Thermoelectric Assembly Research Articles

Physics-based machine learning optimization of thermoelectric assembly for maximizing waste heat recovery

With the increasing energy consumption of data centers around the world, the recovery of low-grade waste heat in data centers has become increasingly important. To maximize the waste heat recovery of thermoelectric modules in data centers, physics-based machine learning optimization of the thermoelectric assembly was carried out. A theoretical model and machine learning model of a fan-heat sink-thermoelectric generator system for waste heat recovery were proposed for predicting the performance of a thermoelectric assembly. Genetic algorithms were used to find the best heat sink geometric parameters for the possible greatest power generation. Given a temperature difference constraint of 75 °C between the heat source and the environment, the greatest output power from the thermoelectric assembly was 3.836 (watts), with the optimal plate fin height of 60 (mm), 50 fins, and 1.7 (mm) of fin pitch over a 120 mm × 120 mm area under the determined parameters of the thermoelectric module with a 120 mm cooling fan. In addition, by comparing different machine learning algorithms, the results revealed the superiority of random forest regression in solving optimal problems. This work provides a convenient and practical means for the fast optimization of thermoelectric assembly.

Local Heating through the Application of a Thermoelectric Heat Pump for Prenursery Pigs

Mathematical formulation of the animal thermal status has been developed, with the account of two convenience conditions and heat balance, for the floor-mounted heating panel for prenursery pigs. The borders of the heat flux variation range for the floor-mounted heating panel have been determined corresponding to the animal-friendly conditions for prenursery pigs of various age groups. The block diagram of the energy-saving floor-mounted heating panel, comprising the thermoelectric assembly operating in the heat pump mode, has been designed. The method has been described and the corresponding calculations have been made for the basic thermal parameters of the floor-mounted local heating installation, for prenursery pigs, with the application of a thermoelectric heat pump. The experimental installation sample of 116 W thermal capacity (for the heat transfer coefficient from 0.9 W·m−2·K−1 to 1.0 W·m−2·K−1 and floor temperature in the range of 5 °C to 6 °C) has been developed and manufactured for local heating for prenursery pigs managed in gestation crates. Laboratory tests of the experimental sample of the floor-mounted heating panel have demonstrated high energy efficiency of the heating installation under development. The energy-saving effect (approx. 15% compared to the series-produced equipment designed for local heating of young stock) of the developed installation was achieved owing to the partial heat recuperation of the exhaust ventilating air.

Development and heat transfer analysis of thermoelectric self‐powered fuel‐fired residential boiler

AbstractSolid‐state thermoelectric (TE) devices offer many interesting features compared with other methods of generation, such as no moving parts, high reliability, low maintenance, and straightforward integration with other heating equipment. In this study, a thermoelectric assembly was integrated into a residential heating boiler to convert a portion of combustion heat to electricity while meeting space and/or water heating needs. A prototype was developed, in which recently developed thermoelectric modules were incorporated into a gas‐fired boiler. The electricity generated by the thermoelectric assembly would be sufficient to power the electrical auxiliary components of the heating system. In this way, the heating system could operate entirely on fuel combustion and provide the consumer with heating system reliability and a reduction in power consumption. A model for the thermoelectric conversion system was established and the thermal resistance analysis was carried out to show the influence of heat transfer coefficients and other parameters on power output and efficiency, and thus improve the system design. In this study, the single‐module integrated assembly can produce a 22.5 W power output. However, each module of the four‐/eight‐module integrated assembly can only generate a power output of 7.85/9.175 W on average. The performance of a single module in a multimodule assembly is worse than that of a single module assembly. The number of modules placed on the furnace wall is not as many as possible but has an optimal value. In this experimental environment, the assembly of eight modules is the optimal choice. Furthermore, it is found that enhancing combustion‐side heat transfer capacity is an effective way to promote system performance. The power output of the assembly composed of four modules will increase by 70% from 7.85 to 13.5 W due to the installation of the fin on the hot end.

