Showing papers on "Thermoelectric effect published in 1988"

Materials for thermoelectric energy conversion

Abstract: The field of thermoelectric energy conversion is reviewed from both a theoretical and an experimental standpoint. The basic theory is introduced and the thermodynamic and solid state views are compared. An overview of the development of thermoelectric materials is presented with particular emphasis being placed on the most recent developments in high-temperature semiconductors. A number of possible device applications are discussed and the successful use and suitability of these devices for space power is manifest.

Principles and Methods of Temperature Measurement

Abstract: The Concept of Temperature. The Thermodynamic Temperature Scale. Entropy, Temperature, and Statistical Mechanics. The International Practical Temperature Scale. General Characteristics of Temperature Measuring Devices and Treatment of Data. Liquid--in--Glass Thermometers. Sealed Liquid or Gas Sensing Instruments and Bimetallic Sensors. Electrical Resistance Temperature Measurement Using Metallic Sensors. Thermistors and Semiconductors for Temperature Measurement. Thermoelectric Temperature Measurement. Theory of Radiant Heat Transfer as a Basis for Temperature Measurement by Radiant Techniques. The Disappearing Filament Optical Pyrometer. Photoelectric Optical Pyrometers (Automatic and Infrared). Total Radiation Pyrometers. Novel Methods of Temperature Measurement. Pyrometric Cones. Calibration Methods. Installation Effects. Dynamic Response of Sensors. Temperature Instrumentation and Control.

Apparatus for controlling the temperature of an integrated circuit package

Abstract: A thermoelectric heat pump is used to maintain the temperature of an integrated circuit under test. Temperature sensors placed on two sides of the integrated circuit measure and generate signals indicative of the temperature at the two surfaces, and the average of the two measured temperatures is compared against a value of a preset temperature to change the temperature of the heat pump to stabilize the temperature of the integrated circuit to a desired value.

Integrated temperature control/alignment system for high performance capillary electrophoretic apparatus

Abstract: An integrated temperature control/alignment system for use with a high performance capillary electrophoretic apparatus is disclosed. In one exemplary embodiment the integrated temperature control/alignment system comprises a pair of capillary column mounting plates for mounting a capillary column as a constituent of the electrophoretic apparatus, a pair of secondary support plates, a pair of thermoelectric plates and external heat sink plates. Detection openings are formed in each of the plates as required so that a continuous detection path exists through the integrated temperature control/alignment system. The capillary column is seated and locked in grooves formed in the capillary column mounting plates so that the detection windows of the capillary column are coordinated with the aligned detection openings formed in the applicable plates of the integrated temperature control/alignment system. The temperature of substantially the entire capillary column, including the detection zone, is controlled or regulated by the temperatures of the thermoelectric plates which comprise one or more thermoelectric circuits utilizing the Peltier effect. Regulation of current flow in the thermoelectric plates controls the temperature effect exerted by the thermoelectric plates, thereby controlling both the direction and rate of heat transfer with the capillary column.

Measurement of Seebeck coefficient using a large thermal gradient

Abstract: The integral method of measuring the Seebeck voltage, V(T), has been applied to short rod-shaped samples. In the present method, one end of the sample is held at a fixed temperature and the other end is automatically varied through a temperature T range of interest, up to a maximum temperature of 1000 C. The Seebeck coefficient is then obtained from the slope of the V(T) vs T curve. The method offers simplicity of sample handling and minimal operator involvement.

Thermoelectric properties of lanthanum sulfide with Sm, Eu, and Yb additives

Abstract: The Seebeck coefficient and electrical resistivity have been measured for the La3−x Mx S4 alloys with the Th3 P4 ‐type structure for M=Sm, Eu, Yb, and x=0.1 to 0.9 in order to determine their potential as high‐temperature thermoelectric energy conversion materials. An analysis of the lattice parameters of these alloys suggests that Sm has a valence of 2.2 over the entire composition range. Furthermore, the variation of the Seebeck coefficient and electrical resistivity as a function of electron concentration is different for the Sm‐doped alloys than for the Eu‐ and Yb‐doped alloys, which are all different from that of the pure binary LaSy alloys. A maximum in the electrical power factor at 1000 °C is found to occur at x ≂ 0.3, but when a reasonable estimate is made of the thermal conductivity the maximum in the figure‐of‐merit at 1000 °C shifts to larger x values (∼0.7) in all alloy systems. The long term stability of the Sm and Eu ternaries is also reported.

