Thermoelectric Transducers Research Articles

Nanofluidic Thermoelectric Transducer with Ultrahigh and Tunable Sensitivity.

Thermosensitive transient receptor potential (thermoTRP) ion channels can transduce external thermal stimuli to neural electrical signals, allowing organisms to detect and respond to changes in environmental temperature. Reproducing such ionic machinery holds promise for advancing the design of highly efficient low-grade thermal energy harvesters and ultrasensitive thermal sensors. However, there still exist challenges for artificial nanofluidic architectures to achieve comparable thermoelectric performance. Here, we report nanofluidic thermoelectric transducers with ultrahigh and tunable sensitivities controlled by electrostatic gating in graphene nanochannels. The equivalent Seebeck coefficient can be significantly boosted and reaches 1 order of magnitude higher than the current state of the art, even beyond thermoTRP ion channels. The improvement is attributed to substantial slippage on the highly charged graphene surface, leading to enhanced electrokinetic ion transport inside the graphene channel, which is confirmed by a scaling theory for thermoelectric coupling as well as molecular dynamic simulations. The dependence of the nanofluidic thermoelectric on the concentration, channel size, and cation types is also investigated to further clarify the underlying mechanism.

Theory and Practice of Temperature Measurement by Thermoelectric Transducers

Temperature is one of the main parameters that determine the quantitative and qualitative indicators of products. Therefore, it is difficult to name a field of technology or a branch of industry where it would not be necessary to measure the temperature of solid, liquid, or gaseous substances. Along with this, it should be noted that in each specific field, the choice of methods and means of temperature measurement is determined by its specificity, which is related to the variety of technological objects, the nature of the process, the physical and chemical characteristics of the environment under investigation, the range of measured temperatures, the requirements for the necessary measurement errors, etc. Therefore, choosing a measurement method for a specific technological object is a difficult task, since it is necessary to take into account a large number of factors that can quite often be contradictory. Thus, liquid-in-glass thermometers make it possible to measure the temperature directly near the technological objects. With the help of manometric thermometers, it is possible to measure the temperature at some distance from the research objects. It should also be noted that such thermometers must be constantly connected to the primary transducer by a connecting capillary. Unlike the above, electric thermometers allow for remote temperature measurements at any distance between the primary transducer and the secondary device. Thermoelectric transducers (thermocouples) and resistance thermotransducers have become the most widely used electric thermometers for industrial applications. This is a review paper and contains information on the features of temperature measurement using thermoelectric transducers (thermocouples).

INVESTIGATION OF SENSITIVE ELEMENTS OF TEMPERATURE TRANSDUCERS BASED ON THERMOMETRIC MATERIAL Lu1-xScxNiSb

INVESTIGATION OF SENSITIVE ELEMENTS OF TEMPERATURE TRANSDUCERS BASED ON THERMOMETRIC MATERIAL Lu1-xScxNiSb

Comprehensive modelling framework for a low temperature gradient thermoelectric generator

Thermoelectric energy harvesting (TEH) is a promising technology enabling the self-sustainable operation of ultra low-power sensing devices performing monitoring tasks. Conventional TEH research mainly focuses on the improvements of the material properties (i.e thermoelectric figure of merit ZT) and thermoelectric module (TEM) geometry. However, enhanced performance of the thermoelectric generator (TEG) can not be practically achieved without optimal integration of the novel TEM with the DC-DC converter. The power converter, having its own input impedance requirements and conversion efficiency curve, may keep the operation point of TEG far from the maximum power point of TEM, leading to power loss. Furthermore, since the physical processes in the thermoelectric transducer are coupled with the electrical processes in the DCDC converter, both components should be analyzed together to achieve the best harvesting performance. Given the system complexity, an accurate simulation model is required to estimate the output power and make an optimal system design. We report on a simulation approach for low temperature gradient TEG that accounts for both the thermoelectric and the power conversion processes. The proposed approach was validated on the TEG testbed by imitating the realistic ambient conditions for thermoelectric transducer connected to a commercial off-the-shelf DC-DC converter. Experimental results are characterized by 9% mean percentage error of power estimation which outperforms the methods based on conventional TEG representations.

