systems, or use small heat flows (TEG for wristwatches).
Thermoelectric cooling makes provision for creation of unique units, may be used in regions where use of other cooling (compression and absorption) is difficult. On the base of thermoelectric coolers it is possible to develop handheld coolers; personal mini-coolers; coolers-showcases and coolers-services; thermoelectric coolers for cosmetics and thermoelectric medicine chests that can be combined with furniture interior; thermoelectric coolers for electronic devices (cameras, computers). Thermoelectric coolers advantage over traditional compression ones is its small response time and highest exactness of cooling temperature establishment, possibility of pumping out small heat fluxes, local cooling that is important in the use of individual minicoolers and coolers for electronic equipment.
7.18. Measurement of parameters of generator modules.
Havrylyuk M.V., Institute of Thermoelectricity, Ukraine.
Investigation of heat balances under the generator module parameters measurements at the temperature range of 80?300°Ñ.
It is presented a calibration method for the heat meter and the assessment of its errors under the given efficiency of the generator modules on the stand.
7.19. Simulation by method of thermoelectric phenomena particles.
Strutynsky M.M., Institute of Thermoelectricity, Ukraine.
Mesoscopic model of thermoelectric phenomena has been studied. The model presents the system of interacting particles in cells. The lattice electron gas dynamic, heat and charge transfer in heterogeneous media have been described. Electromotive force (Seebeck effect) is appeared at different temperatures on the junctions of two conductors represented as a spatial lattice, the appearance of electromotive force leads to additional heat flow on the junctions (Peltier effect). Program realized a spatial model of particles in cells has been developed.
7.20. Computer simulation of relability of thermoelectric multielement generators.
Savchenko L.O., Institute of Thermoelectricity, Ukraine.
A computer model has been firstly developed for the main parameters reliability calculation for the system consisted of parallel-series elements connection. It is necessary to give a program algorithm included the system operation algorithm that consists of parallel-series connected elements, on the base of the composed program with the help of the computer model theory of probability to show arbitrary failure of elements and to make calculation of the reliability main parameters by means of the computer modeling method of random processes.
7.21. Thermoelectric field in a medium with needle inclusions.
ITA academician Melnychuk S.V., ITA academician Luste O.J., Chernivtsi National University, Institute of Thermoelectricity, Ukraine.
7.22. Peculiarities of physics-chemical and thermal processes in low-power catalytic heat sources.
Strutynska L.T., Slavnych Yu.O., Institute of Thermoelectricity, Ukraine.
Physical and chemical processes analysis results and thermal processes in diffusion catalytic heat sources have been presented, their rational thermal powers for effective use in thermogenerators have been determined. Peculiarities of system with repeated heat recirculation and methods of catalytic heat sources efficiency increase due to efficient activation energy decrease of organic fuel combustion process, considerable upper and lower combustion range expansion on composition of fuel-air mixture and heat recuperation have been studied.
7.23. Thermoelectric devices for skin treatment.
Kobylyansky R.R., Mochernyuk Yu.N., Institute of Thermoelectricity, Ukraine.
Thermoelectric cooling (heating is widely used in many branches of medicine such as cryotherapy, cryosyrgery, traumatic surgery, plastic surgery, dermatology, etc. In traumatology thermoelectric devices can be used for cryomassage conduction (stimulation of metabolism, wrinkles smoothing), for pyoinflammatory processes treatment, warts freezing , for tempering conduction of individual parts of humane body and other medical procedures. So development and improvement of thermoelectric medical devices for dermatic deseases treatment is very actual.
Institute of Thermoelectricity of National Academy of Science and Ministry of Education and Science, Ukraine, has developed thermoelectric devices for skin treatment (by liquid and air cooling) which characterized by high reliability, preciseness, functionality and they are easy in handling.
7.24. Eddy thermoelectric currents in thermocouple thermoelements.
ITA academician Luste O.J., Gamal O.N., Institute of Thermoelectricity, Ukraine.
7.25. Optimization of response characteristics of thermoelectric converters for measuring technique.
Bodnaruk V.I., Taschuk D., Institute of Thermoelectricity, Ukraine.
Operating band and measurement error in this band is one of the most important characteristics of AC thermoelectric converters. Geometric parameters and electric characteristics of thermoelectric converter heater have been calculated. Reacting element effects on measuring accuracy have been evaluated. Conditions under which band is expanded and measuring error is decreased, have been established.
7.26. Functionally-graded materials obtained by extrusion method.
Razinkov V.V., Vykhor L.M., Rynzhuk M., Institute of Thermoelectricity, Ukraine.
7.27. Atomic-force microscopy of bismuth crystals and films surface.
Grabov V.M., Demidov E.V., Komarov V.A., A.I.Herzen State Pedagogical University, Russia.
