Showing papers on "Thermoelectric effect published in 1984"

An electron conductivity model for dense plasmas

Abstract: An electron conductivity model for dense plasmas is described which gives a consistent and complete set of transport coefficients including not only electrical conductivity and thermal conductivity, but also thermoelectric power, and Hall, Nernst, Ettinghausen, and Leduc–Righi coefficients. The model is useful for simulating plasma experiments with strong magnetic fields. The coefficients apply over a wide range of plasma temperature and density and are expressed in a computationally simple form. Different formulas are used for the electron relaxation time in plasma, liquid, and solid phases. Comparisons with recent calculations and available experimental measurement show the model gives results which are sufficiently accurate for many practical applications.

Thermoelectric effect in a weakly disordered inversion layer subject to a quantizing magnetic field

Abstract: We demonstrate that the usual Kubo formula for thermal response functions is invalid if a magnetic field is present. There exists a fundamental correction due to a lack of time-reversal symmetry. We show in particular that, in addition to being of general importance in the theory of transport, this leads to a novel thermoelectric effect in a weakly disordered two-dimensional electron gas subject to a quantizing magnetic field. The thermopower tensor is calculated within the self-consistent Born approximation using a generalized Mott formula, which is derived.

Thermoelectric cooling device and gas analyzer

Abstract: There is disclosed a thermoelectric device suitable for drying gases in which a finned heat-dissipating device is in contact with the hot face of a thermoelectric element and a thermal sink is in contact with the cold face thereof. The thermal sink has formed therein a conduit which zig-zags from an inlet at the upper part thereof to a point at the bottom thereof and then upwardly to an outlet at the other side. The conduit is formed by routing out a channel in a block and sealing it off with a face plate to provide the desired conduit. The various elements are held together by face plates spanning the heat-radiating device and the thermal sink, and the space between the two is desirably filled with insulating material. The device is used in combination with a gas analyzer in which exhaust gases, for example, from an internal combustion engine, are fed through the dryer and then into the analyzer.

Thermoelectric device exhibiting decreased stress

Abstract: A thermoelectric device exhibiting both structural integrity and decreased stress across the device notwithstanding the application of thermally cycled temperature differentials thereacross includes, electrically interconnected thermoelectric elements and a rigidly affixed substrate. Thermal stress is relieved by using flexible conductors to interconnect the thermoelectric elements, and by the use of a flexile joint to attach a second substrate to the remainder of the device. Complete elimination of the second substrate may also be used to eliminate stress. Presence of the rigidly affixed substrate gives the device sufficient structural integrity to enable it to withstand rugged conditions.

Thermoelectric figure of merit of the system (GeTe)1−x(AgSbTe2)x

Abstract: The thermoelectric properties of polycrystalline samples of GeTe-rich side solid solutions (GeTe)1−x·(AgSbTe2)x, for the compositions x = 0.00, 0.10, 0.15, 0.20, and 0.29 are investigated. The temperature dependences of the Seebeck coefficient and the electrical resistivity and the dependences of the total thermal conductivity at 300 K versus composition are measured. The temperature dependences of the total thermal conductivity and the thermoelectric figure of merit 2 are calculated. The composition with maximum value of 2 is determined as GeTe + 20 mol% AgSbTe2. The reasons for the maximum thermoelectric figure of merit for this composition and for the anomaly changes in the thermoelectric parameters and the sharp increase of Z in the region of phase transitions (OC) are discussed. Die thermoelektrischen Eigenschaften von polykristallinen Proben der Mischkristalle (GeTe)1−x·(AgSbTe2)x, nahe der VerbindungGeTemit den Zusammensetzungen x = 0,00; 0,10; 0,15; 0,20 und 0,29 werden untersucht. Die Temperaturabhangigkeiten der Thermospannung und des spezifischen elektrischen Widerstandes und die Abhiingigkeiten der thermischen Leitfahigkeit bei 300 K von der Zusammensetzung werden gemessen. Die Temperatura bhangigkeiten der thermischen Leitfahigkeit und des thermischen Wirkungsgrades Z werden berechnet. Die Zusammensetzung mit dem Maximalwert von Z wird bestimmt zu GeTe + 20 Molyo AgSbTe2. Die Ursachen fur den maximalen Wirkungsgrad bei dieser Zusammensetzung und fur das scharfe Anwachsen von Z im Gebiet der Phesenumwandlung (O5h-C53v) fur alle Zusammensetzungen werden diskutiert.