Thermoelectric heat pump/power source device

Abstract: A thermoelectric heat pump or power source device is provided with P-type and N-type elements made of either thin films or thick films for use on flexible or nonflexible substrates. For flexible units the film type elements are formed on substrates of such flexible, electrically insulation material as, for example, MYLAR and TEFLON; while for inflexible units the elements are formed on substrates of such materials as, for example, Beryllia, Alumina, ceramics, or plastics. Further, the elements are patterned on the different substrates for particular usages. For example, radial element patterns used for cooling hot spots and ladder element patterns are used for cooling linear hot bodies. Ladder element patterns may also be used on flexible substrates to be folded to form corrugations having cold strips and hot strips on opposing sides to which sheets of suitable material can be attached to form panels, blankets, therapeutic devices or pipe covers for heating or cooling their contents as desired.

Thermoelectric heat exchanger

Abstract: A thermoelectric heat exchanger includes a first finned heat sink which includes at least two planar regions, at least two second heat sinks, each shaped to fit a respective one of the planar regions. At least two sets of thermoelectric cooling elements are provided, each set made up of three cooling elements arranged in a triangular pattern in a respective one of the planar regions between the first heat sink and the corresponding second heat sink. The cooling elements are connected together in series within each set and an electric voltage is applied in parallel across each of the sets of cooling elements. The second heat sinks are secured to the first heat sink to create a low thermal resistance contact between the cooling elements and the heat sinks, with each of the cooling elements establishing at least point contact with both of the respective heat sinks.

Alkali metal thermoelectric genreator

Abstract: An alkali metal heat engine. A thermoelectric generator which circulates alkali metal through a cationic barrier to produce electricity. The device is capable of operating in a reduced gravity or gravity-free environment and without mechanical pumps because it collects and recirculates the liquid alkali metal with capillary wick structures. One capillary wick moves the alkali metal from the cooler side of the barrier to the hotter side, and another wick is used as a bypass structure to recirculate the undiffused alkali metal back to the heat source.

Thermoelectric properties of boron phosphide

Abstract: This paper describes the thermoelectric properties of boron phosphide wafers prepared using chemical vapour deposition and the thermal constants of a sintered boron phosphide specimen prepared using the r.f. hot pressing technique. The electric conductivity of the n-type boron phosphide wafers increases with temperature, becomes constant and then begins to decrease with temperature. In p-type wafers the conductivity increases with temperature and with a further increase in temperature the intrinsic conduction region is reached. The absolute thermoelectric power of n-type materials has an almost constant value of 500 μV K −1 , but it begins to decrease at a temperature of 650 K owing to the creation of acceptors. The thermoelectric power of p-type materials decreases with increasing temperature, indicating that acceptors and donors contribute to the conduction. Thermal constants were obtained by the laser flash method and were measured using sintered discs as standards. Thermal diffusivity, heat capacity and the corresponding calculated thermal conductivity have an accuracy within ± 5% up to 700 °C. The calculated thermoelectric figure of merit is of the order of 10 −4 K −1 . Therefore, boron phosphide is a promising material for high temperature thermoelectric devices.

Miniature thermoelectric converters

Abstract: A thermoelectric semiconductor multicouple array comprises a substrate of semi-insulating material 10, alternate n-type and p-type strips or legs ion implanted into said substrate and connected together electrically in series, and terminal means 11 connected to said series-connected strips or legs. The array may be incorporated in an integrated circuit chip. A method of making such thermoelectric semiconductor multicouple arrays is also disclosed.

Electrical and thermoelectrical properties of Zn3P2 films grown by the hot wall epitaxy technique

Abstract: Zinc phosphide thin films were prepared by the hot wall epitaxy technique. The transport properties of films grown at different substrate temperatures from 200 to 350 °C were studied from room temperature up to 600 °C. Films were also grown in pure oxygen and nitrogen atmospheres at a pressure of 10−6 Torr, and the conductivity of the films was measured in situ. Thermoelectric measurements on films grown on mica were also done at various temperatures ranging from 300 to 800 K. Arrhenius plots of electrical conductivity yielded an electronic band gap of 1.32 eV and acceptor levels of 0.21 and 0.49 eV corresponding to interstitial phosphorus and absorbed oxygen levels, respectively. Variation of growth temperature, pressure, and nature of the gas present inside the chamber during growth are shown to result in a range of electrical resistivities and to be responsible for changes in carrier concentration. The sign of Seebeck coefficient was found to change from positive to negative at a temperature of 240 °C for a film grown on mica at a substrate temperature of 350 °C.

Apparatus for treating a damaged animal limb

Abstract: Portable apparatus for cooling a limb of an animal comprises a thermoelectric module (10) working on the Peltier principle having a first surface at which heat is extracted and a second surface at which heat is dissipated, via a heat sink. The thermoelectric module (10) and its associated heat sink are provided with fixing means by which the thermoelectric module (10) and associated heat sink are securable to the limb to be cooled with the first surface of the thermoelectric module (10) facing the limb to be cooled. A power source (4) is connectable to the thermoelectric module (10). Means (3) may be provided for forcing convection of heat from the heat sink, e.g. cooling air, or circulating cooling liquid.

Thermoelectric device and manufacture thereof

Abstract: PURPOSE: To reduce the weight, to compact the size, and to enhance the effi ciency of a thermoelectric device by directly intermetallically adhering a thin filmlike N- or P-type semiconductor and a plate or thin filmlike metal by a vacuum thin film manufacturing process. CONSTITUTION: An N-type semiconductor film 10 is formed by a vacuum depositing method on a copper substrate 9. A copper film 11 is deposited on the top of the semiconductor 10, the semiconductor 10 and the film 11 are repeatedly laminated to hold the uppermost and lowermost parts between a copper film 11' and the substrate 9. Then, a copper plate 12 is adhered by soldering to the film 11' at the uppermost part for electrodes and reinforcing. A voltage is externally applied to this thermoelectric device to be cooled and heated. With thus construction, the temperature difference between a low temper ature part and a high temperature part is increased, Joule heat is suppressed, and an available metal amount can be reduced. COPYRIGHT: (C)1989,JPO&Japio

Thermoelectric device and its manufacture

Abstract: PURPOSE: To cool or heat fluid inside and outside a heating tube at the same time by forming thermoelectric elements on the outer wall of the heating tube in which the fluid can flow, which thermoelectric elements are formed by directly bonding and laminating a thin film type semiconductor of N-type or P-type to plate type or thin film type metal by using the upper or lower surface. CONSTITUTION: A thermoelectric element is formed by directly bonding a thin film type semiconductor 10 of N-type or P-type to plate type or thin film type metal 9, 9' by using the upper or lower surface, and a lamination structure is constituted. This thermoelectric element is formed on the outer wall surface of a heating tube 14 in which fluid can flow. For example, each individual thermoelectric element is constituted by the following manner; on a polyimide film substrate 8, copper films 9 and P-type semiconductor films 9 are repeatedly laminated. The lowest part copper film 9 and the highest part copper film 9' are bonded to adjacent laminated thermoelectric elements, and arranged so as to be electrically connected in series. In order that the heating surfaces of the bonded thermoelectric element part may be made to face the same surface for each thermoelectric element, the thermoelectric elements using N-type and P-type semiconductor are alternately bonded, and insulating films 12 are formed between the thermoelectric elements and on the highest part copper film 9'. COPYRIGHT: (C)1990,JPO&Japio

Ionic and electronic conductivity in some simple lithium salts

Abstract: The electrical conductivity (σ) and thermoelectric power (S) of Li3VO4, Li3PO4 and Li3BO3 solidified melts are presented in the temperature range from 415 K to the melting point of each solid. The ionic (σi,) and electronic (σe) contributions toσ have been separated over the entire temperature range with the help of a time-dependence study of the d.c. electrical conductivity. Superionic phases in all three solids have been observed below their melting points in which the conductivity is almost purely ionic. The value of the phase transition temperature below which the solid transforms from superionic to normal phase has been obtained. It has been shown that in the normal phase, these solids are mixed conductors. Data for the temperature variations of bothσi, andσe are also presented and discussed.

A thermoelectric experiment in support of the second law

Abstract: An experiment with a semiconductor thermoelectric device is described supporting the second law of thermodynamics. The device can be treated as an ideal heat engine or an ideal heat pump if reversible processes only are taken into account. The efficiency of the former and the coefficient of performance of the latter can be measured for various temperatures of the hot and the cold reservoir and compared with values derived from the second law. Measured and theoretical values agree within about 2%. Parts of the experiment are done in an undergraduate laboratory.

Thermoelectric Power of MnSi

Abstract: The thermoelectric power of MnSi was measured from liquid He temperature to room temperature. The tangential line of thermoelectric power in the high-temperature region above T N is found not to pass the origin, in disagreement with Mott's expression. This observation is discussed in connection with the spin fluctuation in the sample, and a new expression of the thermoelectric power taking into account the spin fluctuation is proposed.

Charge completion detector

Abstract: A charge completion detector comprises a thermoelectric detecting element outputting a thermally generated electromotive force in correspondence with the rise of temperature incidental to the completion of charging a secondary cell, and detecting means electrically connected to the thermoelectric detecting element for detecting the thermally generated electromotive force generated in the thermoelectric detecting element. The thermoelectric detecting element comprises a base material of semiconductive ceramics and a plurality of pairs of electrodes formed spaced apart from each other by a prescribed distance on the base material for forming hot junctions and cold junctions. A heat radiating member is thermally coupled to the cold junctions of the base material. The temperature of the hot junction side thermally coupled to the secondary cell will be approximately the same as that of the secondary cell while the temperature of the cold junction side is kept at an environmental temperature. The rise of temperature is detected based on the change of the thermally generated electromotive force based on the difference between the temperatures of the hot junctions and cold junctions.

Annealing Group III-V compound doped silicon-germanium alloy for improved thermo-electric conversion efficiency

Abstract: The thermoelectric conversion efficiency of a GaP dope SiGe alloy is improved about 30 percent by annealing the alloy at a temperature above the melting point of the alloy, preferably stepwise from 1200° C. to 1275° C. in air to form large grains having a size over 50 μm and to form a Ge-Ga-P rich phase and a silicon rich phase containing SiP and SiO 2 particles.

Stator winding cooler for rotary electric machine

Abstract: PURPOSE:To improve the cooling performance of a rotary electric machine by providing a thermoelectric element which performs a heat absorption and a heat sink phenomenon by applying a DC voltage between a coil end and a frame. CONSTITUTION:Flat surfaces 1a are provided at a plurality of positions on the inner periphery of a frame 1 opposed to the coil end 3a of a stator winding 3, and the heat sink surface of a thermoelectric element 10 is closely contacted through thermal grease having good thermal conductivity with the flat surfaces 1a. A heat absorption plate 15 having high thermal conductivity, such as aluminum or copper is contacted through the grease having good thermal conductivity with the heat absorption surface of opposite side of the element 10 and a thermoelectric element 10 is clamped fixedly together with the plate 15 by a mounting screw 16 at the frame 1. Then, the element 10 is energized so that the plate 15 absorbs heat by Peltier effect and the frame 1 becomes a heat sink surface.