Development of scanning probe microscopy methods is considerably expand possibilities of structure investigation of crystal, films, mesostructure and nanostructure surfaces, modification of surface structures. In this work the scanning probe microscope of Russian company NT-MDT has been developed for structure investigation of single crystals and bismuth and bismuth antimony alloys surfaces.
New methods for surface structure investigations combining preliminary chemical and electrochemical treatment with subsequent atomic-force microscopy have been developed. Method of defect and grains boundary decoration by natural oxidation during surface exposure in air for a specified time is recognized as the most simple and effective method. Obtaining of detailed information on films structure with the use of the developed methods provides the possibility for correction of film preparation condition by thermal evaporation in vacuum and obtaining of films with structure near to metallic one.
It is also developed a new method for electrochemical modification of surface during the prob scanning of crystals and films that is of interest for nanostructure modification.
7.28. Thermoelectric and thermoelectrokinetic effects in aqueous solutions of ionic compounds.
Grabov V.M., Zaitsev À.À., Kuznetsov D.V., A.I.Herzen State Pedagogical University, I.A.Bunin Yelets State University, Russia.
Science on thermoelectricity has got its essential development as a science on cross phenomena in thermodynamics and electricity, mainly, in solids, metals and semiconductors.
Expanding bands used in electric conductive media as well as thermodynamic conditions up to essentially non-equilibrium ones is of scientific and practical interest.
Experimental investigations of thermoelectric motive force in new media, aqueous solutions of a number of ion compounds, acids, salts and alkali in the temperature range of 20 - 600°Ñ have been conducted. In diluted solutions of ion compounds thermal electric motive force value in the temperature range of 20 - 600°Ñ reaches 0.6-1.8 mV/K and weakly depends on solution concentration and temperature. Thermal electric motive force partial coefficients of ion electrolytes aqueous solutions are weakly depend on solution type and concentration and are about 1,4 0,1 mV/Ê. Thermal electric motive force value and sign of solutions are essentially defined by the ion mobility ratio of opposite signs.
Under kinetic non-equilibrium when heat and mass transfer take place in viscous electric conductive medium, new thermal kinetic phenomena have been disclosed and investigated. It was shown that thermal kinetic electric motive force sign in electrolytes aqueous solutions is defined by the sign of the most mobile ions, value at the fixed temperature difference 20 - 600°Ñ reaches its maximum with the value of some millivolts depending on electrolyte flow rate, linearly depends on solution concentration in the range when the solution may be considered as deputed. The obtained results denote the existing pole of thermal electrokinetic phenomena in the self-organization processes and evolution in outward things.
7.29. Computer simulation of permeable thermoelements in heating mode.
Cherkez R.G., Dudal V.O., Institute of Thermoelectricity, Ukraine.
Method of computer simulation of a permeable thermoelectric element under heating has been presented. Energy characteristics (heating coefficient, heat production, heating of heat-transfer medium) of a permeable thermoelectric element based on
Bi2Òe3,
have been defined and geometric and structural parameters (heat transfer medium pumping rate, legs and channel geometry) have been investigated. Comparison of the obtained results with similar characteristics for classical bulk thermoelectric element has been made. The comparison showed that permeable elements based on Bi2Òe3 exceed bulk ones over the heating coefficient by 40%.
7.30. Efficiency of using the heat of low-grade sources by means of different thermoelectric converters.
7.31. Connection schemes of thermoelectric generators using the exhaust gas heat of internal combustion engines.
7.32. Microthermocouple of bifilar microwires based on thermoelectric Bi2Te3.
7.33. Use of converters without input terminals for thermoelectric device power supply.
7.34. Formal analysis of experiments by Galvani and Volta related to thermoelectricity.
7.35. Enhanced efficiency in optoelectronic systems using thermoelectrics.
7.36. Study of the influence of the thermal resistance in a thermoelectric generation system.
7.37. Domestic refrigerator with cold production by vapour compression and thermoelectricity.
7.38. Design and technology of generator modules of Bi-Te based segmented thermoelements.
7.39. Thermoelectric cooling of CdTe detector of X- and g-radiation instead of using CdZnTe ternary semiconductor.
7.40. Systems providing thermal modes of equipment and devices based on heat pipes and thermoelectric modules.
7.41. Prospects for use of permeable thermoelements in thermoelectric air conditioners.
7.42. Computer simulation of Geiling thermoelement.
7.43. Material for gyrotropic thermoelement.
7.44. Thermopile generator using thermal flows in soil.
7.45. Studies on the reliability of "Altec" generator modules.
7.46. Measurement of parameters of thermoelectric materials on rods.
7.47. Peculiarities of technology for producing increased-diameter Bi-Te-Se-Sb.
7.48. On the properties of gyrotropic thermoelements.
7.49. Industrial equipment for Bi-Te manufacture.
7.50. Method of samples preparation for measurement of thermoelectric material parameters.
7.51. Bi-Sb thermoelectric generator modules.
7.52. Computer research on anisotropic thermoelements.
7.53. ThermoEMF in L1-D1 germanium models under strong hydrostatic stress.
7.54. Thermoelectric generator for heating systems.
7.55. Ultraporous aluminum oxyhydroxide with laminated-fibrous nanostructure as a promising material for thermoelectric converters.
