WorldWideScience

Sample records for thermoelectric temperature control

  1. Thermoelectric Control Of Temperatures Of Pressure Sensors

    Science.gov (United States)

    Burkett, Cecil G., Jr.; West, James W.; Hutchinson, Mark A.; Lawrence, Robert M.; Crum, James R.

    1995-01-01

    Prototype controlled-temperature enclosure containing thermoelectric devices developed to house electronically scanned array of pressure sensors. Enclosure needed because (1) temperatures of transducers in sensors must be maintained at specified set point to ensure proper operation and calibration and (2) sensors sometimes used to measure pressure in hostile environments (wind tunnels in original application) that are hotter or colder than set point. Thus, depending on temperature of pressure-measurement environment, thermoelectric devices in enclosure used to heat or cool transducers to keep them at set point.

  2. Robust Temperature Control of a Thermoelectric Cooler via μ -Synthesis

    Science.gov (United States)

    Kürkçü, Burak; Kasnakoğlu, Coşku

    2018-02-01

    In this work robust temperature control of a thermoelectric cooler (TEC) via μ -synthesis is studied. An uncertain dynamical model for the TEC that is suitable for robust control methods is derived. The model captures variations in operating point due to current, load and temperature changes. A temperature controller is designed utilizing μ -synthesis, a powerful method guaranteeing robust stability and performance. For comparison two well-known control methods, namely proportional-integral-derivative (PID) and internal model control (IMC), are also realized to benchmark the proposed approach. It is observed that the stability and performance on the nominal model are satisfactory for all cases. On the other hand, under perturbations the responses of PID and IMC deteriorate and even become unstable. In contrast, the μ -synthesis controller succeeds in keeping system stability and achieving good performance under all perturbations within the operating range, while at the same time providing good disturbance rejection.

  3. In-situ thermoelectric temperature monitoring and "Closed-loop integrated control" system for concentrator photovoltaic-thermoelectric hybrid receivers

    Science.gov (United States)

    Rolley, Matthew H.; Sweet, Tracy K. N.; Min, Gao

    2017-09-01

    This work demonstrates a new technique that capitalizes on the inherent flexibility of the thermoelectric module to provide a multifunctional platform, and exhibits a unique advantage only available within CPV-TE hybrid architectures. This system is the first to use the thermoelectric itself for hot-side temperature feedback to a PID control system, needing no additional thermocouple or thermistor to be attached to the cell - eliminating shading, and complex mechanical designs for mounting. Temperature measurement accuracy and thermoelectric active cooling functionality is preserved. Dynamic "per-cell" condition monitoring and protection is feasible using this technique, with direct cell-specific temperature measurement accurate to 1°C demonstrated over the entire experimental range. The extrapolation accuracy potential of the technique was also evaluated.

  4. Experimental Investigation of a Temperature-Controlled Car Seat Powered by an Exhaust Thermoelectric Generator

    Science.gov (United States)

    Du, H.; Wang, Y. P.; Yuan, X. H.; Deng, Y. D.; Su, C. Q.

    2016-03-01

    To improve the riding comfort and rational utilization of the electrical energy captured by an automotive thermoelectric generator (ATEG), a temperature-controlled car seat was constructed to adjust the temperature of the car seat surface. Powered by the ATEG and the battery, the seat-embedded air conditioner can improve the riding comfort using a thermoelectric device to adjust the surface temperature of the seat, with an air duct to regulate the cold side and hot side of the thermoelectric device. The performance of the thermoelectric cooler (TEC) and theoretical analysis on the optimum state of the TEC device are put forward. To verify the rationality of the air duct design and to ensure sufficient air supply, the velocity field of the air duct system was obtained by means of the finite element method. To validate the reliability of the numerical simulation, the air velocity around the thermoelectric device was measured by a wind speed transmitter. The performance of the temperature-controlled car seat has been validated and is in good agreement with bench tests and real vehicle tests.

  5. Thermoelectric refrigerator having improved temperature stabilization means

    International Nuclear Information System (INIS)

    Falco, C.M.

    1982-01-01

    A control system for thermoelectric refrigerators is disclosed. The thermoelectric refrigerator includes at least one thermoelectric element that undergoes a first order change at a predetermined critical temperature. The element functions as a thermoelectric refrigerator element above the critical temperature, but discontinuously ceases to function as a thermoelectric refrigerator element below the critical temperature. One example of such an arrangement includes thermoelectric refrigerator elements which are superconductors. The transition temperature of one of the superconductor elements is selected as the temperature control point of the refrigerator. When the refrigerator attempts to cool below the point, the metals become superconductors losing their ability to perform as a thermoelectric refrigerator. An extremely accurate, first-order control is realized

  6. Method of controlling temperature of a thermoelectric generator in an exhaust system

    Science.gov (United States)

    Prior, Gregory P; Reynolds, Michael G; Cowgill, Joshua D

    2013-05-21

    A method of controlling the temperature of a thermoelectric generator (TEG) in an exhaust system of an engine is provided. The method includes determining the temperature of the heated side of the TEG, determining exhaust gas flow rate through the TEG, and determining the exhaust gas temperature through the TEG. A rate of change in temperature of the heated side of the TEG is predicted based on the determined temperature, the determined exhaust gas flow rate, and the determined exhaust gas temperature through the TEG. Using the predicted rate of change of temperature of the heated side, exhaust gas flow rate through the TEG is calculated that will result in a maximum temperature of the heated side of the TEG less than a predetermined critical temperature given the predicted rate of change in temperature of the heated side of the TEG. A corresponding apparatus is provided.

  7. Experimental verification of active IR stealth technology by controlling the surface temperature using a thermoelectric element

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Geon; Han, Kuk Il; Choi, Jun Hyuk; Kim, Tae Kuk [Dept. of Mechanical Engineering, Chung Ang University, Seoul (Korea, Republic of)

    2016-10-15

    In this paper, we propose a technique for IR low-observability that uses an active IR signal tuning through the real time control of the object surface temperature according to the varying background environment. This is achieved by applying the proper object surface temperature obtained to result in the minimum radiance difference between the object and the background. Experimental verification by using the thermoelectric temperature control element shows that the IR radiance contrast between the object and the background can be reduced up to 99% during the night and up to 95% during the day time as compared to the un-tuned original radiance contrast values. The stealth technology demonstrated in this paper may be applied for many military systems needed for the IR stealth performance when a suitable temperature control unit is developed.

  8. Experimental verification of active IR stealth technology by controlling the surface temperature using a thermoelectric element

    International Nuclear Information System (INIS)

    Kim, Dong Geon; Han, Kuk Il; Choi, Jun Hyuk; Kim, Tae Kuk

    2016-01-01

    In this paper, we propose a technique for IR low-observability that uses an active IR signal tuning through the real time control of the object surface temperature according to the varying background environment. This is achieved by applying the proper object surface temperature obtained to result in the minimum radiance difference between the object and the background. Experimental verification by using the thermoelectric temperature control element shows that the IR radiance contrast between the object and the background can be reduced up to 99% during the night and up to 95% during the day time as compared to the un-tuned original radiance contrast values. The stealth technology demonstrated in this paper may be applied for many military systems needed for the IR stealth performance when a suitable temperature control unit is developed

  9. Analysis of a Temperature-Controlled Exhaust Thermoelectric Generator During a Driving Cycle

    Science.gov (United States)

    Brito, F. P.; Alves, A.; Pires, J. M.; Martins, L. B.; Martins, J.; Oliveira, J.; Teixeira, J.; Goncalves, L. M.; Hall, M. J.

    2016-03-01

    Thermoelectric generators can be used in automotive exhaust energy recovery. As car engines operate under wide variable loads, it is a challenge to design a system for operating efficiently under these variable conditions. This means being able to avoid excessive thermal dilution under low engine loads and being able to operate under high load, high temperature events without the need to deflect the exhaust gases with bypass systems. The authors have previously proposed a thermoelectric generator (TEG) concept with temperature control based on the operating principle of the variable conductance heat pipe/thermosiphon. This strategy allows the TEG modules’ hot face to work under constant, optimized temperature. The variable engine load will only affect the number of modules exposed to the heat source, not the heat transfer temperature. This prevents module overheating under high engine loads and avoids thermal dilution under low engine loads. The present work assesses the merit of the aforementioned approach by analysing the generator output during driving cycles simulated with an energy model of a light vehicle. For the baseline evaporator and condenser configuration, the driving cycle averaged electrical power outputs were approximately 320 W and 550 W for the type-approval Worldwide harmonized light vehicles test procedure Class 3 driving cycle and for a real-world highway driving cycle, respectively.

  10. Power output and efficiency of a thermoelectric generator under temperature control

    International Nuclear Information System (INIS)

    Chen, Wei-Hsin; Wu, Po-Hua; Wang, Xiao-Dong; Lin, Yu-Li

    2016-01-01

    Highlights: • Power output and efficiency of a thermoelectric generator (TEG) is studied. • Temperatures at the module’s surfaces are approximated by sinusoidal functions. • Mean output power and efficiency are enhanced by the temperature oscillation. • The maximum mean efficiency of the TEG in this study is 8.45%. • The phase angle of 180° is a feasible operation for maximizing the performance. - Abstract: Operation control is an effective way to improve the output power of thermoelectric generators (TEGs). The present study is intended to numerically investigate the power output and efficiency of a TEG and find the operating conditions for maximizing its performance. The temperature distributions at the hot side and cold side surfaces of the TEG are approximated by sinusoidal functions. The influences of the temperature amplitudes at the hot side surface and the cold side surface, the phase angle, and the figure-of-merit (ZT) on the performance of the TEG are analyzed. The predictions indicate that the mean output power and efficiency of the TEG are significantly enhanced by the temperature oscillation, whereas the mean absorbed heat by the TEG is slightly influenced. An increase in the temperature amplitude of the hot side surface and the phase angle can effectively improve the performance. For the phase angle of 0°, a smaller temperature amplitude at the cold side surface renders the better performance compared to that with a larger amplitude. When the ZT value increases from 0.736 to 1.8, the mean efficiency at the phase angle of 180° is amplified by a factor of 1.72, and the maximum mean efficiency is 8.45%. In summary, a larger temperature amplitude at the hot side surface with the phase angle of 180° is a feasible operation for maximizing the performance.

  11. Low-temperature thermoelectric power factor enhancement by controlling nanoparticle size distribution.

    Science.gov (United States)

    Zebarjadi, Mona; Esfarjani, Keivan; Bian, Zhixi; Shakouri, Ali

    2011-01-12

    Coherent potential approximation is used to study the effect of adding doped spherical nanoparticles inside a host matrix on the thermoelectric properties. This takes into account electron multiple scatterings that are important in samples with relatively high volume fraction of nanoparticles (>1%). We show that with large fraction of uniform small size nanoparticles (∼1 nm), the power factor can be enhanced significantly. The improvement could be large (up to 450% for GaAs) especially at low temperatures when the mobility is limited by impurity or nanoparticle scattering. The advantage of doping via embedded nanoparticles compared to the conventional shallow impurities is quantified. At the optimum thermoelectric power factor, the electrical conductivity of the nanoparticle-doped material is larger than that of impurity-doped one at the studied temperature range (50-500 K) whereas the Seebeck coefficient of the nanoparticle doped material is enhanced only at low temperatures (∼50 K).

  12. Thermoelectric properties control due to doping level and sintering conditions for FGM thermoelectric element

    CERN Document Server

    Kajikawa, T; Shiraishi, K; Ohmori, M; Hirai, T

    1999-01-01

    Thermoelectric performance is determined with three factors, namely, Seebeck coefficient, electrical resistivity and thermal conductivity. For metal and single crystalline semiconductor, those factors have close interrelation each $9 other. However, as the sintered thermoelectric element has various levels of superstructure from macro scale and micro scale in terms of the thermoelectric mechanism, the relationship among them is more complex than that for the $9 melt- grown element, so it is suggested that the control of the temperature dependence of thermoelectric properties is possible to enhance the thermoelectric performance for wide temperature range due to FGM approach. The research $9 objective is to investigate the characteristics of the thermoelectric properties for various doping levels and hot-pressed conditions to make the thermoelectric elements for which the temperature dependence of the performance is $9 controlled due to FGM approach varying the doping levels and sintering conditions. By usage ...

  13. High temperature thermoelectric energy conversion

    International Nuclear Information System (INIS)

    Wood, C.

    1986-01-01

    Considerable advances were made in the late '50's and early early '60's in the theory and development of materials for high-temperature thermoelectric energy conversion. This early work culminated in a variety of materials, spanning a range of temperatures, with the product of the figure of merit, Z, and temperature, T, i.e., the dimensionless figure of merit, ZT, of the order of one. This experimental limitation appeared to be universal and led a number of investigators to explore the possibility that a ZT - also represents a theoretical limitation. It was found not to be so

  14. High Temperature Integrated Thermoelectric Ststem and Materials

    Energy Technology Data Exchange (ETDEWEB)

    Mike S. H. Chu

    2011-06-06

    The final goal of this project is to produce, by the end of Phase II, an all ceramic high temperature thermoelectric module. Such a module design integrates oxide ceramic n-type, oxide ceramic p-type materials as thermoelectric legs and oxide ceramic conductive material as metalizing connection between n-type and p-type legs. The benefits of this all ceramic module are that it can function at higher temperatures (> 700 C), it is mechanically and functionally more reliable and it can be scaled up to production at lower cost. With this all ceramic module, millions of dollars in savings or in new opportunities recovering waste heat from high temperature processes could be made available. A very attractive application will be to convert exhaust heat from a vehicle to reusable electric energy by a thermoelectric generator (TEG). Phase I activities were focused on evaluating potential n-type and p-type oxide compositions as the thermoelectric legs. More than 40 oxide ceramic powder compositions were made and studied in the laboratory. The compositions were divided into 6 groups representing different material systems. Basic ceramic properties and thermoelectric properties of discs sintered from these powders were measured. Powders with different particles sizes were made to evaluate the effects of particle size reduction on thermoelectric properties. Several powders were submitted to a leading thermoelectric company for complete thermoelectric evaluation. Initial evaluation showed that when samples were sintered by conventional method, they had reasonable values of Seebeck coefficient but very low values of electrical conductivity. Therefore, their power factors (PF) and figure of merits (ZT) were too low to be useful for high temperature thermoelectric applications. An unconventional sintering method, Spark Plasma Sintering (SPS) was determined to produce better thermoelectric properties. Particle size reduction of powders also was found to have some positive benefits

  15. High-temperature thermoelectric behavior of lead telluride

    Indian Academy of Sciences (India)

    Usefulness of a material in thermoelectric devices is temperature specific. The central problem in thermoelectric material research is the selection of materials with high figure-of-merit in the given temperature range of operation. It is of considerable interest to know the utility range of the material, which is decided by the ...

  16. Encapsulation of high temperature thermoelectric modules

    Energy Technology Data Exchange (ETDEWEB)

    Salvador, James R.; Sakamoto, Jeffrey; Park, Youngsam

    2017-07-11

    A method of encapsulating a thermoelectric device and its associated thermoelectric elements in an inert atmosphere and a thermoelectric device fabricated by such method are described. These thermoelectric devices may be intended for use under conditions which would otherwise promote oxidation of the thermoelectric elements. The capsule is formed by securing a suitably-sized thin-walled strip of oxidation-resistant metal to the ceramic substrates which support the thermoelectric elements. The thin-walled metal strip is positioned to enclose the edges of the thermoelectric device and is secured to the substrates using gap-filling materials. The strip, substrates and gap-filling materials cooperatively encapsulate the thermoelectric elements and exclude oxygen and water vapor from atmospheric air so that the elements may be maintained in an inert, non-oxidizing environment.

  17. Thermoelectric properties by high temperature annealing

    Science.gov (United States)

    Ren, Zhifeng (Inventor); Chen, Gang (Inventor); Kumar, Shankar (Inventor); Lee, Hohyun (Inventor)

    2009-01-01

    The present invention generally provides methods of improving thermoelectric properties of alloys by subjecting them to one or more high temperature annealing steps, performed at temperatures at which the alloys exhibit a mixed solid/liquid phase, followed by cooling steps. For example, in one aspect, such a method of the invention can include subjecting an alloy sample to a temperature that is sufficiently elevated to cause partial melting of at least some of the grains. The sample can then be cooled so as to solidify the melted grain portions such that each solidified grain portion exhibits an average chemical composition, characterized by a relative concentration of elements forming the alloy, that is different than that of the remainder of the grain.

  18. High-entropy alloys as high-temperature thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Shafeie, Samrand [Surface and Microstructure Engineering Group, Materials and Manufacturing Technology, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Guo, Sheng, E-mail: sheng.guo@chalmers.se [Surface and Microstructure Engineering Group, Materials and Manufacturing Technology, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Hu, Qiang [Institute of Applied Physics, Jiangxi Academy of Sciences, Nanchang 330029 (China); Fahlquist, Henrik [Bruker AXS Nordic AB, 17067 Solna (Sweden); Erhart, Paul [Department of Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Palmqvist, Anders, E-mail: anders.palmqvist@chalmers.se [Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg (Sweden)

    2015-11-14

    Thermoelectric (TE) generators that efficiently recycle a large portion of waste heat will be an important complementary energy technology in the future. While many efficient TE materials exist in the lower temperature region, few are efficient at high temperatures. Here, we present the high temperature properties of high-entropy alloys (HEAs), as a potential new class of high temperature TE materials. We show that their TE properties can be controlled significantly by changing the valence electron concentration (VEC) of the system with appropriate substitutional elements. Both the electrical and thermal transport properties in this system were found to decrease with a lower VEC number. Overall, the large microstructural complexity and lower average VEC in these types of alloys can potentially be used to lower both the total and the lattice thermal conductivity. These findings highlight the possibility to exploit HEAs as a new class of future high temperature TE materials.

  19. Thermoelectric generator cooling system and method of control

    Science.gov (United States)

    Prior, Gregory P; Meisner, Gregory P; Glassford, Daniel B

    2012-10-16

    An apparatus is provided that includes a thermoelectric generator and an exhaust gas system operatively connected to the thermoelectric generator to heat a portion of the thermoelectric generator with exhaust gas flow through the thermoelectric generator. A coolant system is operatively connected to the thermoelectric generator to cool another portion of the thermoelectric generator with coolant flow through the thermoelectric generator. At least one valve is controllable to cause the coolant flow through the thermoelectric generator in a direction that opposes a direction of the exhaust gas flow under a first set of operating conditions and to cause the coolant flow through the thermoelectric generator in the direction of exhaust gas flow under a second set of operating conditions.

  20. Note: Wide-operating-range control for thermoelectric coolers

    Science.gov (United States)

    Peronio, P.; Labanca, I.; Ghioni, M.; Rech, I.

    2017-11-01

    A new algorithm for controlling the temperature of a thermoelectric cooler is proposed. Unlike a classic proportional-integral-derivative (PID) control, which computes the bias voltage from the temperature error, the proposed algorithm exploits the linear relation that exists between the cold side's temperature and the amount of heat that is removed per unit time. Since this control is based on an existing linear relation, it is insensitive to changes in the operating point that are instead crucial in classic PID control of a non-linear system.

  1. High-Temperature High-Efficiency Solar Thermoelectric Generators

    Energy Technology Data Exchange (ETDEWEB)

    Baranowski, LL; Warren, EL; Toberer, ES

    2014-03-01

    Inspired by recent high-efficiency thermoelectric modules, we consider thermoelectrics for terrestrial applications in concentrated solar thermoelectric generators (STEGs). The STEG is modeled as two subsystems: a TEG, and a solar absorber that efficiently captures the concentrated sunlight and limits radiative losses from the system. The TEG subsystem is modeled using thermoelectric compatibility theory; this model does not constrain the material properties to be constant with temperature. Considering a three-stage TEG based on current record modules, this model suggests that 18% efficiency could be experimentally expected with a temperature gradient of 1000A degrees C to 100A degrees C. Achieving 15% overall STEG efficiency thus requires an absorber efficiency above 85%, and we consider two methods to achieve this: solar-selective absorbers and thermally insulating cavities. When the TEG and absorber subsystem models are combined, we expect that the STEG modeled here could achieve 15% efficiency with optical concentration between 250 and 300 suns.

  2. A test system and supervisory control and data acquisition application with programmable logic controller for thermoelectric generators

    International Nuclear Information System (INIS)

    Ahiska, Rasit; Mamur, Hayati

    2012-01-01

    Highlights: ► A new TEG test measurement system with the PLC has been carried out. ► A new SCADA program has been written and tested for the test measurement system. ► An operator panel has been used for monitoring to the instant TEG data. ► All of the measurement data of TEG have been aggregated in the system. - Abstract: In this study, a new test measurement system and supervisory control and data acquisition application with programmable logic controller has been carried out to be enable the collection of the data of thermoelectric generator for the usage of thermoelectric modules as thermoelectric generator. During the production of the electric energy from the thermoelectric generator, the temperatures of the surfaces of the thermoelectric generator, current–voltage values obtained from output of the thermoelectric generator, hot and cold flows have been measured by the newly established system instantly. All these data have been monitored continuously from the computer and recorded by a supervisory control and data acquisition program. At the same time, in environments where there was no computer, an operator panel with the ability to communicate with the programmable logic controller has been added for the monitoring of the instant thermoelectric generator data. All of the measurement data of the thermoelectric generator have been aggregated in the new test measurement and supervisory control and data acquisition system. The setup test measurement system has been implemented on the thermoelectric generator system with about 10 W. Thermoelectric generators, Altec-GM-1 brand-coded have been examined by the new proposed test measurement system and the values of maximum power and thermoelectric generator efficiency were calculated by the programmable logic controller. When the obtained results were compared with the datasheets, the relative error for the maximum power was around 4% and the value for efficiency was below 3%.

  3. High-temperature thermoelectric behavior of lead telluride

    Indian Academy of Sciences (India)

    The central problem in thermoelectric material research is the selection of ... temperature range (400–1000 K), and bismuth telluride-based materials .... parent from the results that band non-parabolicity has a significant effect on the .... M P Singh thankfully acknowledges financial assistance from the Council of Scien-.

  4. The thermo-electric nature of the Debye temperature

    Directory of Open Access Journals (Sweden)

    Mithun Bhowmick

    2018-05-01

    Full Text Available The Debye temperature is typically associated with the heat capacity of a solid and the cut-off of the possible lattice vibrations, but not necessarily to the electric conductivity of the material. By investigating III-V and II-VI compound semiconductors, we reveal that the Debye temperature represents a thermo-electric material parameter, connecting the thermal and electronic properties of a solid via a distinct power law.

  5. High Temperature Thermoelectric Properties of ZnO Based Materials

    DEFF Research Database (Denmark)

    Han, Li

    of the dopants and dopant concentrations, a large power factor was obtainable. The sample with the composition of Zn0.9Cd0.1Sc0.01O obtained the highest zT ∼0.3 @1173 K, ~0.24 @1073K, and a good average zT which is better than the state-of-the-art n-type thermoelectric oxide materials. Meanwhile, Sc-doped Zn......This thesis investigated the high temperature thermoelectric properties of ZnO based materials. The investigation first focused on the doping mechanisms of Al-doped ZnO, and then the influence of spark plasma sintering conditions on the thermoelectric properties of Al, Ga-dually doped Zn......O. Following that, the nanostructuring effect for Al-doped ZnO was systematically investigated using samples with different microstructure morphologies. At last, the newly developed ZnCdO materials with superior thermoelectric properties and thermal stability were introduced as promising substitutions...

  6. High Temperature Thermoelectric Materials for Waste Heat Regeneration

    Science.gov (United States)

    2013-01-01

    ADDRESS. 1. REPORT DATE (DD-MM-YYYY) January 2013 2. REPORT TYPE Final 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE High Temperature...National Aeronautics and Space Administration’s (NASA) deep space explorations, which use radioisotope thermoelectric generators (RTGs) to produce...their octahedral voids (shown in figure 10a) with large rare- earth atoms to reduce their lattice conductivity (20). Ions can also be inserted to

  7. New Materials for High Temperature Thermoelectric Power Generation

    Energy Technology Data Exchange (ETDEWEB)

    Kauzlarich, Susan [Univ. of California, Davis, CA (United States)

    2016-02-03

    The scope of this proposal was to develop two new high ZT materials with enhanced properties for the n- and p-leg of a thermoelectric device capable of operating at a maximum temperature of 1275 K and to demonstrate the efficiency in a working device. Nanostructured composites and new materials based on n– and p–type nanostructured Si1-xGex (ZT1273K ~ 1) and the recently discovered p–type high temperature Zintl phase material, Yb14MnSb11 (ZT1273K ~1) were developed and tested in a working device.

  8. Thermoelectric and thermomagnetic effects in high-temperature superconductors

    International Nuclear Information System (INIS)

    Huebener, R.P.; Ri, H.C.; Gross, R.; Kober, F.

    1992-01-01

    In the mixed state of high-temperature superconductors the dominant part of the Seebeck and Nernst effect is due to the thermal diffusion of quasiparticles and vortices, respectively. The authors' understanding of the Seebeck effect is based on the two-fluid counterflow model of Ginzburg and its extension to the mixed state with the presence of vortices. From the Nernst effect the transport entropy of the vortices is obtained. In this paper summarize the recent thermoelectric and thermomagnetic experiments, paying also attention to the role of the Magnus force (Hall effect) and to the thermal fluctuation effects near T c

  9. Temperature and Voltage Offsets in High-ZT Thermoelectrics

    Science.gov (United States)

    Levy, George S.

    2017-10-01

    Thermodynamic temperature can take on different meanings. Kinetic temperature is an expectation value and a function of the kinetic energy distribution. Statistical temperature is a parameter of the distribution. Kinetic temperature and statistical temperature, identical in Maxwell-Boltzmann statistics, can differ in other statistics such as those of Fermi-Dirac or Bose-Einstein when a field is present. Thermal equilibrium corresponds to zero statistical temperature gradient, not zero kinetic temperature gradient. Since heat carriers in thermoelectrics are fermions, the difference between these two temperatures may explain voltage and temperature offsets observed during meticulous Seebeck measurements in which the temperature-voltage curve does not go through the origin. In conventional semiconductors, temperature offsets produced by fermionic electrical carriers are not observable because they are shorted by heat phonons in the lattice. In high-ZT materials, however, these offsets have been detected but attributed to faulty laboratory procedures. Additional supporting evidence for spontaneous voltages and temperature gradients includes data collected in epistatic experiments and in the plasma Q-machine. Device fabrication guidelines for testing the hypothesis are suggested including using unipolar junctions stacked in a superlattice, alternating n/n + and p/p + junctions, selecting appropriate dimensions, doping, and loading.

  10. Temperature and Voltage Offsets in High- ZT Thermoelectrics

    Science.gov (United States)

    Levy, George S.

    2018-06-01

    Thermodynamic temperature can take on different meanings. Kinetic temperature is an expectation value and a function of the kinetic energy distribution. Statistical temperature is a parameter of the distribution. Kinetic temperature and statistical temperature, identical in Maxwell-Boltzmann statistics, can differ in other statistics such as those of Fermi-Dirac or Bose-Einstein when a field is present. Thermal equilibrium corresponds to zero statistical temperature gradient, not zero kinetic temperature gradient. Since heat carriers in thermoelectrics are fermions, the difference between these two temperatures may explain voltage and temperature offsets observed during meticulous Seebeck measurements in which the temperature-voltage curve does not go through the origin. In conventional semiconductors, temperature offsets produced by fermionic electrical carriers are not observable because they are shorted by heat phonons in the lattice. In high- ZT materials, however, these offsets have been detected but attributed to faulty laboratory procedures. Additional supporting evidence for spontaneous voltages and temperature gradients includes data collected in epistatic experiments and in the plasma Q-machine. Device fabrication guidelines for testing the hypothesis are suggested including using unipolar junctions stacked in a superlattice, alternating n/ n + and p/ p + junctions, selecting appropriate dimensions, doping, and loading.

  11. High Performance High Temperature Thermoelectric Composites with Metallic Inclusions

    Science.gov (United States)

    Ma, James M. (Inventor); Bux, Sabah K. (Inventor); Fleurial, Jean-Pierre (Inventor); Ravi, Vilupanur A. (Inventor); Firdosy, Samad A. (Inventor); Star, Kurt (Inventor); Kaner, Richard B. (Inventor)

    2017-01-01

    The present invention provides a composite thermoelectric material. The composite thermoelectric material can include a semiconductor material comprising a rare earth metal. The atomic percent of the rare earth metal in the semiconductor material can be at least about 20%. The composite thermoelectric material can further include a metal forming metallic inclusions distributed throughout the semiconductor material. The present invention also provides a method of forming this composite thermoelectric material.

  12. Correlation between defect transition levels and thermoelectric operational temperature of doped CrSi2

    Science.gov (United States)

    Singh, Abhishek; Pandey, Tribhuwan

    2014-03-01

    The performance of a thermoelectric material is quantified by figure of merit ZT. The challenge in achieving high ZT value requires simultaneously high thermopower, high electrical conductivity and low thermal conductivity at optimal carrier concentration. So far doping is the most versatile approach used for modifying thermoelectric properties. Previous studies have shown that doping can significantly improve the thermoelectric performance, however the tuning the operating temperature of a thermoelectric device is a main issue. Using first principles density functional theory, we report for CrSi2, a linear relationship between thermodynamic charge state transition levels of defects and temperature at which thermopower peaks. We show for doped CrSi2 that the peak of thermopower occurs at the temperature Tm, which corresponds to the position of defect transition level. Therefore, by modifying the defect transition level, a thermoelectric material with a given operational temperature can be designed. The authors thankfully acknowledge support from ADA under NpMASS.

  13. Distributed detection and control of defective thermoelectric generation modules using sensor nodes

    DEFF Research Database (Denmark)

    Chen, Min

    2014-01-01

    are described, respectively. Defective and potentially healing conditions are dynamically monitored by a voltage sensor node and a temperature sensor node, both of which can judge the defective TEM and decide the related switching actions in a nearly independent way. The periodical wireless transmission from......To maximize the energy productivity, effective in-field detection and real-time control of defective thermoelectric modules (TEMs) are critical in constituting a thermoelectric generation system (TEGS). In this paper, autonomous and distributed sensor nodes are designed to implement the wireless...... a considerable power improvement is illustrated with the proposed measuring method and setup....

  14. Temperature dependent thermoelectric properties of chemically derived gallium zinc oxide thin films

    KAUST Repository

    Barasheed, Abeer Z.; Sarath Kumar, S. R.; Alshareef, Husam N.

    2013-01-01

    In this study, the temperature dependent thermoelectric properties of sol-gel prepared ZnO and 3% Ga-doped ZnO (GZO) thin films have been explored. The power factor of GZO films, as compared to ZnO, is improved by nearly 17% at high temperature. A stabilization anneal, prior to thermoelectric measurements, in a strongly reducing Ar/H2 (95/5) atmosphere at 500°C was found to effectively stabilize the chemically derived films, practically eliminating hysteresis during thermoelectric measurements. Subtle changes in the thermoelectric properties of stabilized films have been correlated to oxygen vacancies and excitonic levels that are known to exist in ZnO-based thin films. The role of Ga dopants and defects, formed upon annealing, in driving the observed complex temperature dependence of the thermoelectric properties is discussed. © The Royal Society of Chemistry 2013.

  15. Controlling the thermoelectric effect by mechanical manipulation of the electron's quantum phase in atomic junctions.

    Science.gov (United States)

    Aiba, Akira; Demir, Firuz; Kaneko, Satoshi; Fujii, Shintaro; Nishino, Tomoaki; Tsukagoshi, Kazuhito; Saffarzadeh, Alireza; Kirczenow, George; Kiguchi, Manabu

    2017-08-11

    The thermoelectric voltage developed across an atomic metal junction (i.e., a nanostructure in which one or a few atoms connect two metal electrodes) in response to a temperature difference between the electrodes, results from the quantum interference of electrons that pass through the junction multiple times after being scattered by the surrounding defects. Here we report successfully tuning this quantum interference and thus controlling the magnitude and sign of the thermoelectric voltage by applying a mechanical force that deforms the junction. The observed switching of the thermoelectric voltage is reversible and can be cycled many times. Our ab initio and semi-empirical calculations elucidate the detailed mechanism by which the quantum interference is tuned. We show that the applied strain alters the quantum phases of electrons passing through the narrowest part of the junction and hence modifies the electronic quantum interference in the device. Tuning the quantum interference causes the energies of electronic transport resonances to shift, which affects the thermoelectric voltage. These experimental and theoretical studies reveal that Au atomic junctions can be made to exhibit both positive and negative thermoelectric voltages on demand, and demonstrate the importance and tunability of the quantum interference effect in the atomic-scale metal nanostructures.

  16. WS2 as an excellent high-temperature thermoelectric material

    KAUST Repository

    Gandi, Appala

    2014-11-25

    The potential of WS2 as a thermoelectric material is assessed. The electronic contribution to the thermoelectric properties is calculated within the constant relaxation time approximation from the electronic band structure, whereas the lattice contribution is evaluated using self-consistently calculated phonon lifetimes. In addition, the dependence of the lattice thermal conductivity on the mean free path of the phonons is determined.

  17. WS2 as an excellent high-temperature thermoelectric material

    KAUST Repository

    Gandi, Appala; Schwingenschlö gl, Udo

    2014-01-01

    The potential of WS2 as a thermoelectric material is assessed. The electronic contribution to the thermoelectric properties is calculated within the constant relaxation time approximation from the electronic band structure, whereas the lattice contribution is evaluated using self-consistently calculated phonon lifetimes. In addition, the dependence of the lattice thermal conductivity on the mean free path of the phonons is determined.

  18. Modeling passive power generation in a temporally-varying temperature environment via thermoelectrics

    International Nuclear Information System (INIS)

    Bomberger, Cory C.; Attia, Peter M.; Prasad, Ajay K.; Zide, Joshua M.O.

    2013-01-01

    This paper presents a model to predict the power generation of a thermoelectric generator in a temporally-varying temperature environment. The model employs a thermoelectric plate sandwiched between two different heat exchangers to convert a temporal temperature gradient in the environment to a spatial temperature gradient within the device suitable for thermoelectric power generation. The two heat exchangers are designed such that their temperatures respond to a change in the environment's temperature at different rates which sets up a temperature differential across the thermoelectric and results in power generation. In this model, radiative and convective heat transfer between the device and its surroundings, and heat flow between the two heat exchangers across the thermoelectric plate are considered. The model is simulated for power generation in Death Valley, CA during the summer using the diurnal variation of air temperature and radiative exchange with the sun and night sky as heat sources and sinks. The optimization of power generation via scaling the device size is discussed. Additional applications of this device are considered. -- Highlights: • Thermoelectric power generation with time-varying temperature is modeled. • The ability to generate power without a natural spatial gradient is demonstrated. • Time dependent heat-transfer and differential heat flow rates are considered. • Optimization of power generation via scaling the device size is discussed

  19. Parametric analysis of temperature gradient across thermoelectric power generators

    Directory of Open Access Journals (Sweden)

    Khaled Chahine

    2016-06-01

    Full Text Available This paper presents a parametric analysis of power generation from thermoelectric generators (TEGs. The aim of the parametric analysis is to provide recommendations with respect to the applications of TEGs. To proceed, the one-dimensional steady-state solution of the heat diffusion equation is considered with various boundary conditions representing real encountered cases. Four configurations are tested. The first configuration corresponds to the TEG heated with constant temperature at its lower surface and cooled with a fluid at its upper surface. The second configuration corresponds to the TEG heated with constant heat flux at its lower surface and cooled with a fluid at its upper surface. The third configuration corresponds to the TEG heated with constant heat flux at its lower surface and cooled by a constant temperature at its upper surface. The fourth configuration corresponds to the TEG heated by a fluid at its lower surface and cooled by a fluid at its upper surface. It was shown that the most promising configuration is the fourth one and temperature differences up to 70˚C can be achieved at 150˚C heat source. Finally, a new concept is implemented based on configuration four and tested experimentally.

  20. Enhanced low-temperature thermoelectrical properties of BiTeCl grown by topotactic method

    International Nuclear Information System (INIS)

    Jacimovic, J.; Mettan, X.; Pisoni, A.; Gaal, R.; Katrych, S.; Demko, L.; Akrap, A.; Forro, L.; Berger, H.; Bugnon, P.; Magrez, A.

    2014-01-01

    We developed a topotactic strategy to grow BiTeCl single crystals. Structural characterization by means of X-ray diffraction was performed, and the high crystallinity of the material was proven. Measurements of the thermoelectrical coefficients electrical resistivity, thermoelectric power and thermal conductivity show an enhanced room temperature power factor of 20 μW cm −1 K −2 . The high value of the figure of merit (ZT = 0.17) confirms that BiTeCl is a promising material for engineering in thermoelectric applications at low temperature

  1. An On-Site Thermoelectric Cooling Device for Cryotherapy and Control of Skin Blood Flow.

    Science.gov (United States)

    Mejia, Natalia; Dedow, Karl; Nguy, Lindsey; Sullivan, Patrick; Khoshnevis, Sepideh; Diller, Kenneth R

    2015-12-01

    Cryotherapy involves the surface application of low temperatures to enhance the healing of soft tissue injuries. Typical devices embody a remote source of chilled water that is pumped through a circulation bladder placed on the treatment site. In contrast, the present device uses thermoelectric refrigeration modules to bring the cooling source directly to the tissue to be treated, thereby achieving significant improvements in control of therapeutic temperature while having a reduced size and weight. A prototype system was applied to test an oscillating cooling and heating protocol for efficacy in regulating skin blood perfusion in the treatment area. Data on 12 human subjects indicate that thermoelectric coolers (TECs) delivered significant and sustainable changes in perfusion for both heating (increase by (±SE) 173.0 ± 66.0%, P device for cryotherapy with local temperature regulation.

  2. An additive approach to low temperature zero pressure sintering of bismuth antimony telluride thermoelectric materials

    Science.gov (United States)

    Catlin, Glenn C.; Tripathi, Rajesh; Nunes, Geoffrey; Lynch, Philip B.; Jones, Howard D.; Schmitt, Devin C.

    2017-03-01

    This paper presents an additive-based approach to the formulation of thermoelectric materials suitable for screen printing. Such printing processes are a likely route to such thermoelectric applications as micro-generators for wireless sensor networks and medical devices, but require the development of materials that can be sintered at ambient pressure and low temperatures. Using a rapid screening process, we identify the eutectic combination of antimony and tellurium as an additive for bismuth-antimony-telluride that enables good thermoelectric performance without a high pressure step. An optimized composite of 15 weight percent Sb7.5Te92.5 in Bi0.5Sb1.5Te3 is scaled up and formulated into a screen-printable paste. Samples fabricated from this paste achieve a thermoelectric figure of merit (ZT) of 0.74 using a maximum processing temperature of 748 K and a total thermal processing budget of 12 K-hours.

  3. First-principles study on doping and temperature dependence of thermoelectric property of Bi2S3 thermoelectric material

    International Nuclear Information System (INIS)

    Guo, Donglin; Hu, Chenguo; Zhang, Cuiling

    2013-01-01

    Graphical abstract: The direction-induced ZT is found. At ZZ direction and n = 1.47 × 10 19 cm −3 , the ZT can reach maximal value, 0.36, which is three times as much as maximal laboratorial value. This result matches well the analysis of electron effective mass. Highlights: ► Electrical transportations of Bi 2 S 3 depend on the concentration and temperature. ► The direction-induced ZT is found. ► At ZZ direction and n = 1.47 × 10 19 cm −3 , the ZT can reach maximal value, 0.36. ► The maximal ZT value is three times as much as maximal laboratorial value. ► By doping and temperature tuning, Bi 2 S 3 is a promising thermoelectric material. - Abstract: The electronic structure and thermoelectric property of Bi 2 S 3 are investigated. The electron and hole effective mass of Bi 2 S 3 is analyzed in detail, from which we find that the thermoelectric transportation varies in different directions in Bi 2 S 3 crystal. Along ac plane the higher figure of merit (ZT) could be achieved. For n-type doped Bi 2 S 3 , the optimal doping concentration is found in the range of (1.0–5.0) × 10 19 cm −3 , in which the maximal ZT reaches 0.21 at 900 K, but along ZZ direction, the maximal ZT reaches 0.36. These findings provide a new understanding of thermoelectricity-dependent structure factors and improving ZT ways. The donor concentration N increases as T increases at one bar of pressure under a suitable chemical potential μ, but above this chemical potential μ, the donor concentration N keeps a constant

  4. Uninterrupted thermoelectric energy harvesting using temperature-sensor-based maximum power point tracking system

    International Nuclear Information System (INIS)

    Park, Jae-Do; Lee, Hohyun; Bond, Matthew

    2014-01-01

    Highlights: • Feedforward MPPT scheme for uninterrupted TEG energy harvesting is suggested. • Temperature sensors are used to avoid current measurement or source disconnection. • MPP voltage reference is generated based on OCV vs. temperature differential model. • Optimal operating condition is maintained using hysteresis controller. • Any type of power converter can be used in the proposed scheme. - Abstract: In this paper, a thermoelectric generator (TEG) energy harvesting system with a temperature-sensor-based maximum power point tracking (MPPT) method is presented. Conventional MPPT algorithms for photovoltaic cells may not be suitable for thermoelectric power generation because a significant amount of time is required for TEG systems to reach a steady state. Moreover, complexity and additional power consumption in conventional circuits and periodic disconnection of power source are not desirable for low-power energy harvesting applications. The proposed system can track the varying maximum power point (MPP) with a simple and inexpensive temperature-sensor-based circuit without instantaneous power measurement or TEG disconnection. This system uses TEG’s open circuit voltage (OCV) characteristic with respect to temperature gradient to generate a proper reference voltage signal, i.e., half of the TEG’s OCV. The power converter controller maintains the TEG output voltage at the reference level so that the maximum power can be extracted for the given temperature condition. This feedforward MPPT scheme is inherently stable and can be implemented without any complex microcontroller circuit. The proposed system has been validated analytically and experimentally, and shows a maximum power tracking error of 1.15%

  5. Thermoelectric energy harvesting from small ambient temperature transients

    Energy Technology Data Exchange (ETDEWEB)

    Moser, Andre

    2012-07-01

    Wireless sensor networks (WSNs) represent a key technology, used, for instance, in structural health monitoring, building automation systems, or traffic surveillance. Supplying power to a network of spatially distributed sensor nodes, especially at remote locations, is a large challenge: power grids are reliable but costly to install, whereas batteries provide a high flexibility in the installation but have a limited lifetime. This dilemma can be overcome by micro energy harvesting which offers both: reliability and flexibility. Micro energy harvesters are able to convert low grade ambient energy into useful electrical energy and thus provide power for wireless sensor networks or other electronic devices - in-situ, off-grid, and with an almost unlimited lifetime. Thermal energy is an omnipresent source of ambient energy: The day-night-cycle of the sun causes a temperature variation in the ambient air as well as arbitrary solids (soil, building walls, etc.). Unlike the air, solids have a large thermal inertia which dampens the temperature variation. This physical process leads to a temperature difference {Delta}T = T{sub air} - T{sub solid} between air and solid that can be converted directly into electrical energy by a thermoelectric generator (TEG). Thermal and electrical interfaces are necessary to connect the TEG to the thermal energy source (T{sub air}, T{sub solid}) and the electrical load (WSN). Reliable operation of the WSN may only be ensured if the harvester provides sufficient electrical energy, i.e. operates at its maximum power point. The goal of this thesis is to study, design, and test thermoelectric harvesters generating electrical energy from small ambient temperature transients in order to self-sufficiently power a WSN. Current research into thermoelectric energy harvesting, especially analytical modeling and application in the field are treated insufficiently. Therefore, a time-dependent analytical model of the harvester's output power is set

  6. Thermoelectric Properties of High-Doped Silicon from Room Temperature to 900 K

    Science.gov (United States)

    Stranz, A.; Kähler, J.; Waag, A.; Peiner, E.

    2013-07-01

    Silicon is investigated as a low-cost, Earth-abundant thermoelectric material for high-temperature applications up to 900 K. For the calculation of module design the Seebeck coefficient and the electrical as well as thermal properties of silicon in the high-temperature range are of great importance. In this study, we evaluate the thermoelectric properties of low-, medium-, and high-doped silicon from room temperature to 900 K. In so doing, the Seebeck coefficient, the electrical and thermal conductivities, as well as the resulting figure of merit ZT of silicon are determined.

  7. Methods of synthesizing thermoelectric materials

    Science.gov (United States)

    Ren, Zhifeng; Chen, Shuo; Liu, Wei-Shu; Wang, Hengzhi; Wang, Hui; Yu, Bo; Chen, Gang

    2016-04-05

    Methods for synthesis of thermoelectric materials are disclosed. In some embodiments, a method of fabricating a thermoelectric material includes generating a plurality of nanoparticles from a starting material comprising one or more chalcogens and one or more transition metals; and consolidating the nanoparticles under elevated pressure and temperature, wherein the nanoparticles are heated and cooled at a controlled rate.

  8. Maximum Power Point Tracking Control of a Thermoelectric Generation System Using the Extremum Seeking Control Method

    Directory of Open Access Journals (Sweden)

    Ssennoga Twaha

    2017-12-01

    Full Text Available This study proposes and implements maximum power Point Tracking (MPPT control on thermoelectric generation system using an extremum seeking control (ESC algorithm. The MPPT is applied to guarantee maximum power extraction from the TEG system. The work has been carried out through modelling of thermoelectric generator/dc-dc converter system using Matlab/Simulink. The effectiveness of ESC technique has been assessed by comparing the results with those of the Perturb and Observe (P&O MPPT method under the same operating conditions. Results indicate that ESC MPPT method extracts more power than the P&O technique, where the output power of ESC technique is higher than that of P&O by 0.47 W or 6.1% at a hot side temperature of 200 °C. It is also noted that the ESC MPPT based model is almost fourfold faster than the P&O method. This is attributed to smaller MPPT circuit of ESC compared to that of P&O, hence we conclude that the ESC MPPT method outperforms the P&O technique.

  9. Maximum Efficiency of Thermoelectric Heat Conversion in High-Temperature Power Devices

    Directory of Open Access Journals (Sweden)

    V. I. Khvesyuk

    2016-01-01

    Full Text Available Modern trends in development of aircraft engineering go with development of vehicles of the fifth generation. The features of aircrafts of the fifth generation are motivation to use new high-performance systems of onboard power supply. The operating temperature of the outer walls of engines is of 800–1000 K. This corresponds to radiation heat flux of 10 kW/m2 . The thermal energy including radiation of the engine wall may potentially be converted into electricity. The main objective of this paper is to analyze if it is possible to use a high efficiency thermoelectric conversion of heat into electricity. The paper considers issues such as working processes, choice of materials, and optimization of thermoelectric conversion. It presents the analysis results of operating conditions of thermoelectric generator (TEG used in advanced hightemperature power devices. A high-temperature heat source is a favorable factor for the thermoelectric conversion of heat. It is shown that for existing thermoelectric materials a theoretical conversion efficiency can reach the level of 15–20% at temperatures up to 1500 K and available values of Ioffe parameter being ZT = 2–3 (Z is figure of merit, T is temperature. To ensure temperature regime and high efficiency thermoelectric conversion simultaneously it is necessary to have a certain match between TEG power, temperature of hot and cold surfaces, and heat transfer coefficient of the cooling system. The paper discusses a concept of radiation absorber on the TEG hot surface. The analysis has demonstrated a number of potentialities for highly efficient conversion through using the TEG in high-temperature power devices. This work has been implemented under support of the Ministry of Education and Science of the Russian Federation; project No. 1145 (the programme “Organization of Research Engineering Activities”.

  10. Low-Temperature Thermoelectric Properties of Fe2VAl with Partial Cobalt Doping

    Science.gov (United States)

    Liu, Chang; Morelli, Donald T.

    2012-06-01

    Ternary metallic alloy Fe2VAl with a pseudogap in its energy band structure has received intensive scrutiny for potential thermoelectric applications. Due to the sharp change in the density of states profile near the Fermi level, interesting transport properties can be triggered to render possible enhancement in the overall thermoelectric performance. Previously, this full-Heusler-type alloy was partially doped with cobalt at the iron sites to produce a series of compounds with n-type conductivity. Their thermoelectric properties in the temperature range of 300 K to 850 K were reported. In this research, efforts were made to extend the investigation on (Fe1- x Co x )2VAl to the low-temperature range. Alloy samples were prepared by arc-melting and annealing. Seebeck coefficient, electrical resistivity, and thermal conductivity measurements were performed from 80 K to room temperature. The effects of cobalt doping on the material's electronic and thermal properties are discussed.

  11. Numerical simulations on the temperature gradient and thermal stress of a thermoelectric power generator

    International Nuclear Information System (INIS)

    Wu, Yongjia; Ming, Tingzhen; Li, Xiaohua; Pan, Tao; Peng, Keyuan; Luo, Xiaobing

    2014-01-01

    Highlights: • An appropriate ceramic plate thickness is effective in alleviating the thermal stress. • A smaller distance between thermo-pins can help prolong lifecycle of the TE module. • Either a thicker or a thinner copper conducting strip effectively reduces thermal stress. • A suitable tin soldering thickness will alleviate thermal stress intensity and increase thermal efficiency. - Abstract: Thermoelectric generator is a device taking advantage of the temperature difference in thermoelectric material to generate electric power, where the higher the temperature difference of the hot-cold ends, the higher the efficiency will be. However, higher temperature or higher heat flux upon the hot end will cause strong thermal stress which will negatively influence the lifecycle of the thermoelectric module. This phenomenon is very common in industrial applications but seldom has research work been reported. In this paper, numerical analysis on the thermodynamics and thermal stress performance of the thermoelectric module has been performed, considering the variation on the thickness of materials; the influence of high heat flux on thermal efficiency, power output, and thermal stress has been examined. It is found that under high heat flux imposing upon the hot end, the thermal stress is so strong that it has a decisive effect on the life expectation of the device. To improve the module’s working condition, different geometrical configurations are tested and the optimum sizes are achieved. Besides, the side effects on the efficiency, power output, and open circuit voltage output of the thermoelectric module are taken into consideration

  12. Influence of nanosized inclusions on the room temperature thermoelectrical properties of a p-type bismuth–tellurium–antimony alloy

    International Nuclear Information System (INIS)

    Bernard-Granger, Guillaume; Addad, Ahmed; Navone, Christelle; Soulier, Mathieu; Simon, Julia; Szkutnik, Pierre-David

    2012-01-01

    Transmission electron microscopy observations and thermoelectrical property measurements (electrical conductivity, Seebeck coefficient and thermal conductivity) at room temperature have been completed on two fully dense polycrystalline p-type bismuth–tellurium–antimony alloy samples. It is shown that the presence of antimony oxide-based nanosized inclusions (controlled as to volume fraction and size distribution), homogeneously dispersed in the surrounding matrix leads to a dimensionless figure of merit (ZT) of ∼1.3 at room temperature. For comparison, when such inclusions are missing the ZT value is only 0.6.

  13. A High Temperature Experimental Characterization Procedure for Oxide-Based Thermoelectric Generator Modules under Transient Conditions

    DEFF Research Database (Denmark)

    Man, Elena Anamaria; Schaltz, Erik; Rosendahl, Lasse

    2015-01-01

    Characterization methods for thermoelectric generator (TEG) modules play an important role in studying their behavior and in enhancing the performance and simulation of TEG systems also. The purpose of this study is to analyze the behavior in transient and steady-state of the temperature applied...

  14. Efficient p-n junction-based thermoelectric generator that can operate at extreme temperature conditions

    DEFF Research Database (Denmark)

    Chavez, Ruben; Angst, Sebastian; Hall, Joseph

    2017-01-01

    In many industrial processes a large proportion of energy is lost in the form of heat. Thermoelectric generators can convert this waste heat into electricity by means of the Seebeck effect. However, the use of thermoelectric generators in practical applications on an industrial scale is limited...... in part because electrical, thermal, and mechanical bonding contacts between the semiconductor materials and the metal electrodes in current designs are not capable of withstanding thermal-mechanical stress and alloying of the metal-semiconductor interface when exposed to the high temperatures occurring...... in many real-world applications. Here we demonstrate a concept for thermoelectric generators that can address this issue by replacing the metallization and electrode bonding on the hot side of the device by a p-n junction between the two semiconductor materials, making the device robust against...

  15. Temperature dependence of the thermoelectric coeffiicients of lithium niobate and lithium tantalate

    International Nuclear Information System (INIS)

    Khachaturyan, O.A.; Gabrielyan, A.I.; Kolesnik, S.P.

    1988-01-01

    Thermoelectric Zeebeck,Thomson, Peltier coefficients for LiNbO 3 and LiTaO 3 monocrystals and their dependence on temperature in 300-1400 K range were investigated. It is shown that Zeebeck (α) coefficient changes its sign, depending on temperature change - the higher is α, the higher is material conductivity in the corresponding temperature region. Thomson and Peltier coefficients were calculated analytically for lithium niobate and tantalate

  16. Thermoelectric properties of high electron concentration materials under large temperature gradients

    International Nuclear Information System (INIS)

    Bulat, L.P.; Stefansky, V.A.

    1994-01-01

    Theoretical methods of investigating of transport properties in solids under large temperature gradients are grounded. The nonlinear and non-local expressions for current density and heat flow are obtained with degenerated of current carriers gas. A number of new effects with large temperature gradients have been tested. Use of large temperature gradients leads to the increasing of the thermoelectric figure of merit. copyright 1995 American Institute of Physics

  17. Thermoelectric Energy Harvesting Using Phase Change Materials (PCMs) in High Temperature Environments in Aircraft

    Science.gov (United States)

    Elefsiniotis, A.; Becker, Th.; Schmid, U.

    2014-06-01

    Wireless, energy-autonomous structural health-monitoring systems in aircraft have the potential of reducing total maintenance costs. Thermoelectric energy harvesting, which seems the best choice for creating truly autonomous health monitoring sensors, is the principle behind converting waste heat to useful electrical energy through the use of thermoelectric generators. To enhance the temperature difference across the two sides of a thermoelectric generator, i.e. increasing heat flux and energy production, a phase change material acting as thermal mass is attached on one side of the thermoelectric generators while the other side is placed on the aircraft structure. The application area under investigation for this paper is the pylon aft fairing, located near the engine of an aircraft, with temperatures reaching on the inside up to 350 °C. Given these harsh operational conditions, the performance of a device, containing erythritol as a phase change material, is evaluated. The harvested energy reaching values up to 81.4 J can be regulated by a power management module capable of storing the excess energy and recovering it from the medium powering a sensor node and a wireless transceiver.

  18. Research for Brazing Materials of High-Temperature Thermoelectric Modules with CoSb3 Thermoelectric Materials

    Science.gov (United States)

    Lee, Yu Seong; Kim, Suk Jun; Kim, Byeong Geun; Lee, Soonil; Seo, Won-Seon; Kim, Il-Ho; Choi, Soon-Mok

    2017-05-01

    Metallic glass (MG) can be a candidate for an alternative brazing material of high-temperature thermoelectric modules, since we can expect both a lower brazing temperature and a high operating temperature for the junction from the MG brazers. Another advantage of MG powders is their outstanding oxidation resistance, namely, high-temperature durability in atmosphere. We fabricated three compositions of Al-based MGs—Al-Y-Ni, Al-Y-Ni-Co, and Al-Y-Ni-Co-La—by using the melt spinning process, and their T gs were 273°C, 264°C, and 249°C, respectively. The electrical resistivity of the Al-Y-Ni MG ribbon dropped significantly after annealing at 300°C. The electrical resistivity of crystallized Al-Y-Ni reduced down to 0.03 mΩ cm, which is an order of magnitude lower than that of the amorphous one. After the MG ribbons were pulverized to sub-100 μm, the average particle size was about 400 μm.

  19. A research on thermoelectric generator's electrical performance under temperature mismatch conditions for automotive waste heat recovery system

    Directory of Open Access Journals (Sweden)

    Z.B. Tang

    2015-03-01

    Full Text Available The thermoelectric generators recover useful energy by the function of thermoelectric modules which can convert waste heat energy into electricity from automotive exhaust. In the actual operation, the electrical connected thermoelectric modules are operated under temperature mismatch conditions and then the problem of decreased power output causes due to the inhomogeneous temperature gradient distribution on heat exchanger surface. In this case study, an individual module test system and a test bench have been carried out to test and analyze the impact of thermal imbalance on the output electrical power at module and system level. Variability of the temperature difference and clamping pressure are also tested in the individual module measurement. The system level experimental results clearly describe the phenomenon of thermoelectric generator's decreased power output under mismatched temperature condition and limited working temperature. This situation is improved with thermal insulation on the modules and proved to be effective.

  20. Temperature-modulated direct thermoelectric gas sensors: thermal modeling and results for fast hydrocarbon sensors

    International Nuclear Information System (INIS)

    Rettig, Frank; Moos, Ralf

    2009-01-01

    Direct thermoelectric gas sensors are a promising alternative to conductometric gas sensors. For accurate results, a temperature modulation technique in combination with a regression analysis is advantageous. However, the thermal time constant of screen-printed sensors is quite large. As a result, up to now the temperature modulation frequency (20 mHz) has been too low and the corresponding principle-related response time (50 s) has been too high for many applications. With a special design, respecting the physical properties of thermal waves and the use of signal processing similar to a lock-in-amplifier, it is possible to achieve response times of about 1 s. As a result, direct thermoelectric gas sensors with SnO 2 as a gas-sensitive material respond fast and are reproducible to the propane concentration in the ambient atmosphere. Due to the path-independent behavior of the thermovoltage and the temperature, the measured thermopower of two sensors is almost identical

  1. Thermoelectric enhancement at low temperature in nonstoichiometric lead-telluride compounds

    International Nuclear Information System (INIS)

    Wang Heng; Li Jingfeng; Kita, Takuji

    2007-01-01

    Pb 1.17 Te thermoelectric polycrystalline materials were fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). The property measurement and microstructural characterization showed that the present material has special features different from traditional Pb 1+x Te ingots with secondary Pb phase. An attractive enhancement of the thermoelectric figure of merit ZT = 0.64 was obtained at 450 K, with a low thermal conductivity of 1.11 W m -1 K -1 at this temperature. Transmission electron microscopy observation showed the existence of randomly dispersed nano features that are responsible for such enhancement, some of which are similar to the nanostructures reported in the AgPb m SbTe m+2 system. The origin of these regions is discussed and their influence on thermal conductivity is revealed. The results confirm the effectiveness of such a kind of nano feature in improving thermoelectric properties, especially in reducing thermal conductivity. They also indicate a new way of obtaining thermoelectric materials with such a kind of nano feature via MA and SPS

  2. Variable cooling circuit for thermoelectric generator and engine and method of control

    Science.gov (United States)

    Prior, Gregory P

    2012-10-30

    An apparatus is provided that includes an engine, an exhaust system, and a thermoelectric generator (TEG) operatively connected to the exhaust system and configured to allow exhaust gas flow therethrough. A first radiator is operatively connected to the engine. An openable and closable engine valve is configured to open to permit coolant to circulate through the engine and the first radiator when coolant temperature is greater than a predetermined minimum coolant temperature. A first and a second valve are controllable to route cooling fluid from the TEG to the engine through coolant passages under a first set of operating conditions to establish a first cooling circuit, and from the TEG to a second radiator through at least some other coolant passages under a second set of operating conditions to establish a second cooling circuit. A method of controlling a cooling circuit is also provided.

  3. Stable and low contact resistance electrical contacts for high temperature SiGe thermoelectric generators

    KAUST Repository

    Zhang, Bo

    2018-04-14

    The thermal stability and contact resistance of TaAlN thin films as electrical contacts to SiGe thermoelectric elements are reported. We demonstrate that a sharp interface is maintained after the device annealed at 800°C for over 100h, indicating that no interdiffusion takes place between TaAlN and SiGe. A specific contact resistivity of (2.1±1.3)×10−6Ω-cm2 for p-type SiGe and (2.8±1.6)×10−5 Ω-cm2 for n-type SiGe is demonstrated after the high temperature annealing. These results show that TaAlN is a promising contact material for high temperature thermoelectrics such as SiGe.

  4. Nano-Like Effects in Crystalline Thermoelectric Materials at High Temperatures

    Science.gov (United States)

    Korzhuev, M. A.; Katin, I. V.

    2013-05-01

    The mechanisms of improving the figure of merit Z and power parameter W of thermoelectric materials (TEMs) in the transitions λph→a and λe→a are considered (Here λph and λe are the mean free path of the phonons and electrons in the sample, and a is the inter atomic distance). It is shown that the same mechanisms are responsible for the growth of Z and W crystalline TEMs at high temperatures.

  5. A review of thermoelectric cooling: Materials, modeling and applications

    International Nuclear Information System (INIS)

    Zhao, Dongliang; Tan, Gang

    2014-01-01

    This study reviews the recent advances of thermoelectric materials, modeling approaches, and applications. Thermoelectric cooling systems have advantages over conventional cooling devices, including compact in size, light in weight, high reliability, no mechanical moving parts, no working fluid, being powered by direct current, and easily switching between cooling and heating modes. In this study, historical development of thermoelectric cooling has been briefly introduced first. Next, the development of thermoelectric materials has been given and the achievements in past decade have been summarized. To improve thermoelectric cooling system's performance, the modeling techniques have been described for both the thermoelement modeling and thermoelectric cooler (TEC) modeling including standard simplified energy equilibrium model, one-dimensional and three-dimensional models, and numerical compact model. Finally, the thermoelectric cooling applications have been reviewed in aspects of domestic refrigeration, electronic cooling, scientific application, and automobile air conditioning and seat temperature control, with summaries for the commercially available thermoelectric modules and thermoelectric refrigerators. It is expected that this study will be beneficial to thermoelectric cooling system design, simulation, and analysis. - Highlights: •Thermoelectric cooling has great prospects with thermoelectric material's advances. •Modeling techniques for both thermoelement and TEC have been reviewed. •Principle thermoelectric cooling applications have been reviewed and summarized

  6. Analytic modeling of a high temperature thermoelectric module for wireless sensors

    International Nuclear Information System (INIS)

    Köhler, J E; Staaf, L G H; Palmqvist, A E C; Enoksson, P

    2014-01-01

    A novel high temperature thermoelectric module with thermoelectric materials never before combined in a module is currently researched. The module placement in the cooling channels of a jet engine where the cold side will be cooled by high flow cooling air (550° C) and the hot side will be at the wall (800° C). The aim of the project is to drastically reduce the length of the wires by replacing wired sensors with wireless sensors and power these (3-10mW) with thermoelectric harvesters. To optimize the design for the temperature range and the environment an analytic model was constructed. Using known models for this purpose was not possible for this project, as many of the models have too many assumptions, e.g. that the temperature gradient is relatively low, that thick electrodes with very low resistance can be used, that the heat transfer through the base plates are perfect or that the aim of the design is to maximize the efficiency. The analytical model in this paper is a combination of several known models with the aim to examine what materials to use in this specific environment to achieve the highest possible specific power (mW/g)

  7. Efficient p-n junction-based thermoelectric generator that can operate at extreme temperature conditions

    Science.gov (United States)

    Chavez, Ruben; Angst, Sebastian; Hall, Joseph; Maculewicz, Franziska; Stoetzel, Julia; Wiggers, Hartmut; Thanh Hung, Le; Van Nong, Ngo; Pryds, Nini; Span, Gerhard; Wolf, Dietrich E.; Schmechel, Roland; Schierning, Gabi

    2018-01-01

    In many industrial processes, a large proportion of energy is lost in the form of heat. Thermoelectric generators can convert this waste heat into electricity by means of the Seebeck effect. However, the use of thermoelectric generators in practical applications on an industrial scale is limited in part because electrical, thermal, and mechanical bonding contacts between the semiconductor materials and the metal electrodes in current designs are not capable of withstanding thermal-mechanical stress and alloying of the metal-semiconductor interface when exposed to the high temperatures occurring in many real-world applications. Here we demonstrate a concept for thermoelectric generators that can address this issue by replacing the metallization and electrode bonding on the hot side of the device by a p-n junction between the two semiconductor materials, making the device robust against temperature induced failure. In our proof-of-principle demonstration, a p-n junction device made from nanocrystalline silicon is at least comparable in its efficiency and power output to conventional devices of the same material and fabrication process, but with the advantage of sustaining high hot side temperatures and oxidative atmosphere.