Determination of the stagnation temperature of high-enthalpy supersonic air flows using a thermoelectric transducer with shielded measuring junction

Determination of the stagnation temperature of high-enthalpy supersonic air flows using a thermoelectric transducer with shielded measuring junction

Conditions and Characteristics of the Processes of Heat Transfer in Junctions of Thermoelectric Transducers

Conditions and Characteristics of the Processes of Heat Transfer in Junctions of Thermoelectric Transducers

Thermoelectric converter based on metal-dielectric-semiconductor-metal structures for cooling processors

A thermoelectric transducer based on MDSM structures of the field-effect transistor (FET) type is proposed, in which the thermal energy of the environment is converted into electrical energy. We use a new principle of converting thermal energy into electrical energy. We show that with the help of such a converter, it is possible to dramatically increase the efficiency of processors due to the heat generated by the processor is converted by this converter again into electricity that transfers to the processor.

Basics of the approach formation to substantiate the temperature field distribution during experimental research on the coal gasification processes

This paper studies the problems related to the research on the temperature conditions during the coal seam gasification. In particular, while maintaining the identity of the “model – nature” system. A review of the specific application of thermal imaging equipment and thermoelectric transducers (thermocouples) is given. Approaches to the research into the gasification modes using thermocouples on a laboratory setup are described and the main disadvantages of their application are revealed. The dependences have been obtained of the change in the temperature field depending on the gasification modes (ignition process, reverse operations, gasification mode). Recommendations have been developed on the possibility of using thermal imaging equipment (thermal imagers) when studying the temperature field of the gasification process in laboratory conditions.

Event Priority Driven Dissemination EPDD management algorithm for low power WSN nodes powered by a dual source energy harvester

This paper proposes a low-power wireless sensor node which is able to deal with energy harvesting mismatches. The hardware incorporates thermoelectric and piezoelectric transducers for a dual energy harvester, energy storage, microcontroller, sensor and wireless transceiver. The software incorporates an energy-aware Event-Priority-Driven-Dissemination algorithm to send data based on priority or event occurrence. This algorithm serves both to detect the availability of the energy source and to control the nodes' sleep mode. The outcomes revealed that the hardware power was 0.16 mW and 2.13 mW in sleep and active modes respectively. Also, energy autonomy was comfortably achieved since the dual harvester energy was 90 mW when both sources were available.

The Results of the Testing of Led Light According to the Method of Measuring the Lighting Engineering Parameters

The paper presents results of the thermographic and numerical analyses of the chosen design of the LED lamp radiator. The LED technology is characterized by the most dynamic development in the ligh ting market. The object of the test is the LED-1 product, which represents the unit module of the multi-module lighting system. Due to high heat fl ux on the small surface of the individual diodes, problems related to the light source cooling become to be one of the basic ones. The parameters of the test modes for the eff ects of changes in temperature are selected taking into account the physical and mechanical properties of the materials used in the manufacture of the product. Tests were conducted in a windless, dark room. Heat was discharged through convection and radiation. The tests in a dark room were conducted. Heat was discharged through convection and radiation. A thermoelectric transducer chromel-copel with dimensions of 400 μm was used to measure the temperature. The temperature was measured by passing a nominal current of 1,67 A through the module. The test results were analyzed and processed. Based on the result it was decided that the works will be continued using the advanced test stand, equipped with the system of the forced air circulation, control and data acquisition system connected with set of the temperature measurers and improved barriers, preventing the interference of the light fl ux with the thermographic measurement.
 The results of studies of thermal conditions and lighting parameters of the sample of the LED lamp in the process of robots are given. The ability of LED modules to resist the destructive action of heat has been determined. Inspection of potentially unreliable structural elements, strength of fasteners has been done. The luminous effi ciency of LED modules is calculated by indirect and direct, thermal and optical measurements. For the clarity of the working picture was a measured base spectral characteristic. The case temperature, with basic measurements, was 45 °C, and the ambient temperature was 24,2 °C. Analyzing the measurement results — the deviation of the light characteristics amounted to < 10 %. Bringing measurement results to model drawings in CAD SolidWorks allowed us to create a consistent computer model of the product. The model allows with sufficient accuracy to carry out all the calculations for thermal and mass-dimensional data.