7.56. ThermoEMF and electric conductivity of solid solutions of lanthanum and neodymium cobaltines-gallates.
7.57. Thermoelectric properties of single-conductor bismuth wire with electron/hole variants with Ñ3
7.58. Aaronov-Bohm thermoEMF oscillations in quantum bismuth wires at 3K.
7.59. Thermoelectric propertres of glass-insulated single-crystalline wires Bi1-xSbx (0«õ«0,12)
7.60. Anisotropy parameters of physical characteristics in solid solution Cd0.5Zn0.5Sb and their related transverse effects.
7.61. Availability of thermoEMF of semiconductors as technique of their investigation.
7.62. A.Volta and problems of thermoelectricity teaching at schools and universities.
7.63. Design procedure of internal mechanical and thermal stresses occurring in thermoelectric devices forming crystal-solder-heat sink (metal).
7.64. Anisotropic thermoelectric converter based on bismuth microwire in glass insulation.
7.65. Thermoelectrical sensors for power meter of laser emission.
Korzhuyev Ì.À., Nikhezina I.Yu., A. Baikov Institute for Metallurgy and Material Science, Russia.
It is known that problem of low-potential heat sources use (PLPHS) may be effectively solve with the help of thermoelectric converters (TEC) - thermoelectric generators (TEG) and heat pumps (coolers (TEC) and heaters (TEH) [1]. Relation L= Q1/À= Ê+1>Ê>>h and L > 1 is observed between TEG's efficiency
h=À/Q1
coefficient of performance Ê= Q0/À
and heating coefficient
L= Q
Korzhuyev Ì.À., A. Baikov Institute for Metallurgy and Material Science, Russia.
Thermoelectric generators (ÒEG), using waste gas heat of internal combustion engines, work on considerable temperature differences
D(Ò)=(Ò1 - Ò0) (where Ò1
up to 800-1000 Ê is a waste gases temperature,
Ò0~20±30 Ê is a cooler temperature (air, water) [1]. As a result, in TEG's legs occur a bulk thermoelectric effects (BTE) that change coefficient of efficiency
s of devices (sh is up to ± 30%) [2].
Meglei D., Dantu M., Donu S., Rusu A., Institute of Electronic Engineering and Industrial Technologies, Moldova.
One of the high-priority domains of development of current technologies is fabrication of low-dimensional devices based on nanostructures and microwires. Optimum parameters of microdevices depend, first of all, on electric, thermoelectric, and mechanical properties.
In this work, we present the results related to the technology of fabrication of glass-isolated bifilar microwires (BMs) with electrodes of different conductivity of thermoelectric materials based on
Bi2Te3
and determination of mechanical properties carried out by methods of deformation and microscopic analysis of structural defects for preparation of microthermocouples on their basis.
Preliminary studies have shown than BMs have higher flexural rigidity in comparison with single wires of the same material. The breaking strength of BMs referring to a unit of the transverse cross-section of a sample (including glass) is in the range of 18 - 6 kg/mm2 corresponding to the diameters 90 - 120 m.
Microthermocouples with the thermoelectric signal value of 2-12 mV in the temperature range 23-50°C have been fabricated. Preparation of thermoelectric microthermocouples of BMs reduces a wide range of technological procedures and considerably increases its resistance to impact and vibrations. Microthermocouples of glass-isolated bifilar microwires are compact, have low dimensions and weight; they may be applied for measurement of temperature in aggressive chemical media.
Korzhuev Ì.À., Àvilov V.S., Svechnikova Ò.Å., A. Baikov Institute for Metallurgy and Material Science, Russia.
Coefficient of efficiency
(h)
of thermoelectric devices (ÒED) is to a greater extent determined by a coefficient of efficiency of power supply units used. Traditional power supply units with a transformer inlet have low coefficient of performance
(h=50%)
large weight and size, output voltage stabilization range in it usually not exceed
sU//±10%
under input voltage differences
DU=180-260V. Current pulse power supply units (PPSU) with transformerless input for voltage conversion use pulse the principle of duration modulation (PDM), or pulse frequency modulation (PFM), and have essentially improved operating characteristics
h=70%,(theoretical limit is 95-99%), low mass and size.