  8. A novel self-powered wireless temperature sensor based on thermoelectric generators

    International Nuclear Information System (INIS)

    Shi, Yongming; Wang, Yao; Deng, Yuan; Gao, Hongli; Lin, Zhen; Zhu, Wei; Ye, Huihong

    2014-01-01

    Highlights: • A self-powered temperature sensor, based on thermoelectric generator, is presented. • This novel sensor can operate without any batteries or other power sources. • This sensor combines signal sensing and power supplying together. • The measurement error is 0.5 K during the sensor operating period. • This sensor can detect temperature fluctuation situations such as fire disaster. - Abstract: A novel self-powered wireless temperature sensor has been designed and presented for solving the power supply problem of temperature sensors. This sensor can autonomously measure temperature under positive temperature fluctuation situations. The self-powered characteristic, realized by using four thermoelectric generators, enables the sensor to operate without any batteries or other power sources. In order to obtain these features, attentions are not only focused on the method to combine signal sensing and power generating together, but also on the method to improve measurement accuracy. Experimental results confirm that this novel sensor has excellent measurement accuracy. The measured performance is consistent with the calculated characteristics. For typical application, this self-powered temperature sensor can detect fire before it develops to flashover state. And the maximum detection distance grows with the growth of burning rate. All the results indicate this innovative sensor is a promising self-powered device which can be used to measure temperature value in positive temperature fluctuation situations

  9. Demonstration of high temperature thermoelectric waste heat recovery from exhaust gases of a combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Trottmann, Matthias; Weidenkaff, Anke; Populoh, Sascha; Brunko, Oliver; Veziridis, Angelika; Bach, Christian; Cabalzar, Urs [Empa, Duebendorf (Switzerland)

    2011-07-01

    The energy efficiency of passenger cars becomes increasingly important due to a growing awareness in terms of climate change and shortages of resources associated with rising fuel prices. In addition to the efforts towards the optimization of the engine's internal efficiency, waste heat recovery is the main objective. In this respect, thermoelectric (TE) devices seem to be suited as heat recuperation systems. Thermoelectric generators allow for direct transformation of thermal into electrical energy. In order to thoroughly investigate this type of recovery system a TE demonstrator was mounted on the muffler of a VW Touran and tested. The waste heat of the exhaust gas was converted into electricity with a conversion rate of {proportional_to}. 3.5%. The limiting factor was the low thermal stability of the commercial modules used in this pre-study to elaborate reference values. Thermoelectric modules based on sustainable and temperature-stable materials are being developed to improve the measured values. A thermoelectric test generator with perovskite-type oxide modules was constructed confirm the function and stability at elevated temperatures. Despite all the advantages of this material class, the TE performance is still to be improved. A quantitative measure of a material's TE performance is the temperature-independent Figure of Merit ZT. ZT increases with decreasing thermal and increasing electrical conductivity. An approach to thermal conductivity reduction is nanostructuring of the material. The Ultrasonic Spray Combustion (USC) technique allows to produce powders with a grain size on the nanoscale and was tested in this study. (orig.)

  10. High thermoelectric figure of merit in nanocrystalline polyaniline at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Nath, Chandrani; Kumar, Ashok, E-mail: ask@tezu.ernet.in, E-mail: okram@csr.res.in [Materials Research Laboratory, Department of Physics, Tezpur University, Tezpur 784 028 (India); Kuo, Yung-Kang [Department of Physics, National Dong-Hwa University, Hualien 974, Taiwan (China); Okram, Gunadhor Singh, E-mail: ask@tezu.ernet.in, E-mail: okram@csr.res.in [Electrical Transport Laboratory, UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 017 (India)

    2014-09-29

    Thermoelectric coolers with figure of merit (ZT) close to unity at low temperatures are the need of the hour with new advances in high temperature superconductors, superconducting microelectronic circuits, quantum computers, and photonics. Here, we demonstrate that the conducting polymer polyaniline (Pani) doped with camphor sulfonic acid synthesized in semi-crystalline nanostructures, possesses a giant Seebeck effect at low temperatures. The resulting enormously large Seebeck coefficient (up to 0.6 V/K) combined with an intrinsically low electrical conductivity and thermal conductivity give rise to a ZT = 0.77 at 45 K and ZT = 2.17 at 17 K.

  11. Study of thermoelectric power of Co-B liquid quenched amorphous alloys at relatively high temperature

    International Nuclear Information System (INIS)

    Naqvi, S.M.N.R.; Rizvi, S.D.H.; Raza, S.M.; Rizvi, S.; Hussain, A.; Rehman, F.

    1999-01-01

    Measurements of thermoelectric power TEP were carried out for the samples of Co-1 alloy with appropriate compositions of constitutions in the temperature range, 350K< T<760K. The analysis of data shows an inverse Gaussian profile. Ziman theoretical model was used to fit the resistivity data which shows an agreement. Dynamic recovery processes as well as formation of vacancies, interstials, intersection of basal dislocations and indeed pyramidal interlocking of dislocations for seeding scattering centers are responsible for residual TEP at relatively high temperatures Co-B LQA alloys also undergo into other structural changes at such temperatures. (author)

  12. Thermoelectrics for waste heat recovery and climate control in automobiles

    Energy Technology Data Exchange (ETDEWEB)

    Maranville, Clay W. [Ford Motor Company, Dearborn, MI (United States); Schmitz, Peter [Ford Forschungszentrum Aachen GmbH, Aachen (Germany)

    2011-07-01

    Thermoelectric (TE) devices have received renewed attention in the past decade for use in light-duty automotive applications. Governmental organizations and private corporations world-wide are sponsoring research at both the basic materials level, as well as for applied research and technology demonstrations. This funding has led to measurable improvement in TE device cost and efficiency, as well as spurring the emergence and growth of a vertically-integrated TE industry. The two broad categories of applications that have been considered for thermoelectrics are power generation through waste-heat recovery and cabin climate control through the use of TE heat pumps. Neither of these uses of TE devices has ever been commercialized in large-scale vehicle applications, in large part due to the challenges of low device efficiency and high costs. While it is still not clear that TEs will emerge as a winner in the marketplace in the near-term, there are several new developments which provide justification for this renewed interest. Among these reasons are increasing electrification of the vehicle fleet, demands from governments and consumers for improvement in fuel economy and reduction in tailpipe CO{sub 2} emissions, and a greater emphasis on occupant comfort. With governments and industry around the world placing substantial financial bets on the promise of this technology to help address national and global concerns for reducing CO{sub 2} and hydrocarbon consumption, it makes sense for the automotive industry to leverage this investment and to re-evaluate TE-based technology for use in vehicles. In this paper, we will present an overview of Ford Motor Company's current and upcoming research efforts into TE technology. This effort is focused on the use of TE waste heat recovery systems in a vehicle exhaust; and the use of TE HVAC systems in hybrid vehicles. We will discuss the role of the automotive OEM in establishing guidelines and targets for cost, power density

  13. High temperature thermoelectric properties of strontium titanate thin films with oxygen vacancy and niobium doping

    KAUST Repository

    Sarath Kumar, S. R.

    2013-08-14

    We report the evolution of high temperature thermoelectric properties of SrTiO3 thin films doped with Nb and oxygen vacancies. Structure-property relations in this important thermoelectric oxide are elucidated and the variation of transport properties with dopant concentrations is discussed. Oxygen vacancies are incorporated during growth or annealing in Ar/H2 above 800 K. An increase in lattice constant due to the inclusion of Nb and oxygen vacancies is found to result in an increase in carrier density and electrical conductivity with simultaneous decrease in carrier effective mass and Seebeck coefficient. The lattice thermal conductivity at 300 K is found to be 2.22 W m-1 K-1, and the estimated figure of merit is 0.29 at 1000 K. © 2013 American Chemical Society.

  14. Potential Usage of Thermoelectric Devices in a High Temperature PEM Fuel Cell System

    DEFF Research Database (Denmark)

    Xin, Gao; Chen, Min; Andreasen, Søren Juhl

    2012-01-01

    Methanol fuelled high temperature polymer electrolyte membrane fuel cell (HTPEMFC) power systems are promising as the next generation of vehicle engines, efficient and environmentally friendly. Currently, their performance still needs to be improved and they still rely on a large Li-ion battery...... for system startup. In this paper, to handle these two issues, the potential of thermoelectric (TE) devices applied in a HTPEMFC power system has been preliminarily evaluated. Firstly, right after the fuel cell stack or the methanol reformer, thermoelectric generators (TEGs) are embedded inside a gas......-liquid heat exchanger to jointly form a heat recovery subsystem for electricity production. It is calculated that the recovered power can increase the system efficiency and mitigate the dependence on Li-ion battery during system startup. To further improve the TEG subsystem performance, a finite...

  15. High temperature thermoelectric properties of strontium titanate thin films with oxygen vacancy and niobium doping

    KAUST Repository

    Sarath Kumar, S. R.; Barasheed, Abeer Z.; Alshareef, Husam N.

    2013-01-01

    We report the evolution of high temperature thermoelectric properties of SrTiO3 thin films doped with Nb and oxygen vacancies. Structure-property relations in this important thermoelectric oxide are elucidated and the variation of transport properties with dopant concentrations is discussed. Oxygen vacancies are incorporated during growth or annealing in Ar/H2 above 800 K. An increase in lattice constant due to the inclusion of Nb and oxygen vacancies is found to result in an increase in carrier density and electrical conductivity with simultaneous decrease in carrier effective mass and Seebeck coefficient. The lattice thermal conductivity at 300 K is found to be 2.22 W m-1 K-1, and the estimated figure of merit is 0.29 at 1000 K. © 2013 American Chemical Society.

  16. Enhanced high temperature thermoelectric response of sulphuric acid treated conducting polymer thin films

    KAUST Repository

    Sarath Kumar, S. R.; Kurra, Narendra; Alshareef, Husam N.

    2015-01-01

    We report the high temperature thermoelectric properties of solution processed pristine and sulphuric acid treated poly(3, 4-ethylenedioxythiophene):poly(4-styrenesulfonate) (or PEDOT:PSS) films. The acid treatment is shown to simultaneously enhance the electrical conductivity and Seebeck coefficient of the metal-like films, resulting in a five-fold increase in thermoelectric power factor (0.052 W/m. K ) at 460 K, compared to the pristine film. By using atomic force micrographs, Raman and impedance spectra and using a series heterogeneous model for electrical conductivity, we demonstrate that acid treatment results in the removal of PSS from the films, leading to the quenching of accumulated charge-induced energy barriers that prevent hopping conduction. The continuous removal of PSS with duration of acid treatment also alters the local band structure of PEDOT:PSS, resulting in simultaneous enhancement in Seebeck coefficient.

  17. Enhanced thermoelectric property of oxygen deficient nickel doped SnO2 for high temperature application

    Science.gov (United States)

    Paulson, Anju; Sabeer, N. A. Muhammad; Pradyumnan, P. P.

    2018-04-01

    Motivated by the detailed investigation on the thermoelectric performance of oxide materials our work concentrated on the influence of acceptor dopants and defect density in the lattice plane for the enhancement of thermoelectric power. The series of Sn1‑x Nix O2 (0.01 ≤ x ≤ 0.05) compositions were prepared by solid state reaction mechanism and found that 3 atomic percentage Ni doped SnO2 can be considered as a good candidate due to its promising electrical and transport properties. Defect lattices were introduced in the sample and the deviation from oxygen stochiometry was ensured using photoluminescence measurement. High power factor was obtained for the 3 atomic percentage nickel doped SnO2 due to the effective number of charge carrier concentration and the depletion of oxygen rich layers. Defect centered and acceptor doped SnO2 lattice opens a new door for energy harvesting at higher temperatures.

  18. Using high thermal stability flexible thin film thermoelectric generator at moderate temperature

    Science.gov (United States)

    Zheng, Zhuang-Hao; Luo, Jing-Ting; Chen, Tian-Bao; Zhang, Xiang-Hua; Liang, Guang-Xing; Fan, Ping

    2018-04-01

    Flexible thin film thermoelectric devices are extensively used in the microscale industry for powering wearable electronics. In this study, comprehensive optimization was conducted in materials and connection design for fabricating a high thermal stability flexible thin film thermoelectric generator. First, the thin films in the generator, including the electrodes, were prepared by magnetron sputtering deposition. The "NiCu-Cu-NiCu" multilayer electrode structure was applied to ensure the thermal stability of the device used at moderate temperature in an air atmosphere. A design with metal layer bonding and series accordant connection was then employed. The maximum efficiency of a single PN thermocouple generator is >11%, and the output power loss of the generator is <10% after integration.

  19. Enhanced high temperature thermoelectric response of sulphuric acid treated conducting polymer thin films

    KAUST Repository

    Sarath Kumar, S. R.

    2015-11-24

    We report the high temperature thermoelectric properties of solution processed pristine and sulphuric acid treated poly(3, 4-ethylenedioxythiophene):poly(4-styrenesulfonate) (or PEDOT:PSS) films. The acid treatment is shown to simultaneously enhance the electrical conductivity and Seebeck coefficient of the metal-like films, resulting in a five-fold increase in thermoelectric power factor (0.052 W/m. K ) at 460 K, compared to the pristine film. By using atomic force micrographs, Raman and impedance spectra and using a series heterogeneous model for electrical conductivity, we demonstrate that acid treatment results in the removal of PSS from the films, leading to the quenching of accumulated charge-induced energy barriers that prevent hopping conduction. The continuous removal of PSS with duration of acid treatment also alters the local band structure of PEDOT:PSS, resulting in simultaneous enhancement in Seebeck coefficient.

  20. Improved microstructure and thermoelectric properties of iodine doped indium selenide as a function of sintering temperature

    Science.gov (United States)

    Dhama, Pallavi; Kumar, Aparabal; Banerji, P.

    2018-04-01

    In this paper, we explored the effect of sintering temperature on the microstructure, thermal and electrical properties of iodine doped indium selenide in the temperature range 300 - 700 K. Samples were prepared by a collaborative process of vacuum melting, ball milling and spark plasma sintering at 570 K, 630 K and 690 K. Single phase samples were obtained at higher sintering temperature as InSe is stable only at lower temperature. With increasing sintering temperature, densities of the samples were found to improve with larger grain size formation. Negative values of Seebeck coefficient were observed which indicates n-type carrier transport. Seebeck coefficient increases with sintering temperature and found to be the highest for the sample sintered at 690 K. Thermal conductivity found to be lower in the samples sintered at lower temperatures. The maximum thermoelectric figure of merit found to be ˜ 1 at 700 K due to the enhanced power factor as a result of improved microstructure.

  1. Controlled thermoelectric response of a tunable Rashba coupled metal-insulator-superconductor junction

    Science.gov (United States)

    Kapri, Priyadarshini; Adhikary, Priyanka; Sinha, Shubham; Basu, Saurabh

    2018-05-01

    Thermoelectric effect for metal, insulator and the superconductor junctions has been studied with Rashba spin-orbit coupling (RSOC) being present at the interfaces via modified Blonder-Tinkham-Klapwijk (BTK) theory. We find that the thermopower, as a function of an effective barrier potential that characterizes the intermediate insulating layer, displays an oscillatory behavior. Interesting interplay between the strength of RSOC and the effective barrier potential has been carried out in details in this regard. For specific ranges of the effective barrier potential, RSOC enhances the thermopower, while the reverse happens for other values. Moreover it is found that the effective barrier potential plays a crucial role in determining the thermopower spectrum. For a tunable Rashba coupling, the thermopower of the junction can be controlled with precision, which may useful for the thermoelectric applications, at low temperatures. Further the efficiency of the system is obtained for different pairing correlations of the superconducting lead where we find that the system with a d-wave symmetry is more efficient as compared to a s-wave correlation, in some selective regions of effective barrier potential. It is found that for some selective regions of effective barrier potential, the efficiency of the system increases with RSOC and the opposite happens for other values.

  2. Effects of environmental temperature fluctuations on the parameters of a thermoelectric battery

    International Nuclear Information System (INIS)

    Kozlov, Yu.F.; Oganov, E.P.

    1980-01-01

    A numerical analysis is presented for the effects of lags on the output parameters of a radioisotope thermoelectric battery under conditions of diurnal temperature variation in the environment. Allowance for the inertial effects causes a phase shift and change in amplitude of the variations in the thermal and electrical parameters. The amplitude of the temperature fluctuations in the hot junctions is substantially reduced, while the output electrical power increases. The data provide a more rigorous basis for choosing the parameters of radioisotope batteries during design. 9 refs

  3. High-temperature and high-power-density nanostructured thermoelectric generator for automotive waste heat recovery

    International Nuclear Information System (INIS)

    Zhang, Yanliang; Cleary, Martin; Wang, Xiaowei; Kempf, Nicholas; Schoensee, Luke; Yang, Jian; Joshi, Giri; Meda, Lakshmikanth

    2015-01-01

    Highlights: • A thermoelectric generator (TEG) is fabricated using nanostructured half-Heusler materials. • The TE unicouple devices produce superior power density above 5 W/cm"2. • A TEG system with over 1 kW power output is demonstrated by recovering automotive waste heat. - Abstract: Given increasing energy use as well as decreasing fossil fuel sources worldwide, it is no surprise that interest in promoting energy efficiency through waste heat recovery is also increasing. Thermoelectric generators (TEGs) are one of the most promising pathways for waste heat recovery. Despite recent thermoelectric efficiency improvement in nanostructured materials, a variety of challenges have nevertheless resulted in few demonstrations of these materials for large-scale waste heat recovery. Here we demonstrate a high-performance TEG by combining high-efficiency nanostructured bulk materials with a novel direct metal brazing process to increase the device operating temperature. A unicouple device generates a high power density of 5.26 W cm"−"2 with a 500 °C temperature difference between hot and cold sides. A 1 kW TEG system is experimentally demonstrated by recovering the exhaust waste heat from an automotive diesel engine. The TEG system operated with a 2.1% heat-to-electricity efficiency under the average temperature difference of 339 °C between the TEG hot- and cold-side surfaces at a 550 °C exhaust temperature. The high-performance TEG reported here open up opportunities to use TEGs for energy harvesting and power generation applications.

  4. Thermoelectric Exhaust Heat Recovery with Heat Pipe-Based Thermal Control

    Science.gov (United States)

    Brito, F. P.; Martins, Jorge; Hançer, Esra; Antunes, Nuno; Gonçalves, L. M.

    2015-06-01

    Heat pipe (HP)-based heat exchangers can be used for very low resistance heat transfer between a hot and a cold source. Their operating temperature depends solely on the boiling point of their working fluid, so it is possible to control the heat transfer temperature if the pressure of the HP can be adjusted. This is the case of the variable conductance HPs (VCHP). This solution makes VCHPs ideal for the passive control of thermoelectric generator (TEG) temperature levels. The present work assesses, both theoretically and experimentally, the merit of the aforementioned approach. A thermal and electrical model of a TEG with VCHP assist is proposed. Experimental results obtained with a proof of concept prototype attached to a small single-cylinder engine are presented and used to validate the model. It was found that the HP heat exchanger indeed enables the TEG to operate at a constant, optimal temperature in a passive and safe way, and with a minimal overall thermal resistance, under part load, it effectively reduces the active module area without deprecating the temperature level of the active modules.

  5. High-temperature thermoelectric properties of La-doped BaSnO3 ceramics

    International Nuclear Information System (INIS)

    Yasukawa, Masahiro; Kono, Toshio; Ueda, Kazushige; Yanagi, Hiroshi; Hosono, Hideo

    2010-01-01

    To elucidate the thermoelectric properties at high temperatures, perovskite-type La-doped BaSnO 3 ceramics were fabricated by a polymerized complex (PC) method and subsequent spark plasma sintering (SPS) technique. Fine powders of Ba 1-x La x SnO 3 (x = 0.00-0.07) were prepared by the PC method using citrate complexes, and SPS treatment converted the powders into dense ceramics with relative densities of 93-97%. The La content dependence of the lattice parameter suggested that the solubility of La for Ba sites was approximately x = 0.03. The temperature dependence of the electrical conductivity σ and Seebeck coefficient S showed that each La-doped ceramic was an n-type degenerate semiconductor in the measured temperature range of 373-1073 K. The La content dependence of the S values indicated that the electron carrier concentration increased successively up to x = 0.03, which was the solubility limit of the La atoms. The thermoelectric power factors S 2 σ increased drastically with La doping, and reached a maximum for x = 0.01 with values of 0.8 x 10 -4 W m -1 K -2 at 373 K to 2.8 x 10 -4 W m -1 K -2 at 1073 K.

  6. Impact Factors Analysis of the Hot Side Temperature of Thermoelectric Module

    Science.gov (United States)

    Zhang, Xingyu; Tan, Gangfeng; Yang, Bo

    2018-03-01

    The thermoelectric generator (TEG) plays a crucial role in converting the waste energy of exhaust into electricity, which ensures energy saving and increased fuel utilization efficiency. In the urban driving cycle, frequent vehicle operation, like deceleration or acceleration, results in continuous variation of the exhaust temperature. In order to make the operating performance stable, and to weaken the adverse effects of the frequent variation of the exhaust temperature on the lifetime and work efficiency of the electronic components of TEG systems, the output voltage of the thermoelectric (TE) module should stay more stable. This article provides an improved method for the temperature stability of the TE material hot side based on sandwiching material. From the view of the TEG system's average output power and the hot side temperature stability of the TE material, the analyzing factors, including the fluctuation frequency of the exhaust temperature and the physical properties and thickness of the sandwiching material are evaluated, respectively, in the sine and new European driving cycle (NEDC) fluctuation condition of the exhaust temperature. The results show few effects of sandwiching material thickness with excellent thermal conductivity on the average output power. During the 150-170 s of the NEDC test condition, the minimum hot side temperatures with a BeO ceramic thickness of 2 mm and 6 mm are, respectively, 537.19 K and 685.70 K, which shows the obvious effect on the hot side temperature stability of the BeO ceramic thickness in the process of acceleration and deceleration of vehicle driving.

  7. Very heavily electron-doped CrSi2 as a high-performance high-temperature thermoelectric material

    International Nuclear Information System (INIS)

    Parker, David; Singh, David J

    2012-01-01

    We analyze the thermoelectric behavior, using first principles and Boltzmann transport calculations, of very heavily electron-doped CrSi 2 and find that at temperatures of 900-1250 K and electron dopings of 1-4 × 10 21 cm -3 , thermopowers as large in magnitude as 200 μV K -1 may be found. Such high thermopowers at such high carrier concentrations are extremely rare, and suggest that excellent thermoelectric performance may be found in these ranges of temperature and doping. (paper)

  8. Optoelectronic and low temperature thermoelectric studies on nanostructured thin films of silver gallium selenide

    International Nuclear Information System (INIS)

    Jacob, Rajani; Philip, Rachel Reena; Nazer, Sheeba; Abraham, Anitha; Nair, Sinitha B.; Pradeep, B.; Urmila, K. S.; Okram, G. S.

    2014-01-01

    Polycrystalline thin films of silver gallium selenide were deposited on ultrasonically cleaned soda lime glass substrates by multi-source vacuum co-evaporation technique. The structural analysis done by X-ray diffraction ascertained the formation of nano structured tetragonal chalcopyrite thin films. The compound formation was confirmed by X-ray photo-electron spectroscopy. Atomic force microscopic technique has been used for surface morphological analysis. Direct allowed band gap ∼1.78eV with high absorption coefficient ∼10 6 /m was estimated from absorbance spectra. Low temperature thermoelectric effects has been investigated in the temperature range 80–330K which manifested an unusual increase in Seebeck coefficient with negligible phonon drag toward the very low and room temperature regime. The electrical resistivity of these n-type films was assessed to be ∼2.6Ωm and the films showed good photo response

  9. Optoelectronic and low temperature thermoelectric studies on nanostructured thin films of silver gallium selenide

    Science.gov (United States)

    Jacob, Rajani; Philip, Rachel Reena; Nazer, Sheeba; Abraham, Anitha; Nair, Sinitha B.; Pradeep, B.; Urmila, K. S.; Okram, G. S.

    2014-01-01

    Polycrystalline thin films of silver gallium selenide were deposited on ultrasonically cleaned soda lime glass substrates by multi-source vacuum co-evaporation technique. The structural analysis done by X-ray diffraction ascertained the formation of nano structured tetragonal chalcopyrite thin films. The compound formation was confirmed by X-ray photo-electron spectroscopy. Atomic force microscopic technique has been used for surface morphological analysis. Direct allowed band gap ˜1.78eV with high absorption coefficient ˜106/m was estimated from absorbance spectra. Low temperature thermoelectric effects has been investigated in the temperature range 80-330K which manifested an unusual increase in Seebeck coefficient with negligible phonon drag toward the very low and room temperature regime. The electrical resistivity of these n-type films was assessed to be ˜2.6Ωm and the films showed good photo response.

  10. Temperature gradient measurements by using thermoelectric effect in CNTs-silicone adhesive composite.

    Directory of Open Access Journals (Sweden)

    Muhammad Tariq Saeed Chani

    Full Text Available This work presents the fabrication and investigation of thermoelectric cells based on composite of carbon nanotubes (CNT and silicone adhesive. The composite contains CNT and silicon adhesive 1∶1 by weight. The current-voltage characteristics and dependences of voltage, current and Seebeck coefficient on the temperature gradient of cell were studied. It was observed that with increase in temperature gradient the open circuit voltage, short circuit current and the Seebeck coefficient of the cells increase. Approximately 7 times increase in temperature gradient increases the open circuit voltage and short circuit current up to 40 and 5 times, respectively. The simulation of experimental results is also carried out; the simulated results are well matched with experimental results.

  11. Ab initio optimization of phonon drag effect for lower-temperature thermoelectric energy conversion

    Science.gov (United States)

    Zhou, Jiawei; Liao, Bolin; Qiu, Bo; Huberman, Samuel; Esfarjani, Keivan; Dresselhaus, Mildred S.; Chen, Gang

    2015-01-01

    Although the thermoelectric figure of merit zT above 300 K has seen significant improvement recently, the progress at lower temperatures has been slow, mainly limited by the relatively low Seebeck coefficient and high thermal conductivity. Here we report, for the first time to our knowledge, success in first-principles computation of the phonon drag effect—a coupling phenomenon between electrons and nonequilibrium phonons—in heavily doped region and its optimization to enhance the Seebeck coefficient while reducing the phonon thermal conductivity by nanostructuring. Our simulation quantitatively identifies the major phonons contributing to the phonon drag, which are spectrally distinct from those carrying heat, and further reveals that although the phonon drag is reduced in heavily doped samples, a significant contribution to Seebeck coefficient still exists. An ideal phonon filter is proposed to enhance zT of silicon at room temperature by a factor of 20 to ∼0.25, and the enhancement can reach 70 times at 100 K. This work opens up a new venue toward better thermoelectrics by harnessing nonequilibrium phonons. PMID:26627231

  12. Probing the Subtle Structure Modifications of Thermoelectric Materials by Variable Temperature Total Scattering

    DEFF Research Database (Denmark)

    Reardon, Hazel; Iversen, Bo Brummerstedt; Blichfeld, Anders Bank

    The complex host-guest structure of Type-I inorganic clathrates has been studied fervently within the CMC based on their low thermal conductivity and promising thermoelectric Figure of Merit (zT). We have recently been focused on understanding unusual features in the high temperature diffraction...... data collected over a number of years on Ba8Ga16Ge30 (BGG), where numerous samples have been prepared in-house using various synthesis methods. This led to a comprehensive thermal stability study of clathrate powders, where PXRD revealed amorphous components in the samples treated at high temperature...... in air. PDF measurements were performed on data collected from ex situ annealed BGG samples. This ex situ study (to be submitted), reveals that the seemingly subtle change in the clathrate structure and the emergence of a significant amorphous phase observed from PXRD data is likely to be the result...

  13. Temperature dependent thermoelectric property of reduced graphene oxide-polyaniline composite

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, Mousumi, E-mail: mousumimitrabesu@gmail.com; Banerjee, Dipali, E-mail: dipalibanerjeebesu@gmail.com [Department of Physics, Indian Institute of Engineering Science and Technology (IIEST), Howrah-711103 (India); Kargupta, Kajari, E-mail: karguptakajari2010@gmail.com [Department of Chemical Engineering, Jadavpur University, Kolkata (India); Ganguly, Saibal, E-mail: gangulysaibal2011@gmail.com [Chemical Engineering department, Universiti Teknologi Petronas, Perak, Tronoh (Malaysia)

    2016-05-06

    A composite material of reduced graphene oxide (rG) nanosheets with polyaniline (PANI) protonated by 5-sulfosalicylic acid has been synthesized via in situ oxidative polymerization method. The morphological and spectral characterizations have been done using FESEM and XRD measurements. The thermoelectric (TE) properties of the reduced graphene oxide-polyaniline composite (rG-P) has been studied in the temperature range from 300-400 K. The electrical conductivity and the Seebeck coefficient of rG-P is higher than the of pure PANI, while the thermal conductivity of the composite still keeps much low value ensuing an increase in the dimensionless figure of merit (ZT) in the whole temperature range.

  14. Nanostructured Thermoelectric Oxides for Energy Harvesting Applications

    KAUST Repository

    Abutaha, Anas I.

    2015-01-01

    of thermoelectrics are still limited to one materials system, namely SiGe, since the traditional thermoelectric materials degrade and oxidize at high temperature. Therefore, oxide thermoelectrics emerge as a promising class of materials since they can operate

  15. Multi Channels PWM Controller for Thermoelectric Cooler Using a Programmable Logic Device and Lab-Windows CVI

    Directory of Open Access Journals (Sweden)

    Eli FLAXER

    2008-09-01

    Full Text Available We present a complete design of a multi channels PID controller for Thermoelectric Cooler (TEC using a pulse width modulation (PWM technique implemented by a dedicated programmable logic device (PLD programmed by VHDL. The PID control loop is implemented by software written by National Instrument Lab-Windows CVI. Due to the fact that the implementation is by a VHDL and PLD the design is modular, as a result, the circuit is very compact in size and very low cost as compared to any commercial product. In addition, since the control loop is implemented by software running on a personal computer (PC using a C language, it is easy to adjust the controller to various environmental conditions and for a width range of sensors like: a thermo couple (TC, thermistor, resistance temperature detectors (RTD etc. We demonstrate the performance of this circuit as a controller for a small incubator using thermistor as the temperature sensor.

  16. Acidity-Controlled Conducting Polymer Films for Organic Thermoelectric Devices with Horizontal and Vertical Architectures

    Science.gov (United States)

    Lee, Woongki; Song, Myeonghun; Park, Soohyung; Nam, Sungho; Seo, Jooyeok; Kim, Hwajeong; Kim, Youngkyoo

    2016-09-01

    Organic thermoelectric devices (OTEDs) are recognized one of the next generation energy conversion platforms because of their huge potentials for securing electricity continuously from even tiny heat sources in our daily life. The advantage of OTEDs can be attributable to the design freedom in device shapes and the low-cost fabrication by employing solution coating processes at low temperatures. As one of the major OTE materials to date, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has been used, but no study has been yet carried out on its acidity control even though the acidic components in OTEDs can seriously affect the device performance upon operation. Here we demonstrate that the addition of aniline (a weak base) can control the acidity of PEDOT:PSS and enhance the performance of OTEDs. In particular, the vertical OTEDs with aniline-doped PEDOT:PSS films (active area = 1.0 cm2) could continuously generate electricity (0.06 nW) even at low temperatures (<38 °C) when they were mounted on a desk lamp (power = 24 W).

  17. High-temperature thermoelectric properties of AgxYyCa2⋅ 8Co4O9 ...

    Indian Academy of Sciences (India)

    temperature thermoelectric properties of AgYCa2.8Co4O9 + ceramics. Youjin Zheng Hui Zhou Tengzhou Ma Guihong Zuo Hongtao Li Taichao Su Chunlei Wu Hailiang Huang Dan Wang Longcheng Yin. Volume 37 Issue 5 August 2014 pp 963- ...

  18. Analysis and Experimental Investigation of Optimum Design of Thermoelectric Cooling/Heating System for Car Seat Climate Control (CSCC)

    Science.gov (United States)

    Elarusi, Abdulmunaem; Attar, Alaa; Lee, HoSung

    2018-02-01

    The optimum design of a thermoelectric system for application in car seat climate control has been modeled and its performance evaluated experimentally. The optimum design of the thermoelectric device combining two heat exchangers was obtained by using a newly developed optimization method based on the dimensional technique. Based on the analytical optimum design results, commercial thermoelectric cooler and heat sinks were selected to design and construct the climate control heat pump. This work focuses on testing the system performance in both cooling and heating modes to ensure accurate analytical modeling. Although the analytical performance was calculated using the simple ideal thermoelectric equations with effective thermoelectric material properties, it showed very good agreement with experiment for most operating conditions.

  19. High-temperature thermoelectric properties of the β-As2−xBixTe3 solid solution

    Directory of Open Access Journals (Sweden)

    J.-B. Vaney

    2016-10-01

    Full Text Available Bi2Te3-based compounds are a well-known class of outstanding thermoelectric materials. β-As2Te3, another member of this family, exhibits promising thermoelectric properties around 400 K when appropriately doped. Herein, we investigate the high-temperature thermoelectric properties of the β-As2−xBixTe3 solid solution. Powder X-ray diffraction and scanning electron microscopy experiments showed that a solid solution only exists up to x = 0.035. We found that substituting Bi for As has a beneficial influence on the thermopower, which, combined with extremely low thermal conductivity values, results in a maximum ZT value of 0.7 at 423 K for x = 0.017 perpendicular to the pressing direction.

  20. Simultaneous control of thermoelectric properties in p- and n-type materials by electric double-layer gating: New design for thermoelectric device

    Science.gov (United States)

    Takayanagi, Ryohei; Fujii, Takenori; Asamitsu, Atsushi

    2015-05-01

    We report a novel design of a thermoelectric device that can control the thermoelectric properties of p- and n-type materials simultaneously by electric double-layer gating. Here, p-type Cu2O and n-type ZnO were used as the positive and negative electrodes of the electric double-layer capacitor structure. When a gate voltage was applied between the two electrodes, holes and electrons accumulated on the surfaces of Cu2O and ZnO, respectively. The thermopower was measured by applying a thermal gradient along the accumulated layer on the electrodes. We demonstrate here that the accumulated layers worked as a p-n pair of the thermoelectric device.

  1. Effect of linear temperature dependence of thermoelectric properties on energy conversion efficiency

    International Nuclear Information System (INIS)

    Yamashita, Osamu

    2008-01-01

    New thermal rate equations were developed by taking the temperature dependences of the electrical resistivity ρ and thermal conductivity κ of the thermoelectric (TE) materials into the thermal rate equations on the assumption that they vary linearly with temperature T. The relative energy conversion efficiency η/η 0 for a single TE element was formulated by approximate analysis, where η and η 0 are the energy conversion efficiencies derived from the new and conventional thermal rate equations, respectively. Applying it to Si-Ge alloys, the temperature dependence of ρ is stronger than that of κ, so the former has a more significant effect on η/η 0 than the latter. However, the degree of contribution from both of them to η/η 0 was a little lower than 1% at the temperature difference ΔT of 600 K. When the temperature dependence of κ was increased to become equal to that of ρ, however, it was found that η/η 0 is increased by about 10% at ΔT = 600 K. It is clarified here that the temperature dependences of ρ and κ are also important factors for an improvement in η

  2. Optimization of a thermoelectric generator subsystem for high temperature PEM fuel cell exhaust heat recovery

    DEFF Research Database (Denmark)

    Gao, Xin; Andreasen, Søren Juhl; Kær, Søren Knudsen

    2014-01-01

    In previous work, a thermoelectric (TE) exhaust heat recovery subsystem for a high temperature polymer electrolyte membrane (HT-PEM) fuel cell stack was developed and modeled. Numerical simulations were conducted and have identified an optimized subsystem configuration and 4 types of compact heat...... modules are now connected into branches. The procedures of designing and optimizing this TE exhaust heat recovery subsystem are drawn out. The contribution of TE exhaust heat recovery to the HT-PEM fuel cell power system is preliminarily concluded. Its feasibility is also discussed....... exchangers with superior performance for further analysis. In this work, the on-design performances of the 4 heat exchangers are more thoroughly assessed on their corresponding optimized subsystem configurations. Afterward, their off-design performances are compared on the whole working range of the fuel...

  3. Study on load temperature control system of ground laser communication

    Science.gov (United States)

    Zhai, Xunhua; Zhang, Hongtao; Liu, Wangsheng; Zhang, Chijun; Zhou, Xun

    2007-12-01

    The ground laser communication terminal as the termination of a communication system, works at the temperature which varies from -40°C to 50°C. We design a temperature control system to keep optical and electronic components working properly in the load. The load is divided into two sections to control temperature respectively. Because the space is limited, we use heater film and thermoelectric cooler to clearify and refrigerate the load. We design a hardware and a software for the temperature control system, establish mathematic model, and emulate it with Matlab.

  4. NATO Advanced Research Workshop on Boron Rich Solids Sensors for Biological and Chemical Detection, Ultra High Temperature Ceramics, Thermoelectrics, Armor

    CERN Document Server

    Orlovskaya, Nina

    2011-01-01

    The objective of this book is to discuss the current status of research and development of boron-rich solids as sensors, ultra-high temperature ceramics, thermoelectrics, and armor. Novel biological and chemical sensors made of stiff and light-weight boron-rich solids are very exciting and efficient for applications in medical diagnoses, environmental surveillance and the detection of pathogen and biological/chemical terrorism agents. Ultra-high temperature ceramic composites exhibit excellent oxidation and corrosion resistance for hypersonic vehicle applications. Boron-rich solids are also promising candidates for high-temperature thermoelectric conversion. Armor is another very important application of boron-rich solids, since most of them exhibit very high hardness, which makes them perfect candidates with high resistance to ballistic impact. The following topical areas are presented: •boron-rich solids: science and technology; •synthesis and sintering strategies of boron rich solids; •microcantileve...

  5. High-Temperature Performance of Stacked Silicon Nanowires for Thermoelectric Power Generation

    Science.gov (United States)

    Stranz, Andrej; Waag, Andreas; Peiner, Erwin

    2013-07-01

    Deep reactive-ion etching at cryogenic temperatures (cryo-DRIE) has been used to produce arrays of silicon nanowires (NWs) for thermoelectric (TE) power generation devices. Using cryo-DRIE, we were able to fabricate NWs of large aspect ratios (up to 32) using a photoresist mask. Roughening of the NW sidewalls occurred, which has been recognized as beneficial for low thermal conductivity. Generated NWs, which were 7 μm in length and 220 nm to 270 nm in diameter, were robust enough to be stacked with a bulk silicon chip as a common top contact to the NWs. Mechanical support of the NW array, which can be created by filling the free space between the NWs using silicon oxide or polyimide, was not required. The Seebeck voltage, measured across multiple stacks of up to 16 bulk silicon dies, revealed negligible thermal interface resistance. With stacked silicon NWs, we observed Seebeck voltages that were an order of magnitude higher than those observed for bulk silicon. Degradation of the TE performance of silicon NWs was not observed for temperatures up to 470°C and temperature gradients up to 170 K.

  6. High-temperature resistivity and thermoelectric properties of coupled substituted Ca3Co2O6

    Directory of Open Access Journals (Sweden)

    Meenakshisundaram Senthilkumar and Rajagopalan Vijayaraghavan

    2009-01-01

    Full Text Available Polycrystalline samples of Ca3−xNaxCo2−xMnxO6 (x=0.0–0.5 have been prepared by the sol-gel cum combustion method using sucrose in order to investigate the effects of the coupled substitution of Na and Mn on Ca and Co sites on the transport properties of Ca3Co2O6(Co326. The products were characterized by Fourier transform infrared spectroscopy, powder x-ray diffraction (XRD, thermogravimetry (TGA, differential thermal analysis and scanning electron microscopy. XRD patterns reveal the formation of single-phase products up to x=0.5. Coupled substitution increases the solubility of both Na and Mn on Ca and Co sites, respectively, in contrast to the limited solubility of Na and Mn (x=0.2 when separately substituted. TGA confirms the formation of the Ca3Co2O6 phase at temperatures ~720 °C. The grain size of the parent and substituted products is in the range 150–250 nm. Electrical resistivity and Seebeck coefficient were measured in the temperature range 300–800 K. Resistivity shows semiconducting behavior for all the compositions, particularly in the low-temperature regime. The Seebeck coefficient increases with temperature throughout the measured temperature range for all compositions. The maximum Seebeck coefficient (200 μV K−1 is observed for x=0.5 at 825 K, and this composition may be optimal for high-temperature thermoelectric applications.

  7. Temperature measurement and control

    CERN Document Server

    Leigh, JR

    1988-01-01

    This book treats the theory and practice of temperature measurement and control and important related topics such as energy management and air pollution. There are no specific prerequisites for the book although a knowledge of elementary control theory could be useful. The first half of the book is an application oriented survey of temperature measurement techniques and devices. The second half is concerned mainly with temperature control in both simple and complex situations.

  8. Thermoelectric materials having porosity

    Science.gov (United States)

    Heremans, Joseph P.; Jaworski, Christopher M.; Jovovic, Vladimir; Harris, Fred

    2014-08-05

    A thermoelectric material and a method of making a thermoelectric material are provided. In certain embodiments, the thermoelectric material comprises at least 10 volume percent porosity. In some embodiments, the thermoelectric material has a zT greater than about 1.2 at a temperature of about 375 K. In some embodiments, the thermoelectric material comprises a topological thermoelectric material. In some embodiments, the thermoelectric material comprises a general composition of (Bi.sub.1-xSb.sub.x).sub.u(Te.sub.1-ySe.sub.y).sub.w, wherein 0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1, 1.8.ltoreq.u.ltoreq.2.2, 2.8.ltoreq.w.ltoreq.3.2. In further embodiments, the thermoelectric material includes a compound having at least one group IV element and at least one group VI element. In certain embodiments, the method includes providing a powder comprising a thermoelectric composition, pressing the powder, and sintering the powder to form the thermoelectric material.

  9. Conceptual design of a FGM thermoelectric energy conversion system for high temperature heat source. 1. Design of thermoelectric energy conversion unit

    International Nuclear Information System (INIS)

    Kambe, Mitsuru; Teraki, Junichi; Hirano, Toru.

    1996-01-01

    Thermoelectric (TE) power conversion system has been focused as a candidate of direct energy conversion systems for high temperature heat source to meet the various power requirements in next century. A concept of energy conversion unit by using TE cell elements combined with FGM compliant pads has been presented to achieve high thermal energy density as well as high energy conversion efficiency. An energy conversion unit consists of 8 couples of P-N cell elements sandwiched between two FGM compliant pads. Performance analysis revealed that the power generated by this unit was 11 watts which is nearly ten times as much as conventional unit of the same size. Energy conversion efficiency of 12% was expected based on the assumption of ZT = 1. All the member of compliant pads as well as TE cells could be bonded together to avoid thermal resistance. (author)

  10. Temperature control in vacuum

    International Nuclear Information System (INIS)

    Dearnaley, G.

    1986-01-01

    The patent concerns a method for controlling the temperature of silicon wafers (or samples), during ion beam treatment of the wafers, in a vacuum. The apparatus and method are described for irradiation and temperature control of the samples. The wafers are mounted on a drum which is rotated through the ion beam, and are additionally heated by infra-red lamps to achieve the desired temperature. (U.K.)

  11. Efficient Space Hardy Thermoelectric Materials with Broad Temperature Range, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of this work is developing new thermoelectric materials for use in fabricating solid state cooling devices and electrical power generators, which are 200 to...

  12. Efficient Space Hardy Thermoelectric Materials with Broad Temperature Range, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of this work is to develop new thermoelectric materials for use in fabricating solid state cooling devices and electrical power generators, which are 200 to...

  13. High – temperature thermoelectric properties of Hg – doped CuInTe2

    Czech Academy of Sciences Publication Activity Database

    Kucek, V.; Drašar, Č.; Kašparová, J.; Plecháček, T.; Navrátil, Jiří; Vlček, Milan; Beneš, L.

    2015-01-01

    Roč. 118, č. 12 (2015), 125105-1 - 125105-7 ISSN 0021-8979 Institutional support: RVO:61389013 Keywords : thermoelectric materials * Hall coefficient * Seebeck coefficient Subject RIV: CA - Inorganic Chemistry Impact factor: 2.101, year: 2015

  14. Thermoelectricity in liquid crystals

    Science.gov (United States)

    Mohd Said, Suhana; Nordin, Abdul Rahman; Abdullah, Norbani; Balamurugan, S.

    2015-09-01

    The thermoelectric effect, also known as the Seebeck effect, describes the conversion of a temperature gradient into electricity. A Figure of Merit (ZT) is used to describe the thermoelectric ability of a material. It is directly dependent on its Seebeck coefficient and electrical conductivity, and inversely dependent on its thermal conductivity. There is usually a compromise between these parameters, which limit the performance of thermoelectric materials. The current achievement for ZT~2.2 falls short of the expected threshold of ZT=3 to allow its viability in commercial applications. In recent times, advances in organic thermoelectrics been significant, improving by over 3 orders of magnitude over a period of about 10 years. Liquid crystals are newly investigated as candidate thermoelectric materials, given their low thermal conductivity, inherent ordering, and in some cases, reasonable electrical conductivity. In this work the thermoelectric behaviour of a discotic liquid crystal, is discussed. The DLC was filled into cells coated with a charge injector, and an alignment of the columnar axis perpendicular to the substrate was allowed to form. This thermoelectric behavior can be correlated to the order-disorder transition. A reasonable thermoelectric power in the liquid crystal temperature regime was noted. In summary, thermoelectric liquid crystals may have the potential to be utilised in flexible devices, as a standalone power source.

  15. High temperature thermoelectric properties of p-type skutterudites BaxYbyCo4-zFezSb12

    KAUST Repository

    Dong, Y.

    2012-01-01

    Several polycrystalline p-type skutterudites with compositions Ba xYb yCo 4-zFe zSb 12, with varying filler concentrations x and y, and z = 1 to 2, were synthesized by reacting the constituents and subsequent solid state annealing, followed by densification by hot-pressing. Their thermoelectric properties were evaluated from 300 to 820 K. The Yb filling fraction increased with Fe content while the amount of Fe substitution had little influence on the Ba filling fraction. High purity specimens were obtained when the Fe content was low. Bipolar conduction contributed to the thermal conductivity at elevated temperatures. A maximum ZT value of 0.7 was obtained at 750 K for the specimen with the highest Fe content and filling fraction. The potential for thermoelectric applications is also discussed. © 2012 American Institute of Physics.

  16. Experimental and analytical study on thermoelectric self cooling of devices

    International Nuclear Information System (INIS)

    Martinez, A.; Astrain, D.; Rodriguez, A.

    2011-01-01

    This paper presents and studies the novel concept of thermoelectric self cooling, which can be introduced as the cooling and temperature control of a device using thermoelectric technology without electricity consumption. For this study, it is designed a device endowed with an internal heat source. Subsequently, a commonly used cooling system is attached to the device and the thermal performance is statistically assessed. Afterwards, it is developed and studied a thermoelectric self cooling system appropriate for the device. Experimental and analytical results show that the thermal resistance between the heat source and the environment reduced by 25-30% when the thermoelectric self cooling system is installed, and indicates the promising applicability of this technology to devices that generate large amounts of heat, such as electrical power converters, transformers and control systems. Likewise, it was statistically proved that the thermoelectric self cooling system leads to significant reductions in the temperature difference between the heat source and the environment, and, what is more, this reduction increases as the heat flow generated by the heat source increases, which makes evident the fact that thermoelectric self cooling systems work as temperature controllers. -- Highlights: → Novel concept of thermoelectric self cooling is presented and studied. → No extra electricity is needed. → Thermal resistance between the heat source and the environment reduces by 25-30%. → Increasing reduction in temperature difference between heat source and environment. → Great applicability to any device that generates heat and must be cooled.

  17. New experimental methodology, setup and LabView program for accurate absolute thermoelectric power and electrical resistivity measurements between 25 and 1600 K: Application to pure copper, platinum, tungsten, and nickel at very high temperatures

    International Nuclear Information System (INIS)

    Abadlia, L.; Mayoufi, M.; Gasser, F.; Khalouk, K.; Gasser, J. G.

    2014-01-01

    In this paper we describe an experimental setup designed to measure simultaneously and very accurately the resistivity and the absolute thermoelectric power, also called absolute thermopower or absolute Seebeck coefficient, of solid and liquid conductors/semiconductors over a wide range of temperatures (room temperature to 1600 K in present work). A careful analysis of the existing experimental data allowed us to extend the absolute thermoelectric power scale of platinum to the range 0-1800 K with two new polynomial expressions. The experimental device is controlled by a LabView program. A detailed description of the accurate dynamic measurement methodology is given in this paper. We measure the absolute thermoelectric power and the electrical resistivity and deduce with a good accuracy the thermal conductivity using the relations between the three electronic transport coefficients, going beyond the classical Wiedemann-Franz law. We use this experimental setup and methodology to give new very accurate results for pure copper, platinum, and nickel especially at very high temperatures. But resistivity and absolute thermopower measurement can be more than an objective in itself. Resistivity characterizes the bulk of a material while absolute thermoelectric power characterizes the material at the point where the electrical contact is established with a couple of metallic elements (forming a thermocouple). In a forthcoming paper we will show that the measurement of resistivity and absolute thermoelectric power characterizes advantageously the (change of) phase, probably as well as DSC (if not better), since the change of phases can be easily followed during several hours/days at constant temperature

  18. New experimental methodology, setup and LabView program for accurate absolute thermoelectric power and electrical resistivity measurements between 25 and 1600 K: application to pure copper, platinum, tungsten, and nickel at very high temperatures.

    Science.gov (United States)

    Abadlia, L; Gasser, F; Khalouk, K; Mayoufi, M; Gasser, J G

    2014-09-01

    In this paper we describe an experimental setup designed to measure simultaneously and very accurately the resistivity and the absolute thermoelectric power, also called absolute thermopower or absolute Seebeck coefficient, of solid and liquid conductors/semiconductors over a wide range of temperatures (room temperature to 1600 K in present work). A careful analysis of the existing experimental data allowed us to extend the absolute thermoelectric power scale of platinum to the range 0-1800 K with two new polynomial expressions. The experimental device is controlled by a LabView program. A detailed description of the accurate dynamic measurement methodology is given in this paper. We measure the absolute thermoelectric power and the electrical resistivity and deduce with a good accuracy the thermal conductivity using the relations between the three electronic transport coefficients, going beyond the classical Wiedemann-Franz law. We use this experimental setup and methodology to give new very accurate results for pure copper, platinum, and nickel especially at very high temperatures. But resistivity and absolute thermopower measurement can be more than an objective in itself. Resistivity characterizes the bulk of a material while absolute thermoelectric power characterizes the material at the point where the electrical contact is established with a couple of metallic elements (forming a thermocouple). In a forthcoming paper we will show that the measurement of resistivity and absolute thermoelectric power characterizes advantageously the (change of) phase, probably as well as DSC (if not better), since the change of phases can be easily followed during several hours/days at constant temperature.

  19. A thermoelectric voltage effect in polyethylene oxide

    CERN Document Server

    Martin, B; Kliem, H

    2003-01-01

    The conductivity of polyethylene oxide (PEO) is described with a three-dimensional hopping model considering electrostatic interactions between the ions. Ions fluctuate over energy-barriers in a multi-well potential. To decide whether positive or negative charges are responsible for this conductivity, the thermoelectric voltage is measured. The samples are embedded between two aluminium-electrodes. The oxide on the interface between the electrodes and the PEO serves as a blocking layer. The temperature of each electrode is controlled by a Peltier element. A temperature step is applied to one electrode by changing the temperature of one of the Peltier elements. Due to this temperature gradient, the mobile charges fluctuate thermally activated from the warmer side to the colder side of the sample. The direction of the measured thermoelectric voltage indicates the type of mobile charges. It is found that positive charges are mobile. Further, it is shown that the absolute value of the thermoelectric voltage depen...

  20. Control of supply temperature

    Energy Technology Data Exchange (ETDEWEB)

    Madsen, H; Nielsen, T S; Soegaard, H T

    1996-09-01

    For many district heating systems, e.g. the system in Hoeje Taastrup, it is desirable to minimize the supply temperature from the heat production unit(s). Lower supply temperature implies lower costs in connection with the production and distribution of heat. Factors having impact on the heat demand are for instance solar radiation, wind speed, wind direction and a climate independent part, which is a function of the time of the day/week/year. By applying an optimization strategy, which minimizes the supply temperature, it is assumed that optimal economical operation can be obtained by minimizing the supply temperature and thereby the heat losses in the system. The models and methods described in this report take such aspects into account, and can therefore be used as elements in a more efficient minimization of the supply temperature. The theoretical part of this report describes models and methods for optimal on-line control of the supply temperature in district heating systems. Some of the models and methods have been implemented - or are going to be implemented - in the computer program PRESS which is a tool for optimal control of supply temperature and forecasting of heat demand in district heating systems. The principles for using transfer function models are briefly described. The ordinary generalized predictive control (OGPC) method is reviewed, and several extensions of this method are suggested. New controller, which is called the extended generalized predictive controller (XGPC), is described. (EG) 57 refs.

  1. THE THERMOELECTRIC VACUUM CROCK-POT AND THE AUTOMATED WORKPLACE FOR ITS RESEARCH AS A CONTROL OBJECT

    Directory of Open Access Journals (Sweden)

    S. Hudz

    2017-08-01

    Full Text Available The technologies of thermal treatment in vacuum are widely used in various fields of production, in particular in the food industry, but their application at farms, hotels or a for domestic purposes is limited because of the big sizes, high cost of processing equipment and complexity of its management at realization of foodstuff processing. Products, made with use of vacuum technologies, keep much more useful substances because they aren't exposed to high-temperature processing and oxidation while preparation. Development and production of the small-sized equipment for realization of heat treatment processes of foodstuff in vacuum would create technical and economic conditions for implementation of temperature processing processes of foodstuff at farms, hotels and even at home that would promote creation of new food, development of new recipes and, in general, development of the new direction in cookery. So the article describes the problem of equipment construction for the process of thermal processing of food in vacuum such as cooking jam, concentration of juices and dairy products, distillation, drying, pickling, and the possibility of building inexpensive compact vacuum unit for the implementation of these processes (crock-pot for use at hotels, farms and even for domestic purposes. The analysis of technological schemes for energy efficient evaporation process in vacuum crock-pot is provided. The developed technological scheme of vacuum crock-pot with thermoelectric converters and principle of its operation are considered. Microprocessor block diagram of a multichannel data acquisition system consisting workstation for investigation of thermoelectric vacuum crock-pot as a control object is presented and control algorithms helping to reduce energy consumption and to increase operational reliability in implementing processes and the quality of ready-made products are provided.

  2. Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials

    Science.gov (United States)

    Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; di, Chong-An; Zhu, Daoben

    2015-09-01

    Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

  3. Length-dependent thermoelectric characteristics of silicon nanowires on plastics in a relatively low temperature regime in ambient air

    International Nuclear Information System (INIS)

    Choi, Jinyong; Cho, Kyoungah; Kim, Sangsig

    2013-01-01

    We report on the thermoelectric characteristics of p-type silicon nanowires (NWs) on plastics in the relatively low temperature regime below 47 ° C, and for temperature differences of less than 10 K in ambient air. Thermal profile images are utilized to directly determine the temperature difference in the NWs generated by Joule heating in air. The Seebeck coefficient of the NWs increases from 294 to 414 μV K −1 as the NW length varies from 40 to 280 μm. For a temperature difference of 7 K, the maximal Seebeck voltage can be estimated to be 2.7 mV for NWs with a length of 280 μm. In contrast, the output power is maximized for NWs length of 240 μm. The maximized output power obtained experimentally in this study is 2.1 pW at a temperature difference of 6 K. The thermoelectric characteristics are analyzed and discussed. (paper)

  4. High Temperature Thermoelectric Oxides Engineered At Multiple Length Scales For Energy Harvesting

    Energy Technology Data Exchange (ETDEWEB)

    Ohuchi, Fumio [Univ. of Washington, Seattle, WA (United States); Bordia, Rajendra [Clemson Univ., SC (United States)

    2014-12-20

    Thermoelectric aspects of the processing parameters the n-type relaxors, including SrxBa1-xNb2O6 (SBN100x), Sr2Nb2O7 (SN) and SrBi2Nb2O9 (SBiN), were investigated. A solution combustion synthesis (SCS) route was devised to fabricate SBN, SN and SBiN nanoparticles with excellent phase purity. X-ray photoelectron spectroscopy (XPS) was used to deduce the local cation site occupancy, and detailed thermoelectric transport processes were investigated. Based on the identified behavior, effectiveness of pore formers on the thermoelectric performance was investigated with the goal of decreasing κ through enhanced phonon scattering while preserving the electron transport characteristics.

  5. Thermoelectric potential in UO2 and (U,Pu)O2 and its influence on oxygen migration in presence of a temperature gradient

    International Nuclear Information System (INIS)

    D'Annucci, F.

    1979-09-01

    Measurement of the thermoelectric power have been carried out in sintered pellets of uranium-oxide and uranium-plutonium mixed oxides up to 1800 K. For the thermal treatment an inducting furnace is used. The temperatures and the thermoelectric potential are measured with two thermocouples wich are contained in two holes in the lower end of the pellet. During the experiments a temperature difference of 80 K is maintained between the two measuring points. The Seebeck coefficients are calculated from the EMF measurements as a function of temperature and of the O/M ratio. The results show that these oxides have the typical electric properties of a classic semiconductor. The conductivity is of p-type up to a defined temperature wich is a function of the stoichiometry. The Seebeck coefficients are characterized by a defined energy of activation wich is independent from the stochiometry in the regions of hypo- and hyperstochiometric oxides. The thermoelectric forces and the lattice forces drive ions along the temperature gradients. Both forces can be described by the heat of transport of oxygen ions wich contains a thermoelectric and a thermal part. The thermoelectric part of the heat of transport is calculated with the values of the Seebeck coefficients and the contribution to the total heat of transport is discussed. (orig.) [de

  6. Thermoelectric power generator with intermediate loop

    Science.gov (United States)

    Bell, Lon E; Crane, Douglas Todd

    2013-05-21

    A thermoelectric power generator is disclosed for use to generate electrical power from heat, typically waste heat. An intermediate heat transfer loop forms a part of the system to permit added control and adjustability in the system. This allows the thermoelectric power generator to more effectively and efficiently generate power in the face of dynamically varying temperatures and heat flux conditions, such as where the heat source is the exhaust of an automobile, or any other heat source with dynamic temperature and heat flux conditions.

  7. Temperature-dependent thermal and thermoelectric properties of n -type and p -type S c1 -xM gxN

    Science.gov (United States)

    Saha, Bivas; Perez-Taborda, Jaime Andres; Bahk, Je-Hyeong; Koh, Yee Rui; Shakouri, Ali; Martin-Gonzalez, Marisol; Sands, Timothy D.

    2018-02-01

    Scandium Nitride (ScN) is an emerging rocksalt semiconductor with octahedral coordination and an indirect bandgap. ScN has attracted significant attention in recent years for its potential thermoelectric applications, as a component material in epitaxial metal/semiconductor superlattices, and as a substrate for defect-free GaN growth. Sputter-deposited ScN thin films are highly degenerate n -type semiconductors and exhibit a large thermoelectric power factor of ˜3.5 ×10-3W /m -K2 at 600-800 K. Since practical thermoelectric devices require both n- and p-type materials with high thermoelectric figures-of-merit, development and demonstration of highly efficient p-type ScN is extremely important. Recently, the authors have demonstrated p-type S c1 -xM gxN thin film alloys with low M gxNy mole-fractions within the ScN matrix. In this article, we demonstrate temperature dependent thermal and thermoelectric transport properties, including large thermoelectric power factors in both n- and p-type S c1 -xM gxN thin film alloys at high temperatures (up to 850 K). Employing a combination of temperature-dependent Seebeck coefficient, electrical conductivity, and thermal conductivity measurements, as well as detailed Boltzmann transport-based modeling analyses of the transport properties, we demonstrate that p-type S c1 -xM gxN thin film alloys exhibit a maximum thermoelectric power factor of ˜0.8 ×10-3W /m -K2 at 850 K. The thermoelectric properties are tunable by adjusting the M gxNy mole-fraction inside the ScN matrix, thereby shifting the Fermi energy in the alloy films from inside the conduction band in case of undoped n -type ScN to inside the valence band in highly hole-doped p -type S c1 -xM gxN thin film alloys. The thermal conductivities of both the n- and p-type films were found to be undesirably large for thermoelectric applications. Thus, future work should address strategies to reduce the thermal conductivity of S c1 -xM gxN thin-film alloys, without affecting

  8. Effect of bath temperature on structure, morphology and thermoelectric properties of CoSb{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Suchitra, E-mail: suchitrayadav87@gmail.com; Pandya, Dinesh K.; Chaudhary, Sujeet [Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi-110016 (India)

    2016-05-23

    CoSb{sub 3} thin films are deposited on conducting glass substrates (FTO) by electrodeposition at different bath temperatures (60°C, 70°C and 80°C) and the resulting influence of the bath temperature on the structure, morphology and electrical properties of films is investigated. X-ray diffraction confirms the formation of CoSb{sub 3} phase in the films. Scanning electron microscopy reveals that different morphologies ranging from branched nano-flakes to nano-needles evolve as bath temperature increases. It is concluded that a growth temperature of 80°C is suitable for producing CoSb{sub 3} films with such properties that show potential feasibility for thermoelectric applications.

  9. Thermoelectric Materials

    Science.gov (United States)

    Gao, Peng; Berkun, Isil; Schmidt, Robert D.; Luzenski, Matthew F.; Lu, Xu; Bordon Sarac, Patricia; Case, Eldon D.; Hogan, Timothy P.

    2014-06-01

    Mg2(Si,Sn) compounds are promising candidate low-cost, lightweight, nontoxic thermoelectric materials made from abundant elements and are suited for power generation applications in the intermediate temperature range of 600 K to 800 K. Knowledge on the transport and mechanical properties of Mg2(Si,Sn) compounds is essential to the design of Mg2(Si,Sn)-based thermoelectric devices. In this work, such materials were synthesized using the molten-salt sealing method and were powder processed, followed by pulsed electric sintering densification. A set of Mg2.08Si0.4- x Sn0.6Sb x (0 ≤ x ≤ 0.072) compounds were investigated, and a peak ZT of 1.50 was obtained at 716 K in Mg2.08Si0.364Sn0.6Sb0.036. The high ZT is attributed to a high electrical conductivity in these samples, possibly caused by a magnesium deficiency in the final product. The mechanical response of the material to stresses is a function of the elastic moduli. The temperature-dependent Young's modulus, shear modulus, bulk modulus, Poisson's ratio, acoustic wave speeds, and acoustic Debye temperature of the undoped Mg2(Si,Sn) compounds were measured using resonant ultrasound spectroscopy from 295 K to 603 K. In addition, the hardness and fracture toughness were measured at room temperature.

  10. The Influence of Spark Plasma Sintering Temperature on the Microstructure and the Thermoelectric Properties of Al, Ga dually-doped ZnO

    DEFF Research Database (Denmark)

    Han, Li; Le, Thanh Hung; Van Nong, Ngo

    2012-01-01

    Al, Ga dually-doped ZnO was prepared by spark plasma sintering with different sintering temperatures. The microstructural evolution and thermoelectric properties of the samples were investigated in detail. The samples with a sintering temperature above 1223K obtained higher relative densities...

  11. High-temperature stability of thermoelectric Ca3Co4O9 thin films

    DEFF Research Database (Denmark)

    Brinks, P.; Van Nong, Ngo; Pryds, Nini

    2015-01-01

    An enhanced thermal stability in thermoelectric Ca3Co4O9 thin films up to 550 °C in an oxygen rich environment was demonstrated by high-temperature electrical and X-ray diffraction measurements. In contrast to generally performed heating in helium gas, it is shown that an oxygen/helium mixture...... provides sufficient thermal contact, while preventing the previously disregarded formation of oxygen vacancies. Combining thermal cycling with electrical measurements proves to be a powerful tool to study the real intrinsic thermoelectric behaviour of oxide thin films at elevated temperatures. © 2015 AIP...

  12. Compliant Interfacial Layers in Thermoelectric Devices

    Science.gov (United States)

    Firdosy, Samad A. (Inventor); Li, Billy Chun-Yip (Inventor); Ravi, Vilupanur A. (Inventor); Fleurial, Jean-Pierre (Inventor); Caillat, Thierry (Inventor); Anjunyan, Harut (Inventor)

    2017-01-01

    A thermoelectric power generation device is disclosed using one or more mechanically compliant and thermally and electrically conductive layers at the thermoelectric material interfaces to accommodate high temperature differentials and stresses induced thereby. The compliant material may be metal foam or metal graphite composite (e.g. using nickel) and is particularly beneficial in high temperature thermoelectric generators employing Zintl thermoelectric materials. The compliant material may be disposed between the thermoelectric segments of the device or between a thermoelectric segment and the hot or cold side interconnect of the device.