Measurement of two-dimensional heat generation rate of pouch type lithium-ion battery using a multifunctional calorimeter

Accurate characterization of the heat generation rate (HGR) of lithium-ion batteries is critical for driving towards a cost-effective and efficient design of a thermal management system for various applications. Because of the increases in battery cell dimensions, as well as more aggressive operating conditions, heat generation seen at the cell level is becoming increasingly unevenly distributed. Proper design of the heat management system requires measurement of heat generation distribution at the cell level as a function of operating conditions, such as charging and discharging profiles, states-of-charge (SOC), temperature, and state-of-health (SOH). Currently, few commercial calorimeters are available for measurement of heat generation distributions under dynamic and varying operating conditions at reasonable price. In this paper, a new calorimeter is developed that allows for measurement of HGR in two-dimensions for a pouch format lithium-ion battery cell in real time, which consists of two thermoelectric assemblies (TEAs) with heat flux sensors to measure the HGR and temperature sensors to regulate the temperature. Distributed HGR of a large format pouch cell for automotive applications are measured as a function of different charging and discharging rates and SOCs as well as the variation of heat generation distribution during cell aging.

Fast Charge and Discharge Characterization and Modeling of Heat Generation at the Cell Level

Fast charging in lithium ion batteries is a critical process in the automotive industry that will drive the adoption of electrified products. The process of fast charging and discharging raises significant engineering challenges at the vehicle level related to thermal management. One key understanding that drives solutions to these thermal management challenges is the heat generation of the battery under high rate operation.Characterization of heat generation rates in a battery requires a highly accurate and dynamic calorimeter coupled with mathematical modeling at multiple scales. Here we present a multifunctional calorimeter for lithium-ion batteries that incorporates thermoelectric assemblies which enables the measurement of the heat generation at the cell level as a function of fast charging and discharging rates, states of charge, and temperatures. Due to the dynamic nature of the calorimeter and the ability to rapidly respond to heat generation changes at the cell level, it is possible to decouple the temperature fluctuations during charging and discharging to determine the entropy coefficient of the cell.For this work, large format battery cells were utilized that are typically seen in the automotive industry which contain a LMO/NMC cathode and a graphite anode. The lumped heat generation rate of the cell is measured, and the heat source terms are characterized and split into reversible and irreversible sources. A model is presented that predicts heat generation and the outputs are compared to measured heat generation from the dynamic calorimeter.

Floor Heating of Piglets Using a Thermoelectric Heat Pump

A functional and process flow diagram of an energy-saving floor heating panel using a thermoelectric assembly operating in a heat pump mode has been developed. The technique and calculation of the main heat-and-power parameters of this installation are presented. Studies of a working prototype of a floor heating panel, which have shown the high energy efficiency of the installation being developed, have been performed. It is shown that energy saving is about 15% in comparison with the serially used equipment for local heating of young animals.

Использование возобновляемой энергии для локального обогрева поросят

The analysis of technologies and technical means of creating a temperature regime in the piglet location zone, where two different temperature fields must be created in the cold season: one for breeding pigs, the other for suckling piglets. The article considers the question of the use of thermoelectric modules and heat pipes as a source of thermal energy in local heating installations for suckling piglets. (Research purpose) There are proposed the functional and technological scheme of the installation for local heating of young animals with the use of thermoelectric modules and heat pipes. (Materials and methods) In the developed scheme, the thermal energy of the hot circuit of thermoelectric modules is used to heat the site on which the piglets are located. (Results and discussion) The heat of the cold circuit of the thermoelectric module assimilates the thermal energy of the removed ventilation air. For the effective operation of a thermoelectric installation for local heating of piglets, it is necessary that the cooling circuit, which absorbs thermal energy from the environment, be involved in some technological process for heat removal, for example, the heated ventilation air being removed. This leads to a significant increase in the efficiency of thermoelectric modules. At the same time, the installation will operate in the heat pump mode, since the amount of heat released in the heat exchanger of the hot circuit of the thermoelectric assembly exceeds the amount of electricity consumed from the network. (Conclusions) The article presents the sample of a thermoelectric installation was developed and its laboratory tests. The article describes the energy efficiency of the use of thermoelectric modules as energy converters in thermal technological processes.