The purpose of the work was to study the possibilities of PPSU used in computer and domestic equipment, for thermoelectric applications.
Advantages of PPSU have been justified in the work (2). Stipulated with high precision voltages U//=±5 Â and ±12 Â, as well as stabilized operating currents of PPSU (I// to 30 À), are suitable for the most TED tests. It was marked the relative cheapness and unshortage of PPSU (in particular in computers), simultaneous connectivity of some thermoelectric modules to PPSU including under durable test conduction (t>100 h).
Korzhuev Ì.À., Katin I.V., A. Baikov Institute for Metallurgy and Material Science, RAS, Russia.
Experiments made by L Galvani and A.Volta (G&V) [1] arouse increased interest of researchers including those who work in the field of thermoelectricity [2] and heuristics theory [3]. Thermoelectric phenomena are stipulated by the connection of thermal and electrical processes in the conductors (electronic (Õ1), [3]), ionic (Y3) and mixed (X1, Y3); solid (X), liquid (Y) and gaseous (plasma) (Z)). G&V used cells in their experiments that consisted of conductors with electronic conduction (metals (X6)) and ionic conduction (liquid electric stoves). The constituents of the latter were fabrics of preparative frogs (F) that had increased sensitivity of nerve endings during the premortal period [1].
Vogelsang A., Tatarinov D., Bastian G., University for Applied Research, Germany.
During the last decades, thermoelectricity has been used in optoelectronic systems for cooling purposes only. Due to limitations of passive cooling, waste heat of LEDs and semiconductor lasers was diverted from the system with Peltier-coolers avoiding overheating of the semiconductor. In addition thermal tuning of the emission wavelength of semiconductor lasers is a well a known application of thermoelectricity.
We have investigated constraints of further applications of thermoelectricity, i.e. thermoelectric generators (TEGs) in mobile optoelectronic systems. In these systems one or more LEDs or lasers emits light at different wavelengths. Key figures are the temperature dependence of the conversion efficiency from electrical to optical energy for a given type of LED or laser as well as the conversion efficiency of fluorescence dyes along with their temperature behavior. We were able to demonstrate how TEGs can improve the total system efficiency of mobile optoelectronic systems like mobile LED-beamers. This approach is compared to alternative measures for enhanced performance like the increase of battery capacity or the improvement of LED efficiency.
J. G. Vian, D. Astrain, A. Rodriguez, A. Martinez, Mechanical Energy and Materials Engineering Department public University of Navarra, Spain.
The thermoelectric generation system is based on the transformation of the calorific energy, directly in electric energy, so a part of the contributed heat, from the hot focal point to the system, is transformed into electric current, while the rest of the heat is transferred to the cold focal point, usually the ambient. The system performance depends, mainly, on the temperatures reached in the sides (hot and cold) in the thermoelectric module, which depends on the focal points temperatures and the thermal resistance between the thermoelectric module side and the thermal focal point.
The use of the residual heat in the thermoelectric generation represents an application with a great prospect of future [1], [2] y [3] taking into account the current energetic crisis. The main inconvenient of this application is the low temperature available in the thermal focal point, what makes that the efficiencies are small
In this research, we have made a computational study of the thermal resistance influence (both in the hot and the cold side) in the efficiency of a thermoelectric generation device.
With this purpose, we have developed a computational model, based on the model applied to thermoelectric refrigeration published in [4]. This model uses the numeric method of the finite differences and simulates (transitory and permanent regimen) the complete behavior of the thermoelectric generation system, including the heat exchangers and the thermal focal points. The accuracy of this computational model has been experimentally checked, with the construction and test of a prototype, obtaining a maximum error of 5%.
J. G. Vian, D. Astrain, A. Rodriguez, A. Martinez, Mechanical Energy and Materials Engineering Department public University of Navarra, Spain.
The vapor compression cooling system has prevailed in the domestic refrigeration, due its good COP. However, the temperature control in the inside is deficient, because the compressor makes cycles of stop and start, obtaining a variation of more than 8°C in the inside, as it is shown in [1], which is harmful to the food preservation.
Moreover, there are thermoelectric refrigerators, as the ones shown in [2], [3] and [4], with a good control of the inside temperature, and consequently, a better food preservation. Furthermore, they have the advantage of being compacter and quieter, because the mobile parts are reduced. However, this cold production system has a low COP, so its consumption is too high.