  13. High-temperature Thermoelectric and Microstructural Characteristics of Ga Substituted on the Co-site in Cobalt-based Oxides

    DEFF Research Database (Denmark)

    Van Nong, Ngo; Yanagiya, S.; Sonne, Monica

    2011-01-01

    The effects of Ga substitution on the Co-site on the high-temperature thermoelectric properties and microstructure are investigated for the misfitlayered Ca3Co4O9 and the complex perovskite-related Sr3RECo4O10.5 (RE = rare earth) cobalt-based oxides. For both systems, substitution of Ga for Co...... results in a simultaneous increase in the Seebeck coefficient (S) and the electrical conductivity (σ), and the influence is more significant in the high temperature region. The power factor (S 2 σ) is thereby remarkably improved by Ga substitution, particularly at high temperatures. Texture factor......0.05O9 shows the best ZT value of 0.45 at 1200 K, which is about 87.5% higher than the nondoped one, a considerable improvement....

  14. Annealing effects on room temperature thermoelectric performance of p-type thermally evaporated Bi-Sb-Te thin films

    Science.gov (United States)

    Singh, Sukhdeep; Singh, Janpreet; Tripathi, S. K.

    2018-05-01

    Bismuth antimony telluride (Bi-Sb-Te) compounds have been investigated for the past many decades for thermoelectric (TE) power generation and cooling purpose. We synthesized this compound with a stoichiometry Bi1.2Sb0.8Te3 through melt cool technique and thin films of as synthesized material were deposited by thermal evaporation. The prime focus of the present work is to study the influence of annealing temperature on the room temperature (RT) power factor of thin films. Electrical conductivity and Seebeck coefficient were studied and power factors were calculated which showed a peak value at 323 K. The compounds performance is comparable to some very efficient Bi-Sb-Te reported stoichiometries at RT scale. The values observed show that material has an enormous potential for energy production at ambient temperature scales.

  15. A power conditioning system for thermoelectric generator based on interleaved Boost converter with MPPT control

    DEFF Research Database (Denmark)

    Ni, L.-X; Sun, K.; Zhang, L.

    2011-01-01

    The thermoelectric generation (TEG) system has its special charactristics of high stablility, low voltage and high current output, which is different from PV modules. The power conditioning system and control schemes used in PV applications cannot be directly applied to TEG applications. A power...... conditioning system for TEG based on interleaved Boost converter with maximum power point tracking (MPPT) control is investigated in this paper. Since an internal resistance exists inside TEG modules, an improved perturbation and observation (P&O) MPPT control scheme with power limit is proposed to extract...... maximum power from TEG by matching the load with internal resistance. Since the battery is usually employed as the load for TEG systems, the interleaved Boost converter operates in two different modes for battery charging: before the battery is fully charged, the system outputs the maximum power (MPPT...

  16. Doping in controlling the type of conductivity in bulk and nanostructured thermoelectric materials

    International Nuclear Information System (INIS)

    Fuks, D.; Komisarchik, G.; Kaller, M.; Gelbstein, Y.

    2016-01-01

    Doping of materials for thermoelectric applications is widely used nowadays to control the type of conductivity. We report the results of ab-initio calculations aimed at developing the consistent scheme for determining the role of impurities that may change the type of conductivity in two attractive thermoelectric classes of materials. It is demonstrated that alloying of TiNiSn with Cu makes the material of n-type, and alloying with Fe leads to p-type conductivity. Similar calculations for PbTe with small amount of Na substituting for Pb leads to p-type conductivity, while Cl substituting for Te makes PbTe an n-type material. It is shown also that for nano-grained materials the n-type conductivity should be observed. The effect of impurities segregating to the grain boundaries in nano-structured PbTe is also discussed. - Highlights: • Bulk and nano-grained TE materials were analyzed by DFT. • The electronic effects on both PbTe and TiNiSn were demonstrated. • The role of impurities on the conductivity type was analyzed. • Interfacial states in nano-grained PbTe affect the conductivity type.

  17. Effect of high-temperature annealing on the microstructure and thermoelectric properties of GaP doped SiGe. M.S. Thesis

    Science.gov (United States)

    Draper, Susan L.

    1987-01-01

    Annealing of GaP doped SiGe will significantly alter the thermoelectric properties of the material resulting in increased performance as measured by the figure of merit Z and the power factor P. The microstructures and corresponding thermoelectric properties after annealing in the 1100 to 1300 C temperature range have been examined to correlate performance improvement with annealing history. The figure of merit and power factor were both improved by homogenizing the material and limiting the amount of cross-doping. Annealing at 1215 C for 100 hr resulted in the best combination of thermoelectric properties with a resultant figure of merit exceeding 1x10 to the -3 deg C to the -1 and a power factor of 44 microW/cm/deg C sq for the temperature range of interest for space power: 400 to 1000 C.

  18. Influence of heat pipe operating temperature on exhaust heat thermoelectric generation

    OpenAIRE

    Brito, F. P.; Martins, Jorge; Gonçalves, L. M.; Antunes, Nuno; Sousa, Diogo

    2013-01-01

    Increasingly stringent targets on energy efficiency and emissions, as well as growing vehicle electrification are making attractive the electric recovery of the energy normally wasted through the tailpipe of Internal Combustion Engines. Recent developments in thermoelectrics (TE) may soon make them a viable solution for such applications. This team has been exploring the potential of using TE modules in combination with variable conductance heat pipes for transferring the exhaust heat to ...

  19. Bi2O2Se nanosheet: An excellent high-temperature n-type thermoelectric material

    Science.gov (United States)

    Yu, Jiabing; Sun, Qiang

    2018-01-01

    Motivated by the recent synthesis of an ultrathin film of layered Bi2O2Se [Wu et al., Nat. Nanotechnol. 12, 530 (2017); Wu et al., Nano Lett. 17, 3021 (2017)], we have systematically studied the thermoelectric properties of a Bi2O2Se nanosheet using first principles density functional theory combined with semiclassical Boltzmann transport theory. The calculated results indicate that the Bi2O2Se nanosheet exhibits a figure of merit (ZT) of 3.35 for optimal n-type doping at 800 K, which is much larger than the ZT value of 2.6 at 923 K in SnSe known as the most efficient thermoelectric material [Zhao et al., Nature 508, 373 (2014)]. Equally important, the high ZT in the n-type doped Bi2O2Se nanosheet highlights the efficiency of the reduced dimension on improving thermoelectric performance as compared with strain engineering by which the ZT of n-type doped bulk Bi2O2Se cannot be effectively enhanced.

  20. Engine Cylinder Temperature Control

    Science.gov (United States)

    Kilkenny, Jonathan Patrick; Duffy, Kevin Patrick

    2005-09-27

    A method and apparatus for controlling a temperature in a combustion cylinder in an internal combustion engine. The cylinder is fluidly connected to an intake manifold and an exhaust manifold. The method and apparatus includes increasing a back pressure associated with the exhaust manifold to a level sufficient to maintain a desired quantity of residual exhaust gas in the cylinder, and varying operation of an intake valve located between the intake manifold and the cylinder to an open duration sufficient to maintain a desired quantity of fresh air from the intake manifold to the cylinder, wherein controlling the quantities of residual exhaust gas and fresh air are performed to maintain the temperature in the cylinder at a desired level.

  1. Design of high precision temperature control system for TO packaged LD

    Science.gov (United States)

    Liang, Enji; Luo, Baoke; Zhuang, Bin; He, Zhengquan

    2017-10-01

    Temperature is an important factor affecting the performance of TO package LD. In order to ensure the safe and stable operation of LD, a temperature control circuit for LD based on PID technology is designed. The MAX1978 and an external PID circuit are used to form a control circuit that drives the thermoelectric cooler (TEC) to achieve control of temperature and the external load can be changed. The system circuit has low power consumption, high integration and high precision,and the circuit can achieve precise control of the LD temperature. Experiment results show that the circuit can achieve effective and stable control of the laser temperature.

  2. Design of PID temperature control system based on STM32

    Science.gov (United States)

    Zhang, Jianxin; Li, Hailin; Ma, Kai; Xue, Liang; Han, Bianhua; Dong, Yuemeng; Tan, Yue; Gu, Chengru

    2018-03-01

    A rapid and high-accuracy temperature control system was designed using proportional-integral-derivative (PID) control algorithm with STM32 as micro-controller unit (MCU). The temperature control system can be applied in the fields which have high requirements on the response speed and accuracy of temperature control. The temperature acquisition circuit in system adopted Pt1000 resistance thermometer as temperature sensor. Through this acquisition circuit, the monitoring actual temperature signal could be converted into voltage signal and transmitted into MCU. A TLP521-1 photoelectric coupler was matched with BD237 power transistor to drive the thermoelectric cooler (TEC) in FTA951 module. The effective electric power of TEC was controlled by the pulse width modulation (PWM) signals which generated by MCU. The PWM signal parameters could be adjusted timely by PID algorithm according to the difference between monitoring actual temperature and set temperature. The upper computer was used to input the set temperature and monitor the system running state via serial port. The application experiment results show that the temperature control system is featured by simple structure, rapid response speed, good stability and high temperature control accuracy with the error less than ±0.5°C.

  3. Design of improved controller for thermoelectric generator used in distributed generation

    Energy Technology Data Exchange (ETDEWEB)

    Molina, M.G. [CONICET, Instituto de Energia Electrica, Universidad Nacional de San Juan, Av. Libertador San Martin Oeste, 1109, J5400ARL, San Juan (Argentina); Juanico, L.E. [CONICET, Centro Atomico Bariloche, 8400 Bariloche (Argentina); Rinalde, G.F.; Taglialavore, E.; Gortari, S. [Centro Atomico Bariloche, 8400 Bariloche (Argentina)

    2010-06-15

    This paper investigates the application of thermal generation based on solid-state devices such as thermoelectric generators (TEGs) as a novel technological alternative of distributed generation (DG). The full detailed modeling and the dynamic simulation of a three-phase grid-connected TEG used as a dispersed generator is studied. Moreover, a new control scheme of the TEG is proposed, which consists of a multi-level hierarchical structure and incorporates a maximum power point tracker (MPPT) for better use of the thermal resource. In addition, reactive power compensation of the electric grid is included, operating simultaneously and independently of the active power generation. Validation of models and control schemes is performed by using the MATLAB/Simulink environment. Moreover, a small-scale TEG experimental set-up was employed to demonstrate the accuracy of proposed models. (author)

  4. Theoretical investigation on thermoelectric properties of (Ca,Sr,Ba)Fe2(As/Bi)2 compounds under temperature

    Science.gov (United States)

    Jayalakshmi, D. S.; Sundareswari, M.; Viswanathan, E.; Das, Abhijeet

    2018-04-01

    The electrical conductivity, resistivity and Seebeck coefficient, Pauli magnetic susceptibility and power factor are computed under temperature (100 K - 800 K) in steps of 100 K for the theoretically designed compounds namely (Ca,Sr,Ba)Fe2Bi2 and their parent compounds namely (Ca,Sr,Ba)Fe2As2 by using Boltzmann transport theory interfaced to the Wien2k program. The Bulk modulus, electron phonon coupling constant, thermoelectric figure of merit (ZT) and transition temperature are calculated for the optimized anti ferromagnetic phase of the proposed compounds. The results are discussed for the novel compounds in view of their superconductivity existence and compared with their parent unconventional superconducting compounds.

  5. Temperature-induced assembly of semiconductor nanocrystals into fractal architectures and thermoelectric power properties in Au/Ge bilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Li Quanbao; Wang Jian; Jiao Zheng [Shanghai Applied Radiation Institute, Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Wu Minghong, E-mail: mhwu@staff.shu.edu.cn [Shanghai Applied Radiation Institute, Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Shek, Chan-Hung; Lawrence Wu, C.M.; Lai, Joseph K.L. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Chen Zhiwen, E-mail: cnzwchen@yahoo.com.cn [Shanghai Applied Radiation Institute, Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong)

    2011-08-15

    Highlights: > Ge fractal architectures were achieved by temperature-induced assembly. > The appearance of fractal architectures influences the thermoelectric power. > But it has little effect on the resistivity. > The values of the superlocalization exponent were within 1.22 {<=} {xi} {<=} 1.29. > It was higher than expected for two-dimension fractal system. - Abstract: Fractal architectures of semiconductor nanocrystals were successfully achieved by temperature-induced assembly of semiconductor nanocrystals in gold/germanium (Au/Ge) bilayer films. New assessment strategies of fractal architectures are of fundamental importance in the development of micro/nano-devices. Temperature-dependent properties including resistivity and thermoelectric power (TEP) of Au/Ge bilayer films with self-similar fractal patterns were investigated in detail. Experimental results indicated that the microstructure of Au film plays an important role in the characteristics of Au/Ge bilayer films after annealing and the crystallization processes of amorphous Ge accompany by fractal formation of Ge nanocrystals via temperature-induced assembly. The appearance of fractal architectures has significantly influence on the TEP but little effect on the resistivity of the annealed bilayer film. By analysis of the data, we found that the values of superlocalization exponent are within 1.22 {<=} {xi} {<=} 1.29, which are higher than expected for two-dimension fractal systems. The results provided possible evidence for the superlocalization on fractal architectures in Au/Ge bilayer films. The TEP measurements are considered a more effective method than the conductivity for investigating superlocalization in a percolating system.

  6. Universal Majorana thermoelectric noise

    Science.gov (United States)

    Smirnov, Sergey

    2018-04-01

    Thermoelectric phenomena resulting from an interplay between particle flows induced by electric fields and temperature inhomogeneities are extremely insightful as a tool providing substantial knowledge about the microscopic structure of a given system. By tuning, e.g., parameters of a nanoscopic system coupled via tunneling mechanisms to two contacts, one may achieve various situations where the electric current induced by an external bias voltage competes with the electric current excited by the temperature difference of the two contacts. Even more exciting physics emerges when the system's electronic degrees freedom split to form Majorana fermions which make the thermoelectric dynamics universal. Here, we propose revealing these unique universal signatures of Majorana fermions in strongly nonequilibrium quantum dots via noise of the thermoelectric transport beyond linear response. It is demonstrated that whereas mean thermoelectric quantities are only universal at large-bias voltages, the noise of the electric current excited by an external bias voltage and the temperature difference of the contacts is universal at any bias voltage. We provide truly universal, i.e., independent of the system's parameters, thermoelectric ratios between nonlinear response coefficients of the noise and mean current at large-bias voltages where experiments may easily be performed to uniquely detect these truly universal Majorana thermoelectric signatures.

  7. The Influence of Spark Plasma Sintering Temperature on the Microstructure and Thermoelectric Properties of Al,Ga Dual-Doped ZnO

    DEFF Research Database (Denmark)

    Han, Li; Le, Thanh Hung; Van Nong, Ngo

    2013-01-01

    ZnO dual-doped with Al and Ga was prepared by spark plasma sintering using different sintering temperatures. The microstructural evolution and thermoelectric properties of the samples were investigated in detail. The samples obtained with sintering temperature above 1223 K had higher relative...... of ZnO particles and microstructure evolution at different sintering temperatures were investigated by simulation of the self-Joule-heating effect of the individual particles....

  8. Development of a New Generation of High-Temperature Thermoelectric Unicouples for Space Applications

    Science.gov (United States)

    Caillat, Thierry; Gogna, P.; Sakamoto, J.; Jewell, A.; Cheng, J.; Blair, R.; Fleurial, J. -P.; Ewell, R.

    2006-01-01

    RTG's have enabled surface and deep space missions since 1961: a) 26 flight missions without any RTG failures; and b) Mission durations in excess of 25 years. Future NASA missions require RTG s with high specific power and high efficiency, while retaining long life (> 14 years) and high reliability, (i.e. 6-8 W/kg, 10-15% efficiency). JPL in partnership with NASA-GRC, NASA-MSFC, DOE, Universities and Industry is developing advanced thermoelectric materials and converters to meet future NASA needs.

  9. High Tc Superconducting Magnet Excited by a Semiconductor Thermoelectric Element

    Science.gov (United States)

    Kuriyama, T.; Ono, M.; Tabe, S.; Oguchi, A.; Okamura, T.

    2006-04-01

    A high Tc superconducting (HTS) magnet excited by a thermal electromotive force of a thermoelectric element is studied. This HTS magnet has the advantages of compactness, lightweight and continuous excitation in comparison with conventional HTS magnets, because this HTS magnet does not need a large external power source. In this system, a heat input into the cryogenic environment is necessary to excite the thermoelectric element for constant operation. This heat generation, however, causes a rise in temperature of an HTS coil and reduces the system performance. In this paper, a newly designed magnet system which adopted a two-stage GM cryocooler was investigated. It enabled us to control the temperature of a thermoelectric element and that of an HTS coil independently. The temperature of the HTS coil could be kept at 10-20 K at the second stage of the GM cryocooler, while the thermoelectric element could be excited at higher temperature in the range of 50-70 K at the first stage, where the performance of the thermoelectric element was higher. The experimental results on this HTS magnet are shown and the possibility of the thermoelectric element as a main power source of the HTS magnets is discussed.

  10. Controlling the transmission line shape of molecular t-stubs and potential thermoelectric applications

    DEFF Research Database (Denmark)

    Stadler, Robert; Markussen, Troels

    2011-01-01

    Asymmetric line shapes can occur in the transmission function describing electron transport in the vicinity of a minimum caused by quantum interference effects. Such asymmetry can be used to increase the thermoelectric efficiency of molecular junctions. So far, however, asymmetric line shapes hav...... calculations for a variety of t-stub molecules and also address their suitability for thermoelectric applications....

  11. Crystal orientation dependent thermoelectric properties of highly oriented aluminum-doped zinc oxide thin films

    KAUST Repository

    Abutaha, Anas I.; Sarath Kumar, S. R.; Alshareef, Husam N.

    2013-01-01

    We demonstrate that the thermoelectric properties of highly oriented Al-doped zinc oxide (AZO) thin films can be improved by controlling their crystal orientation. The crystal orientation of the AZO films was changed by changing the temperature

  12. Green thermoelectrics: Observation and analysis of plant thermoelectric response

    Directory of Open Access Journals (Sweden)

    Goupil Christophe

    2016-01-01

    Full Text Available Plants are sensitive to thermal and electrical effects; yet the coupling of both, known as thermoelectricity, and its quantitative measurement in vegetal systems never were reported. We recorded the thermoelectric response of bean sprouts under various thermal conditions and stress. The obtained experimental data unambiguously demonstrate that a temperature difference between the roots and the leaves of a bean sprout induces a thermoelectric voltage between these two points. Basing our analysis of the data on the force-flux formalism of linear response theory, we found that the strength of the vegetal equivalent to the thermoelectric coupling is one order of magnitude larger than that in the best thermoelectric materials. Experimental data also show the importance of the thermal stress variation rate in the plant’s electrophysiological response. therefore, thermoelectric effects are sufficiently important to partake in the complex and intertwined processes of energy and matter transport within plants.

  13. Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials.

    Science.gov (United States)

    Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; Di, Chong-an; Zhu, Daoben

    2015-09-21

    Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of pressure-sensing sensitivity of up to 28.9 kPa(-1). More importantly, these dual-parameter sensors can be self-powered with outstanding sensing performance. The excellent sensing properties of MFSOTE-based devices, together with their unique advantages of low cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

  14. Effect of linear and non-linear components in the temperature dependences of thermoelectric properties on the energy conversion efficiency

    International Nuclear Information System (INIS)

    Yamashita, Osamu

    2009-01-01

    The new thermal rate equations were built up by taking the linear and non-linear components in the temperature dependences of the Seebeck coefficient α, the electrical resistivity ρ and thermal conductivity κ of a thermoelectric (TE) material into the thermal rate equations on the assumption that their temperature dependences are expressed by a quadratic function of temperature T. The energy conversion efficiency η for a single TE element was formulated using the new thermal rate ones proposed here. By applying it to the high-performance half-Heusler compound, the non-linear component in the temperature dependence of α among those of the TE properties has the greatest effect on η, so that η/η 0 was increased by 11% under the condition of T = 510 K and ΔT = 440 K, where η 0 is a well-known conventional energy conversion efficiency. It was thus found that the temperature dependences of TE properties have a significant influence on η. When one evaluates the accurate achievement rate of η exp obtained experimentally for a TE generator, therefore, η exp should be compared with η the estimated from the theoretical expression proposed here, not with η 0 , particularly when there is a strong non-linearity in the temperature dependence of TE properties.

  15. Solar thermoelectric generator

    Science.gov (United States)

    Toberer, Eric S.; Baranowski, Lauryn L.; Warren, Emily L.

    2016-05-03

    Solar thermoelectric generators (STEGs) are solid state heat engines that generate electricity from concentrated sunlight. A novel detailed balance model for STEGs is provided and applied to both state-of-the-art and idealized materials. STEGs can produce electricity by using sunlight to heat one side of a thermoelectric generator. While concentrated sunlight can be used to achieve extremely high temperatures (and thus improved generator efficiency), the solar absorber also emits a significant amount of black body radiation. This emitted light is the dominant loss mechanism in these generators. In this invention, we propose a solution to this problem that eliminates virtually all of the emitted black body radiation. This enables solar thermoelectric generators to operate at higher efficiency and achieve said efficient with lower levels of optical concentration. The solution is suitable for both single and dual axis solar thermoelectric generators.

  16. Thermoelectrical-electrothermal feedback (te-et f) enhanced performance characteristics of a high temperature superconductor far-infrared bolometer

    International Nuclear Information System (INIS)

    Kaila, M.M.; Russell, G.J.

    2000-01-01

    Full text: It is more than a decade since the discovery of new a High Temperature Superconducting (HTSC) materials. Their adaptation to large scale applications e.g. high magnetic fields, friction-less motors, levitation trains etc., is still long way to go. Small scale applications e.g., far-infrared sensors, has certainly been established as a highly suitable area for immediate economically viable commercial exploitation. The semiconductor counterparts, NT(Neutron Transmutation doped)Ge, CD(Compensation Doped)Si sensors are not only expensive and difficult to manufacture but also require liquid helium refrigeration at mK temperatures to operate. Although the work around the world has centered on photo-electrical bolometers, in our approach we have adopted a much simpler, temperature stable and a better performing photo-thermoelectrical mode of operation. It is well known that the semi-metal BiSb has the highest electronic thermoelectric figure of merit at liquid nitrogen temperatures. One can obtain a value around 1x10 -2 / K by application of a magnetic field to the BiSb leg of a composite. BiSb-HTSC bolometer. We can use this high figure of merit to our advantage in two different modes of operation of the detector. One is the static mode where the thermoelectric power generated across the semi-metal leg (connected in parallel with the HTSC leg) of the bolometer drives the external electronic circuitry. This circuitry can be remotely (no direct electrical contact) coupled to the bolometer e.g. through the primary coil of a SQUID current amplifier, which can be connected in series with the bolometer inside the cryostat, for better noise performance, or outside, for convenience. Second is the heterodyne operation. The external bias is applied in a constant voltage bias mode. The direction of the bias is so chosen that the transient Peltier power generated, from the incident radiation, in the circuit extracts additional heat at the sensitive area of the bolometer

  17. Effect of high temperature annealing on the thermoelectric properties of GaP doped SiGe

    Science.gov (United States)

    Vandersande, Jan W.; Wood, Charles; Draper, Susan

    1987-01-01

    Silicon-germanium alloys doped with GaP are used for thermoelectric energy conversion in the temperature range 300-1000 C. The conversion efficiency depends on Z = S-squared/rho lambda, a material's parameter (the figure of merit), where S is the Seebeck coefficient, rho is the electrical resistivity and lambda is the thermal conductivity. The annealing of several samples in the temperature range of 1100-1300 C resulted in the power factor P (= S-squared/rho) increasing with increased annealing temperature. This increase in P was due to a decrease in rho which was not completely offset by a drop in S-squared suggesting that other changes besides that in the carrier concentration took place. SEM and EDX analysis of the samples indicated the formation of a Ga-P-Ge rich phase as a result of the annealing. It is speculated that this phase is associated with the improved properties. Several reasons which could account for the improvement in the power factor of annealed GaP doped SiGe are given.

  18. Ytterbium silicide (YbSi{sub 2}). A promising thermoelectric material with a high power factor at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Tanusilp, Sora-at; Ohishi, Yuji; Muta, Hiroaki [Graduate School of Engineering, Osaka University, Suita, Osaka (Japan); Yamanaka, Shinsuke [Graduate School of Engineering, Osaka University, Suita, Osaka (Japan); Research Institute of Nuclear Engineering, University of Fukui, Tsuruga (Japan); Nishide, Akinori [Graduate School of Engineering, Osaka University, Suita, Osaka (Japan); Center for Exploratory Research, Research and Development Group, Hitachi, Ltd., Kokubunji, Tokyo (Japan); Hayakawa, Jun [Center for Exploratory Research, Research and Development Group, Hitachi, Ltd., Kokubunji, Tokyo (Japan); Kurosaki, Ken [Graduate School of Engineering, Osaka University, Suita, Osaka (Japan); Research Institute of Nuclear Engineering, University of Fukui, Tsuruga (Japan); JST, PRESTO, Kawaguchi, Saitama (Japan)

    2018-02-15

    Metal silicide-based thermoelectric (TE) materials have attracted attention in the past two decades, because they are less toxic, with low production cost and high chemical stability. Here, we study the TE properties of ytterbium silicide YbSi{sub 2} with a specific layered structure and the mixed valence state of Yb{sup 2+} and Yb{sup 3+}. YbSi{sub 2} exhibits large Seebeck coefficient, S, accompanied by high electrical conductivity, σ, leading to high power factor, S{sup 2}σ, of 2.2 mW m{sup -1} K{sup -2} at room temperature, which is comparable to those of state-of-the-art TE materials such as Bi{sub 2}Te{sub 3} and PbTe. Moreover, YbSi{sub 2} exhibits high Grueneisen parameter of 1.57, which leads to relatively low lattice thermal conductivity, κ{sub lat}, of 3.0 W m{sup -1} K{sup -1} at room temperature. The present study reveals that YbSi{sub 2} can be a good candidate of TE materials working near room temperature. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Temperature controlled 'void' formation

    International Nuclear Information System (INIS)

    Dasgupta, P.; Sharma, B.D.

    1975-01-01

    The nucleation and growth of voids in structural materials during high temperature deformation or irradiation is essentially dependent upon the existence of 'vacancy supersaturation'. The role of temperature dependent diffusion processes in 'void' formation under varying conditions, and the mechanical property changes associated with this microstructure are briefly reviewed. (author)

  20. Analysis of thermoelectric properties of amorphous InGaZnO thin film by controlling carrier concentration

    Directory of Open Access Journals (Sweden)

    Yuta Fujimoto

    2015-09-01

    Full Text Available We have investigated the thermoelectric properties of amorphous InGaZnO (a-IGZO thin films optimized by adjusting the carrier concentration. The a-IGZO films were produced under various oxygen flow ratios. The Seebeck coefficient and the electrical conductivity were measured from 100 to 400 K. We found that the power factor (PF at 300 K had a maximum value of 82 × 10−6 W/mK2, where the carrier density was 7.7 × 1019 cm−3. Moreover, the obtained data was analyzed by fitting the percolation model. Theoretical analysis revealed that the Fermi level was located approximately above the potential barrier when the PF became maximal. The thermoelectric properties were controlled by the relationship between the position of Fermi level and the height of potential energy barriers.

  1. Thermoelectricity for future sustainable energy technologies

    Directory of Open Access Journals (Sweden)

    Weidenkaff Anke

    2017-01-01

    Full Text Available Thermoelectricity is a general term for a number of effects describing the direct interconversion of heat and electricity. Thermoelectric devices are therefore promising, environmental-friendly alternatives to conventional power generators or cooling units. Since the mid-90s, research on thermoelectric properties and their applications has steadily increased. In the course of years, the development of high-temperature resistant TE materials and devices has emerged as one of the main areas of interest focusing both on basic research and practical applications. A wide range of innovative and cost-efficient material classes has been studied and their properties improved. This has also led to advances in synthesis and metrology. The paper starts out with thermoelectric history, basic effects underlying thermoelectric conversion and selected examples of application. The main part focuses on thermoelectric materials including an outline of the design rules, a review on the most common materials and the feasibility of improved future high-temperature thermoelectric converters.

  2. Test System for Thermoelectric Modules and Materials

    Science.gov (United States)

    Hejtmánek, J.; Knížek, K.; Švejda, V.; Horna, P.; Sikora, M.

    2014-10-01

    We present a design for a complex measuring device that enables its user to assess the parameters of power-generating thermoelectric modules (TEMs) (or bulk thermoelectric materials) under a wide range of temperatures ( T cold = 25°C to 90°C, T hot TEM, the actual heat flow through the module, and its mechanical load, which can be varied during the measurement. Key components of our testing setup are (i) a measuring chamber where the TEM/material is compressed between thermally shielded heating blocks equipped with a mechanical loading system and water-cooled copper-based cooler, (ii) an electrical load system, (iii) a type K thermocouple array connected to a data acquisition computer, and (iv) a thermostatic water-based cooling system with electronically controlled flow rate and temperature of cooling water. Our testing setup represents a useful tool able to assess, e.g., the thermoelectric parameters of newly developed TEMs and materials or to evaluate the thermoelectric parameters of commercially available modules and materials for comparison with values declared by the manufacturer.

  3. Simple experiments with a thermoelectric module

    International Nuclear Information System (INIS)

    Kraftmakher, Yaakov

    2005-01-01

    The Seebeck and Peltier effects are explored with a commercially available thermoelectric module and a data-acquisition system. Five topics are presented: (i) thermoelectric heating and cooling, (ii) the Seebeck coefficient, (iii) efficiency of a thermoelectric generator, (iv) the maximum temperature difference provided by a thermoelectric cooler and (v) the Peltier coefficient and the coefficient of performance. Using a data-acquisition system, the measurements are carried out in a reasonably short time. It is shown how to deduce quantities important for the theory and applications of thermoelectric devices

  4. Temperature Control in a Franz Diffusion Cell Skin Sonoporation Setup

    Science.gov (United States)

    Robertson, Jeremy; Becker, Sid

    2017-11-01

    In vitro experimental studies that investigate ultrasound enhanced transdermal drug delivery employ Franz diffusion cells. Because of absorption, the temperature of the coupling fluid often increases drastically during the ultrasound application. The current methodologies for controlling the coupling fluid temperature require either replacement of the coupling fluid during the experiment or the application of a time consuming duty cycle. This paper introduces a novel method for temperature control that allows for a wide variety of coupling fluid temperatures to be maintained. This method employs a peristaltic pump to circulate the coupling fluid through a thermoelectric cooling device. This temperature control method allowed for an investigation into the role of coupling fluid temperature on the inertial cavitation that impacts the skin aperture (inertial cavitation is thought to be the main cause of ultrasound induced skin permeability increase). Both foil pitting and passive cavitation detection experiments indicated that effective inertial cavitation activity decreases with increasing coupling fluid temperature. This finding suggests that greater skin permeability enhancement can be achieved if a lower coupling fluid temperature is maintained during skin insonation.

  5. Electronic cooling using thermoelectric devices

    Energy Technology Data Exchange (ETDEWEB)

    Zebarjadi, M., E-mail: m.zebarjadi@rutgers.edu [Department of Mechanical and Aerospace Engineering, Rutgers University, Piscataway, New Jersey 08854 (United States); Institute of Advanced Materials, Devices, and Nanotechnology, Rutgers University, Piscataway, New Jersey 08854 (United States)

    2015-05-18

    Thermoelectric coolers or Peltier coolers are used to pump heat in the opposite direction of the natural heat flux. These coolers have also been proposed for electronic cooling, wherein the aim is to pump heat in the natural heat flux direction and from hot spots to the colder ambient temperature. In this manuscript, we show that for such applications, one needs to use thermoelectric materials with large thermal conductivity and large power factor, instead of the traditionally used high ZT thermoelectric materials. We further show that with the known thermoelectric materials, the active cooling cannot compete with passive cooling, and one needs to explore a new set of materials to provide a cooling solution better than a regular copper heat sink. We propose a set of materials and directions for exploring possible materials candidates suitable for electronic cooling. Finally, to achieve maximum cooling, we propose to use thermoelectric elements as fins attached to copper blocks.

  6. Behavior of a thermoelectric power generation device based on solar irradiation and the earth’s surface-air temperature difference

    International Nuclear Information System (INIS)

    Zhang, Zhe; Li, Wenbin; Kan, Jiangming

    2015-01-01

    Highlights: • A technical solution to the power supply of wireless sensor networks is presented. • The low voltage produced by TEG is boosted from less than 1 V to more than 4 V. • An output current and voltage of TEG device is acquired as 21.47 mA and 221 mV. • The device successfully provides output power 4.7 mW in no electricity conditions. • The thermo-economic value of TEG device is demonstrated. - Abstract: Motivated by the limited power supply of wireless sensors used to monitor the natural environment, for example, in forests, this study presents a technical solution by recycling solar irradiation heat using thermoelectric generators. Based on solar irradiation and the earth’s surface-air temperature difference, a new type of thermoelectric power generation device has been devised, the distinguishing features of which include the application of an all-glass heat-tube-type vacuum solar heat collection pipe to absorb and transfer solar energy without a water medium and the use of a thin heat dissipation tube to cool the earth surface air temperature. The effects of key parameters such as solar illumination, air temperature, load resistance, the proportional coefficient, output power and power generation efficiency for thermoelectric energy conversion are analyzed. The results of realistic outdoor experiments show that under a state of regular illumination at 3.75 × 10 4 lx, using one TEG module, the thermoelectric device is able to boost the voltage obtained from the natural solar irradiation from 221 mV to 4.41 V, with an output power of 4.7 mW. This means that the electrical energy generated can provide the power supply for low power consumption components, such as low power wireless sensors, ZigBee modules and other low power loads

  7. Band spectrum transformation and temperature dependences of thermoelectric power of Hg1-xRxBa2Ca2Cu3O8+δ system

    Directory of Open Access Journals (Sweden)

    M. Vasyuk

    2011-03-01

    Full Text Available Temperature dependences of thermoelectric power S(T at T>Tc of the Hg-based high temperature superconductors Hg1-xRxBa2Ca2Cu3O8+δ (R=Re, Pb have been analyzed with accounting for strong scattering of charge carriers. Transformation of parameters of a narrow conducting band in the region of the Fermi level was studied. The existence of correlation between the effective bandwidth and the temperature of a superconductive transition Tc is shown.

  8. Temperature-controlled resistor

    Science.gov (United States)

    Perkins, T. G.

    1969-01-01

    Electrical resistance of a carbon-pile resistor is controlled by the compression or relaxation of a pile of carbon disks by a thermally actuated bimetallic spring. The concept is advantageous in that it is direct-acting, can cover a wide range of controllable characteristics, and can handle considerable power directly.

  9. Apparatuses And Systems For Embedded Thermoelectric Generators

    KAUST Repository

    Hussain, Muhammad M.

    2013-08-08

    An apparatus and a system for embedded thermoelectric generators are disclosed. In one embodiment, the apparatus is embedded in an interface where the ambient temperatures on two sides of the interface are different. In one embodiment, the apparatus is fabricated with the interface in integrity as a unitary piece. In one embodiment, the apparatus includes a first thermoelectric material embedded through the interface. The apparatus further includes a second thermoelectric material embedded through the interface. The first thermoelectric material is electrically coupled to the second thermoelectric material. In one embodiment, the apparatus further includes an output structure coupled to the first thermoelectric material and the second thermoelectric material and configured to output a voltage.

  10. Apparatuses And Systems For Embedded Thermoelectric Generators

    KAUST Repository

    Hussain, Muhammad M.; Inayat, Salman Bin; Smith, Casey Eben

    2013-01-01

    An apparatus and a system for embedded thermoelectric generators are disclosed. In one embodiment, the apparatus is embedded in an interface where the ambient temperatures on two sides of the interface are different. In one embodiment, the apparatus is fabricated with the interface in integrity as a unitary piece. In one embodiment, the apparatus includes a first thermoelectric material embedded through the interface. The apparatus further includes a second thermoelectric material embedded through the interface. The first thermoelectric material is electrically coupled to the second thermoelectric material. In one embodiment, the apparatus further includes an output structure coupled to the first thermoelectric material and the second thermoelectric material and configured to output a voltage.

  11. Proposal for a phase-coherent thermoelectric transistor

    International Nuclear Information System (INIS)

    Giazotto, F.; Robinson, J. W. A.; Moodera, J. S.; Bergeret, F. S.

    2014-01-01

    Identifying materials and devices which offer efficient thermoelectric effects at low temperature is a major obstacle for the development of thermal management strategies for low-temperature electronic systems. Superconductors cannot offer a solution since their near perfect electron-hole symmetry leads to a negligible thermoelectric response; however, here we demonstrate theoretically a superconducting thermoelectric transistor which offers unparalleled figures of merit of up to ∼45 and Seebeck coefficients as large as a few mV/K at sub-Kelvin temperatures. The device is also phase-tunable meaning its thermoelectric response for power generation can be precisely controlled with a small magnetic field. Our concept is based on a superconductor-normal metal-superconductor interferometer in which the normal metal weak-link is tunnel coupled to a ferromagnetic insulator and a Zeeman split superconductor. Upon application of an external magnetic flux, the interferometer enables phase-coherent manipulation of thermoelectric properties whilst offering efficiencies which approach the Carnot limit

  12. Proposal for a phase-coherent thermoelectric transistor

    Energy Technology Data Exchange (ETDEWEB)

    Giazotto, F., E-mail: giazotto@sns.it [NEST, Instituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa (Italy); Robinson, J. W. A., E-mail: jjr33@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Moodera, J. S. [Department of Physics and Francis Bitter Magnet Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Bergeret, F. S., E-mail: sebastian-bergeret@ehu.es [Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, Manuel de Lardizabal 4, E-20018 San Sebastián (Spain); Donostia International Physics Center (DIPC), Manuel de Lardizabal 5, E-20018 San Sebastián (Spain)

    2014-08-11

    Identifying materials and devices which offer efficient thermoelectric effects at low temperature is a major obstacle for the development of thermal management strategies for low-temperature electronic systems. Superconductors cannot offer a solution since their near perfect electron-hole symmetry leads to a negligible thermoelectric response; however, here we demonstrate theoretically a superconducting thermoelectric transistor which offers unparalleled figures of merit of up to ∼45 and Seebeck coefficients as large as a few mV/K at sub-Kelvin temperatures. The device is also phase-tunable meaning its thermoelectric response for power generation can be precisely controlled with a small magnetic field. Our concept is based on a superconductor-normal metal-superconductor interferometer in which the normal metal weak-link is tunnel coupled to a ferromagnetic insulator and a Zeeman split superconductor. Upon application of an external magnetic flux, the interferometer enables phase-coherent manipulation of thermoelectric properties whilst offering efficiencies which approach the Carnot limit.

  13. Orientation control and thermoelectric properties of FeSb2 films

    DEFF Research Database (Denmark)

    Sun, Ye; Zhang, Eryun; Johnsen, Simon

    2010-01-01

    FeSb2 has a high potential for technological applications due to its colossal thermoelectric power, giant carrier mobility and large magnetoresistance. Earlier, growth of lang1 0 1rang-textured FeSb2 films on quartz (0 0 0 1) substrates has been reported. Here magnetron sputtering is used to obtain...

  14. Peltier cells as temperature control elements: Experimental characterization and modeling

    International Nuclear Information System (INIS)

    Mannella, Gianluca A.; La Carrubba, Vincenzo; Brucato, Valerio

    2014-01-01

    The use of Peltier cells to realize compact and precise temperature controlled devices is under continuous extension in recent years. In order to support the design of temperature control systems, a simplified modeling of heat transfer dynamics for thermoelectric devices is presented. By following a macroscopic approach, the heat flux removed at the cold side of Peltier cell can be expressed as Q . c =γ(T c −T c eq ), where γ is a coefficient dependent on the electric current, T c and T c eq are the actual and steady state cold side temperature, respectively. On the other hand, a microscopic modeling approach was pursued via finite element analysis software packages. To validate the models, an experimental apparatus was designed and build-up, consisting in a sample vial with the surfaces in direct contact with Peltier cells. Both modeling approaches led to reliable prediction of transient and steady state sample temperature. -- Highlights: • Simplified modeling of heat transfer dynamics in Peltier cells. • Coupled macroscopic and microscopic approach. • Experimental apparatus: temperature control of a sample vial. • Both modeling approaches predict accurately the transient and steady state sample temperature

  15. Temperature control system for the study of single event effects in integrated circuits using a cyclotron accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Bakerenkov, A.S., E-mail: as_bakerenkov@list.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Belyakov, V.V. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Kozyukov, A.E. [Joint-Stock Company Institute of Space Device Engineering (JSC ISDE), Moscow (Russian Federation); Pershenkov, V.S.; Solomatin, A.V.; Shurenkov, V.V. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation)

    2015-02-11

    The temperature control system for the study of single event disruptions produced by hard ion impacts in integrated circuits is described. Heating and cooling of the irradiated device are achieved using thermoelectric modules (Peltier modules). The thermodynamic performance of the system is estimated. The technique for the numerical estimation of the main parameters of the temperature control system for cooling and heating is considered. The results of a test of the system in a vacuum cell of an accelerator are presented.

  16. Temperature control system for the study of single event effects in integrated circuits using a cyclotron accelerator

    International Nuclear Information System (INIS)

    Bakerenkov, A.S.; Belyakov, V.V.; Kozyukov, A.E.; Pershenkov, V.S.; Solomatin, A.V.; Shurenkov, V.V.

    2015-01-01

    The temperature control system for the study of single event disruptions produced by hard ion impacts in integrated circuits is described. Heating and cooling of the irradiated device are achieved using thermoelectric modules (Peltier modules). The thermodynamic performance of the system is estimated. The technique for the numerical estimation of the main parameters of the temperature control system for cooling and heating is considered. The results of a test of the system in a vacuum cell of an accelerator are presented

  17. Central control of body temperature.

    Science.gov (United States)

    Morrison, Shaun F

    2016-01-01

    Central neural circuits orchestrate the behavioral and autonomic repertoire that maintains body temperature during environmental temperature challenges and alters body temperature during the inflammatory response and behavioral states and in response to declining energy homeostasis. This review summarizes the central nervous system circuit mechanisms controlling the principal thermoeffectors for body temperature regulation: cutaneous vasoconstriction regulating heat loss and shivering and brown adipose tissue for thermogenesis. The activation of these thermoeffectors is regulated by parallel but distinct efferent pathways within the central nervous system that share a common peripheral thermal sensory input. The model for the neural circuit mechanism underlying central thermoregulatory control provides a useful platform for further understanding of the functional organization of central thermoregulation, for elucidating the hypothalamic circuitry and neurotransmitters involved in body temperature regulation, and for the discovery of novel therapeutic approaches to modulating body temperature and energy homeostasis.

  18. Development and computational simulation of thermoelectric electromagnetic pumps for controlling the fluid flow in liquid metal cooled space nuclear reactors

    International Nuclear Information System (INIS)

    Borges, E.M.

    1991-01-01

    Thermoelectric Electromagnetic (TEEM) Pumps can be used for controlling the fluid flow in the primary and secondary circuits of liquid metal cooled space nuclear reactor. In order to simulate and to evaluate the pumps performance, in steady-state, the computer program BEMTE has been developed to study the main operational parameters and to determine the system actuation point, for a given reactor operating power. The results for each stage of the program were satisfactory, compared to experimental data. The program shows to be adequate for the design and simulating of direct current electromagnetic pumps. (author)

  19. Photoirradiation system with temperature control

    International Nuclear Information System (INIS)

    Yonadab Lopez, F.; Stolik, S.; La Rosa, J. M. de; Moreno, E.

    2012-01-01

    During application of phototherapy is possible to induce a significant increase in tissue temperature and generate a localized hyperthermia state if the power density of incident light is high enough. We present a controlled temperature phototherapy system, this allows the application of optical radiation at a wavelength of 630nm using a light emitting diode (LED) of high power. The system automatically controls the irradiation time and power which allows irradiating the tissue with an appropriate energy density. A thermocouple is placed in the irradiated tissue to measure and control the temperature by varying the parameters of power density and time. From results of irradiations made in nu / nu mice using doses of 150 J/cm 2 energy and 250 J/cm 2 shows that the temperature control allows the study of photodynamic therapy in synergy with thermo therapy in different diseases external tissues. (Author)

  20. Temperature controller of semiconductor laser

    Czech Academy of Sciences Publication Activity Database

    Matoušek, Vít; Číp, Ondřej

    2003-01-01

    Roč. 73, č. 3 (2003), s. 10 - 12 ISSN 0928-5008 Institutional research plan: CEZ:AV0Z2065902 Keywords : temperature controller * semiconductor laser * laser diode Subject RIV: BH - Optics, Masers, Lasers

  1. A thermoelectric voltage effect in polyethylene oxide

    International Nuclear Information System (INIS)

    Martin, Bjoern; Wagner, Achim; Kliem, Herbert

    2003-01-01

    The conductivity of polyethylene oxide (PEO) is described with a three-dimensional hopping model considering electrostatic interactions between the ions. Ions fluctuate over energy-barriers in a multi-well potential. To decide whether positive or negative charges are responsible for this conductivity, the thermoelectric voltage is measured. The samples are embedded between two aluminium-electrodes. The oxide on the interface between the electrodes and the PEO serves as a blocking layer. The temperature of each electrode is controlled by a Peltier element. A temperature step is applied to one electrode by changing the temperature of one of the Peltier elements. Due to this temperature gradient, the mobile charges fluctuate thermally activated from the warmer side to the colder side of the sample. The direction of the measured thermoelectric voltage indicates the type of mobile charges. It is found that positive charges are mobile. Further, it is shown that the absolute value of the thermoelectric voltage depends on the energy-barrier heights in the multi-well potential

  2. Segmented Thermoelectric Oxide-Based Module for High-Temperature Waste Heat Harvesting

    DEFF Research Database (Denmark)

    Le, Thanh Hung; Van Nong, Ngo; Han, Li

    2015-01-01

    the efficiency and to evaluate the influence of the electrical and thermal losses on the performance of TE modules. Initial long-term stability tests of the module at the hot and the cold side temperatures of 1073 K and 444 K, respectively, showed a promising result with 4% degradation for 48 h operating in air....

  3. Experimental study of a thermoelectrically-driven liquid chiller in terms of COP and cooling down period

    International Nuclear Information System (INIS)

    Faraji, Amir Yadollah; Goldsmid, H.J.; Akbarzadeh, Aliakbar

    2014-01-01

    Highlights: • A COP of 0.8 is achievable for a thermoelectrically-driven water chiller. • With two market available TEC modules with ZT around 0.7 sub-zero temperatures became applicable. • Forced air convection heat exchangers have better COP and CDP compared with natural convection. • A PID controller has several advantages against on–off controller for controlling TEC module. - Abstract: To study COP and other cooling parameters of a thermoelectically-driven liquid chiller, a 430 ml capacity liquid chiller incorporating two commercially available thermoelectric modules as its active components, has been designed, built and assessed. The system can use natural or forced air convection in heat exchangers attached to the thermoelectric module surfaces. The coefficient of performance (COP) and cooling down period (CDP) of the system for different thermoelectric input voltages have been measured. The COP of the thermoelectric chiller was found to be in the range 0.2–1.4 for forced convection and 0.2–1 for natural convection at a cooled liquid temperature of 10 °C and an ambient temperature of 18 °C. For the chiller, heat pumping capacity, minimum achievable water temperature, and temperature difference across the thermoelectric surfaces were investigated for input voltages of 3 V, 5 V, 7 V, 10 V and 12 V. Furthermore, as a basis for reliable and convenient control of the chiller, a proportional integral derivative (PID) controller has been proposed

  4. Geothermal Thermoelectric Generation (G-TEG) with Integrated Temperature Driven Membrane Distillation and Novel Manganese Oxide for Lithium Extraction

    Energy Technology Data Exchange (ETDEWEB)

    Renew, Jay [Southern Research Inst., Birmingham, AL (United States); Hansen, Tim [Southern Research Inst., Birmingham, AL (United States)

    2017-06-01

    Southern Research Institute (Southern) teamed with partners Novus Energy Technologies (Novus), Carus Corporation (Carus), and Applied Membrane Technology, Inc. (AMT) to develop an innovative Geothermal ThermoElectric Generation (G-TEG) system specially designed to both generate electricity and extract high-value lithium (Li) from low-temperature geothermal brines. The process combined five modular technologies including – silica removal, nanofiltration (NF), membrane distillation (MD), Mn-oxide sorbent for Li recovery, and TEG. This project provides a proof of concept for each of these technologies. The first step in the process is silica precipitation through metal addition and pH adjustment to prevent downstream scaling in membrane processes. Next, the geothermal brine is concentrated with the first of a two stage MD system. The first stage MD system is made of a high-temperature material to withstand geothermal brine temperatures up to 150C.° The first stage MD is integrated with a G-TEG module for simultaneous energy generation. The release of energy from the MD permeate drives heat transfer across the TE module, producing electricity. The first stage MD concentrate is then treated utilizing an NF system to remove Ca2+ and Mg2+. The NF concentrate will be disposed in the well by reinjection. The NF permeate undergoes concentration in a second stage of MD (polymeric material) to further concentrate Li in the NF permeate and enhance the efficiency of the downstream Li recovery process utilizing a Mn-oxide sorbent. Permeate from both the stages of the MD can be beneficially utilized as the permeates will contain less contaminants than the feed water. The concentrated geothermal brines are then contacted with the Mn-oxide sorbent. After Li from the geothermal brine is adsorbed on the sorbent, HCl is then utilized to regenerate the sorbent and recover the Li. The research and development project showed that the Si removal goal (>80%) could

  5. Fabrication of Metallic Glass Powder for Brazing Paste for High-Temperature Thermoelectric Modules

    Science.gov (United States)

    Seo, Seung-Ho; Kim, Suk Jun; Lee, Soonil; Seo, Won-Seon; Kim, Il-Ho; Choi, Soon-Mok

    2018-06-01

    Metallic glass (MG) offers the advantage of outstanding oxidation resistance, since it has disordered atomic-scale structure without grain boundaries. We fabricated Al-based MG ribbons (Al84.5Y10Ni5.5) by a melt spinning process. We evaluated the adhesion strength of interfaces between the Al-based MG and a Ni-coated Cu electrode formed under various conditions at high temperature. In addition, we attempted to optimize the process conditions for pulverizing MG ribbons to high-energy ball milling and planetary milling. We confirmed that the electrical resistivity of the Al-based MG ribbon was substantially reduced after annealing at high temperature (over 300°C) due to crystallization.

  6. Stable and low contact resistance electrical contacts for high temperature SiGe thermoelectric generators

    KAUST Repository

    Zhang, Bo; Zheng, Tao; Wang, Qingxiao; Guo, Zaibing; Kim, Moon J.; Alshareef, Husam N.; Gnade, Bruce E.

    2018-01-01

    that no interdiffusion takes place between TaAlN and SiGe. A specific contact resistivity of (2.1±1.3)×10−6Ω-cm2 for p-type SiGe and (2.8±1.6)×10−5 Ω-cm2 for n-type SiGe is demonstrated after the high temperature annealing. These results show that TaAlN is a promising

  7. Low-temperature thermoelectric properties of Pb doped Cu2SnSe3

    Science.gov (United States)

    Prasad K, Shyam; Rao, Ashok; Gahtori, Bhasker; Bathula, Sivaiah; Dhar, Ajay; Chang, Chia-Chi; Kuo, Yung-Kang

    2017-09-01

    A series of Cu2Sn1-xPbxSe3 (0 ≤ x ≤ 0.04) compounds was prepared by solid state synthesis technique. The electrical resistivity (ρ) decreased with increase in Pb content up to x = 0.01, thereafter it increased with further increase in x (till x = 0.03). However, the lowest value of electrical resistivity is observed for Cu2Sn0.96Pb0.04Se3. Analysis of electrical resistivity of all the samples suggests that small poloron hoping model is operative in the high temperature regime while variable range hopping is effective in the low temperature regime. The positive Seebeck coefficient (S) for pristine and doped samples in the entire temperature range indicates that the majority charge carriers are holes. The electronic thermal conductivity (κe) of the Cu2Sn1-xPbxSe3 compounds was estimated by the Wiedemann-Franz law and found that the contribution from κe is less than 1% of the total thermal conductivity (κ). The highest ZT 0.013 was achieved at 400 K for the sample Cu2Sn0.98Pb0.02Se3, about 30% enhancement as compared to the pristine sample.

  8. Application of T2 Control Charts and Hidden Markov Models in Condition-Based Maintenance at Thermoelectric Power Plants

    Directory of Open Access Journals (Sweden)

    Emilija Kisić

    2015-01-01

    Full Text Available An innovative approach to condition-based maintenance of coal grinding subsystems at thermoelectric power plants is proposed in the paper. Coal mill grinding tables become worn over time and need to be replaced through time-based maintenance, after a certain number of service hours. At times such replacement is necessary earlier or later than prescribed, depending on the quality of the coal and of the grinding table itself. Considerable financial losses are incurred when the entire coal grinding subsystem is shut down and the grinding table found to not actually require replacement. The only way to determine whether replacement is necessary is to shut down and open the entire subsystem for visual inspection. The proposed algorithm supports condition-based maintenance and involves the application of T2 control charts to distinct acoustic signal parameters in the frequency domain and the construction of Hidden Markov Models whose observations are coded samples from the control charts. In the present research, the acoustic signals were collected by coal mill monitoring at the thermoelectric power plant “Kostolac” in Serbia. The proposed approach provides information about the current condition of the grinding table.

  9. Digital control programmer for temperature control

    International Nuclear Information System (INIS)

    Rajore, S.B.; Kumar, S.V.

    1993-01-01

    This report describes a PC based digital control programmer for controlling and programming temperature of a high vacuum resistance heating furnace and the software developed to control power using PID algorithm. It also describes the amplifier specially developed to suit the input requirement of the non-standard W5 thermocouple and the software and hardware protections introduced in the system. (author). 5 refs., 8 figs., 1 appendix

  10. New thinking on modeling of thermoelectric devices

    International Nuclear Information System (INIS)

    Zhang, T.

    2016-01-01

    Highlights: • New model was developed for performance calculation of thermoelectric devices. • The model takes into account the temperature-dependent material properties. • It takes into account the spatial-dependent heat flow rate in thermoelement. • It can take into account the heat and electricity losses at the junctions. • It can probe a broad range of parameters for module performance optimization. - Abstract: The performance of a thermoelectric power generation (TEPG) module and a device designed to convert engine exhaust heat directly into electricity was studied under different operating conditions using a proposed thermoelectric (TE) model in this work. The proposed model was obtained from the first law of thermodynamics, Ohm’s law, nonlinear analytical solution of thermoelectric transport equation, and a control volume that represents a typical TEPG module or device such that the temperature-dependent material properties of, the spatial-dependent heat flow rate through the TE element, and the interfacial electrical and thermal losses can be taken into account in the performance calculation. The performance of a typical TEPG module under a broad range of cold-side temperatures and the temperature differences between its hot-side and cold-side was calculated by the proposed model and the results agree very well with the existing model predictions. Comparison between the model predictions and the experimental results confirmed that reducing the interfacial electric resistance can enhance the module performance. The inter-dependence of the key thermal and TEPG system design and optimization parameters was examined for a real TEPG device using the proposed model and an optimal module fill factor of 0.35 was found within the given mass flow rates between 0.0154 and 0.052 kg/s of exhaust stream.

  11. Nanostructured silicon for thermoelectric

    Science.gov (United States)

    Stranz, A.; Kähler, J.; Waag, A.; Peiner, E.

    2011-06-01

    Thermoelectric modules convert thermal energy into electrical energy and vice versa. At present bismuth telluride is the most widely commercial used material for thermoelectric energy conversion. There are many applications where bismuth telluride modules are installed, mainly for refrigeration. However, bismuth telluride as material for energy generation in large scale has some disadvantages. Its availability is limited, it is hot stable at higher temperatures (>250°C) and manufacturing cost is relatively high. An alternative material for energy conversion in the future could be silicon. The technological processing of silicon is well advanced due to the rapid development of microelectronics in recent years. Silicon is largely available and environmentally friendly. The operating temperature of silicon thermoelectric generators can be much higher than of bismuth telluride. Today silicon is rarely used as a thermoelectric material because of its high thermal conductivity. In order to use silicon as an efficient thermoelectric material, it is necessary to reduce its thermal conductivity, while maintaining high electrical conductivity and high Seebeck coefficient. This can be done by nanostructuring into arrays of pillars. Fabrication of silicon pillars using ICP-cryogenic dry etching (Inductive Coupled Plasma) will be described. Their uniform height of the pillars allows simultaneous connecting of all pillars of an array. The pillars have diameters down to 180 nm and their height was selected between 1 micron and 10 microns. Measurement of electrical resistance of single silicon pillars will be presented which is done in a scanning electron microscope (SEM) equipped with nanomanipulators. Furthermore, measurement of thermal conductivity of single pillars with different diameters using the 3ω method will be shown.

  12. Electronic structure and transport in the low-temperature thermoelectric CsBi4Te6: Semiclassical transport equations

    DEFF Research Database (Denmark)

    Lykke, Lars; Iversen, Bo Brummerstedt; Madsen, Georg

    2006-01-01

    The band structure of the low-temperature thermoelectric material, CsBi4Te6, is calculated and analyzed using the semiclassic transport equations. It is shown that to obtain a quantitative agreement with measured transport properties, a band gap of 0.08 eV must be enforced. A gap in reasonable...... agreement with experiment was obtained using the generalized gradient functional of Engel and Vosko [E. Engel and S. H. Vosko, Phys. Rev. B 47, 13164 (1993)]. We found that the experimental p-type sample has a carrier concentration close to optimal. Furthermore, the conduction bands have a form equally well...

  13. Heat pipes for temperature control

    International Nuclear Information System (INIS)

    Groll, M.

    1978-01-01

    Heat pipes have known for years as effective constructional elements for temperature control. With the aid of special techniques (gas, liquid, steam, and voltage control), special operating characteristics can be obtained, e.g. variable heat conduction or diode behaviour. Their main field of application is in spacecraft technology and in nuclear technology in the isothermalisation of irradiation capsules. The different control techniques are presented and critically evaluated on the basis of characteristic properties like heat transfer capacity, volume and mass requirements, complexity of structure and production, reliability, and temperature control characteristics. Advantages and shortcomings of the different concepts are derived and compared. The state of the art of these control techniques is established on the basis of four development levels. Finally, the necessity and direction of further R + D activities are discussed, and suggestions are made for further work. (orig./HP) [de

  14. High-pressure densified solid solutions of alkaline earth hexaborides (Ca/Sr, Ca/Ba, Sr/Ba) and their high-temperature thermoelectric properties

    International Nuclear Information System (INIS)

    Gürsoy, M.; Takeda, M.; Albert, B.

    2015-01-01

    Solid solutions of alkaline earth hexaborides were synthesized and densified by spark plasma sintering at 100 MPa. The high-temperature thermoelectric properties (Seebeck coefficients, electrical and thermal diffusivities, heat capacities) were measured between room temperature and 1073 K. CaB 6 , SrB 6 , BaB 6 and the ternary hexaborides Ca x Sr 1−x B 6 , Ca x Ba 1−x B 6 , Sr x Ba 1−x B 6 (x = 0.25, 0.5, 0.75) are n-type conducting compounds over the whole compositional and thermal ranges. The values of the figure of merit ZT for CaB 6 (ca. 0.3 at 1073 K) were found to be significantly increased compared to earlier investigations which is attributed to the densification process. - Highlights: • Solid solutions of alkaline earth hexaborides were synthesized. • High-temperature thermoelectric properties of mixed calcium borides are excellent. • Spark plasma source densification results in high ZT values. • Borides are rare-earth free and refractory materials

  15. Thermoelectric characterization of an intermediate temperature solid oxide fuel cell system directly fed by dry biogas

    International Nuclear Information System (INIS)

    De Lorenzo, G.; Corigliano, O.; Lo Faro, M.; Frontera, P.; Antonucci, P.; Zignani, S.C.; Trocino, S.; Mirandola, F.A.; Aricò, A.S.; Fragiacomo, P.

    2016-01-01

    Highlights: • Numerical Model (NM) of SOFC Cogenerative System (SCS) fed by dry biogas is set up. • NM simulates new Ni-Fe/CGO protective layer for direct CH_4 consumption at the anode. • NM simulates the anode carbonation phenomenon and is experimentally validated. • The performance parameters trends of SCS fed by three types of dry biogas are shown. • SEM images after 40 h of operation show that there is no anode carbon deposition. - Abstract: A properly manufactured intermediate temperature Solid Oxide Fuel Cell (SOFC) can be directly fed by dry biogas, considering also the electrochemical partial and total oxidation reactions of methane in the biogas at the anode. In this way the methane in the biogas is electrochemically consumed directly at the fuel cell without the need to mix the biogas with any reforming gas (steam, oxygen or carbon dioxide). In this article, a numerical model of an SOFC system with Ni-Fe/CGO electrocatalyst anode protective layer directly fed by dry biogas, in cogenerative arrangement and with anode exhaust gas recirculation is formulated. The influences of biogas composition, of fuel cell operating current density and of percentage of recirculated anode exhaust gas on the SOFC system performances were evaluated by calculation code. An SOFC test bench was set up to validate the calculation code results experimentally. Furthermore, the numerical model also considers the anode carbonation and evaluates the amount of carbon that can be formed in the anode at chemical equilibrium and quasi-equilibrium conditions associated with the specific anode protective layer used.

  16. Express method for contactless measurement of parameters of thermoelectric materials

    Directory of Open Access Journals (Sweden)

    Ashcheulov A. A.

    2015-08-01

    Full Text Available The paper presents an original method for contactless express measurement of parameters of thermoelectric materials. The presence of a combination of AC and DC magnetic fields in the gap of the oscillating circuit, where the monitored sample of the thermoelectric material is located, leads — due to Ampere force — to delamination of geometric regions of the occurrence of half-cycles of Foucault current. This in turn causes the appearance of additional heat losses in the oscillating circuit caused by Peltier effect. Computer modeling of these processes with the use of the software package ComsolFenlab 3.3 allowed determining the nature and magnitude of the electric currents in oscillating circuit, the range of operating frequencies, and the ratio of amplitudes of the variable and fixed components of the magnetic field. These components eventually cause a certain temperature difference along the controlled sample, which difference is proportional to the thermoelectric figure of merit Z of the material. The basic expressions are obtained for determining the value of the Seebeck coefficient a, thermal conductivity ?, electrical conductivity ? and thermoelectric figure of merit Z. A description is given to the design of the device for contactless express measurement of parameters of thermoelectric materials based on Bi—Te—Se—Sb solid solutions. Its distinctive feature is the ability to determine the symmetric and asymmetric components of the electric conductivity of the material values. The actual error in parameter measurement in this case is 2%.

  17. Evaluation of high step-up power electronics stages in thermoelectric generator systems

    DEFF Research Database (Denmark)

    Sun, Kai; Ni, Longxian; Chen, Min

    2013-01-01

    To develop practical thermoelectric generator (TEG) systems, especially radioisotope thermoelectric power supplies for deep-space exploration, a power conditioning stage with high step-up gain is indispensable. This stage is used to step up the low output voltage of thermoelectric generators...... to the required high level. Furthermore, maximum power point tracking control for TEG modules needs to be implemented into the power electronics stages. In this paper, the temperature-dependent electrical characteristics of a thermoelectric generator are analyzed in depth. Three typical high step-up power...... converters suitable for TEG applications are discussed: an interleaved boost converter, a boost converter with a coupled inductor and an interleaved boost converter with an auxiliary transformer. A general comparison of the three high step-up converters is conducted to study the step-up gain, conversion...

  18. Synthesis, Transport, and Thermoelectric Studies of Topological Dirac Semimetal Cd3As2 for Room Temperature Waste Heat Recovery and Energy Conversion

    Science.gov (United States)

    Hosseini, Tahereh A.