Разработка и исследование осушителя и подогревателя воздуха на базе элементов Пельтье

A functional flow diagram of an energy-saving dehumidifier and an air heater based on Peltier elements has been developed. A method for calculating the heat-power and design parameters of a thermoelectric assembly is presented. Physical modeling of the process of dehumidification and heating of air in a thermoelectric installation has been carried out. The results of tests of a working model of the thermoelectric dehumidifier and air heater are presented. Rational operating modes of the installation have been substantiated, and its energy efficiency in the heat pump mode has been shown.

Measurement of heat generation rate and heat sources of pouch type Li-ion cells

Fundamental understanding of heat generation of lithium-ion batteries during operations is crucial to the cost-effective and efficient design of a thermal management system (TMS) in electric vehicles. Accurate characterization of the heat requires a calorimeter that meets inherent dynamics of the heat with accuracy. Therefore, we have developed an isothermal calorimeter using the thermoelectric assemblies (TEAs) along with the temperature control and Kalman filter, which is used to measure the heat generation rate (HGR) of large format pouch type lithium-ion batteries as an example. The measured HGR is a function of charge and discharge rates, state-of-charge (SOC), and temperatures. Analysis has shown that both the HGR and the ratio of the total heat generation to the total energy stored or released (pheat) of the tested cells increase as the current increases or the temperature decreases. In addition, a new calorimetric method is developed which enables a simultaneous determination of the entropy coefficient and internal resistance in the reversible and irreversible heat source terms in the frequency domain. The method can reduce the testing time about 92% compared with those by the conventional potentiometric method and electrochemical impedance spectroscopy (EIS) analysis, respectively, and the determined parameters are in good accordance with the reference values. Moreover, the calculated reversible and irreversible heat sources terms are compared with the experimental measurement and matched each other.

Принцип построения энергосберегающей сушильной установки с применением термоэлектричества

Most drying plants of small capacity for vegetables and fruits are convective without recirculation of the drying agent. Such dryers have a high energy consumption and cannot be attributed to energy-saving installations. (Research purpose) The research purpose is in developing a functional and technological scheme of an energy-efficient thermoelectric dryer that provides a reduction in energy costs during the drying process while maintaining high quality indicators of the finished product and increasing the drying efficiency. (Materials and methods) The methods of system analysis and synthesis of existing knowledge in the field of research on the development of energy-saving dryers, based on the provisions of the theory of drying, heat and mass transfer and thermoelectricity were used. (Results and discussion) The article presents the structural and functional-technological schemes of a convective condensation dryer with recirculation of the drying agent based on Peltier thermoelectric elements. The technological process and the principle of operation of a convective dryer of the condensation type with the use of a thermoelectric assembly operating in the heat pump mode were described. The article proposes a general method for calculating the heat and energy parameters of the dryer based on the heat balance equation. The thermal energy withdrawn by the hot circuit of the thermoelectric assembly, and directed to heating the cooled and drained air, exceeds the energy consumed from the electrical network. The uniform transverse blowing of the drying box with an air ensures uniform drying of the product. (Conclusions) When the drying box is cross-blown and the air flow is relatively fast, the moisture evaporation process is accelerated, the drying time is reduced and the drying quality is improved. It was revealed using preliminary technical and economic calculations that the proposed design provides a reduction in energy consumption compared to traditional dryers by up to 25 percent.

(Invited) Experimental Characterization and Modeling of Heat Generation Rates of Lithium-Ion Batteries with NMC/C Chemistries

The operating temperature of a battery strongly affects overall chemical reactions, ion transport, intercalation and deintercalation process and consequently efficiency, cycle life, and safety of battery systems. Therefore, battery thermal management system (BTMS) should be optimally designed to ensure a highly efficient and reliable operation of the battery system, which requires characterization and analysis of heat generated during operations rather than temperature.Characterization of heat generation rates of a battery requires a highly accurate and dynamic calorimeter that is not commercially available. Therefore, we designed a new multifunctional calorimeter for lithium-ion batteries using thermoelectric assemblies (TEA), which enables the measurement of heat generation rate as a function of C rates, state-of-charge (SOC) and temperatures. In addition, the calorimeter also works as a thermostat that is capable of tracking an alternating reference temperature, so that flexibility and accuracy of experiments are ensured. This capability enables to decouple the temperature fluctuation during charging and discharging operations and the measurement of the entropy coefficient.In this paper, the cells used as an example for the experiments are large format pouch type lithium ion batteries with LMO/NMC-Graphite chemistry. The lumped heat generation rate of the cell is measured at different C rates, state-of-charge (SOC) and temperatures. In addition, analysis of the data has shown that both the heat generation rate and the ratio of the total heat generation to the total energy stored or retrieved of the tested cells increase as the current increases or the temperature decreases.Characterization of the heat source terms includes measurement of reversible and irreversible heat sources that can be determined by calorimetric methods. Particularly, the entropy coefficient (dUOC/dT) in the reversible source is the key parameter that determines the amount of the reversible heat generated during operations. Currently, either potentiometric or calorimetric method is used to measure the value of the entropy coefficient, which drawbacks are long measurement time and inaccuracy. Thus, a new method is proposed based on the calorimeter that works as a thermostat in conjunction with an estimation technique. In order to reduce the measurement time, a time-domain background voltage offset correction and a frequency-domain entropy coefficient determination have been newly developed and applied. Comparison between the developed one and the classical methods has shown a drastic reduction of the measurement time and a similar accuracy to the potentiometric method. The proposed method is also used to investigate effects of temperatures and aging on the entropy coefficient. As a result, the reversible heat source term dependent upon the operating conditions such as SOC, temperature and cycle life can be characterized, which are the important factors for design of battery thermal management systems.Moreover, a calorimetric method for the characterization of the reversible and irreversible heat sources is also developed by applying a sinusoidal current excitation to the cell and analyzing the heat generation response in frequency domain. The determined parameters of both heat sources are compared with those measured by hybridized time frequency domain analysis method and EIS analysis, respectively, which shows a good match. Moreover, the calculated reversible and irreversible heat sources terms are compared with the experimental measurement. Results have shown improved performances in the characterization of irreversible and reversible heat with respect to measurement speed and accuracy.Finally, a thermal model that includes irreversible and reversible heat source terms is developed and then incorporated into a reduced-order electrochemical model (ROM). The electrochemical thermal model is validated against the heat generation rate of the cells measured by the developed calorimeter aforementioned. The model is capable of predicting heat generation rates up to 3C from -30°C to 35°C. Based on the validated thermal model, effects of C rates and temperatures on heat sources can be analyzed. The results have shown that the reversible heat is dominant at low C rates, while the irreversible one is dominant at high C rates because the Joule heating, which is the main irreversible heat source, is proportional to the square of the current. Besides, the reversible heat source is dominant at high temperatures, while the irreversible one is dominant at low C rates because battery internal resistance sources such as contact resistance and ionic resistivity rapidly increase at low temperatures.In addition, the lumped model is used to develop a two-dimensional electrochemical thermal model that is validated with temperature images captured by an Infrared thermal camera.Presented experimental characterization of heat generation and the associated theoretical analysis by electrochemical thermal models can provide basics and fundamentals for an optimal design of future battery thermal management systems.