In this study we have developed a domestic refrigerator which combines both technologies (thermoelectricity and vapor compression) in order to make the most of the machine compression good COP, with the excellent control and inside temperature regulation of the thermoelectric technology. It is composed of three compartments: conservation at 4°C (vapor compression cooling system), freezer at -22°C (vapor compression cooling system) and a new super-conservation space at 0°C (thermoelectric cooling system). The hybrid refrigerator total consumption is 1.15 kWh/day (48.1W), for an ambient temperature of 25°C.
For the design and optimization of this application, we have developed a computational model based on the numeric method of the finite differences, what allows us to simulate the whole hybrid fridge. The accuracy of this method has been experimentally checked, obtaining a maximum error of 1.2°C for the temperature and 8% for the electric consumption.
Vykhor L.M., Termena I.S., Institute of Thermoelectricity, Ukraine.
Physical factors affecting the efficiency of segmented generator thermoelements are analyzed. Methods of optimal control theory are used for the development of computer method of calculating optimal characteristics of generator modules of segmented thermoelements. Fabrication technique peculiarities of such modules of ³-Òå-based materials are described. Theoretical and experimental investigation results on characteristics of generator modules are given.
Kosyachenko L.A., Maslyanchuk O.L., Yu.Fedkovych Chernivtsi National University, Ukraine.
For several decades cadmium telluride (CdTe) has been considered as the most promising material for X- and ?-radiation detectors working without cryogenic cooling. Use of CdTe in detector supposes high material resistivity, hence its high purity and perfection of crystalline structure. In 1990-s it was proved that in going from CdTe to
Cd1-xZnxTe,
solid solution the defectness of crystal is reduced and the energy gap is expanded, hence semiconductor resistivity is increased and detector dark current is reduced. This, in turn, results in the increase of fundamental detector parameter - energy resolution. Requirements to material become considerably less stringent, if one of the ohmic contacts to crystal is replaced by the Schottky contact. The distinct advantage of CdTe detectors with the Schottky diode are exceptionally low dark currents and favourable conditions for collection of charge generated in the absorption of high-energy quantum.
The present paper represents comparative characteristics of CdTe and
Cd1-xZnxTe
with different zinc content and under different temperatures. It is shown that reduction below room temperature by 20-25 K results in the same reduction of dark current as substitution in CdTe of zinc atoms for 20% of cadmium atoms at room temperature. The calculations performed show that detecting efficiency in the range of photon energy up to 500-600 keV for detectors based on CdTe and
Cd1-xZnxTe
with the Schottky diode and to considerably larger photon energies for detectors with two ohmic contacts practically do not differ. Thus, in many cases it is more rational to use thermoelectric cooling of CdTe detector, and not transition to
Cd1-xZnxTe with the accompanying problems of inhomogeneity and reproducibility of material characteristics.
Rassamakin B.M., Khairnasov S.M., Zaripov V.K., Rassamakin A.B., ÍÒÓÓ "Kyiv Polytechnic Institute", Ukraine.
Increasing application recently has been found by different kinds of equipment using the principle of thermoelectric energy generation. The efficiency of this principle implementation is determined not only by the design of thermoelectric modules, but also by the devices of heat input to and removal from the hot and cold module junctions.
One of the most efficient new types of heat transfer devices are heat pipes based on the principle of closed evaporation-condensation cycle. Such devices allow passing considerable heat flows with a very small difference of temperatures between the areas of heat input and removal (the so-called "superconductivity" effect), providing in this case the transformation of heat flow density and high isothermality of sites of elements with a nonuniform heat release.
Therefore, in the systems providing thermal modes of different kinds of equipment and devices with the use of thermoelectricity it is reasonable to combine heat pipes and thermoelectric modules.
The paper describes systems for providing thermal modes of a domestic thermoelectric cooler with heat pipes and cryosurgical instrument based on heat pipe and thermoelectric modules, presents prototype designs, states test results, indicates their heat engineering characteristics.
Cherkez R.G., Institute of Thermoelectricity, Ukraine.
The diagram of thermoelectric conditioner on the basis of the permeable thermoelements is presented. On the basis of the optimal control theory the method of designing conditioner thermoelectric unit is described, which makes it possible to determine the optimal structural and thermophysical parameters of thermoelements in the mode of maximum coefficient of performance.
The results of computer studies for the case when thermoelectric materials based on solid solutions of
Bi2Te3.
are used,, are given. The results indicate the possibility of increasing the coefficient of performance by 40-60% in comparison with the conventional thermoelectric air-conditioning systems.
Nitsovych O.V., Institute of Thermoelectricity, Ukraine.
The limits for the use of the theory of multi-layer Geiling thermoelements have been defined. It has been shown that approximation of layered inhomogeneous medium with a homogeneous anisotropic medium overstates the values of transverse EMF of thermoelements. In case of thermoelement thicknesses commensurate with and smaller than thickness of layers, the theory error is drastically increased.