    Rising rates of the energy consumption and growing concerns over the climate change worldwide have made energy efficiency an urgent problem to address. Nowadays, almost two-thirds of the energy produced by burning fossil fuels to generate electrical power is lost in the form of the heat. On this front, increasing electrical power generation through a waste heat recovery remains one of the highly promising venues of the energy research. Thermo-electric generators (TEGs) directly convert thermal energy into electrical and are the prime candidates for application in low-grade thermal energy/ waste heat recovery. The key commercial TE materials, e.g. PbTe and Bi2Te 3, have room temperature ZT of less than 1, whereas ZT exceeding 3 is required for a TEG to be economically viable. With the thermoelectric efficiency typically within a few percent range and a low efficiency-to-cost ratio of TEGs, there has been a resurgence in the search for new class of thermo-electric materials for developing high efficiency thermo-to-electric energy conversion systems, with phonon-glass electron-crystal materials holding the most promise. Herein, we focus on synthesis, characterization and investigation of electrical, thermo-electrical and thermal characteristics of crystalline Cd 3As2, a high performance 3D topological Dirac semimetal with Dirac fermions dispersing linearly in k3-space and possessing one of the largest electron mobilities known for crystalline materials, i.e. 104-105cm2V-1 s-1. Suppression of carrier backscattering, ultra-high charge carrier mobility, and inherently low thermal conductivity make this semimetal a key candidate for demonstrating high, device-favorable S and in turn ZT. In this work, a low-temperature vapor-based crystallization pathway was developed and optimized to produce free standing 2D cm-size crystals in Cd 3As2. Compared to the bulk crystals produced in previous studies, e.g. Piper-Polich, Bridgman, or flux method, Cd3As 2 samples were synthesized

  19. Low-Temperature Bonding of Bi0.5Sb1.5Te3 Thermoelectric Material with Cu Electrodes Using a Thin-Film In Interlayer

    Science.gov (United States)

    Lin, Yan-Cheng; Yang, Chung-Lin; Huang, Jing-Yi; Jain, Chao-Chi; Hwang, Jen-Dong; Chu, Hsu-Shen; Chen, Sheng-Chi; Chuang, Tung-Han

    2016-09-01

    A Bi0.5Sb1.5Te3 thermoelectric material electroplated with a Ni barrier layer and a Ag reaction layer was bonded with a Ag-coated Cu electrode at low temperatures of 448 K (175 °C) to 523 K (250 °C) using a 4- μm-thick In interlayer under an external pressure of 3 MPa. During the bonding process, the In thin film reacted with the Ag layer to form a double layer of Ag3In and Ag2In intermetallic compounds. No reaction occurred at the Bi0.5Sb1.5Te3/Ni interface, which resulted in low bonding strengths of about 3.2 MPa. The adhesion of the Bi0.5Sb1.5Te3/Ni interface was improved by precoating a 1- μm Sn film on the surface of the thermoelectric element and preheating it at 523 K (250 °C) for 3 minutes. In this case, the bonding strengths increased to a range of 9.1 to 11.5 MPa after bonding at 473 K (200 °C) for 5 to 60 minutes, and the shear-tested specimens fractured with cleavage characteristics in the interior of the thermoelectric material. The bonding at 448 K (175 °C) led to shear strengths ranging from 7.1 to 8.5 MPa for various bonding times between 5 and 60 minutes, which were further increased to the values of 10.4 to 11.7 MPa by increasing the bonding pressure to 9.8 MPa. The shear strengths of Bi0.5Sb1.5Te3/Cu joints bonded with the optimized conditions of the modified solid-liquid interdiffusion bonding process changed only slightly after long-term exposure at 473 K (200 °C) for 1000 hours.

  20. Estimating Seebeck Coefficient of a p-Type High Temperature Thermoelectric Material Using Bee Algorithm Multi-layer Perception

    Science.gov (United States)

    Uysal, Fatih; Kilinc, Enes; Kurt, Huseyin; Celik, Erdal; Dugenci, Muharrem; Sagiroglu, Selami

    2017-08-01

    Thermoelectric generators (TEGs) convert heat into electrical energy. These energy-conversion systems do not involve any moving parts and are made of thermoelectric (TE) elements connected electrically in a series and thermally in parallel; however, they are currently not suitable for use in regular operations due to their low efficiency levels. In order to produce high-efficiency TEGs, there is a need for highly heat-resistant thermoelectric materials (TEMs) with an improved figure of merit ( ZT). Production and test methods used for TEMs today are highly expensive. This study attempts to estimate the Seebeck coefficient of TEMs by using the values of existing materials in the literature. The estimation is made within an artificial neural network (ANN) based on the amount of doping and production methods. Results of the estimations show that the Seebeck coefficient can approximate the real values with an average accuracy of 94.4%. In addition, ANN has detected that any change in production methods is followed by a change in the Seebeck coefficient.

  1. Low start-up voltage dc–dc converter with negative voltage control for thermoelectric energy harvesting

    Directory of Open Access Journals (Sweden)

    Pui-Sun Lei

    2015-01-01

    Full Text Available This Letter presents a low start-up voltage dc–dc converter for low-power thermoelectric systems which uses a native n-type MOS transistor as the start-up switch. The start-up voltage of the proposed converter is 300 mV and the converter does not need batteries to start up. The negative voltage control is proposed to reduce the leakage current caused by native n-type transistor and increase the efficiency. The proposed converter was designed using standard 0.18 µm CMOS process with chip size of 0.388 mm^2. The peak efficiency is 63% at load current of 1.5 mA. The proposed converter provides output voltage >1 V at maximum load current of 3.2 mA.

  2. Fine Art of Thermoelectricity.

    Science.gov (United States)

    Brus, Viktor V; Gluba, Marc; Rappich, Jörg; Lang, Felix; Maryanchuk, Pavlo D; Nickel, Norbert H

    2018-02-07

    A detailed study of hitherto unknown electrical and thermoelectric properties of graphite pencil traces on paper was carried out by measuring the Hall and Seebeck effects. We show that the combination of pencil-drawn graphite and brush-painted poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) films on regular office paper results in extremely simple, low-cost, and environmentally friendly thermoelectric power generators with promising output characteristics at low-temperature gradients. The working characteristics can be improved even further by incorporating n-type InSe flakes. The combination of pencil-drawn n-InSe:graphite nanocomposites and brush-painted PEDOT:PSS increases the power output by 1 order of magnitude.

  3. semiconducting nanostructures: morphology and thermoelectric properties

    Science.gov (United States)

    Culebras, Mario; Torán, Raquel; Gómez, Clara M.; Cantarero, Andrés

    2014-08-01

    Semiconducting metallic oxides, especially perosvkite materials, are great candidates for thermoelectric applications due to several advantages over traditionally metallic alloys such as low production costs and high chemical stability at high temperatures. Nanostructuration can be the key to develop highly efficient thermoelectric materials. In this work, La 1- x Ca x MnO 3 perosvkite nanostructures with Ca as a dopant have been synthesized by the hydrothermal method to be used in thermoelectric applications at room temperature. Several heat treatments have been made in all samples, leading to a change in their morphology and thermoelectric properties. The best thermoelectric efficiency has been obtained for a Ca content of x=0.5. The electrical conductivity and Seebeck coefficient are strongly related to the calcium content.

  4. Effects of Yttrium and Iron co-doping on the high temperature thermoelectric properties of Ca{sub 3}Co{sub 4}O{sub 9+δ}

    Energy Technology Data Exchange (ETDEWEB)

    Wu, NingYu, E-mail: niwu@dtu.dk; Van Nong, Ngo; Pryds, Nini; Linderoth, Søren

    2015-07-25

    Highlights: • The Fe and Fe/Y doping at the Co- and Ca-sites of Ca{sub 3}Co{sub 4}O{sub 9+δ} were investigated. • The rising ρ by Y doping can be mitigated by the coupled Fe doping. • The increased Seebeck coefficient by Y doping can be maintained in co-doped system. • The co-doped system leads to an improvement of the thermoelectric performance. • The co-doped system may preserve the merits from each component doping. - Abstract: A series of Y and Fe co-doped Ca{sub 3−x}Y{sub x}Co{sub 4−y}Fe{sub y}O{sub 9+δ} (0 ⩽ x ⩽ 0.3, 0 ⩽ y ⩽ 0.1) samples synthesized by auto-combustion reaction and followed by a spark plasma sintering (SPS) processing with the effects of Fe and Y doping on the high temperature (RT to 800 °C) thermoelectric properties were systematically investigated. For the Fe-doped system (x = 0, y ⩽ 0.1), the electrical resistivity (ρ) decreased over the whole measured temperature range, while the Seebeck coefficient (S) remained almost the same. For the co-doped system, at any fixed Fe doping content, both ρ and S tended to increase with increasing Y dopants, however, the effect is more substantial on ρ than on S, particularly in the low temperature regime. In contrast to ρ and S, the in-plane thermal conductivity (κ) is only slightly influenced by Y and Fe substitutions. Among all the investigated samples, the co-doped sample with x = 0.1 and y = 0.03 showed a decrease of ρ, enhanced power factor over the measured temperature range, and improved ZT at 800 °C as compared to un-doped Ca{sub 3}Co{sub 4}O{sub 9+δ}.

  5. Microwatt thermoelectric generator

    International Nuclear Information System (INIS)

    Goslee, D.E.; Bustard, T.S.

    1976-01-01

    A microwatt thermoelectric generator suitable for implanting in the body is described. The generator utilizes a nuclear energy source. Provision is made for temporary electrical connection to the generator for testing purposes, and for ensuring that the heat generated by the nuclear source does not bypass the pile. Also disclosed is a getter which is resistant to shrinkage during sintering, and a foil configuration for controlling the radiation of heat from the nuclear source to the hot plate of the pile

  6. Microwatt thermoelectric generator

    International Nuclear Information System (INIS)

    Goslee, D.E.

    1976-01-01

    A microwatt thermoelectric generator suitable for implanting in the body is described. The disclosed generator utilizes a nuclear energy source. Provision is made for temporary electrical connection to the generator for testing purposes, and for ensuring that the heat generated by the nuclear source does not bypass the pile. Also disclosed is a getter which is resistant to shrinkage during sintering, and a foil configuration for controlling the radiation of heat from the nuclear source to the hot plate of the pile

  7. A new microcontroller supervised thermoelectric renal hypothermia system.

    Science.gov (United States)

    Işik, Hakan

    2005-10-01

    In the present study, a thermoelectric system controlled by a microcontroller is developed to induce renal hypothermia. Temperature value was managed by 8-byte microcontroller, PIC16F877, and was programmed using microcontroller MPASM package. In order to ensure hypothermia in the kidney 1-4 modules and sensors perceiving temperature of the area can be selected. Temperature values are arranged proportionately for the selected area and the determined temperature values can be monitored from an Liquid Crystal Display (LCD) screen. The temperature range of the system is between -50 and +50 degrees C. Renal hypothermia system was tried under in vivo conditions on the kidney of a dog.

  8. Spin thermoelectric effects in organic single-molecule devices

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H.L.; Wang, M.X.; Qian, C.; Hong, X.K.; Zhang, D.B.; Liu, Y.S.; Yang, X.F., E-mail: xfyang@cslg.edu.cn

    2017-05-25

    Highlights: • A stronger spin thermoelectric performance in a polyacetylene device is observed. • For the antiferromagnetic (AFM) ordering, a transport gap is opened. Thus the thermoelectric effects are largely enhanced. - Abstract: The spin thermoelectric performance of a polyacetylene chain bridging two zigzag graphene nanoribbons (ZGNRs) is investigated based on first principles method. Two different edge spin arrangements in ZGNRs are considered. For ferromagnetic (FM) ordering, transmission eigenstates with different spin indices distributed below and above Fermi level are observed, leading directly to a strong spin thermoelectric effect in a wide temperature range. With the edge spins arranged in the antiferromagnetic (AFM) ordering, an obvious transport gap appears in the system, which greatly enhances the thermoelectric effects. The presence of a small spin splitting also induces a spin thermoelectric effect greater than the charge thermoelectric effect in certain temperature range. In general, the single-molecule junction exhibits the potential to be used for the design of perfect thermospin devices.

  9. Dynamic thermoelectricity in uniform bipolar semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Volovichev, I.N., E-mail: vin@ire.kharkov.ua

    2016-07-01

    The theory of the dynamic thermoelectric effect has been developed. The effect lies in an electric current flowing in a closed circuit that consists of a uniform bipolar semiconductor, in which a non-uniform temperature distribution in the form of the traveling wave is created. The calculations are performed for the one-dimensional model in the quasi-neutrality approximation. It was shown that the direct thermoelectric current prevails, despite the periodicity of the thermal excitation, the circuit homogeneity and the lack of rectifier properties of the semiconductor system. Several physical reasons underlining the dynamic thermoelectric effect are found. One of them is similar to the Dember photoelectric effect, its contribution to the current flowing is determined by the difference in the electron and hole mobilities, and is completely independent of the carrier Seebeck coefficients. The dependence of the thermoelectric short circuit current magnitude on the semiconductor parameters, as well as on the temperature wave amplitude, length and velocity is studied. It is shown that the magnitude of the thermoelectric current is proportional to the square of the temperature wave amplitude. The dependence of the thermoelectric short circuit current on the temperature wave length and velocity is the nonmonotonic function. The optimum values for the temperature wave length and velocity, at which the dynamic thermoelectric effect is the greatest, have been deduced. It is found that the thermoelectric short circuit current changes its direction with decreasing the temperature wave length under certain conditions. The prospects for the possible applications of the dynamic thermoelectric effect are also discussed.

  10. Numerical model of a thermoelectric generator with compact plate-fin heat exchanger for high temperature PEM fuel cell exhaust heat recovery

    DEFF Research Database (Denmark)

    Xin, Gao; Andreasen, Søren Juhl; Chen, Min

    2012-01-01

    on a finite-element approach. On each discretized segment, fluid properties, heat transfer process and TEG performance are locally calculated for higher model precision. To benefit both the system design and fabrication, the way to model TEG modules is herein reconsidered; a database of commercialized compact......This paper presents a numerical model of an exhaust heat recovery system for a high temperature polymer electrolyte membrane fuel cell (HTPEMFC) stack. The system is designed as thermoelectric generators (TEGs) sandwiched in the walls of a compact plate-fin heat exchanger. Its model is based...... plate-fin heat exchangers is adopted. Then the model is validated against experimental data and the main variables are identified by means of a sensitivity analysis. Finally, the system configuration is optimized for recovering heat from the exhaust gas. The results exhibit the crucial importance...

  11. Technical Feasibility Evaluation on The Use of A Peltier Thermoelectric Module to Recover Automobile Exhaust Heat

    Science.gov (United States)

    Sugiartha, N.; Sastra Negara, P.

    2018-01-01

    A thermoelectric module composes of integrated p-n semiconductors as hot and cold side junctions and uses Seebeck effect between them to function as a thermoelectric generator (TEG) to directly convert heat into electrical power. Exhaust heat from engines as otherwise wasted to the atmosphere is one of the heat sources freely available to drive the TEG. This paper evaluates technical feasibility on the use of a Peltier thermoelectric module for energy recovery application of such kind of waste heat. An experimental apparatus has been setup to simulate real conditions of automobile engine exhaust piping system. It includes a square section aluminium ducting, an aluminium fin heat sink and a TEC1 12706 thermoelectric module. A heater and a cooling fan are employed to simulate hot exhaust gas and ambient air flows, respectively. Electrical loading is controlled by resistors. Dependent variables measured during the test are cold and hot side temperatures, open and loaded circuit output voltages and electrical current. The test results revealed a promising application of the Peltier thermoelectric module for the engine exhaust heat recovery, though the loaded output power produced and loaded output voltage are still far lower than the commercially thermoelectric module originally purposed for the TEG application.

  12. Temperature-Controlled Chameleonlike Cloak

    Science.gov (United States)

    Peng, Ruiguang; Xiao, Zongqi; Zhao, Qian; Zhang, Fuli; Meng, Yonggang; Li, Bo; Zhou, Ji; Fan, Yuancheng; Zhang, Peng; Shen, Nian-Hai; Koschny, Thomas; Soukoulis, Costas M.

    2017-01-01

    Invisibility cloaking based on transformation optics has brought about unlimited space for reverie. However, the design and fabrication of transformation-optics-based cloaks still remain fairly challenging because of the complicated, even extreme, material prescriptions, including its meticulously engineered anisotropy, inhomogeneity and singularity. And almost all the state-of-the-art cloaking devices work within a narrow and invariable frequency band. Here, we propose a novel mechanism for all-dielectric temperature-controllable cloaks. A prototype device was designed and fabricated with SrTiO3 ferroelectric cuboids as building blocks, and its cloaking effects were successfully demonstrated, including its frequency-agile invisibility by varying temperature. It revealed that the predesignated cloaking device based on our proposed strategy could be directly scaled in dimensions to operate at different frequency regions, without the necessity for further efforts of redesign. Our work opens the door towards the realization of tunable cloaking devices for various practical applications and provides a simple strategy to readily extend the cloaking band from microwave to terahertz regimes without the need for reconfiguration.

  13. Temperature-Controlled Chameleonlike Cloak

    Directory of Open Access Journals (Sweden)

    Ruiguang Peng

    2017-03-01

    Full Text Available Invisibility cloaking based on transformation optics has brought about unlimited space for reverie. However, the design and fabrication of transformation-optics-based cloaks still remain fairly challenging because of the complicated, even extreme, material prescriptions, including its meticulously engineered anisotropy, inhomogeneity and singularity. And almost all the state-of-the-art cloaking devices work within a narrow and invariable frequency band. Here, we propose a novel mechanism for all-dielectric temperature-controllable cloaks. A prototype device was designed and fabricated with SrTiO_{3} ferroelectric cuboids as building blocks, and its cloaking effects were successfully demonstrated, including its frequency-agile invisibility by varying temperature. It revealed that the predesignated cloaking device based on our proposed strategy could be directly scaled in dimensions to operate at different frequency regions, without the necessity for further efforts of redesign. Our work opens the door towards the realization of tunable cloaking devices for various practical applications and provides a simple strategy to readily extend the cloaking band from microwave to terahertz regimes without the need for reconfiguration.

  14. Thermoelectric effects in magnetic nanostructures

    NARCIS (Netherlands)

    Hatami, Moosa; Bauer, Gerrit E.W.; Zhang, Q.F.; Kelly, Paul J.

    2009-01-01

    We model and evaluate the Peltier and Seebeck effects in magnetic multilayer nanostructures by a finite-element theory of thermoelectric properties. We present analytical expressions for the thermopower and the current-induced temperature changes due to Peltier cooling/heating. The thermopower of a

  15. Experimental evaluation of an active solar thermoelectric radiant wall system

    International Nuclear Information System (INIS)

    Liu, ZhongBing; Zhang, Ling; Gong, GuangCai; Han, TianHe

    2015-01-01

    Highlights: • A novel active solar thermoelectric radiant wall are proposed and tested. • The novel wall can control thermal flux of building envelope by using solar energy. • The novel wall can eliminate building envelop thermal loads and provide cooling capacity for space cooling. • Typical application issues including connection strategies, coupling with PV system etc. are discussed. - Abstract: Active solar thermoelectric radiant wall (ASTRW) system is a new solar wall technology which integrates thermoelectric radiant cooling and photovoltaic (PV) technologies. In ASTRW system, a PV system transfers solar energy directly into electrical energy to power thermoelectric cooling modes. Both the thermoelectric cooling modes and PV system are integrated into one enclosure surface as radiant panel for space cooling and heating. Hence, ASTRW system presents fundamental shift from minimizing building envelope energy losses by optimizing the insulation thickness to a new regime where active solar envelop is designed to eliminate thermal loads and increase the building’s solar gains while providing occupant comfort in all seasons. This article presents an experimental study of an ASTRW system with a dimension of 1580 × 810 mm. Experimental results showed that the inner surface temperature of the ASTRW is 3–8 °C lower than the indoor temperature of the test room, which indicated that the ASTRW system has the ability to control thermal flux of building envelope by using solar energy and reduce the air conditioning system requirements. Based on the optimal operating current of TE modules and the analysis based upon PV modeling theories, the number and type of the electrical connections for the TE modules in ASTRW system are discussed in order to get an excellent performance in the operation of the ASTRW system

  16. Effect of spark plasma sintering conditions on the thermoelectric properties of (Bi{sub 0.25}Sb{sub 0.75}){sub 2}Te{sub 3} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sang-Soon [Center for Electronic Materials, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Kim, Ju-Heon [High Temp. Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Kwon, Beomjin; Kim, Seong Keun [Center for Electronic Materials, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Park, Hyung-Ho [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Lee, Ki-Suk; Baik, Jeong Min [School of Materials and Science Engineering, UNIST, Ulsan 689-798 (Korea, Republic of); KIST-UNIST Ulsan Center for Convergent Materials, UNIST, Ulsan 689-798 (Korea, Republic of); Choi, Won Jun [Center for Opto-Electronic Materials and Devices, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Kim, Dong-Ik [High Temp. Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Hyun, Dow-Bin; Kim, Jin-Sang [Center for Electronic Materials, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Baek, Seung-Hyub, E-mail: shbaek77@kist.re.kr [Center for Electronic Materials, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); KIST-UNIST Ulsan Center for Convergent Materials, UNIST, Ulsan 689-798 (Korea, Republic of); Department of Nanomaterials Science and Technology, Korea University of Science and Technology, Daejeon, 305-333 (Korea, Republic of)

    2016-09-05

    As a field-assisted technique, spark plasma sintering (SPS) enables densification of specimens in a very short period of time compared to other sintering techniques. For high performance thermoelectric material synthesis, SPS is widely used to fabricate nanograin-structured thermoelectric materials by rapidly densifying the nanopowders suppressing grain growth. However, the microstructural evolution behavior of thermoelectric materials by SPS, another important process during sintering, has been rarely studied. Here, we explore SPS as a tool to control the microstructure by long-time SPS. Using p-type (Bi{sub 0.25}Sb{sub 0.75}){sub 2}Te{sub 3} thermoelectric materials as a model system, we systematically vary SPS temperature and time to understand the correlations between SPS conditions, microstructural evolution, and the thermoelectric properties. Our results show that the relatively low eutectic temperature (∼420 °C) and the existence of volatile tellurium (Te) are critical factors to determine both microstructure and thermoelectric property. In the liquid-phase sintering regime, rapid evaporation of Te leads to a strong dependence of thermoelectric property on SPS time. On the other hand, in the solid-phase sintering regime, there is a weak dependence on SPS time. The optimum thermoelectric figure-of-merit (Z) of 2.93 × 10{sup −3}/K is achieved by SPS at 500 °C for 30 min. Our results will provide an insight on the optimization of SPS conditions for materials containing volatile elements with low eutectic temperature. - Highlights: • Spark plasma sintering (SPS) is used to synthesize the thermoelectric (Bi{sub 0.25}Sb{sub 0.75}){sub 2}Te{sub 3}. • Liquid phase and volatile element are a key for the microstructure and thermoelectric property. • Thermoelectric figure-of-merit of 2.9 × 10{sup −3}/K is achieved at 500 °C for 30 min.

  17. Portable Thermoelectric Power Generator Coupled with Phase Change Material

    OpenAIRE

    Lim Chong C.; Al-Kayiem Hussain H.; Sing Chin Y.

    2014-01-01

    Solar is the intermittent source of renewable energy and all thermal solar systems having a setback on non-functioning during the night and cloudy environment. This paper presents alternative solution for power generation using thermoelectric which is the direct conversion of temperature gradient of hot side and cold side of thermoelectric material to electric voltage. Phase change material with latent heat effect would help to prolong the temperature gradient across thermoelectric material f...

  18. Nanostructured Thermoelectric Oxides for Energy Harvesting Applications

    KAUST Repository

    Abutaha, Anas I.

    2015-11-24

    As the world strives to adapt to the increasing demand for electrical power, sustainable energy sources are attracting significant interest. Around 60% of energy utilized in the world is wasted as heat. Different industrial processes, home heating, and exhausts in cars, all generate a huge amount of unused waste heat. With such a huge potential, there is also significant interest in discovering inexpensive technologies for power generation from waste heat. As a result, thermoelectric materials have become important for many renewable energy research programs. While significant advancements have been done in improving the thermoelectric properties of the conventional heavy-element based materials (such as Bi2Te3 and PbTe), high-temperature applications of thermoelectrics are still limited to one materials system, namely SiGe, since the traditional thermoelectric materials degrade and oxidize at high temperature. Therefore, oxide thermoelectrics emerge as a promising class of materials since they can operate athigher temperatures and in harsher environments compared to non-oxide thermoelectrics. Furthermore, oxides are abundant and friendly to the environment. Among oxides, crystalline SrTiO3 and ZnO are promising thermoelectric materials. The main objective of this work is therefore to pursue focused investigations of SrTiO3 and ZnO thin films and superlattices grown by pulsed laser deposition (PLD), with the goal of optimizing their thermoelectric properties by following different strategies. First, the effect of laser fluence on the thermoelectric properties of La doped epitaxial SrTiO3 films is discussed. Films grown at higher laser fluences exhibit better thermoelectric performance. Second, the role of crystal orientation in determining the thermoelectric properties of epitaxial Al doped ZnO (AZO) films is explained. Vertically aligned (c-axis) AZO films have superior thermoelectric properties compared to other films with different crystal orientations. Third

  19. GEO-TEP. Development of thermoelectric materials for geothermal energy conversion systems. Final report 2008

    Energy Technology Data Exchange (ETDEWEB)

    Bocher, L.; Weidenkaff, A.

    2008-07-01

    Geothermal heat can be directly converted into electricity by using thermoelectric converters. Thermoelectric conversion relies on intrinsic materials properties which have to be optimised. In this work novel environmentally friendly and stable oxide ceramics were developed to fulfil this task. Thus, manganate phases were studied regarding their potential thermoelectric properties for converting geothermal heat into electricity. Perovskite-type phases were synthesized by applying different methods: the ceramic route, and innovative synthesis routes such as the 'chimie douce' method by bulk thermal decomposition of the citrate precursor or using an USC process, and also the polyol-mediated synthesis route. The crystal structures of the manganate phases are evaluated by XRPD, NPD, and ED techniques while specific microstructures such as twinned domains are highlighted by HRTEM imaging. Besides, the thermal stability of the Mn-oxide phases in air atmosphere are controlled over a wide temperature range (T < 1300 K). The thermoelectric figure of merit ZT was enhanced from 0.021 to 0.3 in a broad temperature range for the studied phases which makes these phases the best perovskitic candidates as n-type polycrystalline thermoelectric materials operating in air at high temperatures. (author)

  20. Control of a deareador level of a thermoelectric power station using modern control techniques; Control de nivel de un deareador de una central termoelectrica utilizando tecnicas de control moderno

    Energy Technology Data Exchange (ETDEWEB)

    Chavez Estrada, Jose Israel

    1997-01-01

    The present work shows the implementation of the scheme of predictive control IMC (Internal Model Control) in order to control the level of the deareador of a combined cycle thermoelectric power station of (C.C.T.S.). The implementation has the purpose of looking for alternative strategies of control to the classic ones (PID`s) that more efficiently control the variables of interest, in addition to getting into the new control techniques of control. Following the philosophy of predictive control IMC the form to applying this technique is shown, as well as the implementation of this type of controllers. A comparison of predictive control IMC is made with the scheme of conventional control (three control elements PID`s ) used at present to control the level of the deareador in the Combined Cycle Thermoelectric Power stations of Dos Bocas, Veracruz, Mexico and of Gomez Palacio, Durango, Mexico. [Espanol] El presente trabajo muestra la implementacion del esquema de control predictivo IMC (Control con Modelo Interno) con el objeto de controlar el nivel del deareador de una Central Termoelectrica de Ciclo Combinado (C.T.C.C.). La implementacion tiene la finalidad de buscar estrategias de control alternas a las clasicas (PID`s) que controlen mas eficientemente la variable de interes, ademas de incursionar en las nuevas tecnicas de control. Siguiendo la filosofia del control predictivo IMC se muestra la forma de aplicar esta tecnica, asi como la implementacion de este tipo de controladores. Se hace una comparacion del control predictivo IMC con el esquema de control convencional (control de tres elementos PID`s) utilizando actualmente para controlar el nivel del deareador en las centrales termoelectricas de ciclo combinado de Dos Bocas, Veracruz y de Gomez Palacio, Durango en Mexico.

  1. Thermoelectric generator

    International Nuclear Information System (INIS)

    Purdy, D.L.

    1978-01-01

    The main components of a thermoelectric generator are housed in an evacuated cylindrical vessel. In the middle of it there is the radioactive heat source, e.g. 90 Sr or 238 Pu, enclosed by a gamma radiation shield. This one is surrounded by a heat-insulating screen from getter material or indicidual sheets of titanium. In the bottom of the screen there are arranged several thermocouples on a circle. The thermocouples themselves are contained within casings sealed gas-tight and filled with an inert gas, e.g. argon. By separating the internal space of the generator vessel from the thermocouple casings, made of e.g. n- respectively p-doped lead telluride cylinders, for both the optimal gas state may be obtained. (DG) [de

  2. Simulation of a thermoelectric gas sensor that determines hydrocarbon concentrations in exhausts and the light-off temperature of catalyst materials

    Directory of Open Access Journals (Sweden)

    T. Ritter

    2017-12-01

    Full Text Available Catalyst materials can be characterized with a thermoelectric gas sensor. Screen-printed thermopiles measure the temperature difference between an inert part of the planar sensor and a part that is coated with the catalyst material to be analyzed. If the overall sensor temperature is modulated, the catalytic activity of the material can be varied. Exothermic reactions that occur at the catalyst layer cause a temperature increase that can then be measured as a sensor voltage due to the Seebeck coefficient of the thermopiles. This mechanism can also be employed at stationary conditions at constant sensor temperature to measure gas concentrations. Then, the sensor signal changes linearly with the analyte concentration. Many variables influence the sensing performance, for example, the offset voltage due to asymmetric inflow and the resulting inhomogeneous temperature distributions are an issue. For even better understanding of the whole sensing principle, it is simulated in this study by a 3-D finite element model. By coupling all influencing physical effects (fluid flow, gas diffusion, heat transfer, chemical reactions, and electrical properties a model was set up that is able to mirror the sensor behavior precisely, as the comparison with experimental data shows. A challenging task was to mesh the geometry due to scaling problems regarding the resolution of the thin catalyst layer in the much larger gas tube. Therefore, a coupling of a 3-D and a 1-D geometry is shown. This enables to calculate the overall temperature distribution, fluid flow, and gas concentration distribution in the 3-D model, while a very accurate calculation of the chemical reactions is possible in a 1-D dimension. This work does not only give insight into the results at stationary conditions for varying feed gas concentrations and used substrate materials but shows also how various exhaust gas species behave under transient temperature modulation.

  3. Influence of temperature on thermoelectric properties of Fe{sub x}Co{sub 1−x}S{sub 2} thin films: A semiconductor to semimetal conversion

    Energy Technology Data Exchange (ETDEWEB)

    Clamagirand, J.M.; Ares, J.R., E-mail: joser.ares@uam.es; Flores, E.; Diaz-Chao, P.; Leardini, F.; Ferrer, I.J.; Sánchez, C.

    2016-02-01

    In this work, we investigate the thermoelectric properties of p and n-type thin films obtained by cobalt doping of FeS{sub 2}. Films were synthesized by direct sulfuration of Co–Fe thin bilayers at 300 °C. It is found that at room temperature (RT), the Seebeck coefficient is reduced from 80 μV/K to − 70 μV/K when Co concentration is increased and the electrical resistivity of the films is decreased two orders of magnitude. X-ray diffraction and Raman measurements point out that Co is replacing Fe into the pyrite lattice and, subsequently is promoting a semiconductor to semimetal conversion. The influence of temperature on transport properties of different Fe{sub x}Co{sub 1−x}S{sub 2} films has been investigated. Whereas the Seebeck coefficient is hardly modified, the film resistivity is drastically decreased when temperature increases what has been attributed to the thermal activation of electrical carriers. The influence of Co doping on the band scheme of FeS{sub 2} is shown. To this aim, donor and acceptor states are included into its forbidden gap. Whereas the band scheme of FeS{sub 2} exhibits an acceptor level with an E = 0.11 ± 0.03 eV above the top of the valence band due to iron vacancies, a wide donor level close to the bottom of the conduction band (E = 0.08 ± 0.05 eV) is created by the progressive replacement of iron by cobalt into the FeS{sub 2} lattice. - Highlights: • Thermoelectric properties of pyrite and Co-doped pyrite thin films were measured. • Whereas ρ decreases, S remains practically unaltered on increasing temperature (RT-300 °C). • On increasing Co-concentration, films exhibit a p semiconductor to n type semimetal conversion. • Donor states close to the botton of the conduction band are created by Co doping. • Energy of the donor level decreases and gets wider due to Co-concentration.

  4. Protection and thermal management of thermoelectric generator system using phase change materials: An experimental investigation

    DEFF Research Database (Denmark)

    Ahmadi Atouei, Saeed; Rezaniakolaei, Alireza; Ranjbar, A.A.

    2018-01-01

    In most thermoelectric systems the thermal boundary conditions are transient, and thermal manage-ment of the system is critical to improve electrical performance of the system. In this study, effect of using phase change materials (PCM) to control the hot and cold side temperatures...

  5. Thermoelectric power and electrical conductivity of strontium-doped lanthanum manganite

    DEFF Research Database (Denmark)

    Ahlgren, E.O.; Poulsen, F.W.

    1996-01-01

    Thermoelectric power and electrical conductivity of pure and 5, 10 and 20% strontium-doped lanthanum manganite are determined as function of temperature in air and of P-O2 at 1000 degrees C. At high temperatures the thermoelectric power is negative. Both thermoelectric power and conductivity...

  6. Room temperature Young's modulus, shear modulus, Poisson's ratio and hardness of PbTe-PbS thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Jennifer E [Chemical Engineering and Materials Science Department, Michigan State University, East Lansing, MI 48824 (United States); Case, Eldon D., E-mail: casee@egr.msu.edu [Chemical Engineering and Materials Science Department, Michigan State University, East Lansing, MI 48824 (United States); Khabir, Kristen N; Stewart, Ryan C [Chemical Engineering and Materials Science Department, Michigan State University, East Lansing, MI 48824 (United States); Wu, Chun-I; Hogan, Timothy P [Electrical and Computer Engineering Department, Michigan State University, East Lansing, MI 48824 (United States); Timm, Edward J [Mechanical Engineering Department, Michigan State University, East Lansing, MI 48824 (United States); Girard, Steven N; Kanatzidis, Mercouri G [Department of Chemistry, Northwestern University, Evanston, IL (United States)

    2010-06-15

    Two-phase PbTe-PbS materials, in which PbS is a nanostructured phase, are promising thermoelectric materials for the direct conversion of heat energy into electricity. In this study, a Vickers indentation mean hardness of 1.18 {+-} 0.09 GPa was measured for hot pressed specimens Pb{sub 0.95}Sn{sub 0.05}Te-PbS 8% while the mean hardness of cast specimens was 0.68 {+-} 0.07 GPa. The mean fracture toughness of the not pressed specimens was estimated as 0.35 {+-} 0.04 MPa m{sup 1/2} via Vickers indentation. Resonant Ultrasound Spectroscopy (RUS) measurements on hot pressed specimens gave mean values of Young's modulus, shear modulus and Poisson's ratio of 53.1 GPa, 21.4 GPa and 0.245, respectively while for the cast specimens the Young's and shear moduli were about 10% lower than for the hot pressed, with a mean value of Poisson's ratio of 0.245. The differences between the hardness and elastic moduli values for the cast and hot pressed specimens are discussed.

  7. Optimized Design of the SGA-WZ Strapdown Airborne Gravimeter Temperature Control System

    Directory of Open Access Journals (Sweden)

    Juliang Cao

    2015-12-01

    Full Text Available The temperature control system is one of the most important subsystems of the strapdown airborne gravimeter. Because the quartz flexible accelerometer based on springy support technology is the core sensor in the strapdown airborne gravimeter and the magnet steel in the electromagnetic force equilibrium circuits of the quartz flexible accelerometer is greatly affected by temperature, in order to guarantee the temperature control precision and minimize the effect of temperature on the gravimeter, the SGA-WZ temperature control system adopts a three-level control method. Based on the design experience of the SGA-WZ-01, the SGA-WZ-02 temperature control system came out with a further optimized design. In 1st level temperature control, thermoelectric cooler is used to conquer temperature change caused by hot weather. The experiments show that the optimized stability of 1st level temperature control is about 0.1 °C and the max cool down capability is about 10 °C. The temperature field is analyzed in the 2nd and 3rd level temperature control using the finite element analysis software ANSYS. The 2nd and 3rd level temperature control optimization scheme is based on the foundation of heat analysis. The experimental results show that static accuracy of SGA-WZ-02 reaches 0.21 mGal/24 h, with internal accuracy being 0.743 mGal/4.8 km and external accuracy being 0.37 mGal/4.8 km compared with the result of the GT-2A, whose internal precision is superior to 1 mGal/4.8 km and all of them are better than those in SGA-WZ-01.

  8. Versatile microcomputer-based temperature controller

    International Nuclear Information System (INIS)

    Yarberry, V.R.

    1980-09-01

    The wide range of thermal responses required in laboratory and scientific equipment requires a temperature controller with a great deal of flexibility. While a number of analog temperature controllers are commercially available, they have certain limitations, such as inflexible parameter control or insufficient precision. Most lack digital interface capabilities--a necessity when the temperature controller is part of a computer-controlled automatic data acquisition system. We have developed an extremely versatile microcomputer-based temperature controller to fulfill this need in a variety of equipment. The control algorithm used allows optimal tailoring of parameters to control overshoot, response time, and accuracy. This microcomputer-based temperature controller can be used as a standalone instrument (with a teletype used to enter para-meters), or it can be integrated into a data acquisition system

  9. Microwatt thermoelectric generator

    International Nuclear Information System (INIS)

    Hittman, F.; Bustard, T.S.

    1976-01-01

    A microwatt thermoelectric generator suitable for implanting in the body is described. The generator utilizes a nuclear energy source. Provision is made for temporary electrical connection to the generator for testing purposes, and for ensuring that the heat generated by the nuclear source does not bypass the pile. Also disclosed is a getter which is resistant to shrinkage during sintering, and a foil configuration for controlling the radiation of heat from the nuclear source to the hot plate of the pile. 2 claims, 4 drawing figures

  10. Microwatt thermoelectric generator

    International Nuclear Information System (INIS)

    Barr, H.N.

    1978-01-01

    A microwatt thermoelectric generator suitable for implanting in the body is described. The disclosed generator utilizes a nuclear energy source. Provision is made for temporary electrical connection to the generator for testing purposes, and for ensuring that the heat generated by the nuclear source does not bypass the pile. Also disclosed is a getter which is resistant to shrinkage during sintering, and a foil configuration for controlling the radiation of heat from the nuclear source to the hot plate of the pile. 4 claims, 4 figures

  11. Thermoelectric properties of p-type sb-doped Cu2SnSe3 near room and mid temperature applications

    Science.gov (United States)

    Prasad, K. Shyam; Rao, Ashok; Chauhan, Nagendra S.; Bhardwaj, Ruchi; Vishwakarma, Avinash; Tyagi, Kriti

    2018-02-01

    In this study, we report low and mid temperature range thermoelectric properties of Sb-substituted Cu2SnSe3 compounds. The Cu2Sn1- x Sb x Se3 (0 ≤ x ≤ 0.04) alloys were prepared using conventional solid-state reaction followed by spark plasma sintering. The crystal structure was characterized using XRD and it reveals that all the samples exhibit cubic structure with space group -4/3m. The electrical transport characteristics indicate degenerate semiconducting behavior. Electrical resistivity was found to follow small polaron hopping (SPH) model in the entire temperature range of investigation. The Seebeck coefficient data reveals that the majority of charge carriers are holes and the analysis of Seebeck coefficient data gives negative values of Fermi energy indicating that the Fermi energy is below the edge of valence band. The electronic contribution ( κ e) for total thermal conductivity is found to be less than 1%. The maximum ZT value of 0.64 is observed for the sample with x = 0.03 (at 700 K) which is approximately 2.3 times that of the pristine sample.

  12. Influences of spark plasma sintering temperature on the microstructures and thermoelectric properties of (Sr0.95Gd0.05)TiO3 ceramics

    Science.gov (United States)

    Li, Liang-Liang; Qin, Xiao-Ying; Liu, Yong-Fei; Liu, Quan-Zhen

    2015-06-01

    (Sr0.95Gd0.05)TiO3 (SGTO) ceramics are successfully prepared via spark plasma sintering (SPS) respectively at 1548, 1648, and 1748 K by using submicron-sized SGTO powders synthesized from a sol-gel method. The densities, microstructures, and thermoelectric properties of the SGTO ceramics are studied. Though the Seebeck coefficient shows no obvious difference in the case that SPS temperatures range from 1548 K to 1648 K, the electrical conductivity and the thermal conductivity increase remarkably due to the increase in grain size and density. The sample has a density higher than 98% theoretical density as the sintering temperature increases up to 1648 K and shows average grain sizes increasing from ˜ 0.7 μm to 7 μm until 1748 K. As a result, the maximum of the dimensionless figure of merit of ˜ 0.24 is achieved at ˜ 1000 K for the samples sintered at 1648 K and 1748 K, which was ˜ 71% larger than that (0.14 at ˜ 1000 K) for the sample sintered at 1548 K due to the enhancement of the power factor. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174292, 51101150, and 11374306).

  13. Fracture mode, microstructure and temperature-dependent elastic moduli for thermoelectric composites of PbTe-PbS with SiC nanoparticle additions

    Science.gov (United States)

    Ni, Jennifer E.; Case, Eldon D.; Schmidt, Robert D.; Wu, Chun-I.; Hogan, Timothy P.; Trejo, Rosa M.; Lara-Curzio, Edgar; Kanatzidis, Mercouri G.

    2013-12-01

    Twenty-six (Pb0.95Sn0.05Te)0.92(PbS)0.08-0.055% PbI2-SiC nanoparticle (SiCnp) composite thermoelectric specimens were either hot pressed or pulsed electric current sintered (PECS). Bloating (a thermally induced increase in porosity, P, for as-densified specimens) was observed during annealing at temperatures >603 K for hot-pressed specimens and PECS-processed specimens from wet milled powders, but in contrast seven out of seven specimens densified by PECS from dry milled powders showed no observable bloating following annealing at temperatures up to 936 K. In this study, bloating in the specimens was accessed via thermal annealing induced changes in (i) porosity measured by scanning electron microscopy on fractured specimen surfaces, (ii) specimen volume and (iii) elastic moduli. The moduli were measured by resonant ultrasound spectroscopy. SiCnp additions (1-3.5 vol.%) changed the fracture mode from intergranular to transgranular, inhibited grain growth, and limited bloating in the wet milled PECS specimens. Inhibition of bloating likely occurs due to cleaning of contamination from powder particle surfaces via PECS processing which has been reported previously in the literature.

  14. Applications of thermoelectric modules on heat flow detection.

    Science.gov (United States)

    Leephakpreeda, Thananchai

    2012-03-01

    This paper presents quantitative analysis and practical scenarios of implementation of the thermoelectric module for heat flow detection. Mathematical models of the thermoelectric effects are derived to describe the heat flow from/to the detected media. It is observed that the amount of the heat flow through the thermoelectric module proportionally induces the conduction heat owing to the temperature difference between the hot side and the cold side of the thermoelectric module. In turn, the Seebeck effect takes place in the thermoelectric module where the temperature difference is converted to the electric voltage. Hence, the heat flow from/to the detected media can be observed from both the amount and the polarity of the voltage across the thermoelectric module. Two experiments are demonstrated for viability of the proposed technique by the measurements of the heat flux through the building wall and thermal radiation from the outdoor environment during daytime. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

  15. Nanoscale thermoelectric materials

    International Nuclear Information System (INIS)

    Failamani, F.

    2015-01-01

    Thermoelectric (TE) materials directly convert thermal energy to electrical energy when subjected to a temperature gradient, whereas if electricity is applied to thermoelectric materials, a temperature gradient is formed. The performance of thermoelectric materials is characterized by a dimensionless figure of merit (ZT = S2T/ρλ), which consists of three parameters, Seebeck coefficient (S), electrical resistivity (ρ) and thermal conductivity (λ). To achieve good performance of thermoelectric power generation and cooling, ZT's of thermoelectric materials must be as high as possible, preferably above unity. This thesis comprises three main parts, which are distributed into six chapters: (i) nanostructuring to improve TE performance of trivalent rare earth-filled skutterudites (chapter 1 and 2), (ii) interactions of skutterudite thermolectrics with group V metals as potential electrode or diffusion barrier for TE devices (chapter 3 and 4), and (iii) search for new materials for TE application (chapter 5 and 6). Addition of secondary phases, especially nano sized phases can cause additional reduction of the thermal conductivity of a filled skutterudite which improves the figure of merit (ZT) of thermoelectric materials. In chapter 1 we investigated the effect of various types of secondary phases (silicides, borides, etc.) on the TE properties of trivalent rare earth filled Sb-based skutterudites as commercially potential TE materials. In this context the possibilty to introduce borides as nano-particles (via ball-milling in terms of a skutterudite/boride composite) is also elucidated in chapter 2. As a preliminary study, crystal structure of novel high temperature FeB-type phases found in the ternary Ta-{Ti,Zr,Hf,}-B systems were investigated. In case of Ti and Hf this phase is the high temperature stabilization of binary group IV metal monoborides, whereas single crystal study of (Ta,Zr)B proves that it is a true ternary phase as no stable monoboride exist in the

  16. A comparative study of different heat exchange systems in a thermoelectric refrigerator and their influence on the efficiency

    International Nuclear Information System (INIS)

    Astrain, D.; Aranguren, P.; Martínez, A.; Rodríguez, A.; Pérez, M.G.

    2016-01-01

    Highlights: • Total efficiency optimisation of a thermoelectric refrigerator. • Experimental study of three different types of heat exchangers for thermoelectrics. • Influence of the occupancy ratio in thermal resistance. • Important decrease in the electric consumption of a thermoelectric refrigerator. - Abstract: Thermoelectric refrigeration (TEC) exhibits several advantages compared to vapour-compression, since this technology presents accurate temperature control systems and higher levels of compactness, robustness and noiselessness. However, its low efficiency is acting as a deterrent for it to spread in the refrigeration market. One of the factors determining the efficiency of a thermoelectric refrigerator is the temperature difference between the hot and cold sides of the thermoelectric modules (TEMs). This is dependent on the thermal resistances of the heat exchangers used. This paper discusses the results of an experimental study of different types of heat exchangers for the thermoelectric module hot side: a water–air system comprising a cold plate, pump and fan coil; a finned heat sink with fan; a heat pipe with fan. Expressions of thermal resistance have been obtained for these three types as a function of the air and water mass flows and the number of TEMs per unit of surface area of heat exchanger (occupancy ratio, δ), as well as expressions of the power consumed by the fans and the pump. Finally, a computational study has been carried out on a thermoelectric refrigerator of 15 m"3 of interior volume, in order to obtain the influence of the heat exchanger studied, on the total consumption of the refrigerator and its efficiency. The results have demonstrated that relevant improvements can be made in TEC efficiency by the proper optimisation of the heat exchangers.

  17. Performance and stress analysis of oxide thermoelectric module architecture designed for maximum power output

    DEFF Research Database (Denmark)

    Wijesekara, Waruna; Rosendahl, Lasse; Wu, NingYu

    Oxide thermoelectric materials are promising candidates for energy harvesting from mid to high temperature heat sources. In this work, the oxide thermoelectric materials and the final design of the high temperature thermoelectric module were developed. Also, prototypes of oxide thermoelectric...... of real thermoelectric uni-couples, the three-dimensional governing equations for the coupled heat transfer and thermoelectric effects were developed. Finite element simulations of this system were done using the COMSOL Multiphysics solver. Prototypes of the models were developed and the analytical...... generator were built for high temperature applications. This paper specifically discusses the thermoelectric module design and the prototype validations of the design. Here p type calcium cobalt oxide and n type aluminum doped ZnO were developed as the oxide thermoelectric materials. Hot side and cold side...

  18. Biophysical control of leaf temperature

    Science.gov (United States)

    Dong, N.; Prentice, I. C.; Wright, I. J.

    2014-12-01

    In principle sunlit leaves can maintain their temperatures within a narrower range than ambient temperatures. This is an important and long-known (but now overlooked) prediction of energy balance theory. Net radiation at leaf surface in steady state (which is reached rapidly) must be equal to the combination of sensible and latent heat exchanges with surrounding air, the former being proportional to leaf-to-air temperature difference (ΔT), the latter to the transpiration rate. We present field measurements of ΔT which confirm the existence of a 'crossover temperature' in the 25-30˚C range for species in a tropical savanna and a tropical rainforest environment. This finding is consistent with a simple representation of transpiration as a function of net radiation and temperature (Priestley-Taylor relationship) assuming an entrainment factor (ω) somewhat greater than the canonical value of 0.26. The fact that leaves in tropical forests are typically cooler than surrounding air, often already by solar noon, is consistent with a recently published comparison of MODIS day-time land-surface temperatures with air temperatures. Theory further predicts a strong dependence of leaf size (which is inversely related to leaf boundary-layer conductance, and therefore to absolute magnitude of ΔT) on moisture availability. Theoretically, leaf size should be determined by either night-time constraints (risk of frost damage to active leaves) or day-time constraints (risk of heat stress damage),with the former likely to predominate - thereby restricting the occurrence of large leaves - at high latitudes. In low latitudes, daytime maximum leaf size is predicted to increase with temperature, provided that water is plentiful. If water is restricted, however, transpiration cannot proceed at the Priestley-Taylor rate, and it quickly becomes advantageous for plants to have small leaves, which do not heat up much above the temperature of their surroundings. The difference between leaf

  19. Research for Actively Reducing Infrared Radiation by Thermoelectric Refrigerator

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hoon; Kim, Kyomin; Kim, Woochul [Yonsei Univ., Seoul (Korea, Republic of)

    2017-03-15

    We introduced a technology for reducing infrared radiation through the active cooling of hot surfaces by using a thermoelectric refrigerator. Certain surfaces were heated by aerodynamic heating, and the heat generation processes are proposed here. We calculated the temperatures and radiations from surfaces, while using thermoelectric refrigerators to cool the surfaces. The results showed that the contrast between the radiations of certain surfaces and the ambient environments can be removed using thermoelectric refrigerators.

  20. Mg2BIV: Narrow Bandgap Thermoelectric Semiconductors

    Science.gov (United States)

    Kim, Il-Ho

    2018-05-01

    Thermoelectric materials can convert thermal energy directly into electric energy and vice versa. The electricity generation from waste heat via thermoelectric devices can be considered as a new energy source. For instance, automotive exhaust gas and all industrial processes generate an enormous amount of waste heat that can be converted to electricity by using thermoelectric devices. Magnesium compound Mg2BIV (BIV = Si, Ge or Sn) has a favorable combination of physical and chemical properties and can be a good base for the development of new efficient thermoelectrics. Because they possess similar properties to those of group BIV elemental semiconductors, they have been recognized as good candidates for thermoelectric applications. Mg2Si, Mg2Ge and Mg2Sn with an antifluorite structure are narrow bandgap semiconductors with indirect band gaps of 0.77 eV, 0.74 eV, and 0.35 eV, respectively. Mg2BIV has been recognized as a promising material for thermoelectric energy conversion at temperatures ranging from 500 K to 800 K. Compared to other thermoelectric materials operating in the similar temperature range, such as PbTe and filled skutterudites, the important aspects of Mg2BIV are non-toxic and earth-abundant elements. Based on classical thermoelectric theory, the material factor β ( m* / m e)3/2μκ L -1 can be utilized as the criterion for thermoelectric material selection, where m* is the density-of-states effective mass, me is the mass of an electron, μ is the carrier mobility, and κL is the lattice thermal conductivity. The β for magnesium silicides is 14, which is very high compared to 0.8 for iron silicides, 1.4 for manganese silicides, and 2.6 for silicon-germanium alloys. In this paper, basic phenomena of thermoelectricity and transport parameters for thermoelectric materials were briefly introduced, and thermoelectric properties of Mg2BIV synthesized by using a solid-state reaction were reviewed. In addition, various Mg2BIV compounds were discussed

  1. A thermoelectric cap for seafloor hydrothermal vents

    International Nuclear Information System (INIS)

    Xie, Yu; Wu, Shi-jun; Yang, Can-jun

    2016-01-01

    Highlights: • We developed a thermoelectric cap (TC) to harvest hydrothermal energy. • The TC was deployed at a hydrothermal vent site near Kueishantao islet, Taiwan. • The TC monitored the temperature of the hydrothermal fluids during the field test. • The TC could make the thermal energy of hydrothermal fluids a viable power source. - Abstract: Long-term in situ monitoring is crucial to seafloor scientific investigations. One of the challenges of operating sensors in seabed is the lifespan of the sensors. Such sensors are commonly powered by batteries when other alternatives, such as tidal or solar energy, are unavailable. However, the batteries have a limited lifespan and must be recharged or replaced periodically, which is costly and impractical. A thermoelectric cap, which harvests the thermal energy of hydrothermal fluids through a conduction pipe and converts the heat to electrical energy by using thermoelectric generators, was developed to avoid these inconveniences. The thermoelectric cap was combined with a power and temperature measurement system that enables the thermoelectric cap to power a light-emitting diode lamp, an electronic load (60 Ω), and 16 thermocouples continuously. The thermoelectric cap was field tested at a shallow hydrothermal vent site near Kueishantao islet, which is located offshore of northeastern Taiwan. By using the thermal gradient between hydrothermal fluids and seawater, the thermoelectric cap obtained a sustained power of 0.2–0.5 W during the field test. The thermoelectric cap successfully powered the 16 thermocouples and recorded the temperature of the hydrothermal fluids during the entire field test. Our results show that the thermal energy of hydrothermal fluids can be an alternative renewable power source for oceanographic research.

  2. Effective thermal conductivity in thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Baranowski, LL; Snyder, GJ; Toberer, ES

    2013-05-28

    Thermoelectric generators (TEGs) are solid state heat engines that generate electricity from a temperature gradient. Optimizing these devices for maximum power production can be difficult due to the many heat transport mechanisms occurring simultaneously within the TEG. In this paper, we develop a model for heat transport in thermoelectric materials in which an "effective thermal conductivity" (kappa(eff)) encompasses both the one dimensional steady-state Fourier conduction and the heat generation/consumption due to secondary thermoelectric effects. This model is especially powerful in that the value of kappa(eff) does not depend upon the operating conditions of the TEG but rather on the transport properties of the TE materials themselves. We analyze a variety of thermoelectric materials and generator designs using this concept and demonstrate that kappa(eff) predicts the heat fluxes within these devices to 5% of the exact value. (C) 2013 AIP Publishing LLC.

  3. Thermoelectricity analogy method for computing the periodic heat transfer in external building envelopes

    International Nuclear Information System (INIS)

    Peng Changhai; Wu Zhishen

    2008-01-01

    Simple and effective computation methods are needed to calculate energy efficiency in buildings for building thermal comfort and HVAC system simulations. This paper, which is based upon the theory of thermoelectricity analogy, develops a new harmonic method, the thermoelectricity analogy method (TEAM), to compute the periodic heat transfer in external building envelopes (EBE). It presents, in detail, the principles and specific techniques of TEAM to calculate both the decay rates and time lags of EBE. First, a set of linear equations is established using the theory of thermoelectricity analogy. Second, the temperature of each node is calculated by solving the linear equations set. Finally, decay rates and time lags are found by solving simple mathematical expressions. Comparisons show that this method is highly accurate and efficient. Moreover, relative to the existing harmonic methods, which are based on the classical control theory and the method of separation of variables, TEAM does not require complicated derivation and is amenable to hand computation and programming

  4. Spin-dependent heat and thermoelectric currents in a Rashba ring coupled to a photon cavity

    Science.gov (United States)

    Abdullah, Nzar Rauf; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar

    2018-01-01

    Spin-dependent heat and thermoelectric currents in a quantum ring with Rashba spin-orbit interaction placed in a photon cavity are theoretically calculated. The quantum ring is coupled to two external leads with different temperatures. In a resonant regime, with the ring structure in resonance with the photon field, the heat and the thermoelectric currents can be controlled by the Rashba spin-orbit interaction. The heat current is suppressed in the presence of the photon field due to contribution of the two-electron and photon replica states to the transport while the thermoelectric current is not sensitive to changes in parameters of the photon field. Our study opens a possibility to use the proposed interferometric device as a tunable heat current generator in the cavity photon field.

  5. Temperature and Humidity Control in Livestock Stables

    DEFF Research Database (Denmark)

    Hansen, Michael; Andersen, Palle; Nielsen, Kirsten M.

    2010-01-01

    The paper describes temperature and humidity control of a livestock stable. It is important to have a correct air flow pattern in the livestock stable in order to achieve proper temperature and humidity control as well as to avoid draught. In the investigated livestock stable the air flow...

  6. The thermoelectric performance of bulk three-dimensional graphene

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhi, E-mail: yangzhi@tyut.edu.cn [Key Lab of Advanced Transducers and Intelligent Control System, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024 (China); College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024 (China); Lan, Guoqiang; Ouyang, Bin [Department of Mining and Materials Engineering, McGill University, Montreal H3A 0C5 (Canada); Xu, Li-Chun; Liu, Ruiping [College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Xuguang, E-mail: liuxuguang@tyut.edu.cn [Key Lab of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Song, Jun [Department of Mining and Materials Engineering, McGill University, Montreal H3A 0C5 (Canada)

    2016-11-01

    The electronic and thermoelectric properties of a new carbon bulk material, three-dimensional (3D) graphene, are investigated in this study. Our results show that 3D graphene has unique electronic structure, i.e., near the Fermi level there exist Dirac cones. More importantly, the thermoelectric performance of 3D graphene is excellent, at room temperature the thermoelectric figure of merit (ZT) is 0.21, an order of magnitude higher than that of graphene. By introducing line defects, the ZT of 3D graphene could be enhanced to 1.52, indicating 3D graphene is a powerful candidate for constructing novel thermoelectric materials. - Highlights: • There exist Dirac cones in three-dimensional (3D) graphene. • The thermoelectric performance of 3D graphene is excellent. • The defective 3D graphene has better thermoelectric performance.

  7. Development in Zn4Sb-based thermoelectric materials

    DEFF Research Database (Denmark)

    Yin, Hao

    or thermopower,  the electrical conductivity, the thermal conductivity and T the absolute temperature. The best thermoelectrics are heavily doped semiconductors with high thermoelectric power factors and low thermal conductivities, known as “Phonon Glasses Electrical Crystals”. Zn4Sb3 is one such material......-section. The following part reports the effect of nano-particles on the thermoelectric properties and thermal stability of Zn4Sb3. Though TiO2 nano particles have remarkably enhanced the stability, the thermoelectric performance of all the nano-composites deteriorates. Optimization of the content of the nano...

  8. Optimized Characterization of Thermoelectric Generators for Automotive Application

    Science.gov (United States)

    Tatarinov, Dimitri; Wallig, Daniel; Bastian, Georg

    2012-06-01

    New developments in the field of thermoelectric materials bring the prospect of consumer devices for recovery of some of the waste heat from internal combustion engines closer to reality. Efficiency improvements are expected due to the development of high-temperature thermoelectric generators (TEG). In contrast to already established radioisotope thermoelectric generators, the temperature difference in automotive systems is not constant, and this imposes a set of specific requirements on the TEG system components. In particular, the behavior of the TEGs and interface materials used to link the heat flow from the heat source through the TEG to the heat sink must be examined. Due to the usage patterns of automobiles, the TEG will be subject to cyclic thermal loads, which leads to module degradation. Additionally, the automotive TEG will be exposed to an inhomogeneous temperature distribution, leading to inhomogeneous mechanical loads and reduced system efficiency. Therefore, a characterization rig is required to allow determination of the electrical, thermal, and mechanical properties of such high-temperature TEG systems. This paper describes a measurement setup using controlled adjustment of cold-side and warm-side temperatures as well as controlled feed-in of electrical power for evaluation of TEGs for application in vehicles with combustion engines. The temperature profile in the setup can be varied to simulate any vehicle usage pattern, such as the European standard driving cycle, allowing the power yield of the TEGs to be evaluated for the chosen cycle. The spatially resolved temperature distribution of a TEG system can be examined by thermal imaging. Hotspots or cracks on thermocouples of the TEGs and the thermal resistance of thermal interface materials can also be examined using this technology. The construction of the setup is briefly explained, followed by detailed discussion of the experimental results.

  9. Thermoelectric properties of layered antiferromagnetic CuCrSe2

    International Nuclear Information System (INIS)

    Tewari, Girish C.; Tripathi, T.S.; Yamauchi, Hisao; Karppinen, Maarit

    2014-01-01

    Here we study thermoelectric and magnetic properties of CuCrSe 2 samples sintered at various temperatures. Structural analysis with XRD shows an order-disorder transition for Cr atoms when the sintering temperature is increased above 1273 K. Metal-like electrical resistivity and anomalously large Seebeck coefficient are found about room temperature. Analysis of electrical conductivity and Seebeck coefficient of the partially-disordered phase suggests hopping conduction of charge carriers. For both the ordered and disordered phases magnetic susceptibility follows Curie–Weiss temperature dependence at high temperatures above 150 K and shows an antiferromagnetic transition around 55 K. For the disordered phase, the effective magnetic moment is determined at 3.62 μ B ; this low value in comparison to the spin only value for Cr 3+ of 3.89 μ B indicates spin fluctuations in the paramagnetic state. The thermal conductivity in these phases is low and dominated by the lattice contribution. Values for the thermoelectric figure of merit (ZT) at room temperature are estimated to be 0.17 and 0.05 for the ordered and disordered phases, respectively. - Highlights: • Thermoelectric and magnetic properties of CuCrSe 2 samples are investigated. • The properties strongly depend on the degree of order of chromium atoms. • The degree of order is controlled by the sintering temperature. • Room-temperature figure of merit is estimated at 0.17 for the ordered phase. • For the disordered phase the figure of merit is lower

  10. Thermoelectric nanomaterials materials design and applications

    CERN Document Server

    Koumoto, Kunihito

    2014-01-01

    Presently, there is an intense race throughout the world to develop good enough thermoelectric materials which can be used in wide scale applications. This book focuses comprehensively on very recent up-to-date breakthroughs in thermoelectrics utilizing nanomaterials and methods based in nanoscience. Importantly, it provides the readers with methodology and concepts utilizing atomic scale and nanoscale materials design (such as superlattice structuring, atomic network structuring and properties control, electron correlation design, low dimensionality, nanostructuring, etc.). Furthermore, also

  11. Structural, magnetic and high-temperature thermoelectric properties of La0.4Bi0.4Ca0.2Mn1-xCoxO3 (0 ≤ x ≤ 0.3) perovskites

    Science.gov (United States)

    Hira, Uzma; Sher, Falak

    2018-04-01

    In this study, we have investigated the structural, magnetic and thermoelectric properties of La0.4Bi0.4Ca0.2Mn1-xCoxO3 (0 ≤ x ≤ 0.3) manganites. The crystallographic parameters of samples were determined by the Rietveld refinement of powder X-ray diffraction data. It was observed that Co doping results in change of crystal structures from orthorhombic (space group: Pbnm) to rhombohedral (space group: R-3c) symmetry. Scanning electron microscopy (SEM) images show smooth, clean and densified structures, depicting good crystallinity of samples. The zero field cooled (ZFC) and field cooled (FC) magnetization data were collected in the temperature range 5 to 300 K under an applied magnetic field of 0.1 Tesla. The analysis of temperature dependent magnetization data reveals all samples to be ferromagnetic with Curie temperatures around ∼77 K. The magnetic hysteresis loops, collected at 5 K, show that the saturation magnetization (MS) values decrease from 43 emu/g to 14 emu/g with increase in Co doping. The high temperature thermoelectric properties of all samples are characteristic of a semiconducting behavior, the small polaron hopping model fitting well with the temperature dependent electrical resistivity (ρ) and thermopower (S) data. The thermopower values change sign from positive to negative as temperature is increased from 313 K to 680 K. The maximum thermoelectric power factor (PF = S2/ρ) obtained for x = 0.3 sample at 313 K is 4.60 μW/mK2, is much higher than for the undoped sample.