Peltier junction used for thermal control of solid state devices

Abstract: An electronic device, such as a bubble memory (21), which has a narrow temperature band of operation, is maintained within the narrow temperature band by a Peltier circuit (30). The Peltier circuit (30) includes a Peltier junction (31) which is placed in a heat conducting relationship with the bubble memory (21). The Peltier circuit (30) has the advantage of being able to alternately heat or chill the bubble memory device (21) in order to maintain the bubble memory device (21) within its recommended temperature range.

Internal-integral sodium return line for sodium heat engine

Abstract: A thermoelectric generator device which converts heat energy to electrical energy. An alkali metal is used with a solid electrolyte and a portion of the return line for the alkali metal is located within the generator vacuum space.

Electrical, thermoelectric, and optical properties of strongly degenerate polycrystalline silicon films

Abstract: Low‐pressure chemical vapor deposited polycrystalline silicon films 0.45 μm thick were doped to strongly degenerate concentrations (1–2×1020 cm−3) by thermal diffusion of phosphorus. Thermoelectric power, Hall effect, and resistivity measurements were made over the temperature range of 80 to 340 K. The thermopower results were in good agreement with single crystal degenerate semiconductor theory. Additionally, these results, in conjunction with the measured carrier concentration, showed that the scattering relaxation time is inversely proportional to the square root of the carrier energy which is indicative of lattice scattering. The temperature dependence of the resistivity was found to be of the form ρ=a+bT. The liner term was attributed to acoustic phonon scattering within the grains and the constant term to lattice mismatch at the grain boundaries. Scattering from grain boundary potential barriers due to carrier trapping appeared to play no significant role although this effect dominates at lower do...

Method and apparatus for controlling the temperature and pressure of confined substances

Abstract: An apparatus and method for controlling the temperature and pressure of confined substances is disclosed. Heat may be removed from or added to a substance within a tank or pipe by means of thermal conduction between the substance and a thermoelectric heat pump. As a result, undesired vaporization and soldification of the substance within the tank is prevented and the temperature and pressure thereof may be controlled. A temperature and/or pressure sensor is utilized to activate the heat pump at appropriate times and various ways are disclosed to provide maximum thermal heat transfer between the substance within the tank and the heat pump.

Thermoelectric Aspects of Charge-Density-Wave Transport in TaS3

Abstract: Mesure de la variation du pouvoir thermoelectrique de TaS 3 avec le champ. Etude du coefficient de Peltier du courant electrique non lineaire en fonction de T et du champ. Les resultats obtenus correspondent a ceux d'un condensat en mouvement avec entrainement par phonons a basse temperature

Thermoelectric studies on semiconducting Ag 2 Te thin films: Temperature and dimensional effects

Abstract: ${\mathrm{Ag}}_{2}$Te thin films with thicknesses in the range 600---1400 \AA{} have been prepared by vacuum deposition at a pressure of 5 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}5}$ Torr on clean glass substrates held at room temperature. The thermoelectromotive force of these films has been measured in the temperature range 300---415 K, that is, below the phase-transition temperature. It is found that the thermoelectric power of ${\mathrm{Ag}}_{2}$Te thin films in the above temperature range exhibits degenerate semiconductor behavior, this is, a linear increase in the thermoelectric power with rising temperature. It is also found that the thermoelectric power obeys the inverse thickness dependence predicted by classical size-effect theories.