ITA academician Luste O.J., Institute of Thermoelectricity, Ukraine.
Mykytyuk P.D., Institute of Thermoelectricity, Ukraine.
Havrylyuk M.V., Institute of Thermoelectricity, Ukraine.
Lys'ko V.V., Institute of Thermoelectricity, Ukraine.
Results of elaboration of method for measurement of electric conductivity s on the rods of thermoelectric materials in dynamic mode are given. By means of computer simulation, temporal dependences of temperature distribution in a rod have been found and calibration curves for s determination by the time of rod heating to the assigned temperature have been constructed The process of measurement of electric conductivity s of rods by the two-probe method has been improved by optimization of current supply system and elimination of the Peltier effect influence, enabling considerable improvement of experiment precision. Correction factors have been found to measurements of temperature difference when finding thermoemf by hot probe method depending on the diameter of probe tip.
Ascheulov A.A., Romanyuk I.S., Institute of Thermoelectricity, Open JSC "Kvartz",Ukraine.
Peculiarities of producing increased-diameter crystals of Bi-Te-Se-Sb solid solutions by vertical zone recrystallization method are discussed.
Fedoruk V.G., Institute of Thermoelectricity, Ukraine.
Gyrotropic spiral thermoelement based on the excitation of eddy thermoelectric currents in a gyrotropic medium is considered. Medium gyrotropy is created by a magnetic field, EMF is due to the Nernst-Ettingshausen effect. Analytical expressions have been found for temperature gradient and distribution, integral current, EMF, electric power, voltage drop on external load, heat loss in thermogenerator. Besides, optimization with respect to external load has been made and the efficiency has been calculated.
Razinkov V.V., "Altec-M" Ltd, Ukraine.
Zaparov S.F., Satygo A.V., Institute of Thermoelectricity, Ukraine.
ITA associate member Mykhailovsky V.Ya., Termena I.S. Institute of Thermoelectricity, Ukraine.
Prybyla A.V., Institute of Thermoelectricity, Ukraine.
Computer model of anisotropic thermoelement (ÀÒ) has been created that allowed investigating power characteristics of spiral rectangular anisotropic thermoelement and the distribution of physical fields inside thermoelement in EMF and current generation mode and in heat pump mode.
Optimization of AT design has been made with regard to anisotropy and temperature dependences of material kinetic coefficients.
Dependence of AT power characteristics on dimensions and arrangement of electric heat removing contacts has been established. Their optimization enables AT efficiency increase by 15%.
Chernysh V.V., Cuamba B.S., Eduardo Mondlane University, Mozambique.
The results of the theoretical investigation of pure n-type germanium single crystals under high hydrostatic pressure have been represented in this communication. At the condition of strong elastic deformation an electron transfer takes place from four
L1
-valleys points at the <111> directions at the
L1
points near the L1 zone edge to a higher laying six equivalent
D1
-valleys situated at the <100> directions and, consequently, the energetic structure of n-type Ge is converted into one, similar to the n-type Si structure.
The deformation potentials of
L1 - and D1
1 -valleys and their occupation numbers have been calculated and their pressure behavior has been analyzed under low temperature T=78 K and room temperature T=300 K. The theory of anisotropic scattering has been used to calculate thermoemf.
The intraband mixed scattering of electrons by acoustic phonons and impurity ions and interband nonequivalent electron scattering between L1- and
D1
-valleys as well as interband equivalent f- and g- scattering between D1 -valleys have been considered. The results of the numerical calculations are represented in graphical form.
ITA associate member Mykhailivsky V.Ya., Gischuk V.S., Institute of Thermoelectricity, Ukraine.
Results of research and development of thermoelectric generator for power supply to electric devices of gas heating boilers are presented. Design of sectional generator and its basic energy parameters when operated as part of heated system are given.
Martynov P.N., Askhadullin P.Sh., Yudintsev P.A., "Obninsk Centre for Science and Technologies", Russia.
Results of the development of synthesis technology of ultraporous aluminium oxyhydroxide
Al2O3n( H2O)
(AlOOH aerogel) by controllable selective oxidation of binary liquid metal melt Ga-Al in this paper are presented. Results of the investigations of properties and most perspective fields of practical application of this material are considered.
Materials that are obtained by the above-mentioned method by virtue of its fibrous nanostructure (typical fiber size - diameter depends on the synthesis conditions - 5-50 nm; interval between fibers - 5-100 nm) have a very high controllable open porosity (to 99%), specific porosity (to 800 m2/g), record low thermal conductivity (0,01-0,03 Wt/(mK) at 130 - 1500 K) and density (~ 0.03 - 0.04 g/cm3 initially).