Measurement of the spent fuel rod cladding temperature during the in-pile testing at 500 – 900°C

This paper deals with the problem of measuring the VVER-1000 burnup fuel cladding temperature in a 500–900°C range in the process of experiments in a channel of the MIR research reactor to obtain data on the fuel element behavior under the influence of the parameters typical of the maximum design-basis loss-of-coolant accident (LOCA). Studying the burnup fuel cladding deformation pattern requires measurements of the cladding temperature with no (thermal, mechanical and other) impacts on the cladding in the maximum deformation region. For dynamic experiments in the MIR reactor channel with fuel testing in a vapor-gas environment, a cladding temperature measuring unit has been developed, in which the cladding is not subjected to external impacts in the maximum deformation region. In the process of being installed into the spacer grid, the thermoelectric transducer (TET) has its hot junction forced against the cladding making it possible to prevent the external impact on the cladding. The thermometric characteristic of the TET attachment, which is associated with the impact of the grid as such on its thermal condition, was studied using a laboratory facility. This technique was used in an in-pile experiment to study the fuel cladding deformation pattern.

A Thermoelectric System for Thermal Cosmetic Procedures on the Face

Construction of a system for conducting thermal cosmetic procedures in which the operating unit is a thermoelectric energy transducer is discussed. We present the results of experimental studies of a research prototype. Practical tests demonstrated the applicability of the system in practice and showed that standard thermoelectric modules produced by Russian firms can be used, with short warm-up periods and low inertia on changing thermal operating modes.

Prospects for the Use of Additional Cooling System for the Oil-Immersed Transformers with Thermoelectric Transducers

The main cause of the transformers failure when thermal overload, is the inter-turn short circuit inside of the winding. Therefore, the additional cooling system for the oil-immersed transformers developed, which are able to reduce the peak load and its uniform distribution throughout the operation time, due to the accumulation of cold hours corresponding to the minimum thermal load. Determined the dynamics of the ice covering on the cold surface of the thermoelectric transducer in the tank with a certain amount of water. The theoretical justification of the interaction of flows in the device presented.

Heat-transfer, inside of the ground heat-transfer units, from liquid, additionally cooling the oil-immersed transformer

A device for cooling the oil-immersed transformer by means of thermoelectric transducers has been developed. Their operating principle is based on the fact that at night at minimum ambient temperature, the cold is accumulated inside of a vessel due to formation of water ice layer on the developed surfaces of thermoelectric transducers` ribs. Melting of this layer is used in the hottest time of a day for additional cooling of transformer oil in the cooling system of the transformer. Pre-cooling of the circulating water takes place in vertical ground heat-transfer units (VGHT units), mounted into ground drilled boreholes. Certain estimate calculations of the heat-transfer process have been carried out.

A Nanocurrent Power Management IC for Multiple Heterogeneous Energy Harvesting Sources

This paper presents a fully autonomous power converter IC for energy harvesting from multiple and multitype sources, such as piezoelectric, photovoltaic, thermoelectric, and RF transducers. The converter performs an independent self-adapting input power tracking process for each source. The peak power conversion efficiency measured during single-source operation is 89.6%. With all sources enabled, the intrinsic current consumption is as low as 47.9 nA/source. A self-starting battery-less architecture has been implemented in a 0.32-μm STMicroelectronics BCD technology with a 2142 μm × 2142 μm die area. The IC only requires a single-shared inductor and an external storage capacitor for the basic working configuration. With respect to other multisource energy harvesters, this design specifically introduces a series of nanopower design techniques for extreme minimization of the intrinsic consumption during operation. The small chip size combined with the limited number of required external component, the high conversion efficiency, and the state-of-the-art intrinsic nanocurrent consumption make the IC suitable for many critical applications with very limited available power, such as wearable devices or unobtrusive wireless sensor networks.