Thermoelectric Installation for Dehumidification and Heating of Air in Livestock Premises

General supply and exhaust ventilation is used to combat high humidity in livestock premises. The possibilities of this method in maintaining the air parameters within the required limits are limited. Dehumidifiers based on various physical principles help solving the problem of high humidity. (Research purpose) The research purpose is in substantiation of a rational functional and technological scheme for the installation of dehumidification and heating of air based on Peltier elements in the premises of agricultural production, based on the results of its physical modeling, developing, and testing of a working sample. (Materials and methods) Authors used methods of system analysis and synthesis of existing knowledge in the research field on the development of energy-efficient dehumidifier and air heater based on the theory of heat and mass transfer and thermoelectricity. The article presents a functional and technological scheme of the dehumidifier and air heater based on thermo-electric Peltier elements. Authors developed a prototype sample and performed physical modeling of heat transfer processes from thermoelectric assembly to heat carriers. The article presents a method for calculating the heat and power design parameters of heat exchange devices on the cold and hot sides of the thermoelectric assembly. (Results and discussion) It was found that the heat energy withdrawn by the hot circuit and directed to heating the dried air exceeds the energy consumed from the electrical network by 20-30 percent. (Conclusions) This design solution reduces the energy consumption of a thermoelectric dehumidifier compared to traditionally used equipment. Thermoelectric dehumidifiers are environmentally safe and are intended for small-scale agricultural areas with an air capacity of up to 500 cubic meters per hour.

The Use of the Photovoltaic System in Combination With a Thermal Energy Storage for Heating and Thermoelectric Cooling

The article is focused on the research of the usage of modern accumulation technology. The proposed system is able to improve the thermal comfort of building interiors. That text depicts the technology, which uses a photovoltaics and other renewable energy sources for active heating and cooling. The bases of the presented technology are the phase change material and thermal energy storages. So, it passively improves the thermal capacity of the constructions of the buildings. Moreover, there is a possibility to use it for active heating and cooling. The technology contains thermoelectric assemblies, so, there is a very interesting possibility to store thermal energy with use of renewable energy sources (such as photovoltaic system) and thermoelectric coolers side by side. In the manuscript, there are shown measurements and results of the active operating modes of proposed technology. It was found the technology is able to work in active heating and cooling modes. It works quite well in active heating mode. On the other hand, thermoelectric cooling mode had a problem with overheating. In the end, the problem was solved and the cooling mode works. The measurements and results are described in the text.

Modeling of Failure in Aluminum Alloy Braze for a High Temperature Thermoelectric Assembly

The objective of this work is to design a commercially viable thermoelectric generator (TEG) assembly that can be used in passenger vehicles to be able to withstand extreme environmental conditions. Since the operating temperatures of the TEGs can reach temperature levels higher than 500 °C, aluminum braze alloys offer a good high temperature solution for die attach. However, the evolution of fatigue damage in the aluminum braze must be understood in order to ensure an acceptable reliability of the TEG. In this paper, the proposed design of TEG package assembly was evaluated under extreme temperature conditions. Three-dimensional models of full scale TEG were analyzed using finite element analysis (FEA). The failures of aluminum alloy based braze (high temperature form of solder) material in the TEG application was investigated. Low cycle fatigue using direct cyclic approach was considered for the reliability analysis. Continuum damage mechanics approach was used to study the fatigue failure due to power cycling. Different TEG assembly designs were investigated and compared to determine the best possible solution for the extreme environment application.

Numerical Modeling and Design of Thermoelectric Cooling Systems

Thermoelectric coolers are often used as reliable energy converters in a large range of applications. For design considerations, it is crucial to establish an effective methodology to determine and optimize the TEC performance within the cooling system constraints. For this purpose, firstly, three approaches are used to obtain the internal parameters of a given thermoelectric module. For these three estimating procedures, the simulated pumping powers are in the sequence of method III < method II < method I for each temperature difference. Hence, good precision of the simulated data are obtained by averaging the results of these three methods. Then, design optimizations of a thermoelectric assembly are conducted to obtain the device parameter, efficiency, and maximum power, respectively. Results show it is simple and effective way for design of a thermoelectric cooling system.