The major quality of these materials is long-term stability of their structure at high temperatures (up to 1000 °C initially and up to ~ 1500 °C after the chemical modification). In this connection the density, porosity and structure are well controlled by the temperature and annealing time of the synthesized material. The other significant peculiarity of such structures is almost absolute absence of the closed porosity.
Aerogel AlOOH is unique raw material for production of new materials for specific applications: thermal insulation, new ceramic, composite and functional materials as well as high-temperature filter materials, polymeric and general mechanical rubber goods etc.
Authors of this paper hope that presented results will attract interest among Forum participants and are ready for joint collaboration for realization of projects in the field of thermoelectric energy conversion.
Lubinsky N.N. , Bashkirov L.A., Petrov G.S., Klyndyuk A.I., Belarussian State Technological University, Belarus.
The paper gives the results of experimental study on thermoEMF and electric conductivity at direct current of
LaCo1-xGaxO3 (I) and NdCo1-xGaxO3 (II)
solid solutions in the temperature range 300-1050 K. Measurements were made in the air on pressed ceramic samples of length about 30 mm.
It is shown that temperature dependence of thermoelectric coefficient
(a)
is of complicated nature. Thus, at room temperature in both studied systems, at 0< õ < 0,3,
a
has negative values. With increasing temperature,
a=Ñ-A •ln(a),
, valid for semiconductors with one type of current carriers is satisfactorily met. Based on the resulting data for jumping electric conductivity mechanism, the share of
Ñî3+, ions responsible for electric conductivity was assessed.
Note that all the results for õ 0 were obtained for the first time.
concentration oriented along the wire axis.
Nikolaeva A.A., Konopko L.A., Tsurkan A.C., Huber T.E., Institute of Electronic Engineering and Industrial Technologies, ASM, Republic of Moldova, International Laboratory of High Magnetic Fields and Low Temperatures, Poland, Department of Chemistry, Howard University, USA.
Individual glass-coated Bi wires doped with an acceptor impurity of Sn, with Ñ3 oriented along the wire axis, with diameters from 0.4 to 2 m, were fabricated with a novel process. Samples were obtained by recrystallization of samples grown by the liquid casting method that were single-crystal and are orientated along the ( ), that is with the
C3
axis practically perpendicular to the wirelength. Reorientation was performed by means of laser recrystallization of wires with standard orientation, being preliminarily obtained by liquid phase casting [1]. The recrystallized samples were tested by means of angular diagrams of transverse magnetoresistance and Shubnikov-de Haas (SdH) oscillations. SdH oscillations, both from T-holes in strong magnetic fields up to 14 T and from light carriers in the L-point of the Brillouin zone, were clearly observed. We find that the thermopower in the room temperature range (300 - 260 K) is -120 V/K, which is 3-4 times higher than that in BiSn wires with the standard orientation, ( ). It is found that elastic deformation of glass-coated wires up to 1.7% relative elongation leads to almost twofold increase in thermopower (-200 ?V/K) in absolute magnitude with simultaneous decrease in resistivity by 30-40%; this leads to a significant increase in the power factor, by a factor of 3-4 in comparison with the results obtained for wires of similar composition and diameter.
This work was supported by the Moldavian grant ¹07.408.05.07PA.
Konopko L.A., Nikolaeva A.A., Huber T.E., Para G.I., Tsurkan A.C., Institute of Electronic Engineering and Industrial Technologies, ASM, Republic of Moldova, International Laboratory of High Magnetic Fields and Low Temperatures, Poland, Department of Chemistry, Howard University, USA.
For the first time one could see equidistant Aharonov-Bohm type thermopower oscillations over the direct field in single-crystal Bi whiskers (d=40-50 nm) in magnetic field up to 15 T at T = 1,5 - 4 K.
Single-crystal Bi whiskers in glass encapsulation (d=45-50 nm) were obtained by improved Ulitovsky liquid-phase casting method and corresponded the cylinder single-crystals with standard orientation ( ) along whisker axis at least 1mm long.
It was shown that along with the magnetic flux quantization type oscillations in longitudinal magnetoresistance R(Í) (H||I) with flux period hc/e and hc/2e in magnetothermoelectric power (H||I) ), there are oscillations with two periods over the direct field that are different from periods in longitudinal magnetoresistance R(Í). Oscillation amplitude depending both on R(Í) and a(H)damped with the growth of magnetic field. The sign of thermopower was changed in the function of impressed magnetic field.