  12. Peltier coefficient measurement in a thermoelectric module

    International Nuclear Information System (INIS)

    Garrido, Javier; Casanovas, Alejandro; Chimeno, José María

    2013-01-01

    A new method for measuring the Peltier coefficient in a thermocouple X/Y based on the energy balance at the junction has been proposed recently. This technique needs only the hot and cold temperatures of a thermoelectric module when an electric current flows through it as the operational variables. The temperature evolutions of the two module sides provide an evident and accurate idea of the Peltier effect. From these temperatures, the heat transfer between the module and the ambient is also evaluated. The thermoelectric phenomena are described in the framework of an observable theory. Based on this procedure, an experiment is presented for a university teaching laboratory at the undergraduate level. (paper)

  13. Thermoelectrics and its energy harvesting

    National Research Council Canada - National Science Library

    Rowe, David Michael

    2012-01-01

    .... It details the latest techniques for the preparation of thermoelectric materials employed in energy harvesting, together with advances in the thermoelectric characterisation of nanoscale material...

  14. The thermoelectric figure of merit of poor thermal conductors

    International Nuclear Information System (INIS)

    Dixon, A.J.

    1977-01-01

    Calculations are given to show that for low thermal conductivity materials the radiation losses at even moderate temperatures preclude the use of the Harman technique for measuring the thermoelectric figure of merit. Measurements on liquid Tl 66 Se 34 , which has suitable thermoelectric properties, confirm this. (author)

  15. Introduction to thermoelectricity

    CERN Document Server

    Goldsmid, H Julian

    2010-01-01

    Introduction to Thermoelectricity is the latest work by Professor Julian Goldsmid drawing on his 55 years experience in the field. The theory of the thermoelectric and related phenomena is presented in sufficient detail to enable researchers to understand their observations and develop improved thermoelectric materials. The methods for the selection of materials and their improvement are discussed. Thermoelectric materials for use in refrigeration and electrical generation are reviewed. Experimental techniques for the measurement of properties and for the production of thermoelements are described. Special emphasis is placed on nanotechnology which promises to yield great improvements in the efficiency of thermoelectric devices. Chapters are also devoted to transverse thermoelectric effects and thermionic energy conversion, both techniques offering the promise of important applications in the future.

  16. Experimental analysis with numerical comparison for different thermoelectric generators configurations

    International Nuclear Information System (INIS)

    Favarel, Camille; Bédécarrats, Jean-Pierre; Kousksou, Tarik; Champier, Daniel

    2016-01-01

    Highlights: • 3 experimental TE generators are tested and compared to a numerical model. • Different mass flow rates and temperatures ranges were used. • Maximum output electrical power is guaranty by the use of MPPT DC/DC controllers. • The importance of the occupancy rate for the design of TEG is demonstrated. • The importance of the location of the TE modules is shown. - Abstract: Thermoelectric (TE) energy harvesting is a promising perspective to use waste heat. Due to the low efficiency of thermoelectric materials many analytical and numerical optimization studies have been developed. To be validated, an optimization must necessarily be linked to the experience. There are a lot of results on thermoelectric generators (TEG) based on experiments or model validations. Nevertheless, the validated models concern most of the time one TE module but rarely an entire system. Moreover, these models of complete system mainly concern the optimization of fluid flow rates or of heat exchangers. Our choice is to optimize the number of these modules in a whole system point of view. A numerical model using a software for numerical computation, based on multi-physics equations such as heat transfer, fluid mechanics and thermoelectricity was developed to predict both thermal and electrical powers of TEG. This paper aims to present the experimental validation of this model and shows interesting experimental results on the location of the TE modules. In parallel, an experimental set-up was built to compare and validate this model. This set-up is composed of a thermal loop with a hot gas source, a cold fluid, a hot fin exchanger, a cold tubular exchanger and thermoelectric modules. The number and the place of these modules can be changed to study different configurations. A specific maximum power point tracker DC/DC converter charging a battery is added in order to study the electrical power produced by the TEG. The analysis of the influence of the number of

  17. Controlling LPG temperature for SI engine applications

    International Nuclear Information System (INIS)

    Ceviz, Mehmet Akif; Kaleli, Alirıza; Güner, Erdoğan

    2015-01-01

    In this study, the effects of the LPG temperature on the engine performance and the exhaust emission characteristics have been investigated experimentally on an SI engine. In conventional injection systems, the LPG temperature increases excessively during the phase change in pressure regulator, and reduces the engine volumetric efficiency. According to the test results, engine performance and NO emission characteristics can be improved by controlling the LPG temperature before injecting to the engine intake manifold. A new control system taking into account the results of the study has been developed and tested. In order to control the LPG temperature, the coolant flow rate in pressure regulator circuit was arranged by using a control valve activated by a PID controller unit. Results of the study showed that the engine brake power loss can be increased by about 1.85% and NO emissions can be decreased by about 2% as compared to the operation with the original LPG injection system. - Highlights: • Effects of the LPG temperature have been examined. • Engine performance characteristics and exhaust emissions have been studied. • Results reveal that the LPG temperature should be kept in a range. • A prototype LPG temperature control system has been successfully developed

  18. Temperature Control Diagnostics for Sample Environments

    International Nuclear Information System (INIS)

    Santodonato, Louis J.; Walker, Lakeisha M.H.; Church, Andrew J.; Redmon, Christopher Mckenzie

    2010-01-01

    In a scientific laboratory setting, standard equipment such as cryocoolers are often used as part of a custom sample environment system designed to regulate temperature over a wide range. The end user may be more concerned with precise sample temperature control than with base temperature. But cryogenic systems tend to be specified mainly in terms of cooling capacity and base temperature. Technical staff at scientific user facilities (and perhaps elsewhere) often wonder how to best specify and evaluate temperature control capabilities. Here we describe test methods and give results obtained at a user facility that operates a large sample environment inventory. Although this inventory includes a wide variety of temperature, pressure, and magnetic field devices, the present work focuses on cryocooler-based systems.

  19. Automated Greenhouse : Temperature and soil moisture control

    OpenAIRE

    Attalla, Daniela; Tannfelt Wu, Jennifer

    2015-01-01

    In this thesis an automated greenhouse was built with the purpose of investigating the watering system’s reliability and if a desired range of temperatures can be maintained. The microcontroller used to create the automated greenhouse was an Arduino UNO. This project utilizes two different sensors, a soil moisture sensor and a temperature sensor. The sensors are controlling the two actuators which are a heating fan and a pump. The heating fan is used to change the temperature and the pump is ...

  20. A Review on the Fabrication of Polymer-Based Thermoelectric Materials and Fabrication Methods

    Science.gov (United States)

    Kamarudin, Muhammad Akmal; Sahamir, Shahrir Razey; Datta, Robi Shankar; Long, Bui Duc; Mohd Sabri, Mohd Faizul; Mohd Said, Suhana

    2013-01-01

    Thermoelectricity, by converting heat energy directly into useable electricity, offers a promising technology to convert heat from solar energy and to recover waste heat from industrial sectors and automobile exhausts. In recent years, most of the efforts have been done on improving the thermoelectric efficiency using different approaches, that is, nanostructuring, doping, molecular rattling, and nanocomposite formation. The applications of thermoelectric polymers at low temperatures, especially conducting polymers, have shown various advantages such as easy and low cost of fabrication, light weight, and flexibility. In this review, we will focus on exploring new types of polymers and the effects of different structures, concentrations, and molecular weight on thermoelectric properties. Various strategies to improve the performance of thermoelectric materials will be discussed. In addition, a discussion on the fabrication of thermoelectric devices, especially suited to polymers, will also be given. Finally, we provide the challenge and the future of thermoelectric polymers, especially thermoelectric hybrid model. PMID:24324378

  1. A new cryostat for precise temperature control

    Science.gov (United States)

    Dong, B.; Zhou, G.; Liu, L. Q.; Zhang, X.; Xiong, L. Y.; Li, Q.

    2013-09-01

    Gifford-McMahon (GM) cryocoolers are often used in cryostat as cold sources. It has advantages of simple structure and low operating cost as well as disadvantages of vibration and temperature oscillation, which are fatal for some applications that are very sensitive to temperature stability at low temperature. To solve the problem, a thermal analysis model which is used to simulate heat transfer in the cryostat is built and discussed. According to the analysis results, a cryostat that can provide variable temperature (4-20 K) for the accurate temperature control experiments is designed and manufactured. In this cryostat, a polytetrafluoroethylene (PTFE) sheet is used as a thermal damper to reduce the temperature oscillation, with which, the temperature oscillation of the sample cooling holder is less than 4 mK at the 20 K region.

  2. Internal Temperature Control For Vibration Testers

    Science.gov (United States)

    Dean, Richard J.

    1996-01-01

    Vibration test fixtures with internal thermal-transfer capabilities developed. Made of aluminum for rapid thermal transfer. Small size gives rapid response to changing temperatures, with better thermal control. Setup quicker and internal ducting facilitates access to parts being tested. In addition, internal flows smaller, so less energy consumed in maintaining desired temperature settings.

  3. System for improving measurement accuracy of transducer by measuring transducer temperature and resistance change using thermoelectric voltages

    Science.gov (United States)

    Anderson, Karl F. (Inventor); Parker, Allen R., Jr. (Inventor)

    1993-01-01

    A constant current loop measuring system measures a property including the temperature of a sensor responsive to an external condition being measured. The measuring system includes thermocouple conductors connected to the sensor, sensing first and second induced voltages responsive to the external condition. In addition, the measuring system includes a current generator and reverser generating a constant current, and supplying the constant current to the thermocouple conductors in forward and reverse directions generating first and second measured voltages, and a determining unit receiving the first and second measured voltages from the current generator and reverser, and determining the temperature of the sensor responsive to the first and second measured voltages.

  4. Numerical modeling of the thermoelectric cooler with a complementary equation for heat circulation in air gaps

    Science.gov (United States)

    Fang, En; Wu, Xiaojie; Yu, Yuesen; Xiu, Junrui

    2017-03-01

    In this paper, a numerical model is developed by combining thermodynamics with heat transfer theory. Taking inner and external multi-irreversibility into account, it is with a complementary equation for heat circulation in air gaps of a steady cooling system with commercial thermoelectric modules operating in refrigeration mode. With two modes concerned, the equation presents the heat flowing through air gaps which forms heat circulations between both sides of thermoelectric coolers (TECs). In numerical modelling, a TEC is separated as two temperature controlled constant heat flux reservoirs in a thermal resistance network. In order to obtain the parameter values, an experimental apparatus with a commercial thermoelectric cooler was built to characterize the performance of a TEC with heat source and sink assembly. At constant power dissipation, steady temperatures of heat source and both sides of the thermoelectric cooler were compared with those in a standard numerical model. The method displayed that the relationship between Φf and the ratio Φ_{c}'/Φ_{c} was linear as expected. Then, for verifying the accuracy of proposed numerical model, the data in another system were recorded. It is evident that the experimental results are in good agreement with simulation(proposed model) data at different heat transfer rates. The error is small and mainly results from the instabilities of thermal resistances with temperature change and heat flux, heat loss of the device vertical surfaces and measurements.

  5. Thermoelectric cooling of microelectronic circuits and waste heat electrical power generation in a desktop personal computer

    International Nuclear Information System (INIS)

    Gould, C.A.; Shammas, N.Y.A.; Grainger, S.; Taylor, I.

    2011-01-01

    Thermoelectric cooling and micro-power generation from waste heat within a standard desktop computer has been demonstrated. A thermoelectric test system has been designed and constructed, with typical test results presented for thermoelectric cooling and micro-power generation when the computer is executing a number of different applications. A thermoelectric module, operating as a heat pump, can lower the operating temperature of the computer's microprocessor and graphics processor to temperatures below ambient conditions. A small amount of electrical power, typically in the micro-watt or milli-watt range, can be generated by a thermoelectric module attached to the outside of the computer's standard heat sink assembly, when a secondary heat sink is attached to the other side of the thermoelectric module. Maximum electrical power can be generated by the thermoelectric module when a water cooled heat sink is used as the secondary heat sink, as this produces the greatest temperature difference between both sides of the module.

  6. Low cost thermoelectric module

    Energy Technology Data Exchange (ETDEWEB)

    Kumpeerapun, T.; Hirunlabh, J. [King Mongkut Univ. of Technology, Bangkok (Thailand); Zeghmati, B. [Perpignan Univ., Perpignan (France). Faculty of Sciences; Scherrer, H.; Dauscher, A.; Weber, S.; Jahed, H.M.; Lernoir, B.; Kosalathip, V. [Ecole des Mines, Nancy (France). Laboratoire de Physique des Materiaux; Khedari, J. [South-East Asia Univ., Bangkok (Thailand). Faculty of Engineering

    2006-07-01

    The properties of a bismuth-telluride-antimony (Bi{sub x}Sb{sub 2-8}Te{sub 3}) polycrystalline thermoelectric material prepared using a novel melting and hot pressing process were investigated. The aim of the study was to synthesize the materials without the need for doping. Materials were weighed and placed in a quartz tube, which was sealed under vacuum and heated in a rocking furnace from room temperature to 750 degrees C over a period of 1 hour. Temperatures were maintained at 750 degrees C for a further 2 hours. The sample was then removed from the furnace and suddenly quenched in water. The ingot was then crushed into a powder using an agate mortar and sieved. Samples exhibiting a cylindrical shape were reserved. Samples were then examined using scanning electron microscopy (SEM) to determine their morphology and homogeneity. A sample pellet was then prepared for thermal conductivity measurements at room temperature. the pellet was nickel-plated on both sides and stacked between circular copper disks with thermocouples. Data were collected when the system reached thermal equilibrium. The Seebeck coefficient was measured by applying a small temperature difference. Results showed that the process effectively transformed the base materials into an alloy. It was concluded that the hot pressing successfully synthesized the materials. 6 refs., 1 tab., 6 figs.

  7. Development of thermoelectric power generation system utilizing heat of combustible solid waste

    International Nuclear Information System (INIS)

    Kajikawa, T.; Ito, M.; Katsube, I.; Shibuya, E.

    1994-01-01

    The paper presents the development of thermoelectric power generation system utilizing heat of municipal solid waste. The systematic classification and design guideline are proposed in consideration of the characteristics of solid waste processing system. The conceptual design of thermoelectric power generation system is carried out for a typical middle scale incinerator system (200 ton/day) by the local model. Totally the recovered electricity is 926.5 kWe by 445 units (569,600 couples). In order to achieve detailed design, one dimensional steady state model taking account of temperature dependency of the heat transfer performance and thermoelectric properties is developed. Moreover, small scale on-site experiment on 60 W class module installed in the real incinerator is carried out to extract various levels of technological problems. In parallel with the system development, high temperature thermoelectric elements such as Mn-Si and so on are developed aiming the optimization of ternary compound and high performance due to controlled fine-grain boundary effect. The manganese silicide made by shrinking-rate controlled sintering method performs 5 (μW/cm K2) in power factor at 800 K. copyright 1995 American Institute of Physics

  8. A design approach for integrating thermoelectric devices using topology optimization

    DEFF Research Database (Denmark)

    Soprani, Stefano; Haertel, Jan Hendrik Klaas; Lazarov, Boyan Stefanov

    2016-01-01

    Efficient operation of thermoelectric devices strongly relies on the thermal integration into the energy conversion system in which they operate. Effective thermal integration reduces the temperature differences between the thermoelectric module and its thermal reservoirs, allowing the system...... to operate more efficiently. This work proposes and experimentally demonstrates a topology optimization approach as a design tool for efficient integration of thermoelectric modules into systems with specific design constraints. The approach allows thermal layout optimization of thermoelectric systems...... for different operating conditions and objective functions, such as temperature span, efficiency, and power recoveryrate. As a specific application, the integration of a thermoelectric cooler into the electronics section ofa downhole oil well intervention tool is investigated, with the objective of minimizing...

  9. On the temperature control in self-controlling hyperthermia therapy

    Energy Technology Data Exchange (ETDEWEB)

    Ebrahimi, Mahyar, E-mail: ebrahimi_m@mehr.sharif.ir

    2016-10-15

    In self-controlling hyperthermia therapy, once the desired temperature is reached, the heat generation ceases and overheating is prevented. In order to design a system that generates sufficient heat without thermal ablation of surrounding healthy tissue, a good understanding of temperature distribution and its change with time is imperative. This study is conducted to extend our understanding about the heat generation and transfer, temperature distribution and temperature rise pattern in the tumor and surrounding tissue during self-controlling magnetic hyperthermia. A model consisting of two concentric spheres that represents the tumor and its surrounding tissue is considered and temperature change pattern and temperature distribution in tumor and surrounding tissue are studied. After describing the model and its governing equations and constants precisely, a typical numerical solution of the model is presented. Then it is showed that how different parameters like Curie temperature of nanoparticles, magnetic field amplitude and nanoparticles concentration can affect the temperature change pattern during self-controlling magnetic hyperthermia. The model system herein discussed can be useful to gain insight on the self-controlling magnetic hyperthermia while applied to cancer treatment in real scenario and can be useful for treatment strategy determination. - Highlights: • Temperature change pattern in tumor and surrounding tissue are studied. • The model system herein can be useful for treatment strategy determination. • In the work described herein, emphasis is on the effect of low Curie temperature. • If the equilibrium temperature can be tuned appropriately, the stay time will be infinite.

  10. On the temperature control in self-controlling hyperthermia therapy

    International Nuclear Information System (INIS)

    Ebrahimi, Mahyar

    2016-01-01

    In self-controlling hyperthermia therapy, once the desired temperature is reached, the heat generation ceases and overheating is prevented. In order to design a system that generates sufficient heat without thermal ablation of surrounding healthy tissue, a good understanding of temperature distribution and its change with time is imperative. This study is conducted to extend our understanding about the heat generation and transfer, temperature distribution and temperature rise pattern in the tumor and surrounding tissue during self-controlling magnetic hyperthermia. A model consisting of two concentric spheres that represents the tumor and its surrounding tissue is considered and temperature change pattern and temperature distribution in tumor and surrounding tissue are studied. After describing the model and its governing equations and constants precisely, a typical numerical solution of the model is presented. Then it is showed that how different parameters like Curie temperature of nanoparticles, magnetic field amplitude and nanoparticles concentration can affect the temperature change pattern during self-controlling magnetic hyperthermia. The model system herein discussed can be useful to gain insight on the self-controlling magnetic hyperthermia while applied to cancer treatment in real scenario and can be useful for treatment strategy determination. - Highlights: • Temperature change pattern in tumor and surrounding tissue are studied. • The model system herein can be useful for treatment strategy determination. • In the work described herein, emphasis is on the effect of low Curie temperature. • If the equilibrium temperature can be tuned appropriately, the stay time will be infinite.

  11. Control of p-type and n-type thermoelectric properties of bismuth telluride thin films by combinatorial sputter coating technology

    International Nuclear Information System (INIS)

    Goto, Masahiro; Sasaki, Michiko; Xu, Yibin; Zhan, Tianzhuo; Isoda, Yukihiro; Shinohara, Yoshikazu

    2017-01-01

    Highlights: • p- and n-type bismuth telluride thin films have been synthesized using a combinatorial sputter coating system (COSCOS) while changing only one of the experimental conditions, the RF power. • The dimensionless figure of merit (ZT) was optimized by the technique. • The fabrication of a Π-structured TE device was demonstrated. - Abstract: p- and n-type bismuth telluride thin films have been synthesized by using a combinatorial sputter coating system (COSCOS). The crystal structure and crystal preferred orientation of the thin films were changed by controlling the coating condition of the radio frequency (RF) power during the sputter coating. As a result, the p- and n-type films and their dimensionless figure of merit (ZT) were optimized by the technique. The properties of the thin films such as the crystal structure, crystal preferred orientation, material composition and surface morphology were analyzed by X-ray diffraction, energy-dispersive X-ray spectroscopy and atomic force microscopy. Also, the thermoelectric properties of the Seebeck coefficient, electrical conductivity and thermal conductivity were measured. ZT for n- and p-type bismuth telluride thin films was found to be 0.27 and 0.40 at RF powers of 90 and 120 W, respectively. The proposed technology can be used to fabricate thermoelectric p–n modules of bismuth telluride without any doping process.

  12. Control of p-type and n-type thermoelectric properties of bismuth telluride thin films by combinatorial sputter coating technology

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Masahiro, E-mail: goto.masahiro@nims.go.jp [Thermoelectric Materials Group, Center for Green Research on Energy and Environmental Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Thermal Management and Thermoelectric Materials Group, Center for Materials Research by Information Integration (CMI2), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Sasaki, Michiko [Thermal Management and Thermoelectric Materials Group, Center for Materials Research by Information Integration (CMI2), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Xu, Yibin [Thermal Management and Thermoelectric Materials Group, Center for Materials Research by Information Integration (CMI2), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Materials Database Group, Center for Materials Research by Information Integration (CMI2), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Zhan, Tianzhuo [Thermal Management and Thermoelectric Materials Group, Center for Materials Research by Information Integration (CMI2), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Isoda, Yukihiro [Thermoelectric Materials Group, Center for Green Research on Energy and Environmental Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Shinohara, Yoshikazu [Thermoelectric Materials Group, Center for Green Research on Energy and Environmental Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Thermal Management and Thermoelectric Materials Group, Center for Materials Research by Information Integration (CMI2), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2017-06-15

    Highlights: • p- and n-type bismuth telluride thin films have been synthesized using a combinatorial sputter coating system (COSCOS) while changing only one of the experimental conditions, the RF power. • The dimensionless figure of merit (ZT) was optimized by the technique. • The fabrication of a Π-structured TE device was demonstrated. - Abstract: p- and n-type bismuth telluride thin films have been synthesized by using a combinatorial sputter coating system (COSCOS). The crystal structure and crystal preferred orientation of the thin films were changed by controlling the coating condition of the radio frequency (RF) power during the sputter coating. As a result, the p- and n-type films and their dimensionless figure of merit (ZT) were optimized by the technique. The properties of the thin films such as the crystal structure, crystal preferred orientation, material composition and surface morphology were analyzed by X-ray diffraction, energy-dispersive X-ray spectroscopy and atomic force microscopy. Also, the thermoelectric properties of the Seebeck coefficient, electrical conductivity and thermal conductivity were measured. ZT for n- and p-type bismuth telluride thin films was found to be 0.27 and 0.40 at RF powers of 90 and 120 W, respectively. The proposed technology can be used to fabricate thermoelectric p–n modules of bismuth telluride without any doping process.

  13. Temperature Control System for Mushroom Dryer

    Science.gov (United States)

    Wibowo, I. A.; Indah, Nur; Sebayang, D.; Adam, N. H.

    2018-03-01

    The main problem in mushroom cultivation is the handling after the harvest. Drying is one technique to preserve the mushrooms. Traditionally, mushrooms are dried by sunshine which depends on the weather. This affects the quality of the dried mushrooms. Therefore, this paper proposes a system to provide an artificial drying for mushrooms in order to maintain their quality. The objective of the system is to control the mushroom drying process to be faster compared to the natural drying at an accurate and right temperature. A model of the mushroom dryer has been designed, built, and tested. The system comprises a chamber, heater, blower, temperature sensor and electronic control circuit. A microcontroller is used as the controller which is programmed to implement a bang-bang control that regulates the temperature of the chamber. A desired temperature is inputted as a set point of the control system. Temperature of 45 °C is chosen as the operational drying temperature. Several tests have been carried out to examine the performance of the system including drying speed, the effects of ambient conditions, and the effects of mushroom size. The results show that the system can satisfy the objective.

  14. Method of manufacturing a layer thermoelectric battery. Herstellungsverfahren fuer Schichtthermobatterien

    Energy Technology Data Exchange (ETDEWEB)

    Lidorenko, N.S.; Kolomoets, N.V.; Daschevsky, Z.M.; Granovsky, V.I.; Schemtschuschina, E.A.; Chernousov, L.N.; Schmidt, I.A.; Nikolaschina, L.A.; Gelfgat, D.M.; Sgibnev, I.V.

    1980-08-21

    A method of manufacturing a layer thermoelectric battery is described, whereby a film of a thermoelectric semiconductor material which is an n-type stoichiometric solid solution containing Bi2Te3 and Sb2Te3 is deposited on a substrate. Then heating is effected so that adjacent arms of the film are at different temperatures, some at a temperature of not above 300/sup 0/C, and others at a temperature of not less than 350/sup 0/C.

  15. Thermoelectricity: materials and applications

    International Nuclear Information System (INIS)

    Elberg, S.; Mathonnet, P.

    1975-01-01

    After a brief recall of the basic principles of thermoelectricity, the essential characteristics intervening in the different thermoelectric devices operating modes are defined. Properties of the materials the most used nowadays and performances of the apparatus that they allow to realize are indicated. Advantages and drawbacks of the principal applications in the form of electrical generators, refrigerators and heat pumps are pointed out [fr

  16. Automatic temperature control method of shipping can

    International Nuclear Information System (INIS)

    Nishikawa, Kaoru.

    1992-01-01

    The present invention provides a method of rapidly and accurately controlling the temperature of a shipping can, which is used upon shipping inspection for a nuclear fuel assembly. That is, a measured temperature value of the shipping can is converted to a gas pressure setting value in a jacket of the shipping can by conducting a predetermined logic calculation by using a fuzzy logic. A gas pressure control section compares the pressure setting value of a fuzzy estimation section and the measured value of the gas pressure in the jacket of the shipping can, and conducts air supply or exhaustion of the jacket gas so as to adjust the measured value with the setting value. These fuzzy estimation section and gas pressure control section control the gas pressure in the jacket of the shipping can to control the water level in the jacket. As a result, the temperature of the shipping can is controlled. With such procedures, since the water level in the jacket can be controlled directly and finely, temperature of the shipping can is automatically controlled rapidly and accurately compared with a conventional case. (I.S.)

  17. Uranium casting furnace automatic temperature control development

    International Nuclear Information System (INIS)

    Lind, R.F.

    1992-01-01

    Development of an automatic molten uranium temperature control system for use on batch-type induction casting furnaces is described. Implementation of a two-color optical pyrometer, development of an optical scanner for the pyrometer, determination of furnace thermal dynamics, and design of control systems are addressed. The optical scanning system is shown to greatly improve pyrometer measurement repeatability, particularly where heavy floating slag accumulations cause surface temperature gradients. Thermal dynamics of the furnaces were determined by applying least-squares system identification techniques to actual production data. A unity feedback control system utilizing a proportional-integral-derivative compensator is designed by using frequency-domain techniques. 14 refs

  18. Modelling of thermoelectric materials

    DEFF Research Database (Denmark)

    Bjerg, Lasse

    In order to discover new good thermoelectric materials, there are essentially two ways. One way is to go to the laboratory, synthesise a new material, and measure the thermoelectric properties. The amount of compounds, which can be investigated this way is limited because the process is time...... consuming. Another approach is to model the thermoelectric properties of a material on a computer. Several crystal structures can be investigated this way without use of much man power. I have chosen the latter approach. Using density functional theory I am able to calculate the band structure of a material....... This band structure I can then use to calculate the thermoelectric properties of the material. With these results I have investigated several materials and found the optimum theoretical doping concentration. If materials with these doping concentrations be synthesised, considerably better thermoelectric...

  19. Nano-Micro Materials Enabled Thermoelectricity From Window Glasses

    KAUST Repository

    Inayat, Salman Bin

    2012-11-03

    With growing world population and decreasing fossil fuel reserves we need to explore and utilize variety of renewable and clean energy sources to meet the imminent challenge of energy crisis. Solar energy is considered as the leading promising alternate energy source with the pertinent challenge of off sunshine period and uneven worldwide distribution of usable sun light. Although thermoelectricity is considered as a reasonable energy harvester from wasted heat, its mass scale usage is yet to be developed. By transforming window glasses into generators of thermoelectricity, this doctoral work explores engineering aspects of using the temperature gradient between the hot outdoor heated by the sun and the relatively cold indoor of a building for mass scale energy generation. In order to utilize the two counter temperature environments simultaneously, variety of techniques, including: a) insertion of basic metals like copper and nickel wire, b) sputtering of thermoelectric films on side walls of individual glass strips to form the thickness depth of the glass on subsequent curing of the strips, and c) embedding nano-manufactured thermoelectric pillars, have been implemented for innovative integration of thermoelectric materials into window glasses. The practical demonstration of thermoelectric windows has been validated using a finite element model to predict the behavior of thermoelectric window under variety of varying conditions. MEMS based characterization platform has been fabricated for thermoelectric characterization of thin films employing van der Pauw and four probe modules. Enhancement of thermoelectric properties of the nano- manufactured pillars due to nano-structuring, achieved through mechanical alloying of micro-sized thermoelectric powders, has been explored. Modulation of thermoelectric properties of the nano-structured thermoelectric pillars by addition of sulfur to nano-powder matrix has also been investigated in detail. Using the best possible p

  20. Temperature control in interstitial laser cancer immunotherapy

    Science.gov (United States)

    Bandyopadhyay, Pradip K.; Holmes, Kyland; Burnett, Corinthius; Zharov, Vladimir P.

    2003-07-01

    Positive results of Laser-Assisted Cancer Immunotherapy (LACI) have been reported previously in the irradiation of superficial tumors. This paper reports the effect of LACI using laser interstitial therapy approach. We hypothesize that the maximum immuno response depends on laser induced tumor temperature. The measurement of tumor temperature is crucial to ensure necrosis by thermal damage and immuno response. Wister Furth female rats in this study were inoculated with 13762 MAT B III rat mammary adinocarcinoma. LACI started seven to ten days following inoculation. Contrary to surface irradation, we applied laser interstitial irradiation of tumor volume to maximize the energy deposition. A diode laser with a wavelength of 805 nm was used for tumor irradiation. The laser energy was delivered inside the tumor through a quartz fiber. Tumor temperature was measured with a micro thermocouple (interstitial), while the tumor surface temperature was controlled with an IR detector. The temperature feedback demonstrates that it is possible to maintain the average tumor temperature at the same level with reasonable accuracy in the desired range from 65°C-85°C. In some experiments we used microwave thermometry to control average temperature in deep tissue for considerable period of time, to cause maximum thermal damage to the tumor. The experimental set-up and the different temperature measurement techniques are reported in detail, including the advantages and disadvantages for each method.

  1. Controlling compositional homogeneity and crystalline orientation in Bi0.8Sb0.2 thermoelectric thin films

    Science.gov (United States)

    Rochford, C.; Medlin, D. L.; Erickson, K. J.; Siegal, M. P.

    2015-12-01

    Compositional-homogeneity and crystalline-orientation are necessary attributes to achieve high thermoelectric performance in Bi1-xSbx thin films. Following deposition in vacuum, and upon air exposure, we find that 50%-95% of the Sb in 100-nm thick films segregates to form a nanocrystalline Sb2O3 surface layer, leaving the film bulk as Bi-metal. However, we demonstrate that a thin SiN capping layer deposited prior to air exposure prevents Sb-segregation, preserving a uniform film composition. Furthermore, the capping layer enables annealing in forming gas to improve crystalline orientations along the preferred trigonal axis, beneficially reducing electrical resistivity.

  2. Coordinated control of a combined cycle thermoelectric central; Control coordinado de una central termoelectrica de ciclo combinado

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Parra, Marino; Castelo Cuevas, Luis [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1998-03-01

    In this paper the coordinated control (CC) of the Distributed Control System (Sistema de Control Distribuido) (SICODI) of the Combined Cycle Central of Gomez Palacio, Durango, is presented. The description of the control scheme and its realization in software is made. From the scheme the operation strategies and automation, supervision and control are described in detail. The software components of the programming are described, the program structure and control data and its implementation in working stations VAX 3100 under the operating system VMS (Virtual Memory System), are described. [Espanol] En este articulo se presenta el control coordinado (CC) del Sistema de Control Distribuido (Sicodi) de la central de ciclo combinado Gomez Palacio, Durango. Se describe el esquema de control y su realizacion en software. Del esquema se detallan las estrategias de operacion y automatizacion, supervision y control. Del software se describen los componentes de la programacion, la estructura de programas y datos del control y su implementacion en estaciones de trabajo VAX 3100 bajo el sistema operativo VMS (Virtual Memory System).

  3. ESBWR power maneuvering via feedwater temperature control

    International Nuclear Information System (INIS)

    Saha, P.; Marquino, W.; Tucker, L. J.

    2008-01-01

    The ESBWR is a Generation III+ Boiling Water Reactor (BWR) driven by natural circulation. For a given geometry/hardware, system pressure, downcomer water level and feedwater temperature, the core flow rate in the ESBWR is only a function of reactor power, controlled through the control blade movement. In order to provide operational flexibility, another method of core-wide or global power maneuvering via feedwater temperature control has been developed. This is independent of power maneuvering via control blade movement, and it lowers the linear heat generation rate (LHGR) changes near the tip of control blades, which improves fuel reliability. All required stability, anticipated operational occurrences (AOOs), infrequent events, special events including anticipated transients without scram (ATWS), and loss-of-coolant accident (LOCA) analyses have been performed for the 4500 MWt ESBWR. Based on the results of these analyses at 'high', nominal and 'low' feedwater temperatures, a safe Power - Feedwater Temperature operating domain has been developed. This paper summarizes the results of these analyses and presents the ESBWR Power - Feedwater Temperature operating domain or map. (authors)

  4. A design approach for integrating thermoelectric devices using topology optimization

    International Nuclear Information System (INIS)

    Soprani, S.; Haertel, J.H.K.; Lazarov, B.S.; Sigmund, O.; Engelbrecht, K.

    2016-01-01

    Highlights: • The integration of a thermoelectric (TE) cooler into a robotic tool is optimized. • Topology optimization is suggested as design tool for TE integrated systems. • A 3D optimization technique using temperature dependent TE properties is presented. • The sensitivity of the optimization process to the boundary conditions is studied. • A working prototype is constructed and compared to the model results. - Abstract: Efficient operation of thermoelectric devices strongly relies on the thermal integration into the energy conversion system in which they operate. Effective thermal integration reduces the temperature differences between the thermoelectric module and its thermal reservoirs, allowing the system to operate more efficiently. This work proposes and experimentally demonstrates a topology optimization approach as a design tool for efficient integration of thermoelectric modules into systems with specific design constraints. The approach allows thermal layout optimization of thermoelectric systems for different operating conditions and objective functions, such as temperature span, efficiency, and power recovery rate. As a specific application, the integration of a thermoelectric cooler into the electronics section of a downhole oil well intervention tool is investigated, with the objective of minimizing the temperature of the cooled electronics. Several challenges are addressed: ensuring effective heat transfer from the load, minimizing the thermal resistances within the integrated system, maximizing the thermal protection of the cooled zone, and enhancing the conduction of the rejected heat to the oil well. The design method incorporates temperature dependent properties of the thermoelectric device and other materials. The 3D topology optimization model developed in this work was used to design a thermoelectric system, complete with insulation and heat sink, that was produced and tested. Good agreement between experimental results and

  5. Misfit Layer Compounds and Ferecrystals: Model Systems for Thermoelectric Nanocomposites

    Directory of Open Access Journals (Sweden)

    Devin R. Merrill

    2015-04-01

    Full Text Available A basic summary of thermoelectric principles is presented in a historical context, following the evolution of the field from initial discovery to modern day high-zT materials. A specific focus is placed on nanocomposite materials as a means to solve the challenges presented by the contradictory material requirements necessary for efficient thermal energy harvest. Misfit layer compounds are highlighted as an example of a highly ordered anisotropic nanocomposite system. Their layered structure provides the opportunity to use multiple constituents for improved thermoelectric performance, through both enhanced phonon scattering at interfaces and through electronic interactions between the constituents. Recently, a class of metastable, turbostratically-disordered misfit layer compounds has been synthesized using a kinetically controlled approach with low reaction temperatures. The kinetically stabilized structures can be prepared with a variety of constituent ratios and layering schemes, providing an avenue to systematically understand structure-function relationships not possible in the thermodynamic compounds. We summarize the work that has been done to date on these materials. The observed turbostratic disorder has been shown to result in extremely low cross plane thermal conductivity and in plane thermal conductivities that are also very small, suggesting the structural motif could be attractive as thermoelectric materials if the power factor could be improved. The first 10 compounds in the [(PbSe1+δ]m(TiSe2n family (m, n ≤ 3 are reported as a case study. As n increases, the magnitude of the Seebeck coefficient is significantly increased without a simultaneous decrease in the in-plane electrical conductivity, resulting in an improved thermoelectric power factor.

  6. CaMn(1-x)Nb(x)O3 (x < or = 0.08) perovskite-type phases as promising new high-temperature n-type thermoelectric materials.

    Science.gov (United States)

    Bocher, L; Aguirre, M H; Logvinovich, D; Shkabko, A; Robert, R; Trottmann, M; Weidenkaff, A

    2008-09-15

    Perovskite-type CaMn(1-x)Nb(x)O(3+/-delta) (x = 0.02, 0.05, and 0.08) compounds were synthesized by applying both a "chimie douce" (SC) synthesis and a classical solid state reaction (SSR) method. The crystallographic parameters of the resulting phases were determined from X-ray, electron, and neutron diffraction data. The manganese oxidations states (Mn(4+)/Mn(3+)) were investigated by X-ray photoemission spectroscopy. The orthorhombic CaMn(1-x)Nb(x)O(3+/-delta) (x = 0.02, 0.05, and 0.08) phases were studied in terms of their high-temperature thermoelectric properties (Seebeck coefficient, electrical resistivity, and thermal conductivity). Differences in electrical transport and thermal properties can be correlated with different microstructures obtained by the two synthesis methods. In the high-temperature range, the electron-doped manganate phases exhibit large absolute Seebeck coefficient and low electrical resistivity values, resulting in a high power factor, PF (e.g., for x = 0.05, S(1000K) = -180 microV K(-1), rho(1000K) = 16.8 mohms cm, and PF > 1.90 x 10(-4) W m(-1) K(-2) for 450 K 0.3) make these phases the best perovskitic candidates as n-type polycrystalline thermoelectric materials operating in air at high temperatures.

  7. Thermoelectric cooling container for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Aivazov, A A; Shtern, Y I; Budaguan, B G; Makhrachev, K B; Pastor, M

    1997-07-01

    In this work the thermoelectric cooling container for storing and transportation of the medicine, particularly for insulin, is discussed. In the working volume the temperature is supported on the level of +4 C. The container can work in two operating conditions: with the power supply and without the power supply. Two removable blocks are used for this purpose. One block (thermoelectric) is used for the work with the power supply and another (passive)-for the work without power supply. The thermoelectric block has a 12V power supply, which is used in the automobiles, yachts and other kinds of transport. The temperature in the working volume is supported by the use of the Peltier effect. An electronic device is used in this block and stabilizes temperature on the level of +4 C and indicates information about working conditions. The thermoelectric container has a power supply block for work at 220(110)V. The working temperature in the container can be maintained in the absence of the power supply. In this case the necessary temperature conditions are supported by melting of the crystallized salt. For this purpose the container has a hermetic volume containing this salt and contacting with the working volume.

  8. Silicon nanowire networks for multi-stage thermoelectric modules

    International Nuclear Information System (INIS)

    Norris, Kate J.; Garrett, Matthew P.; Zhang, Junce; Coleman, Elane; Tompa, Gary S.; Kobayashi, Nobuhiko P.

    2015-01-01

    Highlights: • Fabricated flexible single, double, and quadruple stacked Si thermoelectric modules. • Measured an enhanced power production of 27%, showing vertical stacking is scalable. • Vertically scalable thermoelectric module design of semiconducting nanowires. • Design can utilize either p or n-type semiconductors, both types are not required. • ΔT increases with thickness therefore power/area can increase as modules are stacked. - Abstract: We present the fabrication and characterization of single, double, and quadruple stacked flexible silicon nanowire network based thermoelectric modules. From double to quadruple stacked modules, power production increased 27%, demonstrating that stacking multiple nanowire thermoelectric devices in series is a scalable method to generate power by supplying larger temperature gradient. We present a vertically scalable multi-stage thermoelectric module design using semiconducting nanowires, eliminating the need for both n-type and p-type semiconductors for modules

  9. Thermoelectric effects in a rectangular Aharonov-Bohm geometry

    Science.gov (United States)

    Pye, A. J.; Faux, D. A.; Kearney, M. J.

    2016-04-01

    The thermoelectric transport properties of a rectangular Aharonov-Bohm ring at low temperature are investigated using a theoretical approach based on Green's functions. The oscillations in the transmission coefficient as the field is varied can be used to tune the thermoelectric response of the ring. Large magnitude thermopowers are obtainable which, in conjunction with low conductance, can result in a high thermoelectric figure of merit. The effects of single site impurities and more general Anderson disorder are considered explicitly in the context of evaluating their effect on the Fano-type resonances in the transmission coefficient. Importantly, it is shown that even for moderate levels of disorder, the thermoelectric figure of merit can remain significant, increasing the appeal of such structures from the perspective of specialist thermoelectric applications.

  10. The thermoelectric process

    Energy Technology Data Exchange (ETDEWEB)

    Vining, C B

    1997-07-01

    The efficiency of thermoelectric technology today is limited by the properties of available thermoelectric materials and a wide variety of new approaches to developing better materials have recently been suggested. The key goal is to find a material with a large ZT, the dimensionless thermoelectric figure of merit. However, if an analogy is drawn between thermoelectric technology and gas-cycle engines then selecting different materials for the thermoelements is analogous to selecting a different working gas for the mechanical engine. And an attempt to improve ZT is analogous to an attempt to improve certain thermodynamic properties of the working-gas. An alternative approach is to focus on the thermoelectric process itself (rather than on ZT), which is analogous to considering alternate cycles such as Stirling vs. Brayton vs. Rankine etc., rather than merely considering alternative gases. Focusing on the process is a radically different approach compared to previous studies focusing on ZT. Aspects of the thermoelectric process and alternative approaches to efficient thermoelectric conversion are discussed.

  11. High Power Density, Lightweight Thermoelectric Metamaterials for Energy Harvesting

    Data.gov (United States)

    National Aeronautics and Space Administration — Thermoelectric energy harvesting utilizes materials that generate an electrical current when subjected to a temperature gradient, or simply, a hot and cold source of...

  12. Feedwater temperature control methods and systems

    Science.gov (United States)

    Moen, Stephan Craig; Noonan, Jack Patrick; Saha, Pradip

    2014-04-22

    A system for controlling the power level of a natural circulation boiling water nuclear reactor (NCBWR) is disclosed. The system, in accordance with an example embodiment of the present invention, may include a controller configured to control a power output level of the NCBWR by controlling a heating subsystem to adjust a temperature of feedwater flowing into an annulus of the NCBWR. The heating subsystem may include a steam diversion line configured to receive steam generated by a core of the NCBWR and a steam bypass valve configured to receive commands from the controller to control a flow of the steam in the steam diversion line, wherein the steam received by the steam diversion line has not passed through a turbine. Additional embodiments of the invention may include a feedwater bypass valve for controlling an amount of flow of the feedwater through a heater bypass line to the annulus.

  13. Thermoelectric materials and devices made therewith

    International Nuclear Information System (INIS)

    Moore, D.E.

    1985-01-01

    The disclosed invention includes improved devices and materials for thermoelectric conversion, particularly for operation at temperatures of 300 0 C. and below. Disordered p-type semiconductor elements incorporate compound adjuvants of silver and lead to achieve enhanced ''figure of merit'' values and corresponding increased efficiencies of thermoelectric conversion. Similar results are obtained with disordered n-type elements by employing lowered selenium contents, preferably in combination with cuprous bromide. Improved conversion devices include powder pressed elements from one or both of these materials

  14. Coupled Thermoelectric Devices: Theory and Experiment

    Directory of Open Access Journals (Sweden)

    Jaziel A. Rojas

    2016-07-01

    Full Text Available In this paper, we address theoretically and experimentally the optimization problem of the heat transfer occurring in two coupled thermoelectric devices. A simple experimental set up is used. The optimization parameters are the applied electric currents. When one thermoelectric is analysed, the temperature difference Δ T between the thermoelectric boundaries shows a parabolic profile with respect to the applied electric current. This behaviour agrees qualitatively with the corresponding experimental measurement. The global entropy generation shows a monotonous increase with the electric current. In the case of two coupled thermoelectric devices, elliptic isocontours for Δ T are obtained in applying an electric current through each of the thermoelectrics. The isocontours also fit well with measurements. Optimal figure of merit is found for a specific set of values of the applied electric currents. The entropy generation-thermal figure of merit relationship is studied. It is shown that, given a value of the thermal figure of merit, the device can be operated in a state of minimum entropy production.

  15. Improvement In The COP Of Thermoelectric Cooler

    Directory of Open Access Journals (Sweden)

    Jatin Patel

    2015-08-01

    Full Text Available This paper described the study for heat transfer through thermoelectric cooler TEC by use of multistage thermoelectric module. To satisfy the heat dissipation of modern electronic element thermal designers have to increase fin area and fan speed to improve its cooling capacity. However the increase of fin area is restricted by the space. Besides the increase of fan speed would induce noise which damages human health. So air cooling by fan is hardly to meet the requirement of modern electronic component. Recently thermoelectric cooler TEC is applied to electronic cooling with the advantages of small size quietness and reliability. A typical thermoelectric cooler consists of p-type and n-type semiconductor pellets connected electrically in series and sandwiched between two ceramic substrates. Whenever direct current passes through the circuit it causes temperature differential between TEC sides. As a result one face of TEC which is called cold side will be cooled while its opposite face which is called hot side is simultaneously heated. The main problem over the use of TEC is the limited COP and its thermal performance. But these can be eliminated by use of multistage thermoelectric cooler.

  16. Voltammetry under a Controlled Temperature Gradient

    Directory of Open Access Journals (Sweden)

    Jan Krejci, Jr.

    2010-07-01

    Full Text Available Electrochemical measurements are generally done under isothermal conditions. Here we report on the application of a controlled temperature gradient between the working electrode surface and the solution. Using electrochemical sensors prepared on ceramic materials with extremely high specific heat conductivity, the temperature gradient between the electrode and solution was applied here as a second driving force. This application of the Soret phenomenon increases the mass transfer in the Nernst layer and enables more accurate control of the electrode response enhancement by a combination of diffusion and thermal diffusion. We have thus studied the effect of Soret phenomenon by cyclic voltammetry measurements in ferro/ferricyanide. The time dependence of sensor response disappears when applying the Soret phenomenon, and the complicated shape of the cyclic voltammogram is replaced by a simple exponential curve. We have derived the Cotrell-Soret equation describing the steady-state response with an applied temperature difference.

  17. Thermoelectric devices and applications for the same

    Science.gov (United States)

    Olsen, Larry C.; DeSteese, John G.; Martin, Peter M.; Johnston, John W.; Peters, Timothy J.

    2016-03-08

    High performance thin film thermoelectric couples and methods of making the same are disclosed. Such couples allow fabrication of at least microwatt to watt-level power supply devices operating at voltages greater than one volt even when activated by only small temperature differences.

  18. Notes on Computational Methodology and Tools of Thermoelectric Energy Systems

    DEFF Research Database (Denmark)

    Chen, Min; Bach, Inger Palsgaard; Rosendahl, Lasse

    2007-01-01

    The SPICE model allows the concurrent simulation of thermoelectric devices and application electric sub-models. It is an important step to implement the thermoelectric modeling at the system level. In this paper, temperature dependent material properties in the SPICE model, temperature and heat...... flow obtained by the code ANSYS Multiphysics and SPICE (Simulation Program with Integrated Circuit Emphasis), as well as some notes on the 3-D extension of the SPICE model are introduced....

  19. Thermoelectric System Absorbing Waste Heat from a Steel Ladle

    Science.gov (United States)

    Lu, Baiyi; Meng, Xiangning; Zhu, Miaoyong; Suzuki, Ryosuke O.

    2018-06-01

    China's iron and steel industry has made great progress in energy savings and emission reductions with the application of many waste heat recovery technologies. However, most of the medium and low temperature waste heat and radiant waste heat has not been effectively utilized. This paper proposes a thermoelectric system that generates electricity by absorbing the radiant heat from the surface of steel ladles in a steel plant. The thermoelectric behavior of modules in this system is analyzed by a numerical simulation method. The effects of external resistance and module structure on thermoelectric performance are also discussed in the temperature range of the wall surface of a steel ladle. The results show that the wall temperature has a significant influence on the thermoelectric behavior of the module, so its uniformity and stability should be considered in practical application. The ratio of the optimum external resistance to the internal resistance of the thermoelectric module is in the range of 1.6-2.0, which indicates the importance of external load optimization for a given thermoelectric system. In addition, the output power and the conversion efficiency of the module can be significantly improved by increasing the length of the thermoelectric legs and adopting a double-layer structure. Finally, through the optimization of external resistance and structure, the power output can reach 83-304 W/m2. This system is shown to be a promising approach for energy recovery.

  20. Measurement and characterization techniques for thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Tritt, T M

    1997-07-01

    Characterization of thermoelectric materials can pose many problems. A temperature difference can be established across these materials as an electrical current is passed due to the Peltier effect. The thermopower of these materials is quite large and thus large thermal voltages can contribute to many of the measurements necessary to investigate these materials. This paper will discuss the chracterization techniques necessary to investigate these materials and provide an overview of some of the potential systematic errors which can arise. It will also discuss some of the corrections one needs to consider. This should provide an introduction to the characterization and measurement of thermoelectric materials and provide references for a more in depth discussion of the concepts. It should also serve as an indication of the care that must be taken while working with thermoelectric materials.

  1. Graphite moderated reactor for thermoelectric generation

    International Nuclear Information System (INIS)

    Akazawa, Issei; Yamada, Akira; Mizogami, Yorikata

    1998-01-01

    Fuel rods filled with cladded fuel particles distributed and filled are buried each at a predetermined distance in graphite blocks situated in a reactor core. Perforation channels for helium gas as coolants are formed to the periphery thereof passing through vertically. An alkali metal thermoelectric power generation module is disposed to the upper lid of a reactor container while being supported by a securing receptacle. Helium gas in the coolant channels in the graphite blocks in the reactor core absorbs nuclear reaction heat, to be heated to a high temperature, rises upwardly by the reduction of the specific gravity, and then flows into an upper space above the laminated graphite block layer. Then the gas collides against a ceiling and turns, and flows down in a circular gap around the circumference of the alkali metal thermoelectric generation module. In this case, it transfers heat to the alkali metal thermoelectric generation module. (I.N.)

  2. Knudsen pump driven by a thermoelectric material

    International Nuclear Information System (INIS)

    Pharas, Kunal; McNamara, Shamus

    2010-01-01

    The first use of a thermoelectric material in the bidirectional operation of a gas pump using thermal transpiration has been demonstrated. The thermoelectric material maintains a higher temperature difference which favors thermal transpiration and thus increases the efficiency of gas pumping. Since the hot and cold sides of the thermoelectric material are reversible, the direction of the pump may be changed by reversing the electrical current direction. Two different pump designs are presented that illustrate some of the design tradeoffs. The pumps are characterized by measuring the pressure difference that may be generated and by measuring the flow rate in the forward and reverse directions. For a pump composed of a porous material with a pore size of 100 nm, a maximum flow rate of 0.74 cm 3 min −1 and a maximum pressure of 1.69 kPa are achieved

  3. Development of CCD Imaging System Using Thermoelectric Cooling Method

    Directory of Open Access Journals (Sweden)

    Youngsik Park

    2000-06-01

    Full Text Available We developed low light CCD imaging system using thermoelectric cooling method collaboration with a company to design a commercial model. It consists of Kodak KAF-0401E (768x512 pixels CCD chip,thermoelectric module manufactured by Thermotek. This TEC system can reach an operative temperature of -25deg. We employed an Uniblitz VS25S shutter and it has capability a minimum exposure time 80ms. The system components are an interface card using a Korea Astronomy Observatory (hereafter KAO ISA bus controller, image acquisition with AD9816 chip, that is 12bit video processor. The performance test with this imaging system showed good operation within the initial specification of our design. It shows a dark current less than 0.4e-/pixel/sec at a temperature of -10deg, a linearity 99.9+/-0.1%, gain 4.24e-adu, and system noise is 25.3e- (rms. For low temperature CCD operation, we designed a TEC, which uses a one-stage peltier module and forced air heat exchanger. This TEC imaging system enables accurate photometry (+/-0.01mag even though the CCD is not at 'conventional' cryogenic temperatures (140K. The system can be a useful instrument for any other imaging applications. Finally, with this system, we obtained several images of astronomical objects for system performance tests.

  4. Controlling compositional homogeneity and crystalline orientation in Bi0.8Sb0.2 thermoelectric thin films

    Directory of Open Access Journals (Sweden)

    C. Rochford

    2015-12-01

    Full Text Available Compositional-homogeneity and crystalline-orientation are necessary attributes to achieve high thermoelectric performance in Bi1−xSbx thin films. Following deposition in vacuum, and upon air exposure, we find that 50%–95% of the Sb in 100-nm thick films segregates to form a nanocrystalline Sb2O3 surface layer, leaving the film bulk as Bi-metal. However, we demonstrate that a thin SiN capping layer deposited prior to air exposure prevents Sb-segregation, preserving a uniform film composition. Furthermore, the capping layer enables annealing in forming gas to improve crystalline orientations along the preferred trigonal axis, beneficially reducing electrical resistivity.

  5. On-Chip Sensing of Thermoelectric Thin Film’s Merit

    OpenAIRE

    Xiao, Zhigang; Zhu, Xiaoshan

    2015-01-01

    Thermoelectric thin films have been widely explored for thermal-to-electrical energy conversion or solid-state cooling, because they can remove heat from integrated circuit (IC) chips or micro-electromechanical systems (MEMS) devices without involving any moving mechanical parts. In this paper, we report using silicon diode-based temperature sensors and specific thermoelectric devices to characterize the merit of thermoelectric thin films. The silicon diode temperature sensors and thermoelect...

  6. Compatibility of Segments of Thermoelectric Generators

    Science.gov (United States)

    Snyder, G. Jeffrey; Ursell, Tristan

    2009-01-01

    A method of calculating (usually for the purpose of maximizing) the power-conversion efficiency of a segmented thermoelectric generator is based on equations derived from the fundamental equations of thermoelectricity. Because it is directly traceable to first principles, the method provides physical explanations in addition to predictions of phenomena involved in segmentation. In comparison with the finite-element method used heretofore to predict (without being able to explain) the behavior of a segmented thermoelectric generator, this method is much simpler to implement in practice: in particular, the efficiency of a segmented thermoelectric generator can be estimated by evaluating equations using only hand-held calculator with this method. In addition, the method provides for determination of cascading ratios. The concept of cascading is illustrated in the figure and the definition of the cascading ratio is defined in the figure caption. An important aspect of the method is its approach to the issue of compatibility among segments, in combination with introduction of the concept of compatibility within a segment. Prior approaches involved the use of only averaged material properties. Two materials in direct contact could be examined for compatibility with each other, but there was no general framework for analysis of compatibility. The present method establishes such a framework. The mathematical derivation of the method begins with the definition of reduced efficiency of a thermoelectric generator as the ratio between (1) its thermal-to-electric power-conversion efficiency and (2) its Carnot efficiency (the maximum efficiency theoretically attainable, given its hot- and cold-side temperatures). The derivation involves calculation of the reduced efficiency of a model thermoelectric generator for which the hot-side temperature is only infinitesimally greater than the cold-side temperature. The derivation includes consideration of the ratio (u) between the

  7. Thermoelectric power of PrMg3

    Science.gov (United States)

    Isikawa, Yosikazu; Somiya, Kazuya; Koyanagi, Huruto; Mizushima, Toshio; Kuwai, Tomohiko; Tayama, Takashi

    2010-01-01

    PrMg3 is supposed to be one of the strongly correlated electron systems originated from the hybridization between the Pr 4f and conduction electrons, because the gigantic electronic specific heat coefficient C/T was observed at low temperatures. However, a typical behaviour of - ln T dependence was not observed in the temperature dependence of the electrical resistivity. The thermoelectric power S is a powerful tool to investigate the density of states at the Fermi energy. We measured carefully the thermoelectric power of PrMg3 in the temperature range between 2 and 300 K. S is extremely small, ranged within ±1 μV/K over the whole temperature. The value of S/T at low temperature limit was also significantly smaller than expected from the specific heat results. We therefore conclude that the density of state at the Fermi level is not enhanced in PrMg3.

  8. Thermoelectric power of PrMg3

    International Nuclear Information System (INIS)

    Isikawa, Yosikazu; Somiya, Kazuya; Koyanagi, Huruto; Mizushima, Toshio; Kuwai, Tomohiko; Tayama, Takashi

    2010-01-01

    PrMg 3 is supposed to be one of the strongly correlated electron systems originated from the hybridization between the Pr 4f and conduction electrons, because the gigantic electronic specific heat coefficient C/T was observed at low temperatures. However, a typical behaviour of - ln T dependence was not observed in the temperature dependence of the electrical resistivity. The thermoelectric power S is a powerful tool to investigate the density of states at the Fermi energy. We measured carefully the thermoelectric power of PrMg 3 in the temperature range between 2 and 300 K. S is extremely small, ranged within ±1 μV/K over the whole temperature. The value of S/T at low temperature limit was also significantly smaller than expected from the specific heat results. We therefore conclude that the density of state at the Fermi level is not enhanced in PrMg 3 .

  9. Thermoelectric transport in superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Reinecke, T L; Broido, D A

    1997-07-01

    The thermoelectric transport properties of superlattices have been studied using an exact solution of the Boltzmann equation. The role of heat transport along the barrier layers, of carrier tunneling through the barriers, of valley degeneracy and of the well width and energy dependences of the carrier-phonon scattering rates on the thermoelectric figure of merit are given. Calculations are given for Bi{sub 2}Te{sub 3} and for PbTe, and the results of recent experiments are discussed.

  10. Stretchable Helical Architecture Inorganic-Organic Hetero Thermoelectric Generator

    KAUST Repository

    Rojas, Jhonathan Prieto; Singh, Devendra; Conchouso Gonzalez, David; Carreno, Armando Arpys Arevalo; Foulds, Ian G.; Hussain, Muhammad Mustafa

    2016-01-01

    To achieve higher power output from a thermoelectric generator (TEG), one needs to maintain a larger temperature difference between hot and cold end. In that regard, a stretchable TEG can be interesting to adaptively control the temperature difference. Here we show, the development of simple yet versatile and highly stretchable thermoelectric generators (TEGs), by combining well-known inorganic thermoelectric materials Bismuth Telluride and Antimony Telluride (Bi2Te3 and Sb2Te3) with organic substrates (Off-Stoichiometry Thiol-Enes polymer platform – OSTE, polyimide or paper) and novel helical architecture (double-arm spirals) to achieve over 100% stretchability. First, an OSTE-based TEG design demonstrates higher open circuit voltage generation at 100% strain than at rest, although it exhibits high internal resistance and a relatively complex fabrication process. The second, simpler TEG design, achieves a significant resistance reduction and two different structural substrates (PI and paper) are compared. The paper-based TEG generates 17 nW (ΔT = 75 °C) at 60% strain, which represents more than twice the power generation while at rest (zero strain). On the other hand, polyimide produces more conductive TE films and higher power (~35 nW at ΔT = 75 °C) but due to its higher thermal conductivity, power does not increase at stretch. In conclusion, highly stretchable TEGs can lead to higher temperature gradients (thus higher power generation), given that thermal conductivity of the structural material is low enough. Furthermore, either horizontal or vertical displacement can be achieved with double-arm helical architecture, hence allowing to extend the device to any nearby and mobile heat sink for continuous, effectively higher power generation.

  11. Stretchable Helical Architecture Inorganic-Organic Hetero Thermoelectric Generator

    KAUST Repository

    Rojas, Jhonathan Prieto

    2016-10-26

    To achieve higher power output from a thermoelectric generator (TEG), one needs to maintain a larger temperature difference between hot and cold end. In that regard, a stretchable TEG can be interesting to adaptively control the temperature difference. Here we show, the development of simple yet versatile and highly stretchable thermoelectric generators (TEGs), by combining well-known inorganic thermoelectric materials Bismuth Telluride and Antimony Telluride (Bi2Te3 and Sb2Te3) with organic substrates (Off-Stoichiometry Thiol-Enes polymer platform – OSTE, polyimide or paper) and novel helical architecture (double-arm spirals) to achieve over 100% stretchability. First, an OSTE-based TEG design demonstrates higher open circuit voltage generation at 100% strain than at rest, although it exhibits high internal resistance and a relatively complex fabrication process. The second, simpler TEG design, achieves a significant resistance reduction and two different structural substrates (PI and paper) are compared. The paper-based TEG generates 17 nW (ΔT = 75 °C) at 60% strain, which represents more than twice the power generation while at rest (zero strain). On the other hand, polyimide produces more conductive TE films and higher power (~35 nW at ΔT = 75 °C) but due to its higher thermal conductivity, power does not increase at stretch. In conclusion, highly stretchable TEGs can lead to higher temperature gradients (thus higher power generation), given that thermal conductivity of the structural material is low enough. Furthermore, either horizontal or vertical displacement can be achieved with double-arm helical architecture, hence allowing to extend the device to any nearby and mobile heat sink for continuous, effectively higher power generation.

  12. Thermoelectric Effects under Adiabatic Conditions

    Directory of Open Access Journals (Sweden)

    George Levy

    2013-10-01

    Full Text Available This paper investigates not fully explained voltage offsets observed by several researchers during the measurement of the Seebeck coefficient of high Z materials. These offsets, traditionally attributed to faulty laboratory procedures, have proven to have an irreducible component that cannot be fully eliminated in spite of careful laboratory procedures. In fact, these offsets are commonly observed and routinely subtracted out of commercially available Seebeck measurement systems. This paper offers a possible explanation based on the spontaneous formation of an adiabatic temperature gradient in the presence of a force field. The diffusion-diffusion heat transport mechanism is formulated and applied to predict two new thermoelectric effects. The first is the existence of a temperature gradient across a potential barrier in a semiconductor and the second is the Onsager reciprocal of the first, that is, the presence of a measureable voltage that arises across a junction when the temperature gradient is forced to zero by a thermal clamp. Suggested future research includes strategies for utilizing the new thermoelectric effects.

  13. Study for material analogs of FeSb2: Material design for thermoelectric materials

    Science.gov (United States)

    Kang, Chang-Jong; Kotliar, Gabriel

    2018-03-01

    Using the ab initio evolutionary algorithm (implemented in uspex) and electronic structure calculations we investigate the properties of a new thermoelectric material FeSbAs, which is a material analog of the enigmatic thermoelectric FeSb2. We utilize the density functional theory and the Gutzwiller method to check the energetics. We find that FeSbAs can be made thermodynamically stable above ˜30 GPa. We investigate the electronic structure and thermoelectric properties of FeSbAs based on the density functional theory and compare with those of FeSb2. Above 50 K, FeSbAs has higher Seebeck coefficients than FeSb2. Upon doping, the figure of merit becomes larger for FeSbAs than for FeSb2. Another material analog FeSbP, was also investigated, and found thermodynamically unstable even at very high pressure. Regarding FeSb2 as a member of a family of compounds (FeSb2, FeSbAs, and FeSbP) we elucidate what are the chemical handles that control the gaps in this series. We also investigate solubility (As or P for Sb in FeSb2) we found As to be more soluble. Finally, we study a two-band model for thermoelectric properties and find that the temperature dependent chemical potential and the presence of the ionized impurities are important to explain the extremum in the Seebeck coefficient exhibited in experiments for FeSb2.

  14. Ge/SiGe superlattices for nanostructured thermoelectric modules

    International Nuclear Information System (INIS)

    Chrastina, D.; Cecchi, S.; Hague, J.P.; Frigerio, J.; Samarelli, A.; Ferre–Llin, L.; Paul, D.J.; Müller, E.; Etzelstorfer, T.; Stangl, J.; Isella, G.