On thermoelectric power conversion from heat recirculating combustion systems

The thermodynamic theory governing the absolute maximum efficiency of energy conversion by thermoelectric devices that operate as part of the heat recycle in regenerative burners is examined. Comparison with a series of elementary Carnot cycles helps to address the question of whether higher system efficiencies are realizable by rejecting the unconverted heat to the cold surroundings or to the incoming reactants as part of the recycle. While for the second law (Carnot) heat engine cycles the maximum power that can be extracted is independent of the layout, in the case of irreversible thermoelectric assemblies a particular combination of both in a novel configuration is shown to be most advantageous. This heat exchanger/thermoelectric converter configuration consists of a coaxial assembly of many annular thermoelectric elements in series and a section in which heat is rejected to the incoming reactants that is followed by a second section, which discards unconverted heat to the cold surroundings. It is shown that the efficiencies of such devices could substantially exceed the maximum efficiencies of the best present-day thermolectric of such devices could substantially exceed the maximum efficiencies of the best present-day thermoelectric conversion systems, and the theory suggests practical designs for small, combustion-driven, power supplies.

Experimental nuclear thermoelectric assembly ?Gamma? ? A prototype of an unattended self-regulating nuclear thermoelectric station

Experimental nuclear thermoelectric assembly ?Gamma? ? A prototype of an unattended self-regulating nuclear thermoelectric station

An Automatic thermoelectric cooling method and computer-based recording system for supercooling point studies on small invertebrates

An automatic controller is described for use with fluid-cooled thermoelectric assemblies and compatible bipolar controllers in supercooling point studies on small invertebrates. The automatic controller provides constant and repeatable cooling rates in the range of 0.4 to 3 °C min −1 from +25 to −50 °C; under manual control this range can be extended from less than 1 to 15 °C min −1. The controller includes a range of preset lower-limit temperatures and a reset function to heat the system between experiments to the start temperature (+15 °C) in less than 2 min. Supercooling points were sensed, observed, and recorded by a 12-channel, cold-junction-compensated, thermocouple convertor interfaced to a microcomputer, color monitor, and dot-matrix printer. Thermocouples were calibrated against a platinum resistance thermometer to derive polynomial descriptors which were incorporated into a microcomputer program (BASIC, Applesoft) to match thermocouples to ±0.2 °C. Each thermocouple was sampled at 3-sec intervals to ±0.1 °C and temperatures of insect-bearing sensors were plotted against time in distinguishing colors on the monitor, using a second computer program. On completion of an experiment all supercooling points for each thermocouple were printed on the dot-matrix printer; the graphical display could be stored on disk or output to a printer. The computer program can be readily modified to implement individual protocol requirements such as the range of temperatures and related information displayed on the monitor, and the thresholds (time and °C) for the recognition of supercooling points. The thermocouple convertor/microcomputer system could be used with any method of cooling.

A vacuum test device for the measurement of thermoelectric material properties

A vacuum test device for measurement of thermoelectric parameters has been developed, consisting basically of an evacuated chamber containing a constant-temperature heat sink, to which the hot junctions of the test couple are attached, and a temperature-controlled radiation shield which surrounds the cold junction of the test couple. The temperature of the radiation shield is held equal to the cold-junction temperature by a thermoelectric assembly and a temperature-controlled power supply. The Seebeck coefficient and average electrical resistivity of a couple are measured by the zero- ΔT test. The Seebeck coefficient of a couple can also be determined by measuring the Seebeck voltage in the presence of a small temperature difference across the couple. The average thermal conductivity of a couple is determined by measuring the temperature difference established when a small measured quantity of heat is added to the cold junction of the test couple. Determination of the figure of merit for a couple is made by the maximum-† T test. Heat pumping performance of a couple can also be measured.