Methods of Reducing the Effect of the Acquired Thermoelectric Inhomogeneity of Thermocouples on Temperature Measurement Error

The effect of the error of thermoelectric transducers caused by thermoelectric nonuniformity of the thermocouple electrodes, acquired during long-term operation, on the results of temperature measurements is analyzed using well-known correction methods. Ways of developing new correction methods and for compensating errors are proposed.

Bi2Te3 nanowire array preparation and surface polishing by electrochemical deposition

The quantum confinement effect and phonon scattering in low dimensional nanostructure is effective in the improvement of the efficiency of thermoelectric generators. Bi2Te3 nanowire arrays were prepared in Al2O3 templates through the use of electrochemical deposition. Chemical mechanical planarisation was employed to level the upper and lower surfaces of Bi2Te3 samples. The XRD (X-ray Diffractometer) test showed that the crystal grain of Bi2Te3 nanowire was 20–30 nm, attaining a size where the structural properties of the structure induced the quantum confinement effect. It was also indicated that there were dense structures in the fabricated nanowires, the nanowire ends kept at the same level as the hole's edge, solving the problem for the following assembly of thermoelectric transducers. Based on the procedures presented in this paper, there is promise in the future enhancement of the Seebeck coefficient of this nanowire array by introducing nanodoping to the structure.

Advanced materials for solar thermoelectric transducers

Recent achivements in the creation of advanced thermoelectric materials (the thermoelectric quality factor, cost, and workability) have been analyzed. It has been shown that nanostructured materials (quantum dot superlattices and silicate glasses with nanocrystals) can serve as a basis for the creation of highly efficient and easily accessible for mass application thermoelectric transducers converting solar radiation into electric energy. An advantage of thermoelectric transducers is the nonselective character of conversion and the lower sensitivity to changes in the orientation towards an emission source.

Energy Harvesting and Wireless Energy Transmission for Embedded SHM Sensor Nodes

In this article, we present experimental investigations using energy harvesting and wireless energy transmission to power wireless structural health monitoring sensor nodes. The goal of this study is to develop sensing systems that can be permanently embedded within a host structure without the need for an on-board power source. With this approach the required energy will be harvested from the ambient environment, or periodically delivered by a radio-frequency energy source to supplement conventional harvesting approaches. This approach combines several transducer types to harvest energy from multiple sources, providing a more robust solution that does not rely on a single energy source. Both piezoelectric and thermoelectric transducers are considered as energy harvesters to extract the ambient energy commonly available on civil structures such as bridges. Methods of increasing the efficiency, energy storage medium, target applications and the integrated use of energy harvesting sources with wireless energy transmission will be presented.

Complete analytical modeling and analysis of micromachined thermoelectric uncooled IR sensors

This paper deals with a complete analytical modeling and analysis of thermoelectric uncooled infrared sensors compatible with CMOS technology. The operating principle involves a localized thermal assessment resulting from IR radiation absorption, a micromachined membrane on which PolySi/Al thermojunctions have been deposited causing an internal self-generated electromotive force. The model put forward is based on dividing the sensor into three zones, each one being the subject of a thorough thermal study (conduction, convection and radiation thermal effect). Through the analytical thermal gradient analysis developed in each zone of the structure (absorber, part of thermoelectric transducer layer placed under the absorber, thermoelectric transducer) we are able to predict the sensitivity, detectivity and the noise equivalent power to the sensor. Thus, such a kind of analytical approach is worth of interest to optimize thermopile sensor design parameters.