    2013-01-01

    Thermoelectrics are presently used in a number of applications for both turning heat into electricity and also for using electricity to produce cooling. Mature Si/SiGe and Ge/SiGe heteroepitaxial growth technology would allow highly efficient thermoelectric materials to be engineered, which would be compatible and integrable with complementary metal oxide silicon micropower circuits used in autonomous systems. A high thermoelectric figure of merit requires that electrical conductivity be maintained while thermal conductivity is reduced; thermoelectric figures of merit can be improved with respect to bulk thermoelectric materials by fabricating low-dimensional structures which enhance the density of states near the Fermi level and through phonon scattering at heterointerfaces. We have grown and characterized Ge-rich Ge/SiGe/Si superlattices for nanofabricated thermoelectric generators. Low-energy plasma-enhanced chemical vapor deposition has been used to obtain nanoscale-heterostructured material which is several microns thick. Crystal quality and strain control have been investigated by means of high resolution X-ray diffraction. High-resolution transmission electron microscopy images confirm the material and interface quality. Electrical conductivity has been characterized by the mobility spectrum technique. - Highlights: ► High-quality Ge/SiGe multiple quantum wells for thermoelectric applications ► Mobility spectra of systems featuring a large number of parallel conduction channels ► Competitive thermoelectric properties measured in single devices

  15. The development of a thermoelectric power generator dedicated to stove-fireplaces with heat accumulation systems

    International Nuclear Information System (INIS)

    Sornek, Krzysztof; Filipowicz, Mariusz; Rzepka, Kamila

    2016-01-01

    Highlights: • Application of thermoelectric generators in the stove-fireplace with accumulation. • Construction of the thermoelectric generator is limited by the heat accumulation. • Variants of the heat exchanger’s construction are discussed. • The control method is related on velocity of flue gas and water cooling. • The power limit of 30 W for self-sufficient operation is sufficient. - Abstract: A significant part of the world’s population (about 40%) cooks their meals and provides heating for their homes using wood-burning heating devices. Due to the relatively low cost of fuel and their aesthetic design, solid fuel stoves capable of heat accumulation are convenient and common. The use of dedicated small-scale power generators provides also additional benefits. This paper presents the results of a study conducted to verify the possibility of generating power using stove-fireplaces with heat accumulation systems. In such units, the temperature of the flue gas should be kept at a certain level for the purposes of storing heat, which results from certain limitations of the thermoelectric generators. To verify the possibility of applying thermoelectric modules in such heating devices, a dedicated system with thermoelectric generators was selected from among various microcogeneration systems and implemented. Three types of heat exchangers were studied and the most efficient unit was selected for further testing. Two types of generators, with maximum operating temperatures of 320 and 175 °C, were compared. Subsequently, the characteristics of the latter were determined. The conducted tests allowed to determine the performance and the total efficiency of the generators that were used. It has been demonstrated that the maximum power of the generator would not exceed ca. 30 W e and that there is no economic justification for such a device. However, providing a self-powered and self-sufficient operation of stove-fireplaces with heat accumulation systems

  16. Temperature uniformity control in RTP using multivariable adaptive control

    Energy Technology Data Exchange (ETDEWEB)

    Morales, S.; Dahhou, B.; Dilhac, J.M. [Centre National de la Recherche Scientifique (CNRS), 31 - Toulouse (France); Morales, S.

    1995-12-31

    In Rapid Thermal Processing (RTP) control of the wafer temperature during all processing to get good trajectory following, together with spatial temperature uniformity, is essential. It is well know as RTP process is nonlinear, classical control laws are not very efficient. In this work, the authors aim at studying the applicability of MIMO (Multiple Inputs Multiple Outputs) adaptive techniques to solve the temperature control problems in RTP. A multivariable linear discrete time CARIMA (Controlled Auto Regressive Integrating Moving Average) model of the highly non-linear process is identified on-line using a robust identification technique. The identified model is used to compute an infinite time LQ (Linear Quadratic) based control law, with a partial state reference model. This reference model smooths the original setpoint sequence, and at the same time gives a tracking capability to the LQ control law. After an experimental open-loop investigation, the results of the application of the adaptive control law are presented. Finally, some comments on the future difficulties and developments of the application of adaptive control in RTP are given. (author) 13 refs.

  17. Crystal orientation dependent thermoelectric properties of highly oriented aluminum-doped zinc oxide thin films

    KAUST Repository

    Abutaha, Anas I.

    2013-02-06

    We demonstrate that the thermoelectric properties of highly oriented Al-doped zinc oxide (AZO) thin films can be improved by controlling their crystal orientation. The crystal orientation of the AZO films was changed by changing the temperature of the laser deposition process on LaAlO3 (100) substrates. The change in surface termination of the LaAlO3 substrate with temperature induces a change in AZO film orientation. The anisotropic nature of electrical conductivity and Seebeck coefficient of the AZO films showed a favored thermoelectric performance in c-axis oriented films. These films gave the highest power factor of 0.26 W m−1 K−1 at 740 K.

  18. Numerical analysis of the performance prediction for a thermoelectric generator

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chang Nyung [Kyung Hee University, Yongin (Korea, Republic of)

    2015-09-15

    The present study develops a two-dimensional numerical code that can predict the performance of a thermoelectric generator module including a p-leg/n-leg pair and top and bottom electrodes. The present code can simulate the detailed thermoelectric phenomena including the heat flow, electric current, Joule heating, Peltier heating, and Thomson heating, together with the efficiency of the modules whose properties depend on the temperature. The present numerical code can be used for the design optimization of a thermoelectric power generator.

  19. Control system for Fermilab's low temperature upgrade

    International Nuclear Information System (INIS)

    Norris, B.L.

    1996-09-01

    Fermilab recently upgraded the Tevatron Cryogenic Systems to allow for lower temperature operation. This Lower Temperature Upgrade grew out of a desire to increase the Colliding Beam Physics energy from 900 GeV to 1000 GeV. A key element in achieving this goal is the new cryogenic control system designed at Fermilab and installed in 24 satellite refrigerators and 8 compressor buildings. The cryogenic improvements and addition hardware like cold compressors exceeded the capability of the original distributed controls package. The new distributed controls package uses a Multibus II platform and Intel's 80386 microprocessor. Token Ring is used as the link to the systems 6 primary crate locations with Arcnet used as the connection to the systems numerous I/O crates. I/0 capabilities are double the capabilities of the original system. Software has also been upgraded with the introduction of more flexible control loop strategies and Finite State Machines used for automatic sequential control, like quench recovery or cold compressor pump down

  20. Concentrated Solar Thermoelectric Power

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Gang [MIT; Ren, Zhifeng [University of Houston

    2015-07-09

    The goal of this project is to demonstrate in the lab that solar thermoelectric generators (STEGs) can exceed 10% solar-to-electricity efficiency, and STEGs can be integrated with phase-change materials (PCM) for thermal storage, providing operation beyond daylight hours. This project achieved significant progress in many tasks necessary to achieving the overall project goals. An accurate Themoelectric Generator (TEG) model was developed, which included realistic treatment of contact materials, contact resistances and radiative losses. In terms of fabricating physical TEGs, high performance contact materials for skutterudite TE segments were developed, along with brazing and soldering methods to assemble segmented TEGs. Accurate measurement systems for determining device performance (in addition to just TE material performance) were built for this project and used to characterize our TEGs. From the optical components’ side, a spectrally selective cermet surface was developed with high solar absorptance and low thermal emittance, with thermal stability at high temperature. A measurement technique was also developed to determine absorptance and total hemispherical emittance at high temperature, and was used to characterize the fabricated spectrally selective surfaces. In addition, a novel reflective cavity was designed to reduce radiative absorber losses and achieve high receiver efficiency at low concentration ratios. A prototype cavity demonstrated that large reductions in radiative losses were possible through this technique. For the overall concentrating STEG system, a number of devices were fabricated and tested in a custom built test platform to characterize their efficiency performance. Additionally, testing was performed with integration of PCM thermal storage, and the storage time of the lab scale system was evaluated. Our latest testing results showed a STEG efficiency of 9.6%, indicating promising potential for high performance concentrated STEGs.

  1. Potency of Thermoelectric Generator for Hybrid Vehicle

    Directory of Open Access Journals (Sweden)

    Nandy Putra

    2010-10-01

    Full Text Available Thermoelectric Generator (TEG has been known as electricity generation for many years. If the temperature difference occurred between two difference semi conductor materials, the current will flow in the material and produced difference voltage. This principle is known as Seebeck effect that is the opposite of Peltier effect Thermoelectric Cooling (TEC. This research was conducted to test the potential of electric source from twelve peltier modules. Then, these thermoelectric generators were applied in hybrid car by using waste heat from the combustion engine. The experiment has been conducted with variations of peltier module arrangements (series and parallels and heater as heat source for the thermoelectric generator, with variations of heater voltage input (110V and 220V applied. The experimental result showed that twelve of peltier modules arranged in series and heater voltage of 220V generated power output of 8.11 Watts with average temperature difference of 42.82°C. This result shows that TEG has a bright prospect as alternative electric source.

  2. Intermolecular thermoelectric-like effects in molecular nano electronic systems

    International Nuclear Information System (INIS)

    Sabzyan, H.; Safari, R.

    2012-01-01

    Intramolecular thermoelectric-like coefficients are introduced and computed of a single molecule nano electronic system. Values of the electronic Intramolecular thermoelectric-like coefficients are calculated based on the density and energy transfers between different parts of the molecule using quantum theory of atoms in molecule. Since, Joule and Peltier heating are even (symmetrical) and odd (antisymmetric) functions of the external bias, it is possible to divide Intramolecular thermoelectric-like coefficients into two components, symmetrical and antisymmetrical Intramolecular thermoelectric-like coefficients, which describe the intramolecular Joule-like and Peltier-like effects, respectively. In addition, a semiclassical temperature model is presented to describe intramolecular temperature mapping (intramolecular energy distributions) in molecular nano electronic systems.

  3. Lead telluride with increased mechanical stability for cylindrical thermoelectric generators

    International Nuclear Information System (INIS)

    Schmitz, Andreas

    2013-01-01

    The aim of this work is to improve the mechanical stability of lead telluride (PbTe), trying to vary its mechanical properties independently from its thermoelectric properties. Thus the influence of material preparation as well as different dopants on the mechanical and thermoelectric properties of lead telluride is being analysed. When using appropriately set process parameters, milling and sintering of lead telluride increases the material's hardness. With sintering temperatures exceeding 300 C stable material of high relative density can be achieved. Milling lead telluride generates lattice defects leading to a reduction of the material's charge carrier density. These defects can be reduced by increased sintering temperatures. Contamination of the powder due to the milling process leads to bloating during thermal cycling and thus reduced density of the sintered material. In addition to that, evaporation of tellurium at elevated temperatures causes instability of the material's thermoelectric properties. Based on the experimental results obtained in this work, the best thermoelectric and mechanical properties can be obtained by sintering coarse powders at around 400 C. Within this work a concept was developed to vary the mechanical properties of lead telluride via synthesis of PbTe with electrically nondoping elements, which thus may keep the thermoelectric properties unchanged. Therefore, the mechanical and thermoelectric properties of Pb 1-x Ca x Te were investigated. Doping pure PbTe with calcium causes a significant increase of the material's hardness while only slightly decreasing the charge carrier density and thus keeping the thermoelectric properties apart from a slight reduction of the electrical conductivity nearly unchanged. The abovementioned concept is proven using sodium doped lead telluride, as it is used for thermoelectric generators: The additional doping with calcium again increases the material's hardness while its thermoelectric properties

  4. High-temperature brushless DC motor controller

    Science.gov (United States)

    Cieslewski, Crzegorz; Lindblom, Scott C.; Maldonado, Frank J.; Eckert, Michael Nathan

    2017-05-16

    A motor control system for deployment in high temperature environments includes a controller; a first half-bridge circuit that includes a first high-side switching element and a first low-side switching element; a second half-bridge circuit that includes a second high-side switching element and a second low-side switching element; and a third half-bridge circuit that includes a third high-side switching element and a third; low-side switching element. The motor controller is arranged to apply a pulse width modulation (PWM) scheme to switch the first half-bridge circuit, second half-bridge circuit, and third half-bridge circuit to power a motor.

  5. Thermoelectric air-cooling module for electronic devices

    International Nuclear Information System (INIS)

    Chang, Yu-Wei; Chang, Chih-Chung; Ke, Ming-Tsun; Chen, Sih-Li

    2009-01-01

    This article investigates the thermoelectric air-cooling module for electronic devices. The effects of heat load of heater and input current to thermoelectric cooler are experimentally determined. A theoretical model of thermal analogy network is developed to predict the thermal performance of the thermoelectric air-cooling module. The result shows that the prediction by the model agrees with the experimental data. At a specific heat load, the thermoelectric air-cooling module reaches the best cooling performance at an optimum input current. In this study, the optimum input currents are from 6 A to 7 A at the heat loads from 20 W to 100 W. The result also demonstrates that the thermoelectric air-cooling module performs better performance at a lower heat load. The lowest total temperature difference-heat load ratio is experimentally estimated as -0.54 W K -1 at the low heat load of 20 W, while it is 0.664 W K -1 at the high heat load of 100 W. In some conditions, the thermoelectric air-cooling module performs worse than the air-cooling heat sink only. This article shows the effective operating range in which the cooling performance of the thermoelectric air-cooling module excels that of the air-cooling heat sink only.

  6. Portable Thermoelectric Power Generator Coupled with Phase Change Material

    Directory of Open Access Journals (Sweden)

    Lim Chong C.

    2014-07-01

    Full Text Available Solar is the intermittent source of renewable energy and all thermal solar systems having a setback on non-functioning during the night and cloudy environment. This paper presents alternative solution for power generation using thermoelectric which is the direct conversion of temperature gradient of hot side and cold side of thermoelectric material to electric voltage. Phase change material with latent heat effect would help to prolong the temperature gradient across thermoelectric material for power generation. Besides, the concept of portability will enable different power source like solar, wasted heat from air conditioner, refrigerator, stove etc, i.e. to create temperature different on thermoelectric material for power generation. Furthermore, thermoelectric will generate direct current which is used by all the gadgets like Smartphone, tablet, laptop etc. The portable concept of renewable energy will encourage the direct usage of renewable energy for portable gadgets. The working principle and design of portable thermoelectric power generator coupled with phase change material is presented in this paper.

  7. Thermoelectric-figure-of-merit enhancement of silicon-germanium through nanocomposite concept

    Science.gov (United States)

    Wang, Dezhi

    SiGe alloy has been the thermoelectric material element of RTGs (Radioisotope thermoelectric power generators) for more than 20 years because of its good performance at high temperature. It also has a very high potential application in converting exhaust heat into useful electricity, which currently attracts a lot of research interest in the automotive industry where 40% of the energy was rejected as exhaust heat. However, its low conversion efficiency (8%) is a major concern although it is the best in practice. A new concept, namely Si-Ge nanocomposite, was proposed to enhance thermoelectric figure-of-merit. Fast heating pressure sintering was found to be an appropriate synthesizing method and a lab-made direct current-induced hot press system was established. It can reach l200°C within several minutes and many parameters can be controlled. The uniquely designed graphite die assembly can stand l60MPa pressure which is better than the best commercial products (127MPa). Numerous Si-Ge nanocomposite samples were pressed using our DC hot press. Fully dense n-type Si-Ge nanocomposite samples of nanoSi80nanoGe20P were finally obtained. The nanocomposite structure was characterized via XRD, SEM, EDS, and TEM. The proposed nanocomposite structure, dots in a matrix, was observed. Most importantly, the thermoelectric property measurements showed that the Si-Ge nanocomposite of n-type nanoSi80nanoGe20 possessed higher electrical conductivity but lower thermal conductivity, thus a higher ZT than that of n-type nanoSi80microGe20. This result proved that thermoelectric-figure-of-merit enhancement through the nanocomposite concept was the right direction.

  8. Introduction to thermoelectricity

    CERN Document Server

    Goldsmid, H Julian

    2016-01-01

    This book is a comprehensive introduction to all aspects of thermoelectric energy conversion. It covers both theory and practice. The book is timely as it refers to the many improvements that have come about in the last few years through the use of nanostructures. The concept of semiconductor thermoelements led to major advances during the second half of the twentieth century, making Peltier refrigeration a widely used technique. The latest materials herald thermoelectric generation as the preferred technique for exploiting low-grade heat. The book shows how progress has been made by increasing the thermal resistivity of the lattice until it is almost as large as it is for glass. It points the way towards the attainment of similar improvements in the electronic parameters. It does not neglect practical considerations, such as the desirability of making thermocouples from inexpensive and environmentally acceptable materials. The second edition was extended to also include recent advances in thermoelectric ener...

  9. Thermal and thermoelectric transport measurements of an individual boron arsenide microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jaehyun; Sellan, Daniel P.; Ou, Eric; Shi, Li, E-mail: lishi@mail.utexas.edu [Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Evans, Daniel A.; Williams, Owen M.; Cowley, Alan H. [Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712 (United States)

    2016-05-16

    Recent first principles calculations have predicted that boron arsenide (BAs) can possess an unexpectedly high thermal conductivity that depends sensitively on the crystal size and defect concentration. However, few experimental results have been obtained to verify these predictions. In the present work, we report four-probe thermal and thermoelectric transport measurements of an individual BAs microstructure that was synthesized via a vapor transport method. The measured thermal conductivity was found to decrease slightly with temperature in the range between 250 K and 350 K. The temperature dependence suggests that the extrinsic phonon scattering processes play an important role in addition to intrinsic phonon-phonon scattering. The room temperature value of (186 ± 46) W m{sup −1 }K{sup −1} is higher than that of bulk silicon but still a factor of four lower than the calculated result for a defect-free, non-degenerate BAs rod with a similar diameter of 1.15 μm. The measured p-type Seebeck coefficient and thermoelectric power factor are comparable to those of bismuth telluride, which is a commonly used thermoelectric material. The foregoing results also suggest that it is necessary to not only reduce defect and boundary scatterings but also to better understand and control the electron scattering of phonons in order to achieve the predicted ultrahigh intrinsic lattice thermal conductivity of BAs.

  10. Heat shrink formation of a corrugated thin film thermoelectric generator

    International Nuclear Information System (INIS)

    Sun, Tianlei; Peavey, Jennifer L.; David Shelby, M.; Ferguson, Scott; O’Connor, Brendan T.

    2015-01-01

    Highlights: • Demonstrate and characterize a thermoelectric generator with a corrugated geometry. • Employ a novel heat shrink fabrication approach compatible with low-cost processing. • Use thermal impedance modeling to explore design potential. • Corrugated design shown to be advantageous for low heat-flux density applications. - Abstract: A thin film thermoelectric (TE) generator with a corrugated architecture is demonstrated formed using a heat-shrink fabrication approach. Fabrication of the corrugated TE structure consists of depositing thin film thermoelectric elements onto a planar non-shrink polyimide substrate that is then sandwiched between two uniaxial stretch-oriented co-polyester (PET) films. The heat shrink PET films are adhered to the polyimide in select locations, such that when the structure is placed in a high temperature environment, the outer films shrink resulting in a corrugated core film and thermoelectric elements spanning between the outer PET films. The module has a cross-plane heat transfer architecture similar to a conventional bulk TE module, but with heat transfer in the plane of the thin film thermoelectric elements, which assists in maintaining a significant temperature difference across the thermoelectric junctions. In this demonstration, Ag and Ni films are used as the thermoelectric elements and a Seebeck coefficient of 14 μV K −1 is measured with a maximum power output of 0.22 nW per couple at a temperature difference of 7.0 K. We then theoretically consider the performance of this device architecture with high performance thermoelectric materials in the heat sink limited regime. The results show that the heat-shrink approach is a simple fabrication method that may be advantageous in large-area, low power density applications. The fabrication method is also compatible with simple geometric modification to achieve various form factors and power densities to customize the TE generator for a range of applications

  11. Modeling a Thermoelectric Generator Applied to Diesel Automotive Heat Recovery

    Science.gov (United States)

    Espinosa, N.; Lazard, M.; Aixala, L.; Scherrer, H.

    2010-09-01

    Thermoelectric generators (TEGs) are outstanding devices for automotive waste heat recovery. Their packaging, lack of moving parts, and direct heat to electrical conversion are the main benefits. Usually, TEGs are modeled with a constant hot-source temperature. However, energy in exhaust gases is limited, thus leading to a temperature decrease as heat is recovered. Therefore thermoelectric properties change along the TEG, affecting performance. A thermoelectric generator composed of Mg2Si/Zn4Sb3 for high temperatures followed by Bi2Te3 for low temperatures has been modeled using engineering equation solver (EES) software. The model uses the finite-difference method with a strip-fins convective heat transfer coefficient. It has been validated on a commercial module with well-known properties. The thermoelectric connection and the number of thermoelements have been addressed as well as the optimum proportion of high-temperature material for a given thermoelectric heat exchanger. TEG output power has been estimated for a typical commercial vehicle at 90°C coolant temperature.

  12. The system of thermoelectric air conditioning based on permeable thermoelements

    Directory of Open Access Journals (Sweden)

    Cherkez R. G.

    2009-04-01

    Full Text Available There is thermoelectric air conditioner unit on the basis of permeable cooling thermoelements presented. In thermoelectric air conditioner unit the thermoelectric effects and the Joule–Thomson effect have been used for the air stream cooling. There have been described the method of temperature distribution analysis, the determinations of energy conversion power characteristics and design style of permeable thermoelement with maximum coefficient of performance described. The results of computer analysis concerning the application of the thermoelement legs material on the basis of Bi2Te3 have shown the possibility of coefficient of performance increase by a factor of 1,6—1,7 as compared with conventional thermoelectric systems.

  13. High performance p-type half-Heusler thermoelectric materials

    Science.gov (United States)

    Yu, Junjie; Xia, Kaiyang; Zhao, Xinbing; Zhu, Tiejun

    2018-03-01

    Half-Heusler compounds, which possess robust mechanical strength, good high temperature thermal stability and multifaceted physical properties, have been verified as a class of promising thermoelectric materials. During the last two decades, great progress has been made in half-Heusler thermoelectrics. In this review, we summarize some representative work of p-type half-Heusler materials, the thermoelectric performance of which has been remarkably enhanced in recent years. We introduce the features of the crystal and electronic structures of half-Heusler compounds, and successful strategies for optimizing electrical and thermal transport in the p-type RFeSb (R  =  V, Nb, Ta) and MCoSb (M  =  Ti, Zr, Hf) based systems, including band engineering, the formation of solid solutions and hierarchical phonon scattering. The outlook for future research directions of half-Heusler thermoelectrics is also presented.

  14. Enhancing Thermoelectric Performance Using Nonlinear Transport Effects

    Science.gov (United States)

    Jiang, Jian-Hua; Imry, Yoseph

    2017-06-01

    We study nonlinear transport effects on the maximum efficiency and power for both inelastic and elastic thermoelectric generators. The former device refers to phonon-assisted hopping in double quantum dots, while the latter device is represented by elastic tunneling through a single quantum dot. We find that nonlinear thermoelectric transport can lead to enhanced efficiency and power for both types of devices. A comprehensive survey of various quantum-dot energy, temperature, and parasitic heat conduction reveals that the nonlinear transport-induced improvements of the maximum efficiency and power are overall much more significant for inelastic devices than for elastic devices, even for temperature biases as small as Th=1.2 Tc (Th and Tc are the temperatures of the hot and cold reservoirs, respectively). The underlying mechanism is revealed as due to the fact that, unlike the Fermi distribution, the Bose distribution is not bounded when the temperature bias increases. A large flux density of absorbed phonons leads to a great enhancement of the electrical current, output power, and energy efficiency, dominating over the concurrent increase of the parasitic heat current. Our study reveals that nonlinear transport effects can be a useful tool for improving thermoelectric performance.

  15. Systems and methods for the synthesis of high thermoelectric performance doped-SnTe materials

    Science.gov (United States)

    Ren, Zhifeng; Zhang, Qian; Chen, Gang

    2018-02-27

    A thermoelectric composition comprising tin (Sn), tellurium (Te) and at least one dopant that comprises a peak dimensionless figure of merit (ZT) of 1.1 and a Seebeck coefficient of at least 50 .mu.V/K and a method of manufacturing the thermoelectric composition. A plurality of components are disposed in a ball-milling vessel, wherein the plurality of components comprise tin (Sn), tellurium (Te), and at least one dopant such as indium (In). The components are subsequently mechanically and thermally processed, for example, by hot-pressing. In response to the mechanical-thermally processing, a thermoelectric composition is formed, wherein the thermoelectric composition comprises a dimensionless figure of merit (ZT) of the thermoelectric composition is at least 0.8, and wherein a Seebeck coefficient of the thermoelectric composition is at least 50 .mu.V/K at any temperature.

  16. Thermoelectrode for thermoelectric converter

    International Nuclear Information System (INIS)

    Bodiul, Pavel; Bondarciuc, Nicolae; Ghitu, Dumitru; Nikolaeva, Albina; Konopko, Leonid; Turcan, Ana

    2008-01-01

    The invention relates to the electronic engneering and can be used for manufacturing of thermoelectrodes for thermoelectric converters. The thermoelectrode is made of semiconductor anisotropic material in the form of thread in glass insulation. At the same timer, the thread is made of stannum-doped tellurium in the ratio of 0.1...3 at.%.

  17. Study of thermoelectric systems applied to electric power generation

    International Nuclear Information System (INIS)

    Rodriguez, A.; Vian, J.G.; Astrain, D.; Martinez, A.

    2009-01-01

    A computational model has been developed in order to simulate the thermal and electric behavior of thermoelectric generators. This model solves the nonlinear system of equations of the thermoelectric and heat transfer equations. The inputs of the program are the thermoelectric parameters as a function of temperature and the boundary conditions, (room temperature and residual heat flux). The outputs are the temperature values of all the elements forming the thermoelectric generator, (performance, electric power, voltage and electric current generated). The model solves the equation system using the finite difference method and semi-empirical expressions for the convection coefficients. A thermoelectric electric power generation test bench has been built in order to validate and determine the accuracy of the computational model, which maximum error is lower than 5%. The objective of this study is to create a design tool that allows us to solve the system of equations involved in the electric generation process without needing to impose boundary conditions that are not known in the design phase, such as the temperature of the Peltier modules. With the computational model, we study the influence of the heat flux supplied as well as the room temperature on the electric power generated.

  18. Smart building temperature control using occupant feedback

    Science.gov (United States)

    Gupta, Santosh K.

    This work was motivated by the problem of computing optimal commonly-agreeable thermal settings in spaces with multiple occupants. In this work we propose algorithms that take into account each occupant's preferences along with the thermal correlations between different zones in a building, to arrive at optimal thermal settings for all zones of the building in a coordinated manner. In the first part of this work we incorporate active occupant feedback to minimize aggregate user discomfort and total energy cost. User feedback is used to estimate the users comfort range, taking into account possible inaccuracies in the feedback. The control algorithm takes the energy cost into account, trading it off optimally with the aggregate user discomfort. A lumped heat transfer model based on thermal resistance and capacitance is used to model a multi-zone building. We provide a stability analysis and establish convergence of the proposed solution to a desired temperature that minimizes the sum of energy cost and aggregate user discomfort. However, for convergence to the optimal, sufficient separation between the user feedback frequency and the dynamics of the system is necessary; otherwise, the user feedback provided do not correctly reflect the effect of current control input value on user discomfort. The algorithm is further extended using singular perturbation theory to determine the minimum time between successive user feedback solicitations. Under sufficient time scale separation, we establish convergence of the proposed solution. Simulation study and experimental runs on the Watervliet based test facility demonstrates performance of the algorithm. In the second part we develop a consensus algorithm for attaining a common temperature set-point that is agreeable to all occupants of a zone in a typical multi-occupant space. The information on the comfort range functions is indeed held privately by each occupant. Using occupant differentiated dynamically adjusted prices as

  19. Benchmarking of a novel contactless characterisation method for micro thermoelectric modules (μTEMs)

    International Nuclear Information System (INIS)

    Hickey, S; Punch, J; Jeffers, N

    2014-01-01

    Significant challenges exist in the thermal control of Photonics Integrated Circuits (PICs) for use in optical communications. Increasing component density coupled with greater functionality is leading to higher device-level heat fluxes, stretching the capabilities of conventional cooling methods using thermoelectric modules (TEMs). A tailored thermal control solution incorporating micro thermoelectric modules (μTEMs) to individually address hotspots within PICs could provide an energy efficient alternative to existing control methods. Performance characterisation is required to establish the suitability of commercially-available μTEMs for the operating conditions in current and next generation PICs. The objective of this paper is to outline a novel method for the characterisation of thermoelectric modules (TEMs), which utilises infra-red (IR) heat transfer and temperature measurement to obviate the need for mechanical stress on the upper surface of low compression tolerance (∼0.5N) μTEMs. The method is benchmarked using a commercially-available macro scale TEM, comparing experimental data to the manufacturer's performance data sheet.

  20. Benchmarking of a novel contactless characterisation method for micro thermoelectric modules (μTEMs)

    Science.gov (United States)

    Hickey, S.; Punch, J.; Jeffers, N.

    2014-07-01

    Significant challenges exist in the thermal control of Photonics Integrated Circuits (PICs) for use in optical communications. Increasing component density coupled with greater functionality is leading to higher device-level heat fluxes, stretching the capabilities of conventional cooling methods using thermoelectric modules (TEMs). A tailored thermal control solution incorporating micro thermoelectric modules (μTEMs) to individually address hotspots within PICs could provide an energy efficient alternative to existing control methods. Performance characterisation is required to establish the suitability of commercially-available μTEMs for the operating conditions in current and next generation PICs. The objective of this paper is to outline a novel method for the characterisation of thermoelectric modules (TEMs), which utilises infra-red (IR) heat transfer and temperature measurement to obviate the need for mechanical stress on the upper surface of low compression tolerance (~0.5N) μTEMs. The method is benchmarked using a commercially-available macro scale TEM, comparing experimental data to the manufacturer's performance data sheet.

  1. Interference enhanced thermoelectricity in quinoid type structures

    Energy Technology Data Exchange (ETDEWEB)

    Strange, M., E-mail: strange@chem.ku.dk; Solomon, G. C. [Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø (Denmark); Seldenthuis, J. S.; Verzijl, C. J. O.; Thijssen, J. M. [Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft (Netherlands)

    2015-02-28

    Quantum interference (QI) effects in molecular junctions may be used to obtain large thermoelectric responses. We study the electrical conductance G and the thermoelectric response of a series of molecules featuring a quinoid core using density functional theory, as well as a semi-empirical interacting model Hamiltonian describing the π-system of the molecule which we treat in the GW approximation. Molecules with a quinoid type structure are shown to have two distinct destructive QI features close to the frontier orbital energies. These manifest themselves as two dips in the transmission, that remain separated, even when either electron donating or withdrawing side groups are added. We find that the position of the dips in the transmission and the frontier molecular levels can be chemically controlled by varying the electron donating or withdrawing character of the side groups as well as the conjugation length inside the molecule. This feature results in a very high thermoelectric power factor S{sup 2}G and figure of merit ZT, where S is the Seebeck coefficient, making quinoid type molecules potential candidates for efficient thermoelectric devices.

  2. 30 CFR 77.314 - Automatic temperature control instruments.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Automatic temperature control instruments. 77... UNDERGROUND COAL MINES Thermal Dryers § 77.314 Automatic temperature control instruments. (a) Automatic temperature control instruments for thermal dryer system shall be of the recording type. (b) Automatic...

  3. Synthesis and Characterization of Thermoelectric Oxides at Macro- and Nano-scales

    Science.gov (United States)

    Ma, Feiyue

    Thermoelectric materials can directly convert a temperature difference into electrical voltage and vice versa. Due to this unique property, thermoelectric materials are widely used in industry and scientific laboratories for temperature sensing and thermal management applications. Waste heat harvesting, another potential application of thermoelectric materials, has long been limited by the low conversion efficiency of the materials. Potential high temperature applications, such as power plant waste heat harvesting and combustion engine exhaust heat recovery, make thermoelectric oxides a very promising class of thermoelectric materials. In this thesis, the synthesis and characterization of thermoelectric oxide materials are explored. In the first part of this thesis, the measurement methodologies and instrumentation processes employed to investigate different thermoelectric properties, such as the Seebeck coefficient and carrier concentration at the bulk scale and the thermal conductivity at the nanoscale, are detailed. Existing scientific and engineering challenges associated with these measurements are also reviewed. To overcome such problems, original parts and methodologies have been designed. Three fully functional systems were ultimately developed for the characterization of macroscale thermoelectric properties as well as localized thermal conductivity. In the second part of the thesis, the synthesis of NaxCo 2O4, a thermoelectric oxide material, is discussed. Modification of both composition and structure were carried out so as to optimize the thermoelectric performance of NaxCo2O4. Nanostructuring methods, such as ball milling, electrospinning, auto-combustion synthesis, and core-shell structure fabrication, have been developed to refine the grain size of NaxCo2O4 in order to reduce its thermal conductivity. However, the structure of the nanostructured materials is very unstable at high temperature and limited improvement on thermoelectric performance is

  4. Tegen - an onedimensional program to calculate a thermoelectric generator

    International Nuclear Information System (INIS)

    Rosa, M.A.P.; Ferreira, P.A.; Castro Lobo, P.D. de.

    1990-01-01

    A computer program for the solution of the one-dimensional, steady-state temperature equation in the arms of a thermoelectric generator. The discretized equations obtained through a finite difference scheme are solved by Gaussian Elimination. Due to nonlinearities caused by the temperature dependence of the coefficients of such equations, an iterative procedure is used to obtain the temperature distribution in the arms. Such distributions are used in the calculation of the efficiency, electric power, load voltage and other relevant parameters for the design of a thermoelectric generator. (author)

  5. From phase-change materials to thermoelectrics?

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Matthias N.; Rosenthal, Tobias; Oeckler, Oliver [Dept. of Chemistry, Ludwig Maximilian Univ. Munich (Germany); Stiewe, Christian [German Aerospace Center, Cologne (Germany)

    2010-07-01

    Metastable tellurides play an important role as phase-change materials in data storage media and non-volatile RAM devices. The corresponding crystalline phases with very simple basic structures are not stable as bulk materials at ambient conditions, however, for a broad range of compositions they represent stable high-temperature phases. In the system Ge/Sb/Te, rocksalt-type high-temperature phases are characterized by a large number of vacancies randomly distributed over the cation position, which order as 2D vacancy layers upon cooling. Short-range order in quenched samples produces pronounced nanostructures by the formation of twin domains and finite intersecting vacancy layers. As phase-change materials are usually semimetals or small-bandgap semiconductors and efficient data storage requires low thermal conductivity, bulk materials with similar compositions and properties can be expected to exhibit promising thermoelectric characteristics. Nanostructuring by phase transitions that involve partial vacancy ordering may enhance the efficiency of such thermoelectrics. We have shown that germanium antimony tellurides with compositions close to those used as phase-change materials in rewritable Blu-Ray Discs, e.g. (GeTe){sub 12}Sb{sub 2}Te{sub 3}, exhibit thermoelectric figures of merit of up to ZT = 1.3 at 450 C if a nanodomain structure is induced by rapidly quenching the cubic high-temperature phase. Structural changes have been elucidated by X-ray diffraction and high-resolution electron microscopy. (orig.)

  6. Interfacial reactions in thermoelectric modules

    KAUST Repository

    Wu, Hsin-jay

    2018-02-21

    Engineering transport properties of thermoelectric (TE) materials leads to incessantly breakthroughs in the zT values. Nevertheless, modular design holds a key factor to advance the TE technology. Herein, we discuss the structures of TE module and illustrate the inter-diffusions across the interface of constituent layers. For Bi2Te3-based module, soldering is the primary bonding method, giving rise to the investigations on the selections of solder, diffusion barrier layer and electrode. For mid-temperature PbTe-based TE module, hot-pressing or spark plasma sintering are alternative bonding approaches; the inter-diffusions between the diffusion barrier layer, electrode and TE substrate are addressed as well.

  7. Design Optimization of a Thermoelectric Cooling Module Using Finite Element Simulations

    Science.gov (United States)

    Abid, Muhammad; Somdalen, Ragnar; Rodrigo, Marina Sancho

    2018-05-01

    The thermoelectric industry is concerned about the size reduction, cooling performance and, ultimately, the production cost of thermoelectric modules. Optimization of the size and performance of a commercially available thermoelectric cooling module is considered using finite element simulations. Numerical simulations are performed on eight different three-dimensional geometries of a single thermocouple, and the results are further extended for a whole module as well. The maximum temperature rise at the hot and cold sides of a thermocouple is determined by altering its height and cross-sectional area. The influence of the soldering layer is analyzed numerically using temperature dependent and temperature independent thermoelectric properties of the solder material and the semiconductor pellets. Experiments are conducted to test the cooling performance of the thermoelectric module and the results are compared with the results obtained through simulations. Finally, cooling rate and maximum coefficient of performance (COPmax) are computed using convective and non-convective boundary conditions.

  8. Results of metallographical diagnostic examination of Navy half-watt thermoelectric converters degraded by accelerated tests

    International Nuclear Information System (INIS)

    Rosell, F.E. Jr.; Rouklove, P.G.

    1977-01-01

    To verify the 15-year reliability of the Navy half-watt radioisotope thermoelectric generator (RTG), bismuth--telluride thermoelectric converters were submitted to testing at high temperatures which accelerated the degradation and caused failure of the converters. Metallographic diagnostic examination of failed units verified failure mechanisms. Results of diagnostic examinations are presented

  9. Thermoelectric properties of ternary phases of thallium-tin-tellurium system

    Energy Technology Data Exchange (ETDEWEB)

    Dichi, E. [Equipe materiaux et sante, faculte de pharmacie, universite Paris XI, 5, rue J.B, EA 401, Clement 92296 Chatenay-Malabry (France)], E-mail: emma.dichi@cep.u-psud.fr; Sghaier, M. [Equipe materiaux et sante, faculte de pharmacie, universite Paris XI, 5, rue J.B, EA 401, Clement 92296 Chatenay-Malabry (France); Kra, G. [Laboratoire de chimie minerale, universite de Cocody, 22, BP 582, Abidjan 22, Cote d' Ivoire (France)

    2008-06-30

    In this paper, we present the measurements of conductivity and of thermoelectric power. Measurements were taken for the temperature range of 100-330 K for the three ternary phases of Tl-Sn-Te system. The potential of these compounds as thermoelectric materials was studied.

  10. Tuning the Transport Properties of Layered Materials for Thermoelectric Applications using First-Principles Calculations

    KAUST Repository

    Saeed, Yasir

    2014-05-11

    Thermoelectric materials can convert waste heat into electric power and thus provide a way to reduce the dependence on fossil fuels. Our aim is to model the underlying materials properties and, in particular, the transport as controlled by electrons and lattice vibrations. The goal is to develop an understanding of the thermoelectric properties of selected materials at a fundamental level. The structural, electronic, optical, and phononic properties are studied in order to tune the transport, focusing on KxRhO2, NaxRhO2, PtSb2 and Bi2Se3. The investigations are based on density functional theory as implemented in the all electron linearized augmented plane wave plus local orbitals WIEN2k and pseudo potential Quantum-ESPRESSO codes. The thermoelectric properties are derived from Boltzmann transport theory under the constant relaxation time approximation, using the BoltzTraP code. We will discuss first the changes in the electronic band structure under variation of the cation concentration in layered KxRhO2 in the 2H phase and NaxRhO2 in the 3R phase. We will also study the hydrated phase. The deformations of the RhO6 octahedra turn out to govern the thermoelectric properties, where the high Seebeck coefficient results from ”pudding mold" bands. We investigate the thermoelectric properties of electron and hole doped PtSb2, which is not a layered material but shares “pudding mold" bands. PtSb2 has a high Seebeck coefficient at room temperature, which increases significantly under As alloying by bandgap opening and reduction of the lattice thermal conductivity. Bi2Se3 (bulk and thin film) has a larger bandgap then the well-known thermoelectric material Bi2Te3, which is important at high temperature. The structural stability, electronic structure, and transport properties of one to six quintuple layers of Bi2Se3 will be discussed. We also address the effect of strain on a single quintuple layer by phonon band structures. We will analyze the electronic and transport

  11. High-temperature thermoelectric properties of p-type skutterudites Ba0.15Yb x Co3FeSb12 and Yb y Co3FeSb9As3

    KAUST Repository

    Dong, Yongkwan

    2014-08-28

    Two series of p-type polycrystalline skutterudites, Ba0.15YbxCo3FeSb12 and YbyCo3FeSb9As3 with varying Yb concentrations, were synthesized by solid-state reaction and then densified by hot pressing. The phase and stoichiometries of the resulting materials were characterized by powder X-ray diffraction and energy dispersive spectroscopy, while their high-temperature transport properties were investigated from 300 to 800 K. The Seebeck coefficients and electrical resistivities increased linearly with increasing temperature for the double-filled specimens. The Seebeck coefficients and electrical resistivities did not change very much for the As-substituted specimens. The thermal conductivity for all specimens decreased with increasing temperature up to 700 K, corresponding to the plateau in the Seebeck coefficient, and then increased again due to bipolar diffusion. We find that double filling is a more feasible approach to thermoelectric property optimization than single filling with As substitution. © 2014 Springer Science+Business Media New York.

  12. Acido-basic control of the thermoelectric properties of poly(3,4-ethylenedioxythiophene)tosylate (PEDOT-Tos) thin films

    DEFF Research Database (Denmark)

    Khan, Zia Ullah; Bubnova, Olga; Jafari, Mohammad Javad

    2015-01-01

    study the variation in the thermoelectric properties by a simple acido-basic treatment. The emphasis of this study is to elucidate the chemical changes induced by acid (HCl) or base (NaOH) treatment in PEDOT-Tos thin films using various spectroscopic and structural techniques. We could identify changes...... in the nanoscale morphology due to anion exchange between tosylate and Cl- or OH-. But, we identified that changing the pH leads to a tuning of the oxidation level of the polymer, which can explain the changes in thermoelectric properties. Hence, a simple acid-base treatment allows finding the optimum...

  13. Thermoelectrical Generator for a MEMS-Fuze

    Directory of Open Access Journals (Sweden)

    A. K. Efremov

    2015-01-01

    Full Text Available The structure of modern fuzes includes micro-electromechanical systems (MEMS, which have such advanced devices as micro-accelerometers and micro-switches, being triggered at a specified level of setback. Independent power source (PS, as an inherent part of the MEMSfuze, charges an energy storage unit during the shot and triggers the fuze firing circuit when the shell encounters the target. Operating level of the control signal should be achieved within the time of remote arming, determined by the type of ammunition. The paper considers a possibility to develop PS as a thermoelectric generator (TEG with aerodynamic heating of hot junctions due to friction of the projectile body on the incoming airflow. The initial temperature is determined by the driving band cutting into the rifling and friction during the movement of projectile through the tube bore. The paper presents a technique for calculating the temperature field along the body of the projectile from the critical point, located at the top of the shell head. The solution of the equation of heat balance reveals the temporal development of the projectile body temperature. The proposed mathematical model of the TEG describes the process of converting heat into electrical output signal (thermo-EMF. An example of calculation for a specific artillery system – 57-mm anti-aircraft gun S-60 is given. Calculation of the TEG output signal was limited by the time, which is necessary to reach the top of the projectile trajectory. It is shown that at high altitude the temperature difference may drop to zero, thus cutting off the TEG output signal. Selection of capacitive storage parameters can be based on the reliability test conditions of the fuze firing circuit actuators, taking into account the partial storage discharge on the trajectory before the projectile encounters the target.

  14. Silicon Germanium Quantum Well Thermoelectrics

    Science.gov (United States)

    Davidson, Anthony Lee, III

    Today's growing energy demands require new technologies to provide high efficiency clean energy. Thermoelectrics that convert heat to electrical energy directly can provide a method for the automobile industry to recover waste heat to power vehicle electronics, hence improving fuel economy. If large enough efficiencies can be obtained then the internal combustion engine could even be replaced. Exhaust temperature for automotive application range from 400 to 800 K. In this temperature range the current state of the art materials are bulk Si1-xGex alloys. By alternating layers of Si and Si1-xGex alloy device performance may be enhanced through quantum well effects and variations in material thermal properties. In this study, superlattices designed for in-plane operation with varying period and crystallinity are examined to determine the effect on electrical and thermal properties. In-plane electrical resistivity of these materials was found to be below the bulk material at a similar doping at room temperature, confirming the role of quantum wells in electron transport. As period is reduced in the structures boundary scattering limits electron propagation leading to increased resistivity. The Seebeck coefficient measured at room temperature is higher than the bulk material, additionally lending proof to the effects of quantum wells. When examining cross-plane operation the low doping in the Si layers of the device produce high resistivity resulting from boundary scattering. Thermal conductivity was measured from 77 K up to 674 K and shows little variation due to periodicity and temperature, however an order of magnitude reduction over bulk Si1-xGex is shown in all samples. A model is developed that suggests a combination of phonon dispersion effects and strong boundary scattering. Further study of the phonon dispersion effects was achieved through the examination of the heat capacity by combining thermal diffusivity with thermal conductivity. All superlattices show a

  15. Design and analysis of solar thermoelectric power generation system

    Science.gov (United States)

    Vatcharasathien, Narong; Hirunlabh, Jongjit; Khedari, Joseph; Daguenet, Michel

    2005-09-01

    This article reports on the design and performance analysis of a solar thermoelectric power generation plant (STEPG). The system considers both truncated compound parabolic collectors (CPCs) with a flat receiver and conventional flat-plate collectors, thermoelectric (TE) cooling and power generator modules and appropriate connecting pipes and control devices. The design tool uses TRNSYS IIsibat-15 program with a new component we developed for the TE modules. The main input data of the system are the specifications of TE module, the maximum hot side temperature of TE modules, and the desired power output. Examples of the design using truncated CPC and flat-plate collectors are reported and discussed for various slope angle and half-acceptance angle of CPC. To minimize system cost, seasonal adjustment of the slope angle between 0° and 30° was considered, which could give relatively high power output under Bangkok ambient condition. Two small-scale STEPGs were built. One of them uses electrical heater, whereas the other used a CPC with locally made aluminum foil reflector. Measured data showed reasonable agreement with the model outputs. TE cooling modules were found to be more appropriate. Therefore, the TRNSYS software and the developed TE component offer an extremely powerful tool for the design and performance analysis of STEPG plant.

  16. Thermoelectric effects of amorphous Ga-Sn-O thin film

    Science.gov (United States)

    Matsuda, Tokiyoshi; Uenuma, Mutsunori; Kimura, Mutsumi

    2017-07-01

    The thermoelectric effects of an amorphous Ga-Sn-O (a-GTO) thin film have been evaluated as a physical parameter of a novel oxide semiconductor. Currently, a-GTO thin films are greatly desired not only because they do not contain rare metals and are therefore free from problems on the exhaustion of resources and the increase in cost but also because their initial characteristics and performance stabilities are excellent when they are used in thin-film transistors. In this study, an a-GTO thin film was deposited on a quartz substrate by RF magnetron sputtering and postannealing was performed in air at 350 °C for 1 h using an annealing furnace. The Seebeck coefficient and electrical conductivity of the a-GTO thin film were -137 µV/K and 31.8 S/cm at room temperature, and -183 µV/K and 43.8 S/cm at 397 K, respectively, and as a result, the power factor was 1.47 µW/(cm·K2) at 397 K; these values were roughly as high as those of amorphous In-Ga-Zn-O (a-IGZO) thin films. Therefore, a-GTO thin films will be a candidate material for thermoelectric devices fabricated in a large area at a low cost by controlling the carrier mobility, carrier density, device structures, and so forth.

  17. Thermoelectric power in n-InSe

    International Nuclear Information System (INIS)

    Casanovas, A.; Cantarero, A.; Segura, A.

    1985-01-01

    Thermoelectric power of InSe samples doped with tin has been measured as functions of the doping concentration in the range of 0.01 to 10% Sn and of the temperature in the range of 50 to 550 K. In the low temperature range the results obtained are coherent with the two-dimensional behaviour of electrons proposed by other authors. About 100 K the results can be explained successfully by introducing the same scattering mechanisms used to interpret the temperature dependence of the electron mobility

  18. Transient performance of integrated SOFC system including spatial temperature control

    OpenAIRE

    Mueller, F; Fardadi, M; Shaffer, B; Brouwer, J; Jabbari, F

    2010-01-01

    Spatial temperature feedback control has been developed for a simulated integrated non-pressurized simple cycle solid oxide fuel cell (SOFC) system. The fuel cell spatial temperature feedback controller is based on (1) feed-forward set-points that minimize temperature variation in the fuel cell electrode-electrolyte solid temperature profile for the system operating power range, and (2) decentralized proportional-integral based feedback to maintain the fuel cell spatial temperature profile du...

  19. Temperature Control System for Chromel-Alumel Thermocouple

    International Nuclear Information System (INIS)

    Piping Supriatna; Nurhanan; Riswan DJ; Heru K, B.; Edi Karyanta

    2003-01-01

    Nuclear Power Plan Operation Safety needs serious handling on temperature measurement and control. In this report has been done manufacturing Temperature Control System for Chromel-Alumel Thermocouple, accordance to material, equipment and human resource ability in the laboratory. Basic component for the Temperature Control System is LM-741 type of Operation Amplifier, which is functionalized as summer for voltage comparator. Function test for this Control System shown its ability for damping on temperature reference. The Temperature Control System will be implemented on PCB Processing Machine. (author)

  20. Evaluation of Thermoelectric Performance and Durability of Functionalized Skutterudite Legs

    Science.gov (United States)

    Skomedal, Gunstein; Kristiansen, Nils R.; Sottong, Reinhard; Middleton, Hugh

    2017-04-01

    Thermoelectric generators are a promising technology for waste heat recovery. As new materials and devices enter a market penetration stage, it is of interest to employ fast and efficient measurement methods to evaluate the long-term stability of thermoelectric materials in combination with metallization and coating (functionalized thermoelectric legs). We have investigated a method for measuring several thermoelectric legs simultaneously. The legs are put under a common temperature gradient, and the electrical characteristics of each leg are measured individually during thermal cycling. Using this method, one can test different types of metallization and coating applied to skutterudite thermoelectric legs and look at the relative changes over time. Postcharacterization of these initial tests with skutterudite legs using a potential Seebeck microprobe and an electron microscope showed that oxidation and interlayer diffusion are the main reasons for the gradual increase in internal resistance and the decrease in open-circuit voltage. Although we only tested skutterudite material in this work, the method is fully capable of testing all kinds of material, metallization, and coating. It is thus a promising method for studying the relationship between failure modes and mechanisms of functionalized thermoelectric legs.

  1. What Controls the Arctic Lower Stratosphere Temperature?

    Science.gov (United States)

    Newman, Paul A.; Nash, Eric R.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    The temperature of the Arctic lower stratosphere is critical for understanding polar ozone levels. As temperatures drop below about 195 K, polar stratospheric clouds form, which then convert HCl and ClONO2 into reactive forms that are catalysts for ozone loss reactions. Hence, the lower stratospheric temperature during the March period is a key parameter for understanding polar ozone losses. The temperature is basically understood to be a result of planetary waves which drive the polar temperature away from a cold "radiative equilibrium" state. This is demonstrated using NCEP/NCAR reanalysis calculations of the heat flux and the mean polar temperature. The temperature during the March period is fundamentally driven by the integrated impact of large scale waves moving from the troposphere to the stratosphere during the January through February period. We will further show that the recent cold years in the northern polar vortex are a result of this weakened wave driving of the stratosphere.

  2. Performance Evaluation of Waste Heat Recovery in a Charcoal Stove using a Thermo-Electric Module

    Directory of Open Access Journals (Sweden)

    Nnamdi Judges Ajah

    2018-03-01

    Full Text Available Charcoal stoves have widespread use among the poorer households and outdoor food vendors in Nigeria. In order to improve the efficiency of charcoal stoves, various researches have tried integrating a thermoelectric module in the charcoal stove. The researches, however did not exploit the performance of the thermoelectric modules at different ambient temperatures. To evaluate the performance of thermoelectric integrated charcoal stoves in the sub-Saharan Africa, a self-powered, forced air induced thermoelectric charcoal stove experiment was carried out at five different ambient temperatures of 36ºC, 33ºC, 32ºC, 30ºC and 29ºC and an average fuel hotbed temperature of 1023.75ºC. The thermoelectric charcoal stove generated a maximum voltage of 5.25V at an ambient temperature of 29ºC. The least maximum voltage was generated at the highest ambient temperature of 36ºC. It was observed that the maximum voltage increased with decreasing ambient temperature, this could be attributed to the ambient air being used to cool the thermoelectric generator. Therefore, it could be said that the performance of a forced draft thermoelectric charcoal stove increases with decrease in ambient temperature.

  3. Nano-materials Enabled Thermoelectricity from Window Glasses

    KAUST Repository

    Inayat, Salman Bin

    2012-11-13

    With a projection of nearly doubling up the world population by 2050, we need wide variety of renewable and clean energy sources to meet the increased energy demand. Solar energy is considered as the leading promising alternate energy source with the pertinent challenge of off sunshine period and uneven worldwide distribution of usable sun light. Although thermoelectricity is considered as a reasonable renewable energy from wasted heat, its mass scale usage is yet to be developed. Here we show, large scale integration of nano-manufactured pellets of thermoelectric nano-materials, embedded into window glasses to generate thermoelectricity using the temperature difference between hot outside and cool inside. For the first time, this work offers an opportunity to potentially generate 304 watts of usable power from 9 m2 window at a 206C temperature gradient. If a natural temperature gradient exists, this can serve as a sustainable energy source for green building technology.

  4. Design and Implementation of Temperature Controller for a Vacuum Distiller

    OpenAIRE

    Muslim, M. Aziz; N., Goegoes Dwi; F., Ahmad Salmi; R., Akhbar Prachaessardhi

    2014-01-01

    This paper proposed design and implementation of temperature controller for a vacuum distiller. The distiller is aimed to provide distillation process of bioethanol in nearly vacuum condition. Due to varying vacuum pressure, temperature have to be controlled by manipulating AC voltage to heating elements. Two arduino based control strategies have been implemented, PID control and Fuzzy Logic control. Control command from the controller was translated to AC drive using TRIAC based dimmer circu...

  5. Thermoelectric flux effect in superconducting indium

    International Nuclear Information System (INIS)

    Van Harlingen, D.J.

    1977-01-01

    In this paper we discuss a thermoelectric effect in superconductors which provides a mechanism for studying quasiparticle relaxation and scattering processes in non-equilibrium superconductors by transport measurements. We report measurements of the thermoelecric flux effect in samples consisting of indium and lead near the In transition temperature; in this temperature range, the contribution to DELTA/sub TAU/ from the Pb is insignificant and so values of OMEGA(T) are obtained for indium. The results of our experiments may be summarized as follows: (1) we have a thermally-generated flux effect in 5 superconducting In-Pb toroidal samples, (2) experimental tests suggest that the observed effect does indeed arise from the proposed thermoelectric flux effect, (3) OMEGA(T) for indium is found to diverge as (T/sub c/ - T)/sup -3/2/ more rapidly than predicted by simple theory, (4) OMEGA(T) at T/T sub c/ = .999 is nearly 10/sup 5/ larger than initially expected, (5) OMEGA (T) roughly correlates with the magnitude of the normal state thermoelectric coefficient for our samples

  6. Performance evaluation of an automotive thermoelectric generator

    Science.gov (United States)

    Dubitsky, Andrei O.

    Around 40% of the total fuel energy in typical internal combustion engines (ICEs) is rejected to the environment in the form of exhaust gas waste heat. Efficient recovery of this waste heat in automobiles can promise a fuel economy improvement of 5%. The thermal energy can be harvested through thermoelectric generators (TEGs) utilizing the Seebeck effect. In the present work, a versatile test bench has been designed and built in order to simulate conditions found on test vehicles. This allows experimental performance evaluation and model validation of automotive thermoelectric generators. An electrically heated exhaust gas circuit and a circulator based coolant loop enable integrated system testing of hot and cold side heat exchangers, thermoelectric modules (TEMs), and thermal interface materials at various scales. A transient thermal model of the coolant loop was created in order to design a system which can maintain constant coolant temperature under variable heat input. Additionally, as electrical heaters cannot match the transient response of an ICE, modelling was completed in order to design a relaxed exhaust flow and temperature history utilizing the system thermal lag. This profile reduced required heating power and gas flow rates by over 50%. The test bench was used to evaluate a DOE/GM initial prototype automotive TEG and validate analytical performance models. The maximum electrical power generation was found to be 54 W with a thermal conversion efficiency of 1.8%. It has been found that thermal interface management is critical for achieving maximum system performance, with novel designs being considered for further improvement.

  7. Nanocomposites with High Thermoelectric Figures of Merit

    Science.gov (United States)

    Chen, Gang (Inventor); Dresselhaus, Mildred (Inventor); Ren, Zhifeng (Inventor)

    2015-01-01

    The present invention is generally directed to nanocomposite thermoelectric materials that exhibit enhanced thermoelectric properties. The nanocomposite materials include two or more components, with at least one of the components forming nano-sized structures within the composite material. The components are chosen such that thermal conductivity of the composite is decreased without substantially diminishing the composite's electrical conductivity. Suitable component materials exhibit similar electronic band structures. For example, a band-edge gap between at least one of a conduction band or a valence band of one component material and a corresponding band of the other component material at interfaces between the components can be less than about 5k(sub B)T, wherein k(sub B) is the Boltzman constant and T is an average temperature of said nanocomposite composition.

  8. Thermoelectric generation coupling methanol steam reforming characteristic in microreactor

    International Nuclear Information System (INIS)

    Wang, Feng; Cao, Yiding; Wang, Guoqiang

    2015-01-01

    Thermoelectric (TE) generator converts heat to electric energy by thermoelectric material. However, heat removal on the cold side of the generator represents a serious challenge. To address this problem and for improved energy conversion, a thermoelectric generation process coupled with methanol steam reforming (SR) for hydrogen production is designed and analyzed in this paper. Experimental study on the cold spot character in a micro-reactor with monolayer catalyst bed is first carried out to understand the endothermic nature of the reforming as the thermoelectric cold side. A novel methanol steam reforming micro-reactor heated by waste heat or methanol catalytic combustion for hydrogen production coupled with a thermoelectric generation module is then simulated. Results show that the cold spot effect exists in the catalyst bed under all conditions, and the associated temperature difference first increases and then decreases with the inlet temperature. In the micro-reactor, the temperature difference between the reforming and heating channel outlets decreases rapidly with an increase in thermoelectric material's conductivity coefficient. However, methanol conversion at the reforming outlet is mainly affected by the reactor inlet temperature; while at the combustion outlet, it is mainly affected by the reactor inlet velocity. Due to the strong endothermic effect of the methanol steam reforming, heat supply of both kinds cannot balance the heat needed at reactor local areas, resulting in the cold spot at the reactor inlet. When the temperature difference between the thermoelectric module's hot and cold sides is 22 K, the generator can achieve an output voltage of 55 mV. The corresponding molar fraction of hydrogen can reach about 62.6%, which corresponds to methanol conversion rate of 72.6%. - Highlights: • Cold spot character of methanol steam reforming was studied through experiment. • Thermoelectric generation Coupling MSR process has been

  9. Thermoelectric powered wireless sensors for spent fuel monitoring

    International Nuclear Information System (INIS)

    Carstens, T.; Corradini, M.; Blanchard, J.; Ma, Z.

    2011-01-01

    This paper describes using thermoelectric generators to power wireless sensors to monitor spent nuclear fuel during dry-cask storage. OrigenArp was used to determine the decay heat of the spent fuel at different times during the service life of the dry-cask. The Engineering Equation Solver computer program modeled the temperatures inside the spent fuel storage facility during its service life. The temperature distribution in a thermoelectric generator and heat sink was calculated using the computer program Finite Element Heat Transfer. From these temperature distributions the power produced by the thermoelectric generator was determined as a function of the service life of the dry-cask. In addition, an estimation of the path loss experienced by the wireless signal can be made based on materials and thickness of the structure. Once the path loss is known, the transmission power and thermoelectric generator power requirements can be determined. This analysis estimates that a thermoelectric generator can produce enough power for a sensor to function and transmit data from inside the dry-cask throughout its service life. (authors)

  10. Yb14MnSb11 as a High-Efficiency Thermoelectric Material

    Science.gov (United States)

    Snyder, G. Jeffrey; Gascoin, Franck; Brown, Shawna; Kauzlarich, Susan

    2009-01-01

    Yb14MnSb11 has been found to be wellsuited for use as a p-type thermoelectric material in applications that involve hotside temperatures in the approximate range of 1,200 to 1,300 K. The figure of merit that characterizes the thermal-to-electric power-conversion efficiency is greater for this material than for SiGe, which, until now, has been regarded as the state-of-the art high-temperature ptype thermoelectric material. Moreover, relative to SiGe, Yb14MnSb11 is better suited to incorporation into a segmented thermoelectric leg that includes the moderate-temperature p-type thermoelectric material CeFe4Sb12 and possibly other, lower-temperature p-type thermoelectric materials. Interest in Yb14MnSb11 as a candidate high-temperature thermoelectric material was prompted in part by its unique electronic properties and complex crystalline structure, which place it in a class somewhere between (1) a class of semiconducting valence compounds known in the art as Zintl compounds and (2) the class of intermetallic compounds. From the perspective of chemistry, this classification of Yb14MnSb11 provides a first indication of a potentially rich library of compounds, the thermoelectric properties of which can be easily optimized. The concepts of the thermoelectric figure of merit and the thermoelectric compatibility factor are discussed in Compatibility of Segments of Thermo - electric Generators (NPO-30798), which appears on page 55. The traditional thermoelectric figure of merit, Z, is defined by the equation Z = alpha sup 2/rho K, where alpha is the Seebeck coefficient, rho is the electrical resistivity, and k is the thermal conductivity.

  11. Opto-thermoelectric nanotweezers

    Science.gov (United States)

    Lin, Linhan; Wang, Mingsong; Peng, Xiaolei; Lissek, Emanuel N.; Mao, Zhangming; Scarabelli, Leonardo; Adkins, Emily; Coskun, Sahin; Unalan, Husnu Emrah; Korgel, Brian A.; Liz-Marzán, Luis M.; Florin, Ernst-Ludwig; Zheng, Yuebing

    2018-04-01

    Optical manipulation of plasmonic nanoparticles provides opportunities for fundamental and technical innovation in nanophotonics. Optical heating arising from the photon-to-phonon conversion is considered as an intrinsic loss in metal nanoparticles, which limits their applications. We show here that this drawback can be turned into an advantage, by developing an extremely low-power optical tweezing technique, termed opto-thermoelectric nanotweezers. By optically heating a thermoplasmonic substrate, a light-directed thermoelectric field can be generated due to spatial separation of dissolved ions within the heating laser spot, which allows us to manipulate metal nanoparticles of a wide range of materials, sizes and shapes with single-particle resolution. In combination with dark-field optical imaging, nanoparticles can be selectively trapped and their spectroscopic response can be resolved in situ. With its simple optics, versatile low-power operation, applicability to diverse nanoparticles and tunable working wavelength, opto-thermoelectric nanotweezers will become a powerful tool in colloid science and nanotechnology.

  12. La 1-x Ca x MnO 3 semiconducting nanostructures: morphology and thermoelectric properties.

    Science.gov (United States)

    Culebras, Mario; Torán, Raquel; Gómez, Clara M; Cantarero, Andrés

    2014-01-01

    Semiconducting metallic oxides, especially perosvkite materials, are great candidates for thermoelectric applications due to several advantages over traditionally metallic alloys such as low production costs and high chemical stability at high temperatures. Nanostructuration can be the key to develop highly efficient thermoelectric materials. In this work, La 1-x Ca x MnO 3 perosvkite nanostructures with Ca as a dopant have been synthesized by the hydrothermal method to be used in thermoelectric applications at room temperature. Several heat treatments have been made in all samples, leading to a change in their morphology and thermoelectric properties. The best thermoelectric efficiency has been obtained for a Ca content of x=0.5. The electrical conductivity and Seebeck coefficient are strongly related to the calcium content.

  13. Modeling and Experimentation of New Thermoelectric Cooler–Thermoelectric Generator Module

    Directory of Open Access Journals (Sweden)

    Khaled Teffah

    2018-03-01

    Full Text Available In this work, a modeling and experimental study of a new thermoelectric cooler–thermoelectric generator (TEC-TEG module is investigated. The studied module is composed of TEC, TEG and total system heatsink, all connected thermally in series. An input voltage (1–5 V passes through the TEC where the electrons by means of Peltier effect entrain the heat from the upper side of the module to the lower one creating temperature difference; TEG plays the role of a partial heatsink for the TEC by transferring this waste heat to the total system heatsink and converting an amount of this heat into electricity by a phenomenon called Seebeck effect, of the thermoelectric modules. The performance of the TEG as partial heatsink of TEC at different input voltages is demonstrated theoretically using the modeling software COMSOL Multiphysics. Moreover, the experiment validates the simulation result which smooths the path for a new manufacturing thermoelectric cascade model for the cooling and the immediate electric power generation.

  14. Temperature Dependence of Factors Controlling Isoprene Emissions

    Science.gov (United States)

    Duncan, Bryan N.; Yoshida, Yasuko; Damon, Megan R.; Douglass, Anne R.; Witte, Jacquelyn C.

    2009-01-01

    We investigated the relationship of variability in the formaldehyde (HCHO) columns measured by the Aura Ozone Monitoring Instrument (OMI) to isoprene emissions in the southeastern United States for 2005-2007. The data show that the inferred, regional-average isoprene emissions varied by about 22% during summer and are well correlated with temperature, which is known to influence emissions. Part of the correlation with temperature is likely associated with other causal factors that are temperature-dependent. We show that the variations in HCHO are convolved with the temperature dependence of surface ozone, which influences isoprene emissions, and the dependence of the HCHO column to mixed layer height as OMI's sensitivity to HCHO increases with altitude. Furthermore, we show that while there is an association of drought with the variation in HCHO, drought in the southeastern U.S. is convolved with temperature.