Electrode heat balances of electrochemical cells: Application to water electrolysis

Abstract: This paper deals with a method of estimating single electrode heat balances during the electrolysis of molten NaCl-ZnCl2 in a cell using aβ-alumina diaphragm. By measuring the thermoelectric power of the thermogalvanic cells: (T) Na/β-alumina/NaCl-ZnCl2/β-alumina/Na(T+dT) and (T) C,Cl2/NaCl-ZnCl2/Cl2,C(T+dT) the single electrode Peltier heat for sodium deposition and for chlorine evolution at 370° C were estimated to be −0.026±0.001 JC−1 and+0.614±0.096 J C−1, respectively.

Monolithically Peltier-cooled laser diodes

Abstract: A new method of cooling a GaAs/GaAlAs laser in an optical integrated circuit or on a discrete chip, by adding an integral thermoelectric (Peltier) cooling and heat spreading device to the laser, is presented. This cooling both reduces and stabilizes the laser junction temperature to minimize such deleterious effects as wavelength drift due to heating. A unified description of the electrical and thermal properties of a monolithic semiconductor mesa structure is given, Here it is shown that an improvement in thermal characteristics is obtained by depositing a relatively thick metallic layer, and by using this layer as a part of an active Peltier structure. Experimental results reveal a 14-percent increase in emitted power (external quantum efficiency) due to passive heat spreading and a further 8-percent if its Peltier cooler is operated. Fabrication techniques used to obtain devices exhibiting the above performance characteristics are given.

A thermoelectric microscope stage for the measurement of the supercooling points of microscopic organisms

Abstract: SUMMARY The design and construction of a thermoelectric cooling stage and its use for the determination of the supercooling points of microscopic organisms is described. Stage cooling is produced by a Peltier unit with a refrigerated circulator as a heat sink. Control is achieved by automatically comparing the temperature input to a reference ramp and varying the power input to the Peltier module accordingly.

Recovering method of high temperature article surface radiation heat

Abstract: PURPOSE:To improve the utility efficiency of a recovery energy by providing a heat receiver formed by gathering thermoelectric elements opposed to a high temperature article, directly converting thermal energy directly into electric power energy and producing it. CONSTITUTION:A high temperature article 7 such as continuously cast slab in an iron making work is continuously fed on a tape roller group 8, a heat receiver formed by gathering a chalcogenide amorphous thermoelectric elements on the upper and side surfaces is opposed to the article 7 at the heating side 9, and a water cooling jacket 10 is provided on the back surface, thereby producing temperature difference between both ends of the element. The generated electromotive force is produced by a power pickup unit and utilized. Accordingly, the radiation heat from the article 7 can be converted directly to electric energy, and the facility can be therefore simplified, and the utility efficiency of the recovery energy can be remarkably improved.

Solar heat utilizing device

Abstract: PURPOSE:To enable to take out thermal energy and electrical energy in a balanced manner, by a method wherein thermoelectric converting elements are provided, and electrical energy is generated by utilizing a temperature difference between a hot water pipe and a cold water pipe. CONSTITUTION:The hot water pipe 2 attached with a plurality of solar cells 1 on an upper surface thereof and the cold water pipe 3 for passing water to be supplied into the pipe 2 are provided respectively on the upper and lower sides of a plurality of the thermoelectric converting elements 4, and a Flesnel lens 6 is arranged by a frame 5 so that sunlight rays L are focused on the solar cells 1. The solar cells 1 not only generate electric energy according to optical energy of the sunlight rays L but efficiently absorb the sunlight and convert it into heat, whereby cold water flowing into the pipe 2 is heated to be hot water. The solar cells 1 are cooled, so that efficiency of converting optical energy into electrical energy is not lowered. A considerable temperature difference is generated between the hot water pipe 2 and the cold water pipe 3, and the thermoelectric converting elements 4 generate electromotive forces according to the temperature difference.

Effect of temperature-dependent energy-level shifts on a semiconductor's Peltier heat

Abstract: The Peltier heat of a charge carrier in a semiconductor is calculated for the situation in which the electronic energy levels are temperature dependent. The temperature dependences of the electronic energy levels, generally observed optically, arise from their dependences on the vibrational energy of the lattice (e.g., as caused by thermal expansion). It has been suggested that these temperature dependences will typically have a major effect on the Peltier heat. The Peltier heat associated with a given energy level is a thermodynamic quantity; it is the product of the temperature and the change of the entropy of the system when a carrier is added in that level. As such, the energy levels cannot be treated as explicitly temperature dependent. The electron-lattice interaction causing the temperature dependence must be expressly considered. It is found that the carrier's interaction with the atomic vibrations lowers its electronic energy. However, the interaction of the carrier with the atomic vibrations also causes an infinitesimal lowering (approx.1/N) of each of the N vibrational frequencies. As a result, there is a finite carrier-induced increase in the average vibrational energy. Above the Debye temperature, this cancels the lowering of the carrier's electronic energy. Thus, the standard Peltier-heat formula,more » whose derivation generally ignores the temperature dependence of the electronic energy levels, is regained. This explains the apparent success of the standard formula in numerous analyses of electronic transport experiments.« less

Point-contact diodes

Abstract: Point-contact diodes based either on the mechanism of electronic tunnelling through an insulating barrier or on the thermoelectric effect of hot carriers in heavily doped semiconductors are described. The requirements necessary for these devices to be used as harmonic generators and mixers in the 2–200 THz region are emphasized, and some new developments are reported. Outstanding characteristics of the devices which use either the semimetal antimony or the semiconductors SnTe or Bi2Te3 as a diode base are high detection sensitivity and high mechanical stability over long periods of use either as harmonic generators or as mixers.

Study of microscopic heat sources in semiconducting barium titanate ceramics

Abstract: If high electric fields are applied to semiconducting barium titanate ceramics, the rapid temperature rise caused by power dissipation makes it difficult to separate the field dependence of the resistance from its temperature dependence. For that reason the microscopic temperature rise during a voltage pulse was calculated by a theoretical model for the heat production and the heat flow inside a single grain. In addition, the local temperature behavior was measured experimentally by means of an infrared radiometric microscope. The fast temperature rise during a voltage pulse (350 V/mm; 400 μs) and the cooling off immediately after the end of the pulse prove that there are significant heat sources at the grain boundaries. In ceramics with relatively large grains (30–60 μm) temperature differences up to 50 K within a single grain were measured.

Thermoelectric generating composite functioning apparatus

Abstract: A thermoelectric generating composite functioning apparatus used as a glow plug in a diesel engine has sintered semiconductor elements respectively formed in the shape of a bar of N-type and P-type thermoelectric semiconductor materials. The N-type and P-type semiconductor elements are provided oppositely with a gap between them, and their end portions are put in mutual contact to form a P-N junction. A low thermal conductivity insulator is filled in the interval between the N-type and the P-type semiconductor elements. The N-type and P-type semiconductor elements provided in the P-N junction state are contained through the insulator in a housing. Lead terminals connected to the N-type and P-type semiconductor elements are formed in the housing. The apparatus may provide heat to the combustion chamber, or generate electricity from the heat in the combustion chamber.

Experiment to verify the second law of thermodynamics using a thermoelectric device

Abstract: An experiment to verify the second law of thermodynamics using a thermoelectric device is described. The response of the device when it is used as a Seeback‐effect heat engine after filtering out the contributions of the associated irreversible parts is studied as a function of the temperatures of the hot and cold junctions. Likewise its response as a Peltier‐effect heat pump is also investigated. The experimental results are in close agreement with the predictions of the second law of thermodynamics.

Mechanical and Thermoelectric Behavior of Composition Modulated Foils

Abstract: From measurements of independent elastic moduli it has been shown that the large, modulation wavelength dependent enhancement of the biaxial modulis in composition modulated foils is due to the changes in the primary elastic constants. These results provide an explanation for some of the apparently conflicting data in the literature. The plastic and thermoelectric properties of these materials were also found to be anomalous and wavelength dependent.