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A thermoelectric module is a device that converts electrical energy into thermal energy through a mechanism known as the Peltier effect. A Peltier device has hot and cold sides/substrates, and heat can be pumped from the cold side to the hot side under a given voltage. By applying it in buildings and attaching it to building envelope components, such as walls, as a heating and cooling device, the heating and cooling requirements can be met by reversing the voltage applied on these two sides/substrates. In this paper, we describe a novel, panelized, ground source, radiant system design for space heating and cooling in buildings by utilizing the Peltier effect. The system is equipped with water pipes that are attached to one side of the panel and connected with a ground loop to exchange heat between the cold/hot sides of the thermoelectric module and the underground region. The ground loop is inserted in boreholes, similar to those used for a vertical closed-loop Ground Source Heat Pump (GSHP) system, which could be more than a hundred meters deep. Experiments were conducted to evaluate the feasibility of the developed panel system applied in buildings. The results show that: (1) the average cooling Coefficients Of Performance (COP) of the system are low (0.6 or less) even though the ground is used as a heat sink, and thus additional studies are needed to improve it in the future, such as to arrange the thermoelectric modules in cascade and/or develop a new thermoelectric material that has a large Seebeck coefficient; and (2) the developed system using the underground region as the heat source has the potential of meeting heating loads of a building while maintaining at a higher system coefficient of performance (up to ~3.0) for space heating, compared to conventional heating devices, such as furnaces or boilers, especially in a region with mild winters and relatively warm ground.

Graphene is atomically thin, possesses excellent thermal conductivity, and is able to withstand high current densities, making it attractive for many nanoscale applications such as field-effect transistors, interconnects, and thermal management layers. Enabling integration of graphene into such devices requires nanostructuring, which can have a drastic impact on the self-heating properties, in particular at high current densities. Here, we use a combination of scanning thermal microscopy, finite element thermal analysis, and operando scanning transmission electron microscopy techniques to observe prototype graphene devices in operation and gain a deeper understanding of the role of geometry and interfaces during high current density operation. We find that Peltier effects significantly influence the operational limit due to local electrical and thermal interfacial effects, causing asymmetric temperature distribution in the device. Thus, our results indicate that a proper understanding and design of graphene devices must include consideration of the surrounding materials, interfaces, and geometry. Leveraging these aspects provides opportunities for engineered extreme operation devices.

Thermoelectric (TE) based cooling and heating systems offer significant advantages over conventional vapor compression systems including no need for refrigeration or major moving parts, high controllability, and scalability. The purpose of the present study is to provide an energy and economic assessment of the performance of a TE-based radiant cooling and heating system for building applications. It is considered that TE modules are integrated in the ceiling to lower/increase the ceiling temperature through the Peltier effect during the hot/cold season to provide thermal comfort for the occupants via radiation and convection. The study explores the possibility of using rooftop PV panels to produce electricity required for the operation of TE modules. An actual office building located in Melbourne, FL, USA is considered for a test study, and the hourly cooling and heating loads of the building are calculated through building energy simulation in eQuest. Various operating conditions, including different input voltages and temperature gradient across TE modules, are considered, and the system is sized to properly address the year-around cooling/heating demand. It is shown that a nominal cooling capacity of 112.8 W and a nominal PV capacity of 31.35 W per unit area of the building is required to achieve the target goal when the system operates at the optimal condition. An economic analysis is also performed, and estimated cost, as well as potential savings, are calculated for each operating condition. The optimal operating condition with minimum cost is selected accordingly. The results demonstrated that the initial cost of the proposed system is considerably higher than conventional heating/cooling systems. However, the system offers other benefits that can potentially make it an attractive option for building cooling/heating applications.

This work describes the design, construction and testing of a thermo-electric conditioning device installed in a neonatal incubator with the aim of improving the precision in the regulation of the interior air temperature, reducing noise and interior vibration, and improving the life of the neonate. A simplified one-dimensional thermal model has been developed, made up of resistances and thermal capacities that simulate the thermal behaviour of all the elements of the system from end to end. All the equations of the model are obtained in a nodal way, allowing the mathematical relationship between the input and output to be known. This model makes it possible to improve temperature control, avoiding the deviations that occur in the traditional model controlled by sensors at both ends. The computational model allows to predict the variation of temperatures in transient and permanent regime. This model allows the design and sizing of the thermoelectric system for different outdoor environmental conditions and the selection of the number of Peltier modules needed to satisfy the heating demand of other incubators with different geometry and capacity. The results of the computational model show good agreement with the experimental tests, despite being a simplified 1D nodal model. The results obtained show a coefficient of operation (COP) of 1.38, achieving higher performance than the current traditional electrical resistance system (COP = 1). In addition, a CFD study has been carried out to check the air patterns, to see the temperature uniformity and to estimate the number of air changes per hour (HVAC) inside the incubator.