  15. The development of Gallstone solvent temperature adaptive PID control system

    Institute of Scientific and Technical Information of China (English)

    MA; BING; QIAO; BO; YAN

    2012-01-01

    The paper expatiated the work principle,general project,and the control part of the corresponding program of the temperature system in the gallstone dissolving instrument.Gallstone dissolving instrument adopts automatic control solvent cycle of direct solution stone treatment,replacing the traditional external shock wave rock row stone and gallblad-der surgery method.PID control system to realize the gall stone solvent temperature intelligent control,the basic principle of work is as solvent temperature below the set temperature,the relay control heater to solvent to be heated,conversely,no heating,achieve better able to dissolve the the rapeutic effect of gallstones.

  16. Photoacoustic-Based-Close-Loop Temperature Control for Nanoparticle Hyperthermia.

    Science.gov (United States)

    Xiaohua, Feng; Fei, Gao; Yuanjin, Zheng

    2015-07-01

    Hyperthermia therapy requires tight temperature control to achieve selective killing of cancerous tissue with minimal damage on surrounding healthy tissues. To this end, accurate temperature monitoring and subsequent heating control are critical. However, an economic, portable, and real-time temperature control solution is currently lacking. To bridge this gap, we present a novel portable close-loop system for hyperthermia temperature control, in which photoacoustic technique is proposed for noninvasive real-time temperature measurement. Exploiting the high sensitivity of photoacoustics, the temperature is monitored with an accuracy of around 0.18 °C and then fed back to a controller implemented on field programmable gate array (FPGA) for temperature control. Dubbed as portable hyperthermia feedback controller (pHFC), it stabilizes the temperature at preset values by regulating the hyperthermia power with a proportional-integral-derivative (PID) algorithm; and to facilitate digital implementation, the pHFC further converts the PID output into switching values (0 and 1) with the pulse width modulation (PWM) algorithm. Proof-of-concept hyperthermia experiments demonstrate that the pHFC system is able to bring the temperature from baseline to predetermined value with an accuracy of 0.3° and a negligible temperature overshoot. The pHFC can potentially be translated to clinical applications with customized hyperthermia system design. This paper can facilitate future efforts in seamless integration of close-loop temperature control solution and various clinical hyperthermia systems.

  17. Thermoelectric properties of low-dimensional clathrates from first principles

    Science.gov (United States)

    Kasinathan, Deepa; Rosner, Helge

    2011-03-01

    Type-I inorganic clathrates are host-guest structures with the guest atoms trapped in the framework of the host structure. From a thermoelectric point of view, they are interesting because they are semiconductors with adjustable bandgaps. Investigations in the past decade have shown that type-I clathrates X8 Ga 16 Ge 30 (X = Ba, Sr, Eu) may have the unusual property of ``phonon glass-electron crystal'' for good thermoelectric materials. Among the known clathrates, Ba 8 Ga 16 Ge 30 has the highest figure of merit (ZT~1). To enable a more widespread usage of thermoelectric technology power generation and heating/cooling applications, ZT of at least 2-3 is required. Two different research approaches have been proposed for developing next generation thermoelectric materials: one investigating new families of advanced bulk materials, and the other studying low-dimensional materials. In our work, we concentrate on understanding the thermoelectric properties of the nanostructured Ba-based clathrates. We use semi-classical Boltzmann transport equations to calculate the various thermoelectric properties as a function of reduced dimensions. We observe that there exists a delicate balance between the electrical conductivity and the electronic part of the thermal conductivity in reduced dimensions. Insights from these results can directly be used to control particle size in nanostructuring experiments.

  18. Promising bulk nanostructured Cu2Se thermoelectrics via high throughput and rapid chemical synthesis

    DEFF Research Database (Denmark)

    Tafti, Mohsen Y.; Ballikaya, Sedat; Khachatourian, Adrine Malek

    2016-01-01

    of Cu2Se were synthesized. Powder samples and compacted pellets have been characterized in detail for their structural, microstructural and transport properties. α to β phase transition of Cu2Se was confirmed using temperature dependent X-ray powder diffraction and differential scanning calorimetry...... truncated morphology. Through a detailed investigation of different parameters in the compaction process, such as applied load, heating rate, and cooling profiles, pellets with preserved nanostructured grains were obtained. An applied load during the controlled cooling profile was demonstrated to have a big...... impact on the final thermoelectric efficiency of the consolidated pellets. A very high thermoelectric figure of merit (ZT) above 2 was obtained at 900 K for SPS-compacted Cu2Se nanopowders in the absence of the applied load during the controlled cooling step. The obtained ZT exceeds the state of the art...

  19. Thermoelectric efficiency of nanoscale devices in the linear regime

    Science.gov (United States)

    Bevilacqua, G.; Grosso, G.; Menichetti, G.; Pastori Parravicini, G.

    2016-12-01

    We study quantum transport through two-terminal nanoscale devices in contact with two particle reservoirs at different temperatures and chemical potentials. We discuss the general expressions controlling the electric charge current, heat currents, and the efficiency of energy transmutation in steady conditions in the linear regime. With focus in the parameter domain where the electron system acts as a power generator, we elaborate workable expressions for optimal efficiency and thermoelectric parameters of nanoscale devices. The general concepts are set at work in the paradigmatic cases of Lorentzian resonances and antiresonances, and the encompassing Fano transmission function: the treatments are fully analytic, in terms of the trigamma functions and Bernoulli numbers. From the general curves here reported describing transport through the above model transmission functions, useful guidelines for optimal efficiency and thermopower can be inferred for engineering nanoscale devices in energy regions where they show similar transmission functions.

  20. Steam temperature control of essential oil extraction system using ...

    African Journals Online (AJOL)

    This research proposed a closed-loop temperature control using a self-tuning fuzzy fractional-order PI (FOPI) controller to overcome the problem. The controller will regulate the steam temperature at a desired level to protect the oil from excessive heat. Self capability of fuzzy rules was found to facilitate the tuning using only ...

  1. Electrochemically deposited BiTe-based nano wires for thermoelectric applications

    International Nuclear Information System (INIS)

    Inn-Khuan, N.; Kuan-Ying, K.; Che Zuraini Che Abdul Rahman; Nur Ubaidah Saidin; Suhaila Hani Ilias; Thye-Foo, C.

    2013-01-01

    Full-text: Nano structured materials systems such as thin-films and nano wires (NWs) are promising for thermoelectric power generation and refrigeration compared to traditional counterparts in bulk, due to their enhanced thermoelectric figures-of-merit. BiTe and its derivative compounds, in particular, are well-known for their near-room temperature thermoelectric performance. In this work, both the binary and ternary BiTe-based nano wires namely, BiTe and BiSbTe, were synthesized using template-assisted electrodeposition. Diameters of the nano wires were controlled by the pore sizes of the anodised alumina (AAO) templates used. Systematic study on the compositional change as a function of applied potential was carried out via Linear Sweep Voltametry (LSV). Chemical compositions of the nano wires were studied using Energy Dispersive X-ray Spectrometry (EDXS) and their microstructures evaluated using diffraction and imaging techniques. Results from chemical analysis on the nano wires indicated that while the Sb content in BiSbTe nano wires increased with more negative deposition potentials, the formation of Te 0 and Bi 2 Te 3 were favorable at more positive potentials. (author)

  2. Thermoelectric generators incorporating phase-change materials for waste heat recovery from engine exhaust

    Science.gov (United States)

    Meisner, Gregory P; Yang, Jihui

    2014-02-11

    Thermoelectric devices, intended for placement in the exhaust of a hydrocarbon fuelled combustion device and particularly suited for use in the exhaust gas stream of an internal combustion engine propelling a vehicle, are described. Exhaust gas passing through the device is in thermal communication with one side of a thermoelectric module while the other side of the thermoelectric module is in thermal communication with a lower temperature environment. The heat extracted from the exhaust gasses is converted to electrical energy by the thermoelectric module. The performance of the generator is enhanced by thermally coupling the hot and cold junctions of the thermoelectric modules to phase-change materials which transform at a temperature compatible with the preferred operating temperatures of the thermoelectric modules. In a second embodiment, a plurality of thermoelectric modules, each with a preferred operating temperature and each with a uniquely-matched phase-change material may be used to compensate for the progressive lowering of the exhaust gas temperature as it traverses the length of the exhaust pipe.

  3. LaBiTe3: An unusual thermoelectric material

    KAUST Repository

    Singh, Nirpendra

    2014-06-18

    Using first-principles calculations and semi-classical Boltzmann transport theory, the thermoelectric properties of LaBiTe3 are studied. The band gap and, hence, the thermoelectric response are found to be easily tailored by application of strain. Independent of the temperature, the figure of merit turns out to be maximal at a doping of about 1.6 × 1021 cm-3. At room temperature we obtain values of 0.4 and 0.5 for unstrained and moderately strained LaBiTe3, which increases to 1.1 and 1.3 at 800 K. A large spin splitting is observed in the conduction band at the T point. Therefore, LaBiTe3 merges characteristics that are interesting for thermoelectric as well as spintronic devices.

  4. LaBiTe3: An unusual thermoelectric material

    KAUST Repository

    Singh, Nirpendra; Schwingenschlö gl, Udo

    2014-01-01

    Using first-principles calculations and semi-classical Boltzmann transport theory, the thermoelectric properties of LaBiTe3 are studied. The band gap and, hence, the thermoelectric response are found to be easily tailored by application of strain. Independent of the temperature, the figure of merit turns out to be maximal at a doping of about 1.6 × 1021 cm-3. At room temperature we obtain values of 0.4 and 0.5 for unstrained and moderately strained LaBiTe3, which increases to 1.1 and 1.3 at 800 K. A large spin splitting is observed in the conduction band at the T point. Therefore, LaBiTe3 merges characteristics that are interesting for thermoelectric as well as spintronic devices.

  5. Thermoelectric detection of inclusions in metallic biomaterials by magnetic sensing

    Directory of Open Access Journals (Sweden)

    Hector Carreon

    2017-05-01

    Full Text Available The detectability of small inclusions and subtle imperfections by magnetic measurements that senses thermoelectric currents produced by a temperature gradient is ultimately limited by the intrinsic thermoelectric anisotropy and inhomogeneity of the material to be inspected. The probability of detection (POD of a given material flaw is determined by the resulting signal-to-noise ratio rather than by the absolute magnitude of the signal itself. The strength of the magnetic field to be detected greatly depends on the physical nature of the host medium and dimensions of the imperfection. This paper presents experimental data for the magnetic field produced by thermoelectric currents around tin inclusions in different host medium such as 316LVM stainless steel and Ti-6Al-4V titanium alloy under external thermal excitation. The diameter of the inclusions and the lift-off distance varied from 0.39 to 3.175 mm and from 1 to 10 mm, respectively. A 0.6 °C/cm temperature gradient in the samples produced peak magnetic flux densities ranging from 0.1 to 280 nT, that was measured by a fluxgate magnetometer. The numerical results were found to be in good agreement with theoretical predictions and demonstrated that both property anisotropy and gradient in thermoelectric materials can significantly influence the induced thermoelectric currents and magnetic fields.

  6. Thermoelectric detection of inclusions in metallic biomaterials by magnetic sensing

    Science.gov (United States)

    Carreon, Hector

    2017-05-01

    The detectability of small inclusions and subtle imperfections by magnetic measurements that senses thermoelectric currents produced by a temperature gradient is ultimately limited by the intrinsic thermoelectric anisotropy and inhomogeneity of the material to be inspected. The probability of detection (POD) of a given material flaw is determined by the resulting signal-to-noise ratio rather than by the absolute magnitude of the signal itself. The strength of the magnetic field to be detected greatly depends on the physical nature of the host medium and dimensions of the imperfection. This paper presents experimental data for the magnetic field produced by thermoelectric currents around tin inclusions in different host medium such as 316LVM stainless steel and Ti-6Al-4V titanium alloy under external thermal excitation. The diameter of the inclusions and the lift-off distance varied from 0.39 to 3.175 mm and from 1 to 10 mm, respectively. A 0.6 °C/cm temperature gradient in the samples produced peak magnetic flux densities ranging from 0.1 to 280 nT, that was measured by a fluxgate magnetometer. The numerical results were found to be in good agreement with theoretical predictions and demonstrated that both property anisotropy and gradient in thermoelectric materials can significantly influence the induced thermoelectric currents and magnetic fields.

  7. Thermoelectric properties of SnSe compound

    Energy Technology Data Exchange (ETDEWEB)

    Guan, Xinhong [State Key Laboratory of Information Photonics and Optical Communications, Ministry of Education, Beijing University of Posts and Telecommunications, P.O. Box 72, Beijing 100876 (China); Lu, Pengfei, E-mail: photon@bupt.edu.cn [State Key Laboratory of Information Photonics and Optical Communications, Ministry of Education, Beijing University of Posts and Telecommunications, P.O. Box 72, Beijing 100876 (China); Wu, Liyuan; Han, Lihong [State Key Laboratory of Information Photonics and Optical Communications, Ministry of Education, Beijing University of Posts and Telecommunications, P.O. Box 72, Beijing 100876 (China); Liu, Gang [School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Song, Yuxin [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Wang, Shumin [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg (Sweden)

    2015-09-15

    Highlights: • The electronic and thermoelectric properties of SnSe bulk material are studied. • The ZT can reach as high as 1.87 along yy and 1.6 along zz direction at 800k. • SnSe is an indirect-band material, and SOC has little effect on the band structure. • The high ZT can be attributed to the intrinsically ultralow thermal conductivity. - Abstract: A first-principles study and Boltzmann transport theory have been performed to evaluate the electronic structure and thermoelectric properties of SnSe compound. The energy band structure and density of states are studied in detail. The electronic transport coefficients are then calculated as a function of chemical potential or temperature within the assumption of the constant relaxation time. The figure of merit ZT is obtained with the use of calculated thermoelectric properties and can reach as high as 1.87 along yy and 1.6 along zz direction at 800 K. Our theoretical result agrees well with previous experimental data.

  8. Thermoelectric properties of SnSe compound

    International Nuclear Information System (INIS)

    Guan, Xinhong; Lu, Pengfei; Wu, Liyuan; Han, Lihong; Liu, Gang; Song, Yuxin; Wang, Shumin

    2015-01-01

    Highlights: • The electronic and thermoelectric properties of SnSe bulk material are studied. • The ZT can reach as high as 1.87 along yy and 1.6 along zz direction at 800k. • SnSe is an indirect-band material, and SOC has little effect on the band structure. • The high ZT can be attributed to the intrinsically ultralow thermal conductivity. - Abstract: A first-principles study and Boltzmann transport theory have been performed to evaluate the electronic structure and thermoelectric properties of SnSe compound. The energy band structure and density of states are studied in detail. The electronic transport coefficients are then calculated as a function of chemical potential or temperature within the assumption of the constant relaxation time. The figure of merit ZT is obtained with the use of calculated thermoelectric properties and can reach as high as 1.87 along yy and 1.6 along zz direction at 800 K. Our theoretical result agrees well with previous experimental data

  9. Advances on development of suction and temperature controlled oedometer cell

    International Nuclear Information System (INIS)

    Ye Weimin; Zhang Yawei; Chen Bao; Wang Min

    2010-01-01

    Oedometer cells for unsaturated soils can be classified into two types, that is, conventional unsaturated oedometer cells (high-suction unsaturated oedometer cell, high-suction and high-pressure unsaturated oedometer cell) and temperature controlled unsaturated oedometer cells. Among them, the osmotic, vapor equilibrium and axis translation techniques are often employed for suction control. The thermostat bath method and thermostatically controlled heater method are commonly used for temperature control. The lever loading system, hydraulic loading system and air pressure loading system are commonly means used for vertical pressure. Combination of osmotic (or axis translation) technique with vapor equilibrium method employed for the full range suction control, thermostatically liquid temperature control method, and the hydraulic loading system, could be used for suction, temperature and loading control in the design for unsaturated oedometer cells in the future, which can be used for study of buffer/backfill materials under high-temperature, high pressure and full range suction conditions. (authors)

  10. MRI feedback temperature control for focused ultrasound surgery

    International Nuclear Information System (INIS)

    Vanne, A; Hynynen, K

    2003-01-01

    A temperature feedback controller routine using a physical model for temperature evolution was developed for use with focused ultrasound surgery. The algorithm for the controller was a multi-input, single-output linear quadratic regulator (LQR) derived from Pennes' bioheat transfer equation. The controller was tested with simulated temperature data that had the same characteristics as those obtained with magnetic resonance imaging (MRI). The output of the controller was the appropriate power level to be used by the transducer. Tissue parameters estimated prior to the simulated treatments were used to determine the controller parameters. The controller performance was simulated in three dimensions with varying system parameters, and sufficient temperature tracking was achieved. The worst-case overshoot was 7 deg. C and the steady-state error was 5 deg. C. The simulated behaviour of the controller suggests satisfactory performance and that the controller may be useful in controlling the power output during MRI-monitored ultrasound surgery

  11. Diode temperature sensor array for measuring and controlling micro scale surface temperature

    International Nuclear Information System (INIS)

    Han, Il Young; Kim, Sung Jin

    2004-01-01

    The needs of micro scale thermal detecting technique are increasing in biology and chemical industry. For example, thermal finger print, Micro PCR(Polymer Chain Reaction), TAS and so on. To satisfy these needs, we developed a DTSA(Diode Temperature Sensor Array) for detecting and controlling the temperature on small surface. The DTSA is fabricated by using VLSI technique. It consists of 32 array of diodes(1,024 diodes) for temperature detection and 8 heaters for temperature control on a 8mm surface area. The working principle of temperature detection is that the forward voltage drop across a silicon diode is approximately proportional to the inverse of the absolute temperature of diode. And eight heaters (1K) made of poly-silicon are added onto a silicon wafer and controlled individually to maintain a uniform temperature distribution across the DTSA. Flip chip packaging used for easy connection of the DTSA. The circuitry for scanning and controlling DTSA are also developed

  12. Lunar base thermoelectric power station study

    Science.gov (United States)

    Determan, William; Frye, Patrick; Mondt, Jack; Fleurial, Jean-Pierre; Johnson, Ken; Stapfer, G.; Brooks, Michael D.; Heshmatpour, Ben

    2006-01-01

    Under NASA's Project Prometheus, the Nuclear Systems Program, the Jet Propulsion Laboratory, Pratt & Whitney Rocketdyne, and Teledyne Energy Systems have teamed with a number of universities, under the Segmented Thermoelectric Multicouple Converter (STMC) program, to develop the next generation of advanced thermoelectric converters for space reactor power systems. Work on the STMC converter assembly has progressed to the point where the lower temperature stage of the segmented multicouple converter assembly is ready for laboratory testing and the upper stage materials have been identified and their properties are being characterized. One aspect of the program involves mission application studies to help define the potential benefits from the use of these STMC technologies for designated NASA missions such as the lunar base power station where kilowatts of power are required to maintain a permanent manned presence on the surface of the moon. A modular 50 kWe thermoelectric power station concept was developed to address a specific set of requirements developed for this mission. Previous lunar lander concepts had proposed the use of lunar regolith as in-situ radiation shielding material for a reactor power station with a one kilometer exclusion zone radius to minimize astronaut radiation dose rate levels. In the present concept, we will examine the benefits and requirements for a hermetically-sealed reactor thermoelectric power station module suspended within a man-made lunar surface cavity. The concept appears to maximize the shielding capabilities of the lunar regolith while minimizing its handling requirements. Both thermal and nuclear radiation levels from operation of the station, at its 100-m exclusion zone radius, were evaluated and found to be acceptable. Site preparation activities are reviewed and well as transport issues for this concept. The goal of the study was to review the entire life cycle of the unit to assess its technical problems and technology

  13. Thermoelectric integrated membrane evaporation water recovery technology

    Science.gov (United States)

    Roebelen, G. J., Jr.; Winkler, H. E.; Dehner, G. F.

    1982-01-01

    The recently developed Thermoelectric Integrated Membrane Evaporation Subsystem (TIMES) offers a highly competitive approach to water recovery from waste fluids for future on-orbit stations such as the Space Operations Center. Low power, compactness and gravity insensitive operation are featured in this vacuum distillation subsystem that combines a hollow fiber membrane evaporator with a thermoelectric heat pump. The hollow fiber elements provide positive liquid/gas phase control with no moving parts other than pumps and an accumulator, thus solving problems inherent in other reclamation subsystem designs. In an extensive test program, over 850 hours of operation were accumulated during which time high quality product water was recovered from both urine and wash water at an average steady state production rate of 2.2 pounds per hour.

  14. Application of high precision temperature control technology in infrared testing

    Science.gov (United States)

    Cao, Haiyuan; Cheng, Yong; Zhu, Mengzhen; Chu, Hua; Li, Wei

    2017-11-01

    In allusion to the demand of infrared system test, the principle of Infrared target simulator and the function of the temperature control are presented. The key technology of High precision temperature control is discussed, which include temperature gathering, PID control and power drive. The design scheme of temperature gathering is put forward. In order to reduce the measure error, discontinuously current and four-wire connection for the platinum thermal resistance are adopted. A 24-bits AD chip is used to improve the acquisition precision. Fuzzy PID controller is designed because of the large time constant and continuous disturbance of the environment temperature, which result in little overshoot, rapid response, high steady-state accuracy. Double power operational amplifiers are used to drive the TEC. Experiments show that the key performances such as temperature control precision and response speed meet the requirements.

  15. Temperature control system for liquid-fed ceramic melters

    International Nuclear Information System (INIS)

    Westsik, J.H. Jr.

    1986-10-01

    A temperature-feedback system has been developed for controlling electrical power to liquid-fed ceramic melters (LFCM). Software, written for a microcomputer-based data acquisition and process monitoring system, compares glass temperatures with a temperature setpoint and adjusts the electrical power accordingly. Included in the control algorithm are steps to reject failed thermocouples, spatially average the glass temperatures, smooth the averaged temperatures over time using a digital filter, and detect foaming in the glass. The temperature control system has proved effective during all phases of melter operation including startup, steady operation, loss of feed, and shutdown. This system replaces current, power, and resistance feedback control systems used previously in controlling the LFCM process

  16. Dynamic heat transfer modeling and parametric study of thermoelectric radiant cooling and heating panel system

    International Nuclear Information System (INIS)

    Luo, Yongqiang; Zhang, Ling; Liu, Zhongbing; Wang, Yingzi; Wu, Jing; Wang, Xiliang

    2016-01-01

    Highlights: • Dynamic model of thermoelectric radiant panel system is established. • The internal parameters of thermoelectric module are dynamically calculated in simulation. • Both artificial neural networks model and system model are verified through experiment data. • Optimized system structure is obtained through parametric study. - Abstract: Radiant panel system can optimize indoor thermal comfort with lower energy consumption. The thermoelectric radiant panel (TERP) system is a new and effective prototype of radiant system using thermoelectric module (TEM) instead of conventional water pipes, as heat source. The TERP can realize more stable and easier system control as well as lower initial and operative cost. In this study, an improved system dynamic model was established by combining analytical system model and artificial neural networks (ANN) as well as the dynamic calculation functions of internal parameters of TEM. The double integral was used for the calculation of surface average temperature of TERP. The ANN model and system model were in good agreement with experiment data in both cooling and heating mode. In order to optimize the system design structure, parametric study was conducted in terms of the thickness of aluminum panel and insulation, as well as the arrangement of TEMs on the surface of radiant panel. It was found through simulation results that the optimum thickness of aluminum panel and insulation are respectively around 1–2 mm and 40–50 mm. In addition, TEMs should be uniformly installed on the surface of radiant panel and each TEM should stand at the central position of a square-shaped typical region with length around 0.387–0.548 m.

  17. Thermoelectric properties of boron and boron phosphide CVD wafers

    Energy Technology Data Exchange (ETDEWEB)

    Kumashiro, Y.; Yokoyama, T.; Sato, A.; Ando, Y. [Yokohama National Univ. (Japan)

    1997-10-01

    Electrical and thermal conductivities and thermoelectric power of p-type boron and n-type boron phosphide wafers with amorphous and polycrystalline structures were measured up to high temperatures. The electrical conductivity of amorphous boron wafers is compatible to that of polycrystals at high temperatures and obeys Mott`s T{sup -{1/4}} rule. The thermoelectric power of polycrystalline boron decreases with increasing temperature, while that of amorphous boron is almost constant in a wide temperature range. The weak temperature dependence of the thermal conductivity of BP polycrystalline wafers reflects phonon scattering by grain boundaries. Thermal conductivity of an amorphous boron wafer is almost constant in a wide temperature range, showing a characteristic of a glass. The figure of merit of polycrystalline BP wafers is 10{sup -7}/K at high temperatures while that of amorphous boron is 10{sup -5}/K.

  18. Effective use of thermal energy at both hot and cold side of thermoelectric module for developing efficient thermoelectric water distillation system

    International Nuclear Information System (INIS)

    Al-Madhhachi, Hayder; Min, Gao

    2017-01-01

    Highlights: • New distillation process using thermoelectric to assist evaporation/condensation. • Novel thermoelectric distillation system with reduced specific energy consumption. • Freshwater production by thermoelectrically assisted evaporation and condensation. - Abstract: An efficient thermoelectric distillation system has been designed and constructed for production of drinkable water. The unique design of this system is to use the heat from hot side of the thermoelectric module for water evaporation and the cold side for vapour condensation simultaneously. This novel design significantly reduces energy consumption and improves the system performance. The results of experiments show that the average water production is 28.5 mL/h with a specific energy consumption of 0.00114 kW h/mL in an evaporation chamber filled with 10 × 10 × 30 mm"3 of water. This is significantly lower than the energy consumption required by other existing thermoelectric distillation systems. The results also show that a maximum temperature difference between the hot and cold side of the thermoelectric module is 42.3 °C, which led to temperature increases of 26.4 °C and 8.4 °C in water and vapour, respectively.

  19. Controlling the temperature in Canadian homes

    International Nuclear Information System (INIS)

    Dewis, G.

    2008-01-01

    Programmable thermostats can be used to optimize the operation of heating and cooling systems by reducing system usage when occupants are asleep or when dwellings are unoccupied. This paper used the results of a 2006 households and the environment survey to examine how programmable thermostats are currently being used in Canadian households. The demographic factors associated with thermostat use were discussed, as well as how their usage varied in different areas of Canada. The study showed that most Canadian households set their temperature at between 20 to 22 degrees C during times when they are home and awake. Home temperatures were reduced to between 16 and 18 degrees C when household members were away or asleep. Only 4 out of 10 households used programmable thermostats. Of those who used programmable thermostats, only 7 in 10 programmed the thermostat to lower the temperature when occupants were asleep. Senior citizens and people with lower levels of education were less likely to use programmable thermostats. It was concluded that incentive programs and the distribution of free programmable thermostats will increase their use in households. Assistance in programming during the installation process should also be provided. Factor analyses must also be conducted to examine the influence of age, education, and income and the decisions made by households in relation to temperature regulation. 7 tabs

  20. Recycling temperature elevation device and temperature control method for control rod driving system

    International Nuclear Information System (INIS)

    Okamura, Hajime.

    1996-01-01

    The present invention concerns a device for and a method of controlling a recycling temperature control device for control rod drives (CRD) of a nuclear power plant, which can prevent occurrence of cavitation and keep the amount of cooling water to be transferred to a water source transfer pipeline thereby improving maintenanciability, operationability and reliability. Namely, a supply pipeline supplies cooling water required for the control rod drives from a water source. A CRD pump elevates the pressure of the cooling water. A recycling pipeline is branched from the downstream of the CRD pump of the supply pipeline and connected to the supply pipeline at the upstream of the CRD pump. A first pressure element and a restricting valve disposed at the upstream thereof are connected to the upstream of the CRD pump and the water source transfer pipeline. The water source transfer pipeline is branched from the recycling pipeline and connected to the water source. A second pressure element is disposed to a recycling pipeline at the downstream of the branched point from the water source transfer pipeline. (I.S.)

  1. Evaluation of RTD and thermocouple for PID temperature control in ...

    African Journals Online (AJOL)

    Evaluation of RTD and thermocouple for PID temperature control in distributed control system laboratory. D. A. A. Nazarudin, M. K. Nordin, A. Ahmad, M. Masrie, M. F. Saaid, N. M. Thamrin, M. S. A. M. Ali ...

  2. Superlattices in thermoelectric applications

    International Nuclear Information System (INIS)

    Sofo, J.O.; Mahan, G.D.; Tennessee Univ., Knoxville, TN

    1994-08-01

    The electrical conductivity, thermopower and the electronic contribution to the thermal conductivity of a superlattice, are calculated with the electric field and the thermal gradient applied parallel to the interfaces. Tunneling between quantum wells is included. The broadening of the lowest subband when the period of the superlattice is decreased produces a reduction of the thermoelectric figure of merit. However, we found that a moderate increase of the figure of merit may be expected for intermediate values of the period, due to the enhancement of the density of states produced by the superlattice structure

  3. Semiconductor thermoelectric generators

    CERN Document Server

    Fahrner, Wolfgang R

    2009-01-01

    It is well-known that fossil fuels are being rapidly depleted, and that atomic power is rejected by many people. As a consequence, there is a strong trend towards alternative sources such as wind, photovoltaics, solar heat and biomass. Strangely enough, quite another power source is generally neglected: namely, the thermoelectric generator (a device which converts heat, i.e. thermal energy, directly into electrical energy). The reason for this neglect is probably the low conversion efficiency, which is of the order of a few percent at most. However, there are two arguments in favor of the ther

  4. The Design of Temperature and Humidity Chamber Monitor and Controller

    OpenAIRE

    Tibebu, Simachew

    2016-01-01

    The temperature and humidity chamber, (climate chamber) is a device located at the Technobothnia Education and Research Center that simulates different climate conditions. The simulated environment is used to test the capabilities of electrical equipment in different temperature and humidity conditions. The climate chamber, among other things houses a dedicated computer, the control PC, and a control software running in it which together are responsible for running and control-ling these simu...

  5. The thermoelectric generators use for waste heat utilization from cement plant

    Directory of Open Access Journals (Sweden)

    Sztekler Karol

    2017-01-01

    Production often entails the formation of by-product which is waste heat. One of the equipment processing heat into electricity is a thermoelectric generator. Its operation is based on the principle of thermoelectric phenomenon, which is known as a Seebeck phenomenon. The simplicity of thermoelectric phenomena allows its use in various industries, in which the main waste product is in the form of heat with the temperature of several hundred degrees. The study analyses the possibility of the thermoelectric systems use for the waste heat utilization resulting in the cement production at the cement plant. The location and design of the thermoelectric system that could be implemented in cement plant is chosen. The analysis has been prepared in the IPSEpro software.

  6. Fuzzy Logic Temperature Control System For The Induction Furnace

    Directory of Open Access Journals (Sweden)

    Lei Lei Hnin

    2015-08-01

    Full Text Available This research paper describes the fuzzy logic temperature control system of the induction furnace. Temperature requirement of the heating system varies during the heating process. In the conventional control schemes the switching losses increase with the change in the load. A closed loop control is required to have a smooth control on the system. In this system pulse width modulation based power control scheme for the induction heating system is developed using the fuzzy logic controller. The induction furnace requires a good voltage regulation to have efficient response. The controller controls the temperature depending upon weight of meat water and time. This control system is implemented in hardware system using microcontroller. Here the fuzzy logic controller is designed and simulated in MATLAB to get the desire condition.

  7. Temperature Dependence of the Seebeck Coefficient in Zinc Oxide Thin Films

    Science.gov (United States)

    Noori, Amirreza; Masoumi, Saeed; Hashemi, Najmeh

    2017-12-01

    Thermoelectric devices are reliable tools for converting waste heat into electricity as they last long, produce no noise or vibration, have no moving elements, and their light weight makes them suitable for the outer space usage. Materials with high thermoelectric figure of merit (zT) have the most important role in the fabrication of efficient thermoelectric devices. Metal oxide semiconductors, specially zinc oxide has recently received attention as a material suitable for sensor, optoelectronic and thermoelectric device applications because of their wide direct bandgap, chemical stability, high-energy radiation endurance, transparency and acceptable zT. Understanding the thermoelectric properties of the undoped ZnO thin films can help design better ZnO-based devices. Here, we report the results of our experimental work on the thermoelectric properties of the undoped polycrystalline ZnO thin films. These films are deposited on alumina substrates by thermal evaporation of zinc in vacuum followed by a controlled oxidation process in air carried out at the 350-500 °C temperature range. The experimental setup including gradient heaters, thermometry system and Seebeck voltage measurement equipment for high resistance samples is described. Seebeck voltage and electrical resistivity of the samples are measured at different conditions. The observed temperature dependence of the Seebeck coefficient is discussed.

  8. Prospects for Engineering Thermoelectric Properties in La1/3NbO3 Ceramics Revealed via Atomic-Level Characterization and Modeling.

    Science.gov (United States)

    Kepaptsoglou, Demie; Baran, Jakub D; Azough, Feridoon; Ekren, Dursun; Srivastava, Deepanshu; Molinari, Marco; Parker, Stephen C; Ramasse, Quentin M; Freer, Robert

    2018-01-02

    A combination of experimental and computational techniques has been employed to explore the crystal structure and thermoelectric properties of A-site-deficient perovskite La 1/3 NbO 3 ceramics. Crystallographic data from X-ray and electron diffraction confirmed that the room temperature structure is orthorhombic with Cmmm as a space group. Atomically resolved imaging and analysis showed that there are two distinct A sites: one is occupied with La and vacancies, and the second site is fully unoccupied. The diffuse superstructure reflections observed through diffraction techniques are shown to originate from La vacancy ordering. La 1/3 NbO 3 ceramics sintered in air showed promising high-temperature thermoelectric properties with a high Seebeck coefficient of S 1 = -650 to -700 μV/K and a low and temperature-stable thermal conductivity of k = 2-2.2 W/m·K in the temperature range of 300-1000 K. First-principles electronic structure calculations are used to link the temperature dependence of the Seebeck coefficient measured experimentally to the evolution of the density of states with temperature and indicate possible avenues for further optimization through electron doping and control of the A-site occupancies. Moreover, lattice thermal conductivity calculations give insights into the dependence of the thermal conductivity on specific crystallographic directions of the material, which could be exploited via nanostructuring to create high-efficiency compound thermoelectrics.

  9. Paper-Based Origami Flexible and Foldable Thermoelectric Nanogenerator

    KAUST Repository

    Rojas, Jhonathan Prieto; Conchouso Gonzalez, David; Carreno, Armando Arpys Arevalo; Singh, Devendra; Foulds, Ian G.; Hussain, Muhammad Mustafa

    2016-01-01

    Paper has been an essential material in our daily life since ancient times. Its affordability, accessibility, adaptability, workability and its easiness of usage makes it an attractive structural material to develop many kind of technologies such as flexible electronics, energy storage and harvesting devices. Additionally, the scientific community has increased its interest on waste heat as an environmentally friendly energy source to support the increasing energy demand. Therefore, in this paper we described two affordable and flexible thermoelectric nanogenerators (TEGs) developed on paper substrates by the usage of simple micromachining and microfabrication techniques. Moreover, they exhibit mechanical stability and adaptability (through folding and cutting techniques) for a diverse set of scenarios where vertical or horizontal schemes can be conveniently used depending on the final application. The first TEG device, implemented on standard paper, generated a power of 0.5 nW (ΔT = 50 K). By changing the substrate to a tearless and extra-smooth polyester paper, the TEG performance was optimized achieving less internal resistance and a greater power of ~80 nW (ΔT = 75 K), at the cost of more rigidity in the substrate. This power represented over three times higher power production than the standard paper–based TEG with same dimensions, number of thermoelectric pairs and temperature difference. Another interesting aspect of paper based TEG is due to its foldability, one can control the temperature difference by unfolding (larger separation between hot and cold ends) and folding (smaller separation). Finally, one of the underlying objectives of this work is to spread the availability of essential technologies to the broad population by inclusion of everyday materials and simple processes.

  10. Paper-Based Origami Flexible and Foldable Thermoelectric Nanogenerator

    KAUST Repository

    Rojas, Jhonathan Prieto

    2016-11-12

    Paper has been an essential material in our daily life since ancient times. Its affordability, accessibility, adaptability, workability and its easiness of usage makes it an attractive structural material to develop many kind of technologies such as flexible electronics, energy storage and harvesting devices. Additionally, the scientific community has increased its interest on waste heat as an environmentally friendly energy source to support the increasing energy demand. Therefore, in this paper we described two affordable and flexible thermoelectric nanogenerators (TEGs) developed on paper substrates by the usage of simple micromachining and microfabrication techniques. Moreover, they exhibit mechanical stability and adaptability (through folding and cutting techniques) for a diverse set of scenarios where vertical or horizontal schemes can be conveniently used depending on the final application. The first TEG device, implemented on standard paper, generated a power of 0.5 nW (ΔT = 50 K). By changing the substrate to a tearless and extra-smooth polyester paper, the TEG performance was optimized achieving less internal resistance and a greater power of ~80 nW (ΔT = 75 K), at the cost of more rigidity in the substrate. This power represented over three times higher power production than the standard paper–based TEG with same dimensions, number of thermoelectric pairs and temperature difference. Another interesting aspect of paper based TEG is due to its foldability, one can control the temperature difference by unfolding (larger separation between hot and cold ends) and folding (smaller separation). Finally, one of the underlying objectives of this work is to spread the availability of essential technologies to the broad population by inclusion of everyday materials and simple processes.

  11. High-performance and flexible thermoelectric films by screen printing solution-processed nanoplate crystals.

    Science.gov (United States)

    Varghese, Tony; Hollar, Courtney; Richardson, Joseph; Kempf, Nicholas; Han, Chao; Gamarachchi, Pasindu; Estrada, David; Mehta, Rutvik J; Zhang, Yanliang

    2016-09-12

    Screen printing allows for direct conversion of thermoelectric nanocrystals into flexible energy harvesters and coolers. However, obtaining flexible thermoelectric materials with high figure of merit ZT through printing is an exacting challenge due to the difficulties to synthesize high-performance thermoelectric inks and the poor density and electrical conductivity of the printed films. Here, we demonstrate high-performance flexible films and devices by screen printing bismuth telluride based nanocrystal inks synthesized using a microwave-stimulated wet-chemical method. Thermoelectric films of several tens of microns thickness were screen printed onto a flexible polyimide substrate followed by cold compaction and sintering. The n-type films demonstrate a peak ZT of 0.43 along with superior flexibility, which is among the highest reported ZT values in flexible thermoelectric materials. A flexible thermoelectric device fabricated using the printed films produces a high power density of 4.1 mW/cm(2) with 60 °C temperature difference between the hot side and cold side. The highly scalable and low cost process to fabricate flexible thermoelectric materials and devices demonstrated here opens up many opportunities to transform thermoelectric energy harvesting and cooling applications.

  12. Optimization Strategies for a Portable Thermoelectric Vaccine Refrigeration System in Developing Communities

    Science.gov (United States)

    Ohara, B.; Sitar, R.; Soares, J.; Novisoff, P.; Nunez-Perez, A.; Lee, H.

    2015-06-01

    The traditional approach to determine an optimum current for thermoelectric cooling assumes that a refrigeration chamber is insulated and has no thermal resistance to a thermoelectric module. As a result, minimum temperature occurs when Peltier cooling matches with parasitic heat transfer and Joule heating. In practical application, minimum temperature happens when heat addition from the environment is matched with heat extracted by a thermoelectric module, and the optimum current differs from that anticipated by the traditional approach. Hence, consideration for insulation and thermal resistances via thermoelectric module should be made to achieve desirable cooling performance/refrigeration temperature. This paper presents a modeling approach to determine the optimum current as well as the optimum geometry to power a small thermoelectric vaccine delivery system for developing communities under the World Health Organization requirements. The model is derived from three energy conservation equations for temperatures at both ends of the thermoelectric materials within a module, as well as the refrigeration chamber temperature. A prototype was built and demonstrated a minimum temperature of 3.4°C. With optimized module geometry, the system is estimated to reduce power consumption by over 50% while achieving twice the temperature difference.

  13. Studies on preparation and adaptive thermal control performance of novel PTC (positive temperature coefficient) materials with controllable Curie temperatures

    International Nuclear Information System (INIS)

    Cheng, Wen-long; Yuan, Shuai; Song, Jia-liang

    2014-01-01

    PTC (positive temperature coefficient) material is a kind of thermo-sensitive material. In this study, a series of novel PTC materials adapted to thermal control of electron devices are prepared. By adding different low-melting-point blend matrixes into GP (graphite powder)/LDPE (low density polyethylene) composite, the Curie temperatures are adjusted to 9 °C, 25 °C, 34 °C and 41 °C, and the resistance–temperature coefficients are enhanced to 1.57/°C–2.15/°C. These PTC materials remain solid in the temperature region of PTC effect, which makes it possible to be used as heating element to achieve adaptive temperature control. In addition, the adaptive thermal control performances of this kind of materials are investigated both experimentally and theoretically. The result shows that the adaptive effect becomes more significant while the resistance–temperature coefficient increases. A critical heating power defined as the initial heating power which makes the equilibrium temperature reach terminal temperature is presented. The adaptive temperature control will be effective only if the initial power is below this value. The critical heating power is determined by the Curie temperature and resistance–temperature coefficient of PTC materials, and a higher Curie temperature or resistance–temperature coefficient will lead to a larger critical heating power. - Highlights: • A series of novel PTC (positive temperature coefficient) materials were prepared. • The Curie point of PTC material can be adjusted by choosing different blend matrixes. • The resistance–temperature coefficient of PTC materials is enhanced to 2.15/°C. • The material has good adaptive temperature control ability with no auxiliary method. • A mathematical model is established to analyze the performance and applicability

  14. Increasing the thermoelectric power factor of Ge17Sb2Te20 by adjusting the Ge/Sb ratio

    Science.gov (United States)

    Williams, Jared B.; Mather, Spencer P.; Page, Alexander; Uher, Ctirad; Morelli, Donald T.

    2017-07-01

    We have investigated the thermoelectric properties of Ge17Sb2Te20. This compound is a known phase change material with electronic properties that depend strongly on temperature. The thermoelectric properties of this compound can be tuned by altering the stoichiometry of Ge and Sb without the use of additional foreign elements during synthesis. This tuning results in a 26% increase in the thermoelectric power factor at 723 K. Based on a single parabolic band model we show that the pristine material is optimally doped, and thus, a reduction in the lattice thermal conductivity of pure Ge17Sb2Te20 should result in an enhanced thermoelectric figure of merit.

  15. AUTOMATIC BIOMASS BOILER WITH AN EXTERNAL THERMOELECTRIC GENERATOR

    OpenAIRE

    Marian Brázdil; Ladislav Šnajdárek; Petr Kracík; Jirí Pospíšil

    2014-01-01

    This paper presents the design and test results of an external thermoelectric generator that utilizes the waste heat from a small-scale domestic biomass boiler with nominal rated heat output of 25 kW. The low-temperature Bi2Te3 generator based on thermoelectric modules has the potential to recover waste heat from gas combustion products as effective energy. The small-scale generator is constructed from independent segments. Measurements have shown that up to 11 W of electricity can be generat...

  16. Overview of industry interest in new thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, Jr, H B

    1997-07-01

    The technology base for air conditioning, refrigeration, component cooling below ambient temperatures and power generation will be required to meet several new challenges. The main lines of these challenges will be presented in a way which relates them to the several new thermoelectric materials and materials engineering options being pursued by the research community. The potential benefits of thermoelectric devices are only partially met by enhancing the figure of merit ZT, the nature of the design challenge and the resulting systems approach are presented. The research and the industry are entering into a new era.

  17. A Thermoelectric Generator Replacing Radiator for Internal Combustion Engine Vehicles

    Directory of Open Access Journals (Sweden)

    Shiho Kim

    2011-12-01

    Full Text Available We have proposed and developed a low temperature thermoelectric generator (TEG using engine water coolant of light-duty vehicles. Experimental results from test vehicle, of which engine size is about 2.0 liters, show that fabricated prototype Thermoelectric Generator generates more than 75W for driving condition of 80 km/hour, and output power is about 28W during idle condition. The proposed TEG can replace conventional radiator without additional water pumps or mechanical devices except for basic components of legacy water cooling system of radiator.

  18. Weight Penalty Incurred in Thermoelectric Recovery of Automobile Exhaust Heat

    Science.gov (United States)

    Rowe, D. M.; Smith, J.; Thomas, G.; Min, G.

    2011-05-01

    Thermoelectric recovery of automobile waste exhaust heat has been identified as having potential for reducing fuel consumption and environmentally unfriendly emissions. Around 35% of combustion energy is discharged as heat through the exhaust system, at temperatures which depend upon the engine's operation and range from 800°C to 900°C at the outlet port to less than 50°C at the tail-pipe. Beneficial reduction in fuel consumption of 5% to 10% is widely quoted in the literature. However, comparison between claims is difficult due to nonuniformity of driving conditions. In this paper the available waste exhaust heat energy produced by a 1.5 L family car when undergoing the new European drive cycle was measured and the potential thermoelectric output estimated. The work required to power the vehicle through the drive cycle was also determined and used to evaluate key parameters. This enabled an estimate to be made of the engine efficiency and additional work required by the engine to meet the load of a thermoelectric generating system. It is concluded that incorporating a thermoelectric generator would attract a penalty of around 12 W/kg. Employing thermoelectric modules fabricated from low-density material such as magnesium silicide would considerably reduce the generator weight penalty.

  19. Validation, Optimization and Simulation of a Solar Thermoelectric Generator Model

    Science.gov (United States)

    Madkhali, Hadi Ali; Hamil, Ali; Lee, HoSung

    2017-12-01

    This study explores thermoelectrics as a viable option for small-scale solar thermal applications. Thermoelectric technology is based on the Seebeck effect, which states that a voltage is induced when a temperature gradient is applied to the junctions of two differing materials. This research proposes to analyze, validate, simulate, and optimize a prototype solar thermoelectric generator (STEG) model in order to increase efficiency. The intent is to further develop STEGs as a viable and productive energy source that limits pollution and reduces the cost of energy production. An empirical study (Kraemer et al. in Nat Mater 10:532, 2011) on the solar thermoelectric generator reported a high efficiency performance of 4.6%. The system had a vacuum glass enclosure, a flat panel (absorber), thermoelectric generator and water circulation for the cold side. The theoretical and numerical approach of this current study validated the experimental results from Kraemer's study to a high degree. The numerical simulation process utilizes a two-stage approach in ANSYS software for Fluent and Thermal-Electric Systems. The solar load model technique uses solar radiation under AM 1.5G conditions in Fluent. This analytical model applies Dr. Ho Sung Lee's theory of optimal design to improve the performance of the STEG system by using dimensionless parameters. Applying this theory, using two cover glasses and radiation shields, the STEG model can achieve a highest efficiency of 7%.

  20. Microprocessor Based Temperature Control of Liquid Delivery with Flow Disturbances.

    Science.gov (United States)

    Kaya, Azmi

    1982-01-01

    Discusses analytical design and experimental verification of a PID control value for a temperature controlled liquid delivery system, demonstrating that the analytical design techniques can be experimentally verified by using digital controls as a tool. Digital control instrumentation and implementation are also demonstrated and documented for…

  1. Development and Processing of p-type Oxide Thermoelectric Materials

    DEFF Research Database (Denmark)

    Wu, NingYu; Van Nong, Ngo

    The main aim of this research is to investigate and develop well-performing p-type thermoelectric oxide materials that are sufficiently stable at high temperatures for power generating applications involving industrial processes. Presently, the challenges facing the widespread implementation...

  2. Compact, single-tube scanning tunneling microscope with thermoelectric cooling.

    Science.gov (United States)

    Jobbins, Matthew M; Agostino, Christopher J; Michel, Jolai D; Gans, Ashley R; Kandel, S Alex

    2013-10-01

    We have designed and built a scanning tunneling microscope with a compact inertial-approach mechanism that fits inside the piezoelectric scanner tube. Rigid construction allows the microscope to be operated without the use of external vibration isolators or acoustic enclosures. Thermoelectric cooling and a water-ice bath are used to increase temperature stability when scanning under ambient conditions.

  3. Development and Analysis of Hybrid Thermoelectric Refrigerator Systems

    Science.gov (United States)

    Saifizi, M.; Zakaria, M. S.; Yaacob, Sazali; Wan, Khairunizam

    2018-03-01

    Thermoelectric module (TEM) is a type of solid-state devices which has the capability to maintain the accuracy of small temperature variation application. In this study, a hybrid thermoelectric refrigerator system is introduced by utilizing TEMs; direct and air to air thermoelectric heat pump to cool down and maintain low temperature for vaccines storage. Two different materials which are aluminum and stainless steel are used as container in hybrid thermoelectric refrigerator (HTER) configuration to investigate the response of every system in transient and steady state mode. A proper temperature sensor calibration technique is implemented to make certain real time data acquisition of the systems are not affected very much from the noise generated. From step response analysis, it is indicated that HTER I (aluminum) has rapid settling time from transient to steady state than HTER II (stainless steel) since aluminum has better thermal conductivity as compared to stainless steel. It is found that HTER I is better in cooling capability with the same input current instead of HTER II which required a longer time to achieve steady state mode. Besides, in Pseudo Random Binary Sequence (PRBS) response analysis injected to both systems shows HTER I is very sensitive to current input as the sequence length of HTER I is shorter than HTER II. However both systems depict the varying temperature in the range of 4 oC due to differences in thermal conductivity of container.

  4. About thermo-electric properties of bismuth telluride doped by gadolinium

    International Nuclear Information System (INIS)

    Akperov, M.M.; Ismailov, Sh.S.; Shukyurova, A.A.

    2004-01-01

    Results of study of the Gd impurities effect on the bismuth telluride thermo-electric properties are presented. The experiment was carried out within the temperature range T=300-700 K. It is determined, that at temperature increase the energy level is appreciably closing up to bismuth telluride forbidden zone which makes up 0.16-0.24 eV. Such anomalous energy properties of gadolinium in telluride affect on material thermoelectric properties

  5. Ambient growth of highly oriented Cu{sub 2}S dendrites of superior thermoelectric behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Mulla, Rafiq; Rabinal, M.K., E-mail: mkrabinal@yahoo.com

    2017-03-01

    Highlights: • A simple and ambient route to synthesize highly oriented dendrites of copper sulfide is proposed. • Remarkable enhancement is observed in Seebeck coefficient by room temperature, solution phase doping. • High thermoelectric power factor is observed at room temperature, indicating promising behaviour. - Abstract: Low-cost, non-toxic and efficient material is an urgent need for the thermoelectric energy conversion. Here, a rapid and ambient chemical route has been developed to grow dense and highly oriented dendrites of copper sulfide (Cu{sub 2}S) on copper substrate in a very simple approach, these films are uniform and covered with dense nanosheets. Room temperature solution doping of copper ions is carried out to improve thermoelectric performance. The Seebeck coefficient increased from ∼100 to 415 μV K{sup −1} with a slight decrease in electrical conductivity, this gives a high power factor (S{sup 2}σ) of about ∼400 μW m{sup −1} K{sup −2}. The improved thermoelectric properties in these films are accounted for resonant energy level doping and high phonon scattering. Such films with improved thermoelectric behaviour can be promising materials for energy conversion. The earth abundant, low cost, non toxic with a good thermoelectric property makes copper sulfide as a promising thermoelectric material for future applications.

  6. Thermoelectric properties and performance of flexible reduced graphene oxide films up to 3,000 K

    Science.gov (United States)

    Li, Tian; Pickel, Andrea D.; Yao, Yonggang; Chen, Yanan; Zeng, Yuqiang; Lacey, Steven D.; Li, Yiju; Wang, Yilin; Dai, Jiaqi; Wang, Yanbin; Yang, Bao; Fuhrer, Michael S.; Marconnet, Amy; Dames, Chris; Drew, Dennis H.; Hu, Liangbing

    2018-02-01

    The development of ultrahigh-temperature thermoelectric materials could enable thermoelectric topping of combustion power cycles as well as extending the range of direct thermoelectric power generation in concentrated solar power. However, thermoelectric operation temperatures have been restricted to under 1,500 K due to the lack of suitable materials. Here, we demonstrate a thermoelectric conversion material based on high-temperature reduced graphene oxide nanosheets that can perform reliably up to 3,000 K. After a reduction treatment at 3,300 K, the nanosheet film exhibits an increased conductivity to 4,000 S cm-1 at 3,000 K and a high power factor S2σ = 54.5 µW cm-1 K-2. We report measurements characterizing the film's thermoelectric properties up to 3,000 K. The reduced graphene oxide film also exhibits a high broadband radiation absorbance and can act as both a radiative receiver and a thermoelectric generator. The printable, lightweight and flexible film is attractive for system integration and scalable manufacturing.

  7. Parametric optimization of thermoelectric elements footprint for maximum power generation

    DEFF Research Database (Denmark)

    Rezania, A.; Rosendahl, Lasse; Yin, Hao

    2014-01-01

    The development studies in thermoelectric generator (TEG) systems are mostly disconnected to parametric optimization of the module components. In this study, optimum footprint ratio of n- and p-type thermoelectric (TE) elements is explored to achieve maximum power generation, maximum cost......-performance, and variation of efficiency in the uni-couple over a wide range of the heat transfer coefficient on the cold junction. The three-dimensional (3D) governing equations of the thermoelectricity and the heat transfer are solved using the finite element method (FEM) for temperature dependent properties of TE...... materials. The results, which are in good agreement with the previous computational studies, show that the maximum power generation and the maximum cost-performance in the module occur at An/Ap

  8. Thinking Like a Chemist: Intuition in Thermoelectric Materials.

    Science.gov (United States)

    Zeier, Wolfgang G; Zevalkink, Alex; Gibbs, Zachary M; Hautier, Geoffroy; Kanatzidis, Mercouri G; Snyder, G Jeffrey

    2016-06-06

    The coupled transport properties required to create an efficient thermoelectric material necessitates a thorough understanding of the relationship between the chemistry and physics in a solid. We approach thermoelectric material design using the chemical intuition provided by molecular orbital diagrams, tight binding theory, and a classic understanding of bond strength. Concepts such as electronegativity, band width, orbital overlap, bond energy, and bond length are used to explain trends in electronic properties such as the magnitude and temperature dependence of band gap, carrier effective mass, and band degeneracy and convergence. The lattice thermal conductivity is discussed in relation to the crystal structure and bond strength, with emphasis on the importance of bond length. We provide an overview of how symmetry and bonding strength affect electron and phonon transport in solids, and how altering these properties may be used in strategies to improve thermoelectric performance. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Research of fuel temperature control in fuel pipeline of diesel engine using positive temperature coefficient material

    Directory of Open Access Journals (Sweden)

    Xiaolu Li

    2016-01-01

    Full Text Available As fuel temperature increases, both its viscosity and surface tension decrease, and this is helpful to improve fuel atomization and then better combustion and emission performances of engine. Based on the self-regulated temperature property of positive temperature coefficient material, this article used a positive temperature coefficient material as electric heating element to heat diesel fuel in fuel pipeline of diesel engine. A kind of BaTiO3-based positive temperature coefficient material, with the Curie temperature of 230°C and rated voltage of 24 V, was developed, and its micrograph and element compositions were also analyzed. By the fuel pipeline wrapped in six positive temperature coefficient ceramics, its resistivity–temperature and heating characteristics were tested on a fuel pump bench. The experiments showed that in this installation, the surface temperature of six positive temperature coefficient ceramics rose to the equilibrium temperature only for 100 s at rated voltage. In rated power supply for six positive temperature coefficient ceramics, the temperature of injection fuel improved for 21°C–27°C within 100 s, and then could keep constant. Using positive temperature coefficient material to heat diesel in fuel pipeline of diesel engine, the injection mass per cycle had little change, approximately 0.3%/°C. This study provides a beneficial reference for improving atomization of high-viscosity liquids by employing positive temperature coefficient material without any control methods.

  10. Feedforward temperature control using a heat flux microsensor

    OpenAIRE

    Lartz, Douglas John

    1993-01-01

    The concept of using heat flux measurements to provide the input for a feedforward temperature control loop is investigated. The feedforward loop is added to proportional and integral feedback control to increase the speed of the response to a disturbance. Comparison is made between the feedback and the feedback plus feedforward control laws. The control law with the feedforward control loop is also compared to the conventional approach of adding derivative control to speed up ...

  11. The practical performance forecast and analysis of thermoelectric module from macro to micro

    International Nuclear Information System (INIS)

    Shen, Limei; Chen, Huanxin; Xiao, Fu; Wang, Shengwei

    2015-01-01

    Highlights: • We analyze the practical performance of TEMs to meet specific requirements. • The influence of different input power sources are discussed. • The step-change phenomena of thermoelectric cooling are found and discussed. • The influence ratio of hot side heat exchanger and input power source is compared. - Abstract: The practical operating conditions of thermoelectric products, such as the input power source and the thermal resistance of hot side heat exchanger, are different from the theoretical study. Thus the equations, which are used to estimate the practical maximum cooling performance just according to the datum in datasheet of commercial thermoelectric module (TEM), are given. The nested loop method is adopted to solve the numerical model. This study provides a method to choose a suitable TEM for thermoelectric product to meet the application requirement. It finds that the minimum cold side temperature increase and the voltage for achieving the minimum cold side temperature step decrease with the increase of thermal resistance of hot side heat exchanger, respectively. The maximum temperature difference increase and the voltage for achieving the maximum temperature difference step increase with the increase of thermal resistance of hot side heat exchanger, respectively. According to the dimension, three kinds of thermoelectric module, bulk TEM, miniature TEM and micro TEM, are studied. The novel scale effect are discovered by comparing these TEMs. It found that the step-change phenomenon become more and more obvious with the decrease of the dimension of thermoelectric module. The influence ratio of thermal resistance of hot side heat exchanger on the maximum cooling performance increases and the influence ratio of input power source decreases from macro to micro, respectively. It forecasts that there exists a critical value for the dimension of thermoelectric module, when the dimension of thermoelectric module is smaller than this critical

  12. Peltier Effect Based Temperature Controlled System for Dielectric Spectroscopy

    Science.gov (United States)

    Mukda, T.; Jantaratana, P.

    2017-09-01

    The temperature control system was designed and built for application in dielectric spectroscopy. It is based on the dual-stage Peltier element that decreases electrical power and no cryogenic fluids are required. A proportional integral derivative controller was used to keep the temperature stability of the system. A Pt100 temperature sensor was used to measure temperature of the sample mounting stage. Effect of vacuum isolation and water-cooling on accuracy and stability of the system were also studied. With the incorporation of vacuum isolation and water-cooling at 18 °C, the temperature of the sample under test can be controlled in the range of -40 °C to 150 °C with temperature stability ± 0.025 °C.

  13. System for controlling the operating temperature of a fuel cell

    Science.gov (United States)

    Fabis, Thomas R.; Makiel, Joseph M.; Veyo, Stephen E.

    2006-06-06

    A method and system are provided for improved control of the operating temperature of a fuel cell (32) utilizing an improved temperature control system (30) that varies the flow rate of inlet air entering the fuel cell (32) in response to changes in the operating temperature of the fuel cell (32). Consistent with the invention an improved temperature control system (30) is provided that includes a controller (37) that receives an indication of the temperature of the inlet air from a temperature sensor (39) and varies the heat output by at least one heat source (34, 36) to maintain the temperature of the inlet air at a set-point T.sub.inset. The controller (37) also receives an indication of the operating temperature of the fuel cell (32) and varies the flow output by an adjustable air mover (33), within a predetermined range around a set-point F.sub.set, in order to maintain the operating temperature of the fuel cell (32) at a set-point T.sub.opset.

  14. Energy harvesting using a thermoelectric material

    Science.gov (United States)

    Nersessian, Nersesse [Van Nuys, CA; Carman, Gregory P [Los Angeles, CA; Radousky, Harry B [San Leandro, CA

    2008-07-08

    A novel energy harvesting system and method utilizing a thermoelectric having a material exhibiting a large thermally induced strain (TIS) due to a phase transformation and a material exhibiting a stress induced electric field is introduced. A material that exhibits such a phase transformation exhibits a large increase in the coefficient of thermal expansion over an incremental temperature range (typically several degrees Kelvin). When such a material is arranged in a geometric configuration, such as, for a example, a laminate with a material that exhibits a stress induced electric field (e.g. a piezoelectric material) the thermally induced strain is converted to an electric field.

  15. Modeling, Prediction, and Control of Heating Temperature for Tube Billet

    Directory of Open Access Journals (Sweden)

    Yachun Mao

    2015-01-01

    Full Text Available Annular furnaces have multivariate, nonlinear, large time lag, and cross coupling characteristics. The prediction and control of the exit temperature of a tube billet are important but difficult. We establish a prediction model for the final temperature of a tube billet through OS-ELM-DRPLS method. We address the complex production characteristics, integrate the advantages of PLS and ELM algorithms in establishing linear and nonlinear models, and consider model update and data lag. Based on the proposed model, we design a prediction control algorithm for tube billet temperature. The algorithm is validated using the practical production data of Baosteel Co., Ltd. Results show that the model achieves the precision required in industrial applications. The temperature of the tube billet can be controlled within the required temperature range through compensation control method.

  16. Thermal and stress analyses in thermoelectric generator with tapered and rectangular pin configurations

    International Nuclear Information System (INIS)

    Yilbas, Bekir Sami; Akhtar, S.S.; Sahin, A.Z.

    2016-01-01

    Thermal stress developed in thermoelectric generators is critical for long service applications. High temperature gradients, due to a large temperature difference across the junctions, causes excessive stress levels developed in the device pins and electrodes at the interfaces. In the present study, a thermoelectric generator with horizontal pin configuration is considered and thermal stress analysis in the device is presented. Ceramic wafer is considered to resemble the high temperature plate and copper electrodes are introduced at the pin junctions to reduce the electrical resistance between the pins and the high and low temperature junction plates during the operation. Finite element code is used to simulate temperature and stress fields in the thermoelectric generator. In the simulations, convection and radiation losses from the thermoelectric pins are considered and bismuth telluride pin material with and without tapering is incorporated. It is found that von Mises stress attains high values at the interface between the hot and cold junctions and the copper electrodes. Thermal stress developed in tapered pin configuration attains lower values than that of rectangular pin cross-section. - Highlights: • Different cold junction temperatures improves thermoelectric generator performance. • von Mises stress remains high across copper electrodes and hot junction ceramics. • von Mises stress reduces along pin length towards cold junction. • Pin tapering lowers stress levels in thermoelectric generator.

  17. Interfacial reactions in thermoelectric modules

    KAUST Repository

    Wu, Hsin-jay; Wu, Albert T.; Wei, Pei-chun; Chen, Sinn-wen

    2018-01-01

    Engineering transport properties of thermoelectric (TE) materials leads to incessantly breakthroughs in the zT values. Nevertheless, modular design holds a key factor to advance the TE technology. Herein, we discuss the structures of TE module

  18. Material parameters for thermoelectric performance

    Indian Academy of Sciences (India)

    The thermoelectric performance of a thermoelement is ideally defined in terms of the so-called ... However, there are other parameters which are fairly good indicators ... Whereas a final deciding factor reflecting on .... matter of a future work.

  19. Robust velocity and load control of a steam turbine in a combined cycle thermoelectric power station; Control robusto de velocidad y carga de una turbina de vapor en una central termoelectrica de ciclo combinado

    Energy Technology Data Exchange (ETDEWEB)

    Reyes Archundia, Enrique

    1998-12-31

    This research work is oriented to design, develop and validate an algorithm of modern control, that allows obtaining better performances in the control of speed of a steam turbine pertaining to a combined cycle thermoelectric power station, in all the operation interval, as well as obtaining better performances in the control of the amount of generated megawatts by the same when it is connected to an electric power generator, comparing the performance with the one obtained by means of the existing conventional controller. The changes in the speed reference or load are at the request of the operator and they always occur in incline form, indicating the rapidity with which it is desired to carry out the change of value in the reference. This is the reason for why the main objective of the control to design is to make a good follow up to references of the incline type. In the subsystem of the existing steam turbine the disadvantage is that the valves that regulate the steam flow to the turbine present a connection with the bypass valve that allows to derive the steam flow towards the main condenser without going through the turbine. It is for this reason that a multi-variable control that contemplates the interaction that occurs among the valves just mentioned, departing from a single variable design. The robust control H{infinity} has the following characteristics that allow it to be applied to the steam turbine process: the design can be made to have two poles in the origin, with which a good follow up to references of incline type is obtained; it allows the uncertainty handling, with which good results in everything are expected an entire operation interval; and it allows the design of multi-variable controllers, with which the existing interaction between the valves of control and bypass is considered. It is very difficult to be able to make tests with the real process, due to the cost and risks that it implies, nevertheless, the developments achieved in the areas

  20. A Comparative Study on Temperature Control of CSTR using PI Controller, PID Controller and PID (Two Degree of Freedom) Controller

    OpenAIRE

    Bikash Dey; Lusika Roy

    2014-01-01

    This paper present three different control strategies based on PI Control, PID control and Two degree of freedom PID control for Continuous Stirred Tank Reactor (CSTR).CSTR which offers a diverse range of application in the field of chemical engineering as well as in the control engineering and is an attractive research area for process control researchers. Our objective is to control the temperature of CSTR in presence of the set point. MATLAB SIMULINK software is used for mo...

  1. Theoretical analysis of thermoelectric power of nanocrystalline ReSi2 thin film

    International Nuclear Information System (INIS)

    Kchoudhary, K; Kaurav; Gupta, N; Varshney, D

    2007-01-01

    The formulation is developed for the predictive modeling of thermoelectric power (S) of nano-crystalline ReSi 2 . We have evaluated the phonon thermoelectric power by incorporating the scattering of phonons with impurities, grain boundaries, charge careers and phonons. It is noticed that at low temperatures (T < 400 K), S increases and show power temperature dependence because of the larger mean free path of phonon, S shows a broad peak at about 550 K, which is artefact of the competition among umklapp scattering and grain boundaries scattering. Further, by increasing temperature S decreases with change in slope. The anomalies are well accounted in terms of interaction among the phonons-impurity, phonon grain boundaries and the umklapp scattering. Under certain conditions grain boundary scattering is expected to be more effective on heat carrying phonons than on Umklapp scattering, causing an increased thermoelectric power. Numerical analysis of thermoelectric power from the present model shows similar results as those revealed from experiments

  2. Analytical thermal model validation for Cassini radioisotope thermoelectric generator

    International Nuclear Information System (INIS)

    Lin, E.I.

    1997-01-01

    The Saturn-bound Cassini spacecraft is designed to rely, without precedent, on the waste heat from its three radioisotope thermoelectric generators (RTGs) to warm the propulsion module subsystem, and the RTG end dome temperature is a key determining factor of the amount of waste heat delivered. A previously validated SINDA thermal model of the RTG was the sole guide to understanding its complex thermal behavior, but displayed large discrepancies against some initial thermal development test data. A careful revalidation effort led to significant modifications and adjustments of the model, which result in a doubling of the radiative heat transfer from the heat source support assemblies to the end domes and bring up the end dome and flange temperature predictions to within 2 C of the pertinent test data. The increased inboard end dome temperature has a considerable impact on thermal control of the spacecraft central body. The validation process offers an example of physically-driven analytical model calibration with test data from not only an electrical simulator but also a nuclear-fueled flight unit, and has established the end dome temperatures of a flight RTG where no in-flight or ground-test data existed before

  3. Reactivity control system of the high temperature engineering test reactor

    International Nuclear Information System (INIS)

    Tachibana, Yukio; Sawahata, Hiroaki; Iyoku, Tatsuo; Nakazawa, Toshio

    2004-01-01

    The reactivity control system of the high temperature engineering test reactor (HTTR) consists of a control rod system and a reserve shutdown system. During normal operation, reactivity is controlled by the control rod system, which consists of 32 control rods (16 pairs) and 16 control rod drive mechanisms except for the case when the center control rods are removed to perform an irradiation test. In an unlikely event that the control rods fail to be inserted, reserve shutdown system is provided to insert pellets of neutron-absorbing material into the core. Alloy 800H is chosen for the metallic parts of the control rods. Because the maximum temperature of the control rods reaches about 900 deg. C at reactor scrams, structural design guideline and design material data on Alloy 800H are needed for the high temperature design. The design guideline for the HTTR control rod is based on ASME Code Case N-47-21. Design material data is also determined and shown in this paper. Observing the guideline, temperature and stress analysis were conducted; it can be confirmed that the target life of the control rods of 5 years can be achieved. Various tests conducted for the control rod system and the reserve shutdown system are also described

  4. SMART core power control method by coolant temperature variation

    International Nuclear Information System (INIS)

    Lee, Chung Chan; Cho, Byung Oh

    2001-08-01

    SMART is a soluble boron-free integral type pressurized water reactor. Its moderator temperature coefficient (MTC) is strongly negative throughout the cycle. The purpose of this report is how to utilize the primary coolant temperature as a second reactivity control system using the strong negative MTC. The reactivity components associated with reactor power change are Doppler reactivity due to fuel temperature change, moderator temperature reactivity and xenon reactivity. Doppler reactivity and moderator temperature reactivity take effects almost as soon as reactor power changes. On the other hand, xenon reactivity change takes more than several hours to reach an equilibrium state. Therefore, coolant temperature at equilibrium state is chosen as the reference temperature. The power dependent reference temperature line is limited above 50% power not to affect adversely in reactor safety. To compensate transient xenon reactivity, coolant temperature operating range is expanded. The suggested coolant temperature operation range requires minimum control rod motion for 50% power change. For smaller power changes such as 25% power change, it is not necessary to move control rods to assure that fuel design limits are not exceeded

  5. Microcontroller based automatic temperature control for oyster mushroom plants

    Science.gov (United States)

    Sihombing, P.; Astuti, T. P.; Herriyance; Sitompul, D.

    2018-03-01

    In the cultivation of Oyster Mushrooms need special treatment because oyster mushrooms are susceptible to disease. Mushroom growth will be inhibited if the temperature and humidity are not well controlled because temperature and inertia can affect mold growth. Oyster mushroom growth usually will be optimal at temperatures around 22-28°C and humidity around 70-90%. This problem is often encountered in the cultivation of oyster mushrooms. Therefore it is very important to control the temperature and humidity of the room of oyster mushroom cultivation. In this paper, we developed an automatic temperature monitoring tool in the cultivation of oyster mushroom-based Arduino Uno microcontroller. We have designed a tool that will control the temperature and humidity automatically by Android Smartphone. If the temperature increased more than 28°C in the room of mushroom plants, then this tool will turn on the pump automatically to run water in order to lower the room temperature. And if the room temperature of mushroom plants below of 22°C, then the light will be turned on in order to heat the room. Thus the temperature in the room oyster mushrooms will remain stable so that the growth of oyster mushrooms can grow with good quality.

  6. Optimization of Thermoelectric Components for Automobile Waste Heat Recovery Systems

    Science.gov (United States)

    Kumar, Sumeet; Heister, Stephen D.; Xu, Xianfan; Salvador, James R.

    2015-10-01

    For a typical spark ignition engine approximately 40% of available thermal energy is lost as hot exhaust gas. To improve fuel economy, researchers are currently evaluating technology which exploits exhaust stream thermal power by use of thermoelectric generators (TEGs) that operate on the basis of the Seebeck effect. A 5% improvement in fuel economy, achieved by use of TEG output power, is a stated objective for light-duty trucks and personal automobiles. System modeling of thermoelectric (TE) components requires solution of coupled thermal and electric fluxes through the n and p-type semiconductor legs, given appropriate thermal boundary conditions at the junctions. Such applications have large thermal gradients along the semiconductor legs, and material properties are highly dependent on spatially varying temperature profiles. In this work, one-dimensional heat flux and temperature variations across thermoelectric legs were solved by using an iterative numerical approach to optimize both TE module and TEG designs. Design traits were investigated by assuming use of skutterudite as a thermoelectric material with potential for automotive applications in which exhaust gas and heat exchanger temperatures typically vary from 100°C to over 600°C. Dependence of leg efficiency, thermal fluxes and electric power generation on leg geometry, fill fractions, electric current, thermal boundary conditions, etc., were studied in detail. Optimum leg geometries were computed for a variety of automotive exhaust conditions.

  7. Thermoelectricity in correlated narrow-gap semiconductors

    Science.gov (United States)

    Tomczak, Jan M.

    2018-05-01

    We review many-body effects, their microscopic origin, as well as their impact on thermoelectricity in correlated narrow-gap semiconductors. Members of this class—such as FeSi and FeSb2—display an unusual temperature dependence in various observables: insulating with large thermopowers at low temperatures, they turn bad metals at temperatures much smaller than the size of their gaps. This insulator-to-metal crossover is accompanied by spectral weight-transfers over large energies in the optical conductivity and by a gradual transition from activated to Curie–Weiss-like behaviour in the magnetic susceptibility. We show a retrospective of the understanding of these phenomena, discuss the relation to heavy-fermion Kondo insulators—such as Ce3Bi4Pt3 for which we present new results—and propose a general classification of paramagnetic insulators. From the latter, FeSi emerges as an orbital-selective Kondo insulator. Focussing on intermetallics such as silicides, antimonides, skutterudites, and Heusler compounds we showcase successes and challenges for the realistic simulation of transport properties in the presence of electronic correlations. Further, we explore new avenues in which electronic correlations may contribute to the improvement of thermoelectric performance.

  8. Thermoelectric transport through quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Merker, Lukas Heinrich

    2016-06-30

    In this thesis the thermoelectric properties (electrical conductance, Seebeck coefficient and thermal conductance)of quantum dots described by the Anderson impurity model have been investigated by using the numerical renormalization group (NRG) method. In order to make accurate calculations for thermoelectric properties of quantum impurity systems, a number of recent developments and refinements of the NRG have been implemented. These include the z-averaging and Campo discretization scheme, which enable the evaluation of physical quantities on an arbitrary temperature grid and at large discretization parameter Λ and the full density matrix (FDM) approach, which allows a more accurate calculation of spectral functions and transport coefficients. The implementation of the z-averaging and Campo discretization scheme has been tested within a new method for specific heats of quantum impurities. The accuracy of this new method was established by comparison with the numerical solution of the Bethe-ansatz equations for the Anderson model. The FDM approach was implemented and tested within a new approach to the calculation of impurity contributions to the uniform susceptibilities. Within this method a non-negligible contribution from the ''environmental'' degrees of freedom needs to be taken into account to recover the correct susceptibility, as shown by comparison with the Bethe-ansatz approach. An accurate method to calculate the conductance of a quantum dot is implemented, enabling the extraction of the Fermi liquid scaling coefficients c{sub T} and c{sub B} to high accuracy, being able to verify the results of the renormalized super perturbation theory approach (within its regime of validity). The method was generalized to higher order moments of the local level spectral function. This, as well as reduction of the SU(2) code to the U(1) symmetry, enabled the investigation of the effect of a magnetic field on the thermoelectric properties of quantum

  9. AUTOMATIC CONTROL SYSTEM OF THE DRUM BOILER SUPERHEATED STEAM TEMPERATURE.

    Directory of Open Access Journals (Sweden)

    Juravliov A.A.

    2006-04-01

    Full Text Available The control system of the temperature of the superheated steam of the drum boiler is examined. Main features of the system are the PI-controller in the external control loop and introduction of the functional component of the error signal of the external control loop with the negative feedback of the error signal between the prescribed value of steam flowrate and the signal of the steam flowrate in the exit of the boiler in the internal control loop.

  10. Compressive strain induced enhancement in thermoelectric-power-factor in monolayer MoS2 nanosheet

    International Nuclear Information System (INIS)

    Dimple; Jena, Nityasagar; De Sarkar, Abir

    2017-01-01

    Strain and temperature induced tunability in the thermoelectric properties in monolayer MoS 2 (ML-MoS 2 ) has been demonstrated using density functional theory coupled to semi-classical Boltzmann transport theory. Compressive strain, in general and uniaxial compressive strain (along the zig-zag direction), in particular, is found to be most effective in enhancing the thermoelectric power factor, owing to the higher electronic mobility and its sensitivity to lattice compression along this direction. Variation in the Seebeck coefficient and electronic band gap with strain is found to follow the Goldsmid–Sharp relation. n-type doping is found to raise the relaxation time-scaled thermoelectric power factor higher than p-type doping and this divide widens with increasing temperature. The relaxation time-scaled thermoelectric power factor in optimally n-doped ML-MoS 2 is found to undergo maximal enhancement under the application of 3% uniaxial compressive strain along the zig-zag direction, when both the ( direct ) electronic band gap and the Seebeck coefficient reach their maximum, while the electron mobility drops down drastically from 73.08 to 44.15 cm 2 V −1 s −1 . Such strain sensitive thermoelectric responses in ML-MoS 2 could open doorways for a variety of applications in emerging areas in 2D-thermoelectrics, such as on-chip thermoelectric power generation and waste thermal energy harvesting. (paper)

  11. TEMPERATURE DISTRIBUTION MONITORING AND ANALYSES AT DIFFERENT HEATING CONTROL PRINCIPLES

    DEFF Research Database (Denmark)

    Simone, Angela; Rode, Carsten; Olesen, Bjarne W.

    2010-01-01

    under different control strategies of the heating system (Pseudo Random Binary Sequence signal controlling all the heaters (PRBS) or thermostatic control of the heaters (THERM)). A comparison of the measured temperatures within the room, for the five series of experiments, shows a better correlation...

  12. Central control of body temperature [version 1; referees: 3 approved

    Directory of Open Access Journals (Sweden)

    Shaun F. Morrison

    2016-05-01

    Full Text Available Central neural circuits orchestrate the behavioral and autonomic repertoire that maintains body temperature during environmental temperature challenges and alters body temperature during the inflammatory response and behavioral states and in response to declining energy homeostasis. This review summarizes the central nervous system circuit mechanisms controlling the principal thermoeffectors for body temperature regulation: cutaneous vasoconstriction regulating heat loss and shivering and brown adipose tissue for thermogenesis. The activation of these thermoeffectors is regulated by parallel but distinct efferent pathways within the central nervous system that share a common peripheral thermal sensory input. The model for the neural circuit mechanism underlying central thermoregulatory control provides a useful platform for further understanding of the functional organization of central thermoregulation, for elucidating the hypothalamic circuitry and neurotransmitters involved in body temperature regulation, and for the discovery of novel therapeutic approaches to modulating body temperature and energy homeostasis.

  13. Impact of microstructure on the thermoelectric properties of the ternary compound Ce{sub 3}Cu{sub 3}Sb{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Witas, Piotr, E-mail: pwitas@us.edu.pl [Institute of Physics, University of Silesia, Uniwersytecka 4, Katowice 40-007 (Poland); Goraus, Jerzy; Zajdel, Paweł; Balin, Katarzyna; Koperski, Janusz [Institute of Physics, University of Silesia, Uniwersytecka 4, Katowice 40-007 (Poland); Lelątko, Józef [Institute of Materials Science, University of Silesia, 75 Pułku Piechoty 1a, Chorzów 41-500 (Poland); Ślebarski, Andrzej [Institute of Physics, University of Silesia, Uniwersytecka 4, Katowice 40-007 (Poland)

    2017-01-15

    We present detailed structural and thermoelectric studies of the ternary compound Ce{sub 3}Cu{sub 3}Sb{sub 4}. This material is of interest due to previously reported considerable thermopower above room temperature (∼ 100 μV/K) and low thermal conductivity (2 W/(m K)). Here, we present detailed studies concerning microstructural and thermoelectric data, their variation across the samples and possible explanations for the observed behaviour. We have used X-ray diffraction, scanning electron microscopy (SEM), and time-of-flight secondary ion mass spectrometry (TOF-SIMS) for microstructural analysis. The thermoelectric properties were examined using a physical property measurement system (PPMS). We analyse the impact of the sample quality on the thermoelectric properties. The most unstable parameter is the material resistivity which varies between 1.5 and 15 mΩ cm at room temperature. The properties variability is mainly due to structural defects caused by stresses during material preparation and also due to formation of foreign phases CeCuSb{sub 2} and CeSb. The figure of merit ZT is also strongly dependent on the quality of the sample. The largest value ZT ≈ 0.15 at 400 K is determined for the almost stoichiometric sample with small amounts of a impurity phases. - Highlights: •The Ce{sub 3}Cu{sub 3}Sb{sub 4} has considerable thermoelectric properties and potential for further chemical and/or structural modification. •The control over foreign phases formation is challenging. •The defects arising during arc melting process highly deteriorate ZT of material.

  14. Strain-induced bi-thermoelectricity in tapered carbon nanotubes

    Science.gov (United States)

    Algharagholy, L. A. A.; Pope, T.; Lambert, C. J.

    2018-03-01

    We show that carbon-based nanostructured materials are a novel testbed for controlling thermoelectricity and have the potential to underpin the development of new cost-effective environmentally-friendly thermoelectric materials. In single-molecule junctions, it is known that transport resonances associated with the discrete molecular levels play a key role in the thermoelectric performance, but such resonances have not been exploited in carbon nanotubes (CNTs). Here we study junctions formed from tapered CNTs and demonstrate that such structures possess transport resonances near the Fermi level, whose energetic location can be varied by applying strain, resulting in an ability to tune the sign of their Seebeck coefficient. These results reveal that tapered CNTs form a new class of bi-thermoelectric materials, exhibiting both positive and negative thermopower. This ability to change the sign of the Seebeck coefficient allows the thermovoltage in carbon-based thermoelectric devices to be boosted by placing CNTs with alternating-sign Seebeck coefficients in tandem.

  15. Synchronous temperature rate control for refrigeration with reduced energy consumption

    Science.gov (United States)

    Gomes, Alberto Regio; Keres, Stephen L.; Kuehl, Steven J.; Litch, Andrew D.; Richmond, Peter J.; Wu, Guolian

    2015-09-22

    Methods of operation for refrigerator appliance configurations with a controller, a condenser, at least one evaporator, a compressor, and two refrigeration compartments. The configuration may be equipped with a variable-speed or variable-capacity compressor, variable speed evaporator or compartment fans, a damper, and/or a dual-temperature evaporator with a valve system to control flow of refrigerant through one or more pressure reduction devices. The methods may include synchronizing alternating cycles of cooling each compartment to a temperature approximately equal to the compartment set point temperature by operation of the compressor, fans, damper and/or valve system. The methods may also include controlling the cooling rate in one or both compartments. Refrigeration compartment cooling may begin at an interval before or after when the freezer compartment reaches its lower threshold temperature. Freezer compartment cooling may begin at an interval before or after when the freezer compartment reaches its upper threshold temperature.

  16. Synchronous temperature rate control for refrigeration with reduced energy consumption

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Alberto Regio; Keres, Stephen L.; Kuehl, Steven J.; Litch, Andrew D.; Richmond, Peter J.; Wu, Guolian

    2017-11-07

    Methods of operation for refrigerator appliance configurations with a controller, a condenser, at least one evaporator, a compressor, and two refrigeration compartments. The configuration may be equipped with a variable-speed or variable-capacity compressor, variable speed evaporator or compartment fans, a damper, and/or a dual-temperature evaporator with a valve system to control flow of refrigerant through one or more pressure reduction devices. The methods may include synchronizing alternating cycles of cooling each compartment to a temperature approximately equal to the compartment set point temperature by operation of the compressor, fans, damper and/or valve system. The methods may also include controlling the cooling rate in one or both compartments. Refrigeration compartment cooling may begin at an interval before or after when the freezer compartment reaches its lower threshold temperature. Freezer compartment cooling may begin at an interval before or after when the freezer compartment reaches its upper threshold temperature.

  17. Fiber Fabry-Perot interferometer with controllable temperature sensitivity.

    Science.gov (United States)

    Zhang, Xinpu; Peng, Wei; Zhang, Yang

    2015-12-01

    We proposed a fiber taper based on the Fabry-Perot (FP) interferometer structure with controllable temperature sensitivity. The FP interferometer is formed by inserting a segment of tapered fiber tip into the capillary and subsequently splicing the other end of the capillary to a single-mode fiber (SMF), the tapered fiber endface, and the spliced face form the FP cavity. Through controlling the inserted tapered fiber length, a series of FP interferometers were made. Because the inserted taper tip has the degree of freedom along the fiber axial, when the FP interferometer is subjected to temperature variation, the thermal expansion of the fiber taper tip will resist the FP cavity length change caused by the evolution of capillary length, and we can control the temperature sensitivity by adjusting the inserted taper length. In this structure, the equivalent thermal expansion coefficient of the FP interferometer can be defined; it was used to evaluate the temperature sensitivity of the FP interferometer, which provides an effective method to eliminate the temperature effect and to enhance other measurement accuracy. We fabricated the FP interferometers and calibrated their temperature characters by measuring the wavelength shift of the resonance dips in the reflection spectrum. In a temperature range of 50°C to 150°C, the corresponding temperature sensitivities can be controlled between 0 and 1.97 pm/°C when the inserted taper is between 75 and 160 μm. Because of its controllable temperature sensitivity, ease of fabrication, and low cost, this FP interferometer can meet different temperature sensitivity requirements in various application areas, especially in the fields which need temperature insensitivity.

  18. Apparatus, System, and Method for On-Chip Thermoelectricity Generation

    KAUST Repository

    Hussain, Muhammad Mustafa

    2012-01-26

    An apparatus, system, and method for a thermoelectric generator. In some embodiments, the thermoelectric generator comprises a first thermoelectric region and a second thermoelectric region, where the second thermoelectric region may be coupled to the first thermoelectric region by a first conductor. In some embodiments, a second conductor may be coupled to the first thermoelectric region and a third conductor may be coupled to the second thermoelectric region. In some embodiments, the first conductor may be in a first plane, the first thermoelectric region and the second thermoelectric region may be in a second plane, and the second conductor and the third conductor may be in a third plane.

  19. Apparatus, System, and Method for On-Chip Thermoelectricity Generation

    KAUST Repository

    Hussain, Muhammad Mustafa; Fahad, Hossain M.; Rojas, Jhonathan Prieto

    2012-01-01

    An apparatus, system, and method for a thermoelectric generator. In some embodiments, the thermoelectric generator comprises a first thermoelectric region and a second thermoelectric region, where the second thermoelectric region may be coupled to the first thermoelectric region by a first conductor. In some embodiments, a second conductor may be coupled to the first thermoelectric region and a third conductor may be coupled to the second thermoelectric region. In some embodiments, the first conductor may be in a first plane, the first thermoelectric region and the second thermoelectric region may be in a second plane, and the second conductor and the third conductor may be in a third plane.

  20. Drifting temperature climate control for archives and stores

    DEFF Research Database (Denmark)

    Klenz Larsen, Poul; Padfield, Tim; Ryhl-Svendsen, Morten

    2017-01-01

    The climate within museum stores and archives can be regulated by dehumidifying a building whose temperature is allowed to vary seasonally without explicit control. The ground beneath the building provides thermal inertia to hold the annual temperature cycle around 8 – 16°C, in northern Europe...

  1. Deployable Thermoelectric Metamaterial Energy Harvesting Monitoring System

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will combine a novel asynchronous monitoring system with the first-of-its-kind thermoelectric metamaterial.  The thermoelectric prototype is constructed...

  2. Multi-Temperature Zone, Droplet-based Microreactor for Increased Temperature Control in Nanoparticle Synthesis

    KAUST Repository

    Erdem, E. Yegâ n; Cheng, Jim C.; Doyle, Fiona M.; Pisano, Albert P.

    2013-01-01

    Microreactors are an emerging technology for the controlled synthesis of nanoparticles. The Multi-Temperature zone Microreactor (MTM) described in this work utilizes thermally isolated heated and cooled regions for the purpose of separating

  3. Temperature-controlled irrigated tip radiofrequency catheter ablation

    DEFF Research Database (Denmark)

    Petersen, H H; Chen, X; Pietersen, Adrian

    1998-01-01

    INTRODUCTION: In patients with ventricular tachycardias due to structural heart disease, catheter ablation cures radiofrequency ablation. Irrigated tip radiofrequency ablation using power control and high infusion rates enlarges lesion......: We conclude that temperature-controlled radiofrequency ablation with irrigated tip catheters using low target temperature and low infusion rate enlarges lesion size without increasing the incidence of cratering and reduces coagulum formation of the tip....

  4. Weld Nugget Temperature Control in Thermal Stir Welding

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2014-01-01

    A control system for a thermal stir welding system is provided. The control system includes a sensor and a controller. The sensor is coupled to the welding system's containment plate assembly and generates signals indicative of temperature of a region adjacent and parallel to the welding system's stir rod. The controller is coupled to the sensor and generates at least one control signal using the sensor signals indicative of temperature. The controller is also coupled to the welding system such that at least one of rotational speed of the stir rod, heat supplied by the welding system's induction heater, and feed speed of the welding system's weld material feeder are controlled based on the control signal(s).

  5. Thermoelectric power generator for variable thermal power source

    Science.gov (United States)

    Bell, Lon E; Crane, Douglas Todd

    2015-04-14

    Traditional power generation systems using thermoelectric power generators are designed to operate most efficiently for a single operating condition. The present invention provides a power generation system in which the characteristics of the thermoelectrics, the flow of the thermal power, and the operational characteristics of the power generator are monitored and controlled such that higher operation efficiencies and/or higher output powers can be maintained with variably thermal power input. Such a system is particularly beneficial in variable thermal power source systems, such as recovering power from the waste heat generated in the exhaust of combustion engines.

  6. Direct digital temperature control of the A-1 nuclear reactor

    International Nuclear Information System (INIS)

    Karpeta, C.

    1975-01-01

    The application is described of one of the modern control methods for designing an experimental digital temperature control system for heavy water moderated gas cooled reactors. The synthesis of the optimal stochastic regulator for reactor control in the area of the rated steady state was carried out using the method of dynamic programming and the Kalman filter technique. The analysis of the feedback circuit was conducted using control simulation on a universal digital computer. Results and experience are summed up. (author)

  7. Enhanced Temperature Control Method Using ANFIS with FPGA

    Directory of Open Access Journals (Sweden)

    Chiung-Wei Huang

    2014-01-01

    Full Text Available Temperature control in etching process is important for semiconductor manufacturing technology. However, pressure variations in vacuum chamber results in a change in temperature, worsening the accuracy of the temperature of the wafer and the speed and quality of the etching process. This work develops an adaptive network-based fuzzy inference system (ANFIS using a field-programmable gate array (FPGA to improve the effectiveness. The proposed method adjusts every membership function to keep the temperature in the chamber stable. The improvement of the proposed algorithm is confirmed using a medium vacuum (MV inductively-coupled plasma- (ICP- type etcher.

  8. Study on a Battery Thermal Management System Based on a Thermoelectric Effect

    Directory of Open Access Journals (Sweden)

    Chuan-Wei Zhang

    2018-01-01

    Full Text Available As is known to all, a battery pack is significantly important for electric vehicles. However, its performance is easily affected by temperature. In order to address this problem, an enhanced battery thermal management system is proposed, which includes two parts: a modified cooling structure and a control unit. In this paper, more attention has been paid to the structure part. According to the heat generation mechanism of a battery and a thermoelectric chip, a simplified heat generation model for a single cell and a special cooling model were created in ANSYS 17.0. The effects of inlet velocity on the performance of different heat exchanger structures were studied. The results show that the U loop structure is more reasonable and the flow field distribution is the most uniform at the inlet velocity of 1.0 m/s. Then, on the basis of the above heat exchanger and the liquid flow velocity, the cooling effect of the improved battery temperature adjustment structure and the traditional liquid temperature regulating structure were analyzed. It can be seen that the liquid cooling structure combined with thermoelectric cooling demonstrates a better performance. With respect to the control system, the corresponding hardware and software were also developed. In general, the design process for this enhanced battery thermal management system can provide a wealth of guidelines for solving similar problems. The H commutation circuit, matrix switch circuit, temperature measurement circuit, and wireless communication modules were designed in the control system and the temperature control strategy was also developed.

  9. Model predictive control of room temperature with disturbance compensation

    Science.gov (United States)

    Kurilla, Jozef; Hubinský, Peter

    2017-08-01

    This paper deals with temperature control of multivariable system of office building. The system is simplified to several single input-single output systems by decoupling their mutual linkages, which are separately controlled by regulator based on generalized model predictive control. Main part of this paper focuses on the accuracy of the office temperature with respect to occupancy profile and effect of disturbance. Shifting of desired temperature and changing of weighting coefficients are used to achieve the desired accuracy of regulation. The final structure of regulation joins advantages of distributed computing power and possibility to use network communication between individual controllers to consider the constraints. The advantage of using decoupled MPC controllers compared to conventional PID regulators is demonstrated in a simulation study.

  10. Half-Heusler Alloys as Promising Thermoelectric Materials

    Science.gov (United States)

    Page, Alexander A.

    This thesis describes Ph.D. research on the half-Heusler class of thermoelectric materials. Half-Heusler alloys are a versatile class of materials that have been studied for use in photovoltaics, phase change memory, and thermoelectric power generation. With respect to thermoelectric power generation, new approaches were recently developed in order to improve the thermoelectric figure of merit, ZT, of half-Heusler alloys. Two of the strategies discussed in this work are adding excess Ni within MNiSn (M = Ti, Zr, or Hf) compounds to form full-Heusler nanostructures and using isoelectronic substitution of Ti, Zr, and Hf in MNiSn compounds to create microscale grain boundaries. This work uses computational simulations based on density functional theory, combined with the cluster expansion method, to predict the stable phases of pseudo-binary and pseudo-ternary composition systems. Statistical mechanics methods were used to calculate temperature-composition phase diagrams that relate the equilibrium phases. It is shown that full-Heusler nanostructures are predicted to remain stable even at high temperatures, and the microscale grain boundaries observed in (Ti,Zr,Hf)NiSn materials are found to be thermodynamically unstable at equilibrium. A new strategy of combining MNiSn materials with ZrNiPb has also recently emerged, and theoretical and experimental work show that a solid solution of the two materials is stable.

  11. Thermoelectric Generation Of Current - Theoretical And Experimental Analysis

    Science.gov (United States)

    Ruciński, Adam; Rusowicz, Artur

    2017-12-01

    This paper provides some information about thermoelectric technology. Some new materials with improved figures of merit are presented. These materials in Peltier modules make it possible to generate electric current thanks to a temperature difference. The paper indicates possible applications of thermoelectric modules as interesting tools for using various waste heat sources. Some zero-dimensional equations describing the conditions of electric power generation are given. Also, operating parameters of Peltier modules, such as voltage and electric current, are analyzed. The paper shows chosen characteristics of power generation parameters. Then, an experimental stand for ongoing research and experimental measurements are described. The authors consider the resistance of a receiver placed in the electric circuit with thermoelectric elements. Finally, both the analysis of experimental results and conclusions drawn from theoretical findings are presented. Voltage generation of about 1.5 to 2.5 V for the temperature difference from 65 to 85 K was observed when a bismuth telluride thermoelectric couple (traditionally used in cooling technology) was used.

  12. Thermoelectric Generation Of Current – Theoretical And Experimental Analysis

    Directory of Open Access Journals (Sweden)

    Ruciński Adam

    2017-12-01

    Full Text Available This paper provides some information about thermoelectric technology. Some new materials with improved figures of merit are presented. These materials in Peltier modules make it possible to generate electric current thanks to a temperature difference. The paper indicates possible applications of thermoelectric modules as interesting tools for using various waste heat sources. Some zero-dimensional equations describing the conditions of electric power generation are given. Also, operating parameters of Peltier modules, such as voltage and electric current, are analyzed. The paper shows chosen characteristics of power generation parameters. Then, an experimental stand for ongoing research and experimental measurements are described. The authors consider the resistance of a receiver placed in the electric circuit with thermoelectric elements. Finally, both the analysis of experimental results and conclusions drawn from theoretical findings are presented. Voltage generation of about 1.5 to 2.5 V for the temperature difference from 65 to 85 K was observed when a bismuth telluride thermoelectric couple (traditionally used in cooling technology was used.

  13. Thermoelectric Power Factor Limit of a 1D Nanowire

    Science.gov (United States)

    Chen, I.-Ju; Burke, Adam; Svilans, Artis; Linke, Heiner; Thelander, Claes

    2018-04-01

    In the past decade, there has been significant interest in the potentially advantageous thermoelectric properties of one-dimensional (1D) nanowires, but it has been challenging to find high thermoelectric power factors based on 1D effects in practice. Here we point out that there is an upper limit to the thermoelectric power factor of nonballistic 1D nanowires, as a consequence of the recently established quantum bound of thermoelectric power output. We experimentally test this limit in quasiballistic InAs nanowires by extracting the maximum power factor of the first 1D subband through I -V characterization, finding that the measured maximum power factors conform to the theoretical limit. The established limit allows the prediction of the achievable power factor of a specific nanowire material system with 1D electronic transport based on the nanowire dimension and mean free path. The power factor of state-of-the-art semiconductor nanowires with small cross section and high crystal quality can be expected to be highly competitive (on the order of mW /m K2 ) at low temperatures. However, they have no clear advantage over bulk materials at, or above, room temperature.

  14. Exact Optimum Design of Segmented Thermoelectric Generators

    Directory of Open Access Journals (Sweden)

    M. Zare

    2016-01-01

    Full Text Available A considerable difference between experimental and theoretical results has been observed in the studies of segmented thermoelectric generators (STEGs. Because of simplicity, the approximate methods are widely used for design and optimization of the STEGs. This study is focused on employment of exact method for design and optimization of STEGs and comparison of exact and approximate results. Thus, using new highly efficient thermoelectric materials, four STEGs are proposed to operate in the temperature range of 300 to 1300 kelvins. The proposed STEGs are optimally designed to achieve maximum efficiency. Design and performance characteristics of the optimized generators including maximum conversion efficiency and length of elements are calculated through both exact and approximate methods. The comparison indicates that the approximate method can cause a difference up to 20% in calculation of some design characteristics despite its appropriate results in efficiency calculation. The results also show that the maximum theoretical efficiency of 23.08% is achievable using the new proposed STEGs. Compatibility factor of the selected materials for the proposed STEGs is also calculated using both exact and approximate methods. The comparison indicates a negligible difference in calculation of compatibility factor, despite the considerable difference in calculation of reduced efficiency (temperature independence efficiency.

  15. Thermoelectric mini cooler coupled with micro thermosiphon for CPU cooling system

    International Nuclear Information System (INIS)

    Liu, Di; Zhao, Fu-Yun; Yang, Hong-Xing; Tang, Guang-Fa

    2015-01-01

    In the present study, a thermoelectric mini cooler coupling with a micro thermosiphon cooling system has been proposed for the purpose of CPU cooling. A mathematical model of heat transfer, depending on one-dimensional treatment of thermal and electric power, is firstly established for the thermoelectric module. Analytical results demonstrate the relationship between the maximal COP (Coefficient of Performance) and Q c with the figure of merit. Full-scale experiments have been conducted to investigate the effect of thermoelectric operating voltage, power input of heat source, and thermoelectric module number on the performance of the cooling system. Experimental results indicated that the cooling production increases with promotion of thermoelectric operating voltage. Surface temperature of CPU heat source linearly increases with increasing of power input, and its maximum value reached 70 °C as the prototype CPU power input was equivalent to 84 W. Insulation between air and heat source surface can prevent the condensate water due to low surface temperature. In addition, thermal performance of this cooling system could be enhanced when the total dimension of thermoelectric module matched well with the dimension of CPU. This research could benefit the design of thermal dissipation of electronic chips and CPU units. - Highlights: • A cooling system coupled with thermoelectric module and loop thermosiphon is developed. • Thermoelectric module coupled with loop thermosiphon can achieve high heat-transfer efficiency. • A mathematical model of thermoelectric cooling is built. • An analysis of modeling results for design and experimental data are presented. • Influence of power input and operating voltage on the cooling system are researched

  16. Microstructure and thermoelectric properties of β-FeSi2 ceramics fabricated by hot-pressing and spark plasma sintering

    International Nuclear Information System (INIS)

    Qu Xiurong; Lue Shuchen; Hu Jianmin; Meng Qingyu

    2011-01-01

    Highlights: → With increasing hot-pressing (HP) temperature, the thermoelectric figure of merit of β-FeSi 2 ceramics is improved slightly. → The grain size of the sample sintered by the spark plasma sintering (SPS) process is smaller than that by the HP process. → The SPS sample shows excellent thermoelectric performance attributed to low thermal conductivity. - Abstract: The microstructure and thermoelectric properties of β-FeSi 2 ceramics by hot pressing (HP) and spark plasma sintering (SPS) are investigated. With increasing hot-pressing temperature, the density, electronic conductivity and thermal conductivity of the samples increase significantly, the thermoelectric figure of merit is improved slightly. The microstructure study indicates that the sizes of the β-FeSi 2 and ε-FeSi phases in the sample sintered by the SPS process are smaller than that by the HP process. The SPS sample shows excellent thermoelectric performance due to the low thermal conductivity.

  17. Control of phonon transport by the formation of the Al2O3 interlayer in Al2O3-ZnO superlattice thin films and their in-plane thermoelectric energy generator performance.

    Science.gov (United States)

    Park, No-Won; Ahn, Jay-Young; Park, Tae-Hyun; Lee, Jung-Hun; Lee, Won-Yong; Cho, Kwanghee; Yoon, Young-Gui; Choi, Chel-Jong; Park, Jin-Seong; Lee, Sang-Kwon

    2017-06-01

    Recently, significant progress has been made in increasing the figure-of-merit (ZT) of various nanostructured materials, including thin-film and quantum dot superlattice structures. Studies have focused on the size reduction and control of the surface or interface of nanostructured materials since these approaches enhance the thermopower and phonon scattering in quantum and superlattice structures. Currently, bismuth-tellurium-based semiconductor materials are widely employed for thermoelectric (TE) devices such as TE energy generators and coolers, in addition to other sensors, for use at temperatures under 400 K. However, new and promising TE materials with enhanced TE performance, including doped zinc oxide (ZnO) multilayer or superlattice thin films, are also required for designing solid-state TE power generating devices with the maximum output power density and for investigating the physics of in-plane TE generators. Herein, we report the growth of Al 2 O 3 /ZnO (AO/ZnO) superlattice thin films, which were prepared by atomic layer deposition (ALD), and the evaluation of their electrical and TE properties. All the in-plane TE properties, including the Seebeck coefficient (S), electrical conductivity (σ), and thermal conductivity (κ), of the AO/ZnO superlattice (with a 0.82 nm-thick AO layer) and AO/ZnO films (with a 0.13 nm-thick AO layer) were evaluated in the temperature range 40-300 K, and the measured S, σ, and κ were -62.4 and -17.5 μV K -1 , 113 and 847 (Ω cm) -1 , and 0.96 and 1.04 W m -1 K -1 , respectively, at 300 K. Consequently, the in-plane TE ZT factor of AO/ZnO superlattice films was found to be ∼0.014, which is approximately two times more than that of AO/ZnO films (ZT of ∼0.007) at 300 K. Furthermore, the electrical power generation efficiency of the TE energy generator consisting of four couples of n-AO/ZnO superlattice films and p-Bi 0.5 Sb 1.5 Te 3 (p-BST) thin-film legs on the substrate was demonstrated. Surprisingly, the output

  18. Electronic temperature control and measurements reactor fuel rig circuits

    Energy Technology Data Exchange (ETDEWEB)

    Glowacki, S W

    1980-01-01

    The electronic circuits of two digital temperature meters developed for the thermocouple of Ni-NiCr type are described. The output thermocouple signal as converted by means of voltage-to-freguency converter. The frequency is measured by a digital scaler controled by quartz generator signals. One of the described meter is coupled with digital temperature controler which drives the power stage of the reactor rig heater. The internal rig temperature is measured by the thermocouple providing the input signal to the mentioned voltage-to-frequency converter, that means the circuits work in the negative feedback loop. The converter frequency-to-voltage ratio is automatically adjusted to match to thermocouple sensitivity changes in the course of the temperature variations. The accuracy of measuring system is of order of +- 1degC for thermocouple temperature changes from 523 K up to 973 K (50degC up to 700degC).

  19. The electronic temperature control and measurements reactor fuel rig circuits

    International Nuclear Information System (INIS)

    Glowacki, S.W.

    1980-01-01

    The electronic circuits of two digital temperature meters developed for the thermocouple of Ni-NiCr type are described. The output thermocouple signal as converted by means of voltage-to-freguency converter. The frequency is measured by a digital scaler controled by quartz generator signals. One of the described meter is coupled with digital temperature controler which drives the power stage of the reactor rig heater. The internal rig temperature is measured by the thermocouple providing the input signal to the mentioned voltage-to-frequency converter, that means the circuits work in the negative feedback loop. The converter frequency-to-voltage ratio is automatically adjusted to match to thermocouple sensitivity changes in the course of the temperature variations. The accuracy of measuring system is of order of +- 1degC for thermocouple temperature changes from 523 K up to 973 K (50degC up to 700degC). (author)

  20. Combustion synthesis: A new approach for preparation of thermoelectric zinc antimonide compounds

    Energy Technology Data Exchange (ETDEWEB)

    Rouessac, F., E-mail: Florence.Rouessac@univ-montp2.fr [Institut Charles Gerhardt Montpellier, UMR 5253 CNRS-UM2-ENSCM-UM1, C2M Universite Montpellier 2, CC 1504 Place Eugene Bataillon, 34095 Montpellier Cedex 5 (France); Ayral, R.-M. [Institut Charles Gerhardt Montpellier, UMR 5253 CNRS-UM2-ENSCM-UM1, C2M Universite Montpellier 2, CC 1504 Place Eugene Bataillon, 34095 Montpellier Cedex 5 (France)

    2012-07-25

    Highlights: Black-Right-Pointing-Pointer Reliable preparation method of thermoelectric materials. Black-Right-Pointing-Pointer Formation of zinc antimonide by the combustion synthesis method is investigated. Black-Right-Pointing-Pointer XRD and Raman spectroscopy as a function of temperature. Black-Right-Pointing-Pointer SHS: a new way for synthesizing thermoelectric materials. - Abstract: Due to the interesting properties of Zn{sub 4}Sb{sub 3} thermoelectric material, a reliable preparation method of this material is required. In this study, the formation of zinc antimonides by the combustion synthesis method is investigated and subjected to characterization using X-ray diffraction and Raman spectroscopy as a function of temperature. The results show that combustion synthesis can be a new way for synthesizing these thermoelectric materials.

  1. Thermoelectric power of the Ni and Cd substituted YBCO system

    International Nuclear Information System (INIS)

    Mukherjee, C.D.; Ranganathan, R.; Raychaudhuri, A.K.; Chatterjee, N.

    1989-01-01

    The thermoelectric power behaviour in the range between 250 K and the superconducting transition temperature T c of YBa 2 Cu 3-x A x O 7-y (where A = Ni or Cd and x = 0.2 and 0.4) samples has been examined. The normalized resistance and thermopower of substituted samples as functions of temperature are plotted and discussed. It was concluded that nickel has a slight positive role in causing overall thermopower generation in the YBCO system

  2. Feasibility study of a green energy powered thermoelectric chip based air conditioner for electric vehicles

    International Nuclear Information System (INIS)

    Miranda, Á.G.; Chen, T.S.; Hong, C.W.

    2013-01-01

    Traditional compressed-refrigerant air conditioning systems consume substantial energy that may reduce the driving performance and cruising mileage of electric vehicles considerably. It is crucial to design a new climate control system, using a direct energy conversion principle, to further aid in the commercialization of modern electric vehicles. A solid state air conditioner model consisting on TECs (thermoelectric chips) as the load, DSSCs (dye sensitized solar cells) as the renewable energy source and high power LiBs (lithium-ion batteries) as an energy storage device are considered for a personal mobility vehicle. The power management between the main power net and the solid state air conditioner interface is designed with an outer proportional-integral controller and an inner passivity based current controller with a loss included model for perfect tracking. This model is intended to comprise thermal and electrical elements which can be tunable for performance benchmarking and optimization of a solid state air conditioning system. Dynamic performance simulations of the solid-state air conditioner are performed, alongside guidelines for feasibility. - Highlights: • Alternative model extraction for dye sensitized solar cells. • Improved and computationally fast model for the cabin air temperature dynamics. • Euler–Lagrange loss included modeling of a buck converter. • Loss-included passivity based inner loop current control. • The thermoelectric chip air conditioner is tested in simulated cooling/heating scenarios

  3. Body Temperature Cycles Control Rhythmic Alternative Splicing in Mammals.

    Science.gov (United States)

    Preußner, Marco; Goldammer, Gesine; Neumann, Alexander; Haltenhof, Tom; Rautenstrauch, Pia; Müller-McNicoll, Michaela; Heyd, Florian

    2017-08-03

    The core body temperature of all mammals oscillates with the time of the day. However, direct molecular consequences of small, physiological changes in body temperature remain largely elusive. Here we show that body temperature cycles drive rhythmic SR protein phosphorylation to control an alternative splicing (AS) program. A temperature change of 1°C is sufficient to induce a concerted splicing switch in a large group of functionally related genes, rendering this splicing-based thermometer much more sensitive than previously described temperature-sensing mechanisms. AS of two exons in the 5' UTR of the TATA-box binding protein (Tbp) highlights the general impact of this mechanism, as it results in rhythmic TBP protein levels with implications for global gene expression in vivo. Together our data establish body temperature-driven AS as a core clock-independent oscillator in mammalian peripheral clocks. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Thermoelectric performance of electron and hole doped PtSb2

    KAUST Repository

    Saeed, Yasir; Singh, Nirpendra; Parker, D.; Schwingenschlö gl, Udo

    2013-01-01

    We investigate the thermoelectric properties of electron and hole doped PtSb2. Our results show that for doping of 0.04 holes per unit cell ( 1.5×1020 cm−3 ) PtSb2 shows a high Seebeck coefficient at room temperature, which can also be achieved at other temperatures by controlling the carrier concentration (both electron and hole). The electrical conductivity becomes temperature independent when the doping exceeds some 0.2 electrons/holes per unit cell. The figure of merit at 800 K in electron and hole doped PtSb2 is comparatively low at 0.13 and 0.21, respectively, but may increase significantly with As alloying due to the likely opening of a band gap and reduction of the lattice thermal conductivity.

  5. Thermoelectric performance of electron and hole doped PtSb2

    KAUST Repository

    Saeed, Yasir

    2013-04-30

    We investigate the thermoelectric properties of electron and hole doped PtSb2. Our results show that for doping of 0.04 holes per unit cell ( 1.5×1020 cm−3 ) PtSb2 shows a high Seebeck coefficient at room temperature, which can also be achieved at other temperatures by controlling the carrier concentration (both electron and hole). The electrical conductivity becomes temperature independent when the doping exceeds some 0.2 electrons/holes per unit cell. The figure of merit at 800 K in electron and hole doped PtSb2 is comparatively low at 0.13 and 0.21, respectively, but may increase significantly with As alloying due to the likely opening of a band gap and reduction of the lattice thermal conductivity.

  6. Fuzzy Logic Applied to an Oven Temperature Control System

    Directory of Open Access Journals (Sweden)

    Nagabhushana KATTE

    2011-10-01

    Full Text Available The paper describes the methodology of design and development of fuzzy logic based oven temperature control system. As simple fuzzy logic controller (FLC structure with an efficient realization and a small rule base that can be easily implemented in existing underwater control systems is proposed. The FLC has been designed using bell-shaped membership function for fuzzification, 49 control rules in its rule base and centre of gravity technique for defuzzification. Analog interface card with 16-bits resolution is designed to achieve higher precision in temperature measurement and control. The experimental results of PID and FLC implemented system are drawn for a step input and presented in a comparative fashion. FLC exhibits fast response and it has got sharp rise time and smooth control over conventional PID controller. The paper scrupulously discusses the hardware and software (developed using ‘C’ language features of the system.

  7. Effect of nanostructure on thermoelectric properties of La0.7Sr0.3MnO3 in 300–600 K temperature range

    Science.gov (United States)

    Singh, Saurabh; Srivastav, Simant Kumar; Patel, Ashutosh; Chatterjee, Ratnamala; Pandey, Sudhir K.

    2018-05-01

    In oxide materials, nanostructuring effect has been found a very promising approach for the enhancement of figure-of-merit, ZT. In the present work, we have synthesized La0.7Sr0.3MnO3 (LSMO) compound using sol-gel method and samples of crystallite size of ∼20, ∼41, and ∼49 nm were obtained by giving different heat treatment. Seebeck coefficient (α), electrical resistivity (ρ), and thermal conductivity (κ) measurements were carried out in 300–600 K temperature range. The systematic change in the values of α from ∼‑19 μV/K to ∼‑24 μV/K and drastic reduction in the values of κ from ∼0.88 W/mK to ∼0.23 W/mK are observed as crystallite size is reduced from 49 nm to 20 nm at ∼600 K. Also, fall in the values of ρ in the paramagnetic (PM) insulator phase (400–600 K) are effectively responsible for the increasing trend in the values of ZT at high temperature. For the crystallite size of 41 nm, the value of ZT at 600 K was found to be ∼0.017.

  8. Numerical Investigation for Strengthening Heat Transfer Mechanism of the Tube-Row Heat Exchanger in a Compact Thermoelectric Generator

    Science.gov (United States)

    Zhang, Zheng; Chen, Zijian; Liu, Hongwu; Yue, Hao; Chen, Dongbo; Qin, Delei

    2018-06-01

    According to the basic principle of heat transfer enhancement, a 1-kW compact thermoelectric generator (TEG) is proposed that is suitable for use at high temperatures and high flow speeds. The associated heat exchanger has a tube-row structure with a guide-plate to control the thermal current. The heat exchanger has a volume of 7 L, and the TEG has a mass of 8 kg (excluding the thermoelectric modules (TEMs)). In this paper, the heat transfer process of the tube-row exchanger is modeled and analyzed numerically; and the influences of its structure on the heat transfer and temperature status of the TEMs are investigated. The results show that use of the thin - wall pipes and increase of surface roughness inside the pipes are effective ways to improve the heat transfer efficiency, obtain the rated surface temperature, and make the TEG compact and lightweight. Furthermore, under the same conditions, the calculated results are compared with the data of a fin heat exchanger. The comparison results show that the volume and mass of the tube-row heat exchanger are 19% and 33% lower than those of the fin type unit, and that the pressure drop is reduced by 16%. In addition, the average temperature in the tube-row heat exchanger is increased by 15°C and the average temperature difference is increased by 19°C; the tube-row TEG has a more compact volume and better temperature characteristics.

  9. Numerical Investigation for Strengthening Heat Transfer Mechanism of the Tube-Row Heat Exchanger in a Compact Thermoelectric Generator

    Science.gov (United States)

    Zhang, Zheng; Chen, Zijian; Liu, Hongwu; Yue, Hao; Chen, Dongbo; Qin, Delei

    2018-04-01

    According to the basic principle of heat transfer enhancement, a 1-kW compact thermoelectric generator (TEG) is proposed that is suitable for use at high temperatures and high flow speeds. The associated heat exchanger has a tube-row structure with a guide-plate to control the thermal current. The heat exchanger has a volume of 7 L, and the TEG has a mass of 8 kg (excluding the thermoelectric modules (TEMs)). In this paper, the heat transfer process of the tube-row exchanger is modeled and analyzed numerically; and the influences of its structure on the heat transfer and temperature status of the TEMs are investigated. The results show that use of the thin - wall pipes and increase of surface roughness inside the pipes are effective ways to improve the heat transfer efficiency, obtain the rated surface temperature, and make the TEG compact and lightweight. Furthermore, under the same conditions, the calculated results are compared with the data of a fin heat exchanger. The comparison results show that the volume and mass of the tube-row heat exchanger are 19% and 33% lower than those of the fin type unit, and that the pressure drop is reduced by 16%. In addition, the average temperature in the tube-row heat exchanger is increased by 15°C and the average temperature difference is increased by 19°C; the tube-row TEG has a more compact volume and better temperature characteristics.

  10. Effects of ball milling on microstructures and thermoelectric properties of higher manganese silicides

    International Nuclear Information System (INIS)

    Chen, Xi; Shi, Li; Zhou, Jianshi; Goodenough, John B.

    2015-01-01

    Highlights: • The already low κ L of HMS can be suppressed further by decreasing the grain size. • The ball milling process can lead to the formation of secondary MnSi and W/C-rich phases. • The formation of the MnSi ad W/C rich phases is found to suppress the thermoelectric power factor. - Abstract: Bulk nanostructured higher manganese silicide (HMS) samples with different grain size are prepared by melting, subsequent ball milling (BM), and followed by spark plasma sintering (SPS). The effects of BM time on the microstructures and thermoelectric properties of these samples are investigated. It is found that BM effectively reduces the grain size to about 90 nm in the sample after SPS, which leads to a decrease in both the thermal conductivity and electrical conductivity. By prolonging the BM time, MnSi and tungsten/carbon-rich impurity phases are formed due to the impact-induced decomposition of HMS and contamination from the tungsten carbide jar and balls during the BM, respectively. These impurities result in a reduced Seebeck coefficient and increased thermal conductivity above room temperature. The measured size-dependent lattice thermal conductivities agree qualitatively with the reported calculation results based on a combined phonon and diffuson model. The size effects are found to be increasingly significant as temperature decreases. Because of the formation of the impurity phases and a relatively large grain size, the ZT values are not improved in the ball-milled HMS samples. These findings suggest the need of alternative approaches for the synthesis of pure HMS with further reduced grain size and controlled impurity doping in order to enhance the thermoelectric figure-of-merit of HMS via nanostructuring

  11. Effects of ball milling on microstructures and thermoelectric properties of higher manganese silicides

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xi [Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712 (United States); Shi, Li, E-mail: lishi@mail.utexas.edu [Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712 (United States); Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712 (United States); Zhou, Jianshi; Goodenough, John B. [Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712 (United States); Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712 (United States)

    2015-08-25

    Highlights: • The already low κ{sub L} of HMS can be suppressed further by decreasing the grain size. • The ball milling process can lead to the formation of secondary MnSi and W/C-rich phases. • The formation of the MnSi ad W/C rich phases is found to suppress the thermoelectric power factor. - Abstract: Bulk nanostructured higher manganese silicide (HMS) samples with different grain size are prepared by melting, subsequent ball milling (BM), and followed by spark plasma sintering (SPS). The effects of BM time on the microstructures and thermoelectric properties of these samples are investigated. It is found that BM effectively reduces the grain size to about 90 nm in the sample after SPS, which leads to a decrease in both the thermal conductivity and electrical conductivity. By prolonging the BM time, MnSi and tungsten/carbon-rich impurity phases are formed due to the impact-induced decomposition of HMS and contamination from the tungsten carbide jar and balls during the BM, respectively. These impurities result in a reduced Seebeck coefficient and increased thermal conductivity above room temperature. The measured size-dependent lattice thermal conductivities agree qualitatively with the reported calculation results based on a combined phonon and diffuson model. The size effects are found to be increasingly significant as temperature decreases. Because of the formation of the impurity phases and a relatively large grain size, the ZT values are not improved in the ball-milled HMS samples. These findings suggest the need of alternative approaches for the synthesis of pure HMS with further reduced grain size and controlled impurity doping in order to enhance the thermoelectric figure-of-merit of HMS via nanostructuring.

  12. A Chemical, High-Temperature Way to Ag1.9Te via Quasi-Topotactic Reaction of Stuetzite-type Ag1.54Te: Structural and Thermoelectric Properties.

    Science.gov (United States)

    Baumer, Franziska; Nilges, Tom

    2017-11-20

    Semiconducting silver tellurides gained reasonable interest in the past years due to its thermoelectric, magneto-caloric, and nonlinear optic properties. Nanostructuring has been frequently used to address quantum-confinement effects of minerals and synthetic compounds in the Ag-Te system. Here, we report on the structural, thermal, and thermoelectric properties of stuetzite-like Ag 1.54 Te (or Ag 4.63 Te 3 ) and Ag 1.9 Te. By a quasi-topotactic reaction upon tellurium evaporation Ag 1.54 Te can be transferred to Ag 1.9 Te after heat treatment. Crystal structures, thermal and thermoelectric properties of stuetzite-like Ag 1.54 Te (or Ag 4.63 Te 3 ) and Ag 1.9 Te were determined by ex situ and in situ experiments. This method represents an elegant chemical way to Ag 1.9 Te, which was so far only accessible electrochemically via electrochemical removal of silver from the mineral hessite (Ag 2 Te). The mixed conductors show reasonable high total electric conductivities, very low thermal conductivities, and large Seebeck coefficients, which result in a significant high thermoelectric figure of 0.57 at 680 K.

  13. Arsenene and Antimonene: Two-Dimensional Materials with High Thermoelectric Figures of Merit

    KAUST Repository

    Sharma, S.

    2017-10-25

    We study the thermoelectric properties of As and Sb monolayers (arsenene and antimonene) using density-functional theory and the semiclassical Boltzmann transport approach. The materials show large band gaps combined with low lattice thermal conductivities. Specifically, the small phonon frequencies and group velocities of antimonene lead to an excellent thermoelectric response at room temperature. We show that n-type doping enhances the figure of merit.

  14. Thermoelectric materials -- New directions and approaches. Materials Research Society symposium proceedings, Volume 478

    Energy Technology Data Exchange (ETDEWEB)

    Tritt, T M; Kanatzidis, M G; Lyon, Jr, H B; Mahan, G D [eds.

    1997-07-01

    Thermoelectric materials are utilized in a wide variety of applications related to solid-state refrigeration or small-scale power generation. Thermoelectric cooling is an environmentally friendly method of small-scale cooling in specific applications such as cooling computer chips and laser diodes. Thermoelectric materials are used in a wide range of applications from beverage coolers to power generation for deep-space probes such as the Voyager missions. Over the past thirty years, alloys based on the Bi-Te systems {l{underscore}brace}(Bi{sub 1{minus}x}Sb{sub x}){sub 2} (Te{sub 1{minus}x}Se{sub x}){sub 3}{r{underscore}brace} and Si{sub 1{minus}x}Ge{sub x} systems have been extensively studied and optimized for their use as thermoelectric materials to perform a variety of solid-state thermoelectric refrigeration and power generation tasks. Despite this extensive investigation of the traditional thermoelectric materials, there is still a substantial need and room for improvement, and thus, entirely new classes of compounds will have to be investigated. Over the past two-to-three years, research in the field of thermoelectric materials has been undergoing a rapid rebirth. The enhanced interest in better thermoelectric materials has been driven by the need for much higher performance and new temperature regimes for thermoelectric devices in many applications. The essence of a good thermoelectric is given by the determination of the material's dimensionless figure of merit, ZT = ({alpha}{sup 2}{sigma}/{lambda})T, where {alpha} is the Seebeck coefficient, {sigma} the electrical conductivity and {lambda} the total thermal conductivity. The best thermoelectric materials have a value of ZT = 1. This ZT = 1 has been an upper limit for more than 30 years, yet no theoretical or thermodynamic reason exits for why it can not be larger. The focus of the symposium is embodied in the title, Thermoelectric Materials: New Directions and Approaches. Many of the researchers in the

  15. Nonlinear thermoelectric effects in high-field superconductor-ferromagnet tunnel junctions

    Directory of Open Access Journals (Sweden)

    Stefan Kolenda

    2016-11-01

    Full Text Available Background: Thermoelectric effects result from the coupling of charge and heat transport and can be used for thermometry, cooling and harvesting of thermal energy. The microscopic origin of thermoelectric effects is a broken electron–hole symmetry, which is usually quite small in metal structures. In addition, thermoelectric effects decrease towards low temperatures, which usually makes them vanishingly small in metal nanostructures in the sub-Kelvin regime.Results: We report on a combined experimental and theoretical investigation of thermoelectric effects in superconductor/ferromagnet hybrid structures. We investigate the dependence of thermoelectric currents on the thermal excitation, as well as on the presence of a dc bias voltage across the junction.Conclusion: Large thermoelectric effects are observed in superconductor/ferromagnet and superconductor/normal-metal hybrid structures. The spin-independent signals observed under finite voltage bias are shown to be reciprocal to the physics of superconductor/normal-metal microrefrigerators. The spin-dependent thermoelectric signals in the linear regime are due to the coupling of spin and heat transport, and can be used to design more efficient refrigerators.

  16. Nanostructured Bulk Thermoelectric Generator for Efficient Power Harvesting for Self-powered Sensor Networks

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yanliang [Idaho National Lab. (INL), Idaho Falls, ID (United States); Butt, Darryl [Idaho National Lab. (INL), Idaho Falls, ID (United States); Agarwal, Vivek [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-07-01

    The objective of this Nuclear Energy Enabling Technology research project is to develop high-efficiency and reliable thermoelectric generators for self-powered wireless sensors nodes utilizing thermal energy from nuclear plant or fuel cycle. The power harvesting technology has crosscutting significance to address critical technology gaps in monitoring nuclear plants and fuel cycle. The outcomes of the project will lead to significant advancement in sensors and instrumentation technology, reducing cost, improving monitoring reliability and therefore enhancing safety. The self-powered wireless sensor networks could support the long-term safe and economical operation of all the reactor designs and fuel cycle concepts, as well as spent fuel storage and many other nuclear science and engineering applications. The research is based on recent breakthroughs in high-performance nanostructured bulk (nanobulk) thermoelectric materials that enable high-efficiency direct heat-to-electricity conversion over a wide temperature range. The nanobulk thermoelectric materials that the research team at Boise State University and University of Houston has developed yield up to a 50% increase in the thermoelectric figure of merit, ZT, compared with state-of-the-art bulk counterparts. This report focuses on the selection of optimal thermoelectric materials for this project. The team has performed extensive study on two thermoelectric materials systems, i.e. the half-Heusler materials, and the Bismuth-Telluride materials. The report contains our recent research results on the fabrication, characterization and thermoelectric property measurements of these two materials.

  17. An automated thermoelectric power apparatus using electro-optic relays

    International Nuclear Information System (INIS)

    Chakravarti, A.; Ranganathan, R.

    1992-01-01

    We report the design and construction of a thermoelectric power apparatus using home-made electro-optic relays with Z-80A microprocessor for automatic data acquisition and control. The advantages of such relays made out of LED-LDR combinations for the measurement of ΔE and ΔT are discussed in details. (author). 7 refs., 5 figs

  18. Spintronics and thermoelectrics in exfoliated and epitaxial graphene

    NARCIS (Netherlands)

    van den Berg, Jan Jasper

    2016-01-01

    This thesis is about two subjects: graphene spintronics and graphene thermoelectrics. Spintronics is about the creation and manipulation of spin currents. These are electrical currents in which we can control the spin orientation (up or down) of the conduction electrons. The second subject,

  19. Temperature control of power semiconductor devices in traction applications

    Science.gov (United States)

    Pugachev, A. A.; Strekalov, N. N.

    2017-02-01

    The peculiarity of thermal management of traction frequency converters of a railway rolling stock is highlighted. The topology and the operation principle of the automatic temperature control system of power semiconductor modules of the traction frequency converter are designed and discussed. The features of semiconductors as an object of temperature control are considered; the equivalent circuit of thermal processes in the semiconductors is suggested, the power losses in the two-level voltage source inverters are evaluated and analyzed. The dynamic properties and characteristics of the cooling fan induction motor electric drive with the scalar control are presented. The results of simulation in Matlab are shown for the steady state of thermal processes.

  20. Enhanced thermoelectric properties of N-type polycrystalline In4Se3-x compounds via thermally induced Se deficiency

    Science.gov (United States)

    Zhao, Ran; Shu, Yu-Tian; Guo, Fu

    2014-03-01

    In4Se3-x compound is considered as a potential thermoelectric material due to its comparably low thermal conductivity among all existing ones. While most studies investigated In4Se3-x thermoelectric properties by controlling selennium or other dopants concentrations, in the current study, it was found that even for a fixed initial In/Se ratio, the resulting In/Se ratio varied significantly with different thermal processing histories (i.e., melting and annealing), which also resulted in varied thermoelectric properties as well as fracture surface morphologies of In4Se3-x polycrystalline specimens. Single phase polycrystalline In4Se3-x compounds were synthesized by combining a sequence of melting, annealing, pulverizing, and spark plasma sintering. The extension of previous thermal history was observed to significantly improve the electrical conductivity (about 121%) and figure of merit (about 53%) of In4Se3-x polycrystalline compounds. The extended thermal history resulted in the increase of Se deficiency (x) from 0.39 to 0.53. This thermally induced Se deficiency was observed to associate with increasing carrier mobility but decreasing concentration, which differs from the general trend observed for the initially adjusted Se deficiency at room temperature. Unusually large dispersed grains with nanosize layers were observed in specimens with the longest thermal history. The mechanism(s) by which previous thermal processing enhances carrier mobility and affect microstructural evolution are briefly discussed.