It was determined that elastic extension of whiskers led to the oscillation disappearance both in R(Í) and a(H)). Observed effect of thermopower oscillation is discussed from Aharonov-Bohm point of view as well as from the point of view of existing theory connected with insignificant electron interaction in quantum sized systems [1,2,3].
Bodiul P.P., Moloshnik E.F, Popov I.A., Botnari O.V., Istrate E., Institute of Electronic Engineering and Industrial Technologies, ASM, Republic of Moldova.
This paper is dedicated to experimental investigation of thermoelectric properties of single-crystal
Bi1-xSbx
at Ò>80 Ê.
Glass-coated single-crystal wires of bismuth and bismuth-antimony alloys with diameters 0,3 - 10 µm and antimony concentration 3, 6, 8, 10 and 12% were obtained by liquid phase casting by the Ulitovsky method. Single crystallinity of samples was checked by means of angular revolution diagrams of transverse magntoresistance and controlled by means of X-ray diffraction method. Dependences of thermoEMF and resistivity on temperature and magnetic filed were measured. The resulting dependences were used to calculate and build the respective dependences of power factor
Ð.f.=a2s
în temperature, composition and wire diameter d.
It was established that thermolectric properties of bismuth-antimony alloys are improved with increased concentration of antimony and sample diameter. Maximum value of power factor was obtained on the samples with 12% concentration of antimony and diameter 1,5 - 2 µm, at Ò =135 K, that made
1.1· 10-4 Â/ñì Ê2.
It was shown that maximum of thermoelectric figure of merit in the wires is shifted toward higher temperatures and, accordingly, ZT in the wires exceeds ZT in the bulk samples of respective composition more than twice.
As long as wire samples are glass-coated and protected from external effects in assembly and from environmental influence, they offer important advantages over other types of samples of these compositions. Moreover, to get considerable quantity of single-crystal wires of certain size and orientation will require relatively small quantity of source material, which is important in connection with the possibility of their practical use.
This work was partially supported by the Moldavian grant.
Kharkhalis L.Yu., Bercha D.M., Shnyder M., Hlukhov K.E., Institute of Solid State Physics and Chemistry, Uzhgorod National University, Ukraine; Institute of Physics Zheshuv University, Poland.
Lashkarev H.V., Institute for Semiconductor Physics of NASU, Ukraine.
Pasichnik Yu.A., National Pedagogical Dragomanov University, Ukraine.
Ìykhalchenko V.P., Institute of Thermoelectricity, Ukraine.
Optimal requirements to materials used in the design and manufacture of various-purpose products are set forth, to provide minimization of internal mechanical and thermal stresses due to the difference in physical properties of crystal-solder-heat-sink (metal) system components. Procedure for calculation of residual mechanical stresses after the assembly of thermoelectric products is presented.
Nikolaeva A.A., Konopko L.A., Huber T.E., Institute of Electronic Engineering and Industrial Technologies, ASM, Republic of Moldova.
Thermoelectrically anisotropic media give rise to electric field transverse to temperature gradient. And, accordingly, on passing electric current through such medium, it gives rise to transverse heat flow. The efficiency of anisotropic thermoelement is largely determined by the value of thermoEMF anisotropy.
We have studied the possibility of using bismuth microwire for creation of anisotropic thermoelectric generator. Glass-coated microwire of pure and Sn-doped bismuth was prepared by the Ulitovsky method and constituted a cylinder single crystal with [1011] orientation along the wire axis, the
Ñ3
axis being deflected by angle 70î to microwire axis. It is known that dimensional effect considerably changes thermoelectric properties of microwire and results in the increase of thermoelectric figure of merit. In so doing, the transverse magnetic field (~ 0.4 T) increases considerably the thermoEMF anisotropy. Experimentally, temperature gradient
D(t)=1-5 K
was created perpendicular to microwire axis and the microwire could revolve in transverse temperature gradient, the revolution diagrams being used to determine preferable orientation of the microwire. Based on the preliminary results for bismuth microwire of diameter 10 µm over the thread and 35 µm over the glass coating, we obtained transverse thermoEMF of order
100 µV/ (K·cm).
The resulting data allow one to expect that optimization of the microwire composition è diameter ratio, as well as the use of transverse magnetic field will make possible anisotropic generator for power supply to devices with low consumption currents.
Razinkov V.V., Bukharaeva N.R., Demchuk B.N., Shustakov V.Yu., Bohmeyer V.,
Lang K., Institute of Thermoelectricity, Ukraine; "Sensor und Lasertechnik", Germany.
The paper describes designs of elaborated thermoelectric semiconductor converters of laser radiation power intended for operation in the power range of 10-5-102 W and the wavelength 0.4-11?m. The results of experimental research on the zone inhomogeneity of sensitivity are given.