Thermal cloaking and camouflage have attracted increasing attention with the progress of infrared surveillance technologies. Previous studies have been mainly focused on emissivity manipulation or using sophisticated thermal metamaterials. However, emissivity control is only applicable for objects that are warmer than the environment and lower emissivity is usually accompanied with high reflectance of the surrounding thermal signals if they have nonuniform temperature. Metamaterial‐based thermal camouflage holds great promise but their applications on human subjects are yet to be realized. Direct temperature control represents a more desirable strategy to realize dynamically adjustable camouflage within a wide ambient temperature range, but a wearable, portable, and adjustable thermo‐regulation system that is suitable for human subjects has not been developed. This work demonstrates a wearable and adaptive infrared camouflage device responding to the background temperature change based on the thermoelectric cooling and heating effect. The flexible thermoelectric device can realize the infrared camouflage effect to effectively shield the metabolic heat from skin within a wide range of background temperature: 7 °C below and 15 °C above the ambient temperature, showing promise for a broad range of potential applications, such as security, counter‐surveillance, and adaptive heat shielding and thermal control. [ABSTRACT FROM AUTHOR]

Spin thermo-electric phenomena have attracted wide attention recently, e.g., the spin Peltier effect—heat generation by magnonic spin currents. Here, we find that the spin Peltier effect also manifests as a heat wave accompanying fast moving magnetic textures. High speed and extreme magnetic excitation localisation are paramount for efficient transfer of energy from the spin-degrees of freedom to electrons and lattice. While satisfying both conditions is subject to severe restrictions in ferromagnets, we find that domain walls in antiferromagnets can overcome these limitations due to their ultrahigh mobility and ultra-small widths originating from the relativistic contraction. To illustrate our findings, we show that electric current driven domain wall motion in the antiferromagnetic metal Mn2Au can carry a localised heat wave with temperature up to 1 K. Since domain walls are localised magnetic objects, this effect has the potential for nanoscale heating sensing and functionalities. The spin Peltier effect describes the temperature modulation of a system in response to a spin current and has potential application for thermal nanosensors. Here, the authors theoretically demonstrate that for an antiferromagnetic system, via the spin Peltier effect, a current driven domain wall can carry a localised heat wave with a temperature of 1 K. [ABSTRACT FROM AUTHOR]

• Counter-flow arrangement of Peltier modules increases system efficiency. • Optimal number of modules was calculated as a function of thermal load. • Splitting each stream into parallel channels further improves the COP. • COP of counter-flow arrangement is higher than ideal COP of cascade unit. We evaluate the thermal behavior of a thermoelectric cooler composed of Peltier modules connected in series by two air streams in counter-current flow, i.e., in the so-called horizontal stack configuration. An advantage of this configuration over cascade (pyramid-like, or vertical stack) arrangements to achieve large temperature spans is the comparatively higher coefficients of performance of the former at large values of heating load and temperature span. In the counter-flow configuration, the temperature span per Peltier module is relatively small, giving rise to much higher individual (i.e., per module) coefficients of performance. In this paper, we outline a procedure to determine the optimal number of modules in a counter-current flow unit as a function of the applied thermal load (up to approximately 200 W), considering all relevant loss mechanisms (Joule heating and heat conduction in the semiconductors and fluid friction). Pin-fin heat sinks are employed to reduce the fluid-surface temperature differences on the hot and cold sides of the thermoelectric modules. An assessment of the influence of the number of parallel channels on each stream (hot or cold) was also carried out. [ABSTRACT FROM AUTHOR]

Considering the thermal issues of sever, a thermal simulation model is built using the lumped parameter method. It finds that the high temperature areas are mainly concentrated in CPU and north bridge chip. With regard to CPU, the fin thickness and fins number of heat pipe radiator are optimized through nonlinear curve fitting method. The optimized radiator could reduce the maximum temperature of CPU by 3.45–6.67 °C, varied by CPU load. With regard to north bridge chip, a chip-level cooling method based on Peltier effect is proposed. The macro-scale and micro-scale thermoelectric cooler (TEC) are respectively introduced to cool the chip and its hot spot. It finds that the added TEC could reduce the temperature rise of north bridge chip by 0.99–8.32 °C, and the hot spot temperature of north bridge chip can be significantly reduced by utilizing a mini-contact structure. [ABSTRACT FROM AUTHOR]

• Broader optimum coupling on a semiconductor refrigeration system is analyzed. • Optimum external parameters for a maximum cooling capacity are demonstrated. • Optimum external parameters for a maximum COP value are demonstrated. • Enhancing poor heat dissipation at the hot side could be a better strategy for optimization. Semiconductor refrigeration utilizes Peltier effects to achieve cooling, and does not use any refrigerants. Due to its simple and compact structure, semiconductor refrigeration has become one of the most promising cooling technologies. However, as a semiconductor refrigeration system, the interactions among the main external factors that affect its performance are complicated. Based on experimental results and thermodynamic models, deeper insights are presented into semiconductor refrigeration in this study. Broader coupling between performance and main external parameters are analyzed, including the driving voltage of fans at both the hot and cold sides, and the working voltage of the semiconductor refrigeration chip. Optimal external parameters corresponding to a maximum COP and a maximum cooling capacity are obtained. For example, under the optimal working voltage of a semiconductor refrigeration chip with a fan driving voltage of 4 V at the hot side and 6 V at the cold side, Q c,max was increased by 60%, and was 326% higher than chips under 2 V and 10 V working voltages. Under the optimal fan driving voltage at the hot side with a 6 V fan driving voltage at the cold side and a 3 V working voltage of the chip, the maximum value of COP was respectively 140.3% and 104.3% larger than those with 0 V and 12 V fan driving voltages at the hot side. It is also found that the driving voltage of fans at the hot side has a greater influence on the optimal working voltage of a semiconductor refrigeration chip. This investigation could be applied in the optimization of the design and operational control of semiconductor refrigeration systems. [ABSTRACT FROM AUTHOR]

The electric power produced by a thermoelectric generator (TEG) is strongly influenced by the applied heat sink. While a TEG is aimed at harvesting waste heat, the optimization of the efficiency of the heat sink is a key task for the design of waste heat recovery systems implementing TEG. A TEG model is proposed and implemented in an open source toolbox for field operation and manipulation (OpenFOAM) for the purpose of performing optimizations of the heat sink, using a commercially available TEG as basis. This model includes the multi-physics thermoelectric coupled effects. Conservation principles of energy and current are considered simultaneously. This includes the thermal and electric conduction, Seebeck effect, Peltier effect, Thomson effect, and Joule heating. Particular attention is given to a proper modeling of the boundary conditions. The thermoelectric model is implemented in such a way that it can readily be combined with other physical models in OpenFOAM. The model is validated by comparing the predictions to analytical results, measurements as well as the simulation data of other authors. [ABSTRACT FROM AUTHOR]

A nonlinear model of coupled thermoelectricity is presented and implemented in the finite element method. The model accounts for the Seebeck, Peltier and Thomson effects in thermoelectric materials within the framework of the coupled thermal and electrical behaviors governed by the Fourier and Ohm's laws. The resulting finite element system of equations is expressed directly in terms of the potential variables, i.e. voltage and temperature, and it is solved using the Newton method by formulating the stiffness and Jacobian matrices with respect to these fundamental variables. The model is verified by comparing its predictions with the analytical solution resulting from the system of ordinary differential equations that represent the simplified model for the one-dimensional case. Then, the finite element model is applied to estimate the energy conversion performance of nanostructured thermoelectric materials compared with that of traditional bulk materials. The study illustrates the excellent behavior of nanostructured materials in terms of their power output and conversion efficiency. The analysis shows the advantages of developing nanostructured thermoelectric materials for increased performance and miniaturization. • A novel finite element model is developed for thermoelectric materials. • Single stage thermoelectric generators are simulated. • The performance of nanostructured thermoelectrics is compared to that of their bulk counterparts. • Nanostructured thermoelectrics exhibit superior power output and conversion efficiency. [ABSTRACT FROM AUTHOR]

The thermoelectric cooler (TEC) is a kind of cooling equipment which used to dissipate heat from the devices by Peltier effect. The cooling capacity (Qc) and coefficient of performance (COP) are both significant performance parameters of a thermoelectric cooler. In this article, three-dimensional numerical simulations are carried out by finite element analysis based on the temperature-dependent materials properties. The experimental and geometrical parameters have important effects on the TEC performance which have been analysed, such as electrical current, geometric configuration of thermoelectric leg, Thomson effect, thermal contact resistances and electrical contact resistances. The results show when the Thomson effect is ignored, the maximum difference in the cooling capacity is 7.638 W while the maximum difference in the COP is 0.09. When contact effect is not considered, the maximum difference in the cooling capacity is 22.06 W while the maximum difference in the COP is 0.75. Furthermore, the cooling capacity and COP have also been simultaneously optimized according to the multi-objective genetic algorithm. The best optimal value is obtained making use of TOPSIS (technique for order preference by similarity to an ideal solution) method from Pareto frontier. Investigated on these optimal design parameters which were anticipated to provide real guidance in industry. [ABSTRACT FROM AUTHOR]

Described herein is a detailed and comprehensive multiphysics model of a thermoelectric generator (TEG). The one-dimensional model uses electrical–thermal analogies solved for transient response using SPICE. There are many advantages and applications of thermoelectric generators. Wider use and application advancements are generally limited by the tools available for engineering and scientific studies. Currently, available modeling tools are limited by some combination of speed, platform capabilities, or missing physics that are not used or assumed to be negligible. The TEG module model herein is made up of two sub-models, the thermoelement model and the non-thermoelement model. Rather than a lumped thermoelement model, the model herein makes use of distributed physics that include the following: Thomson effect, temperature dependence, mass, Joule heat, thermal resistance, Seebeck effect, and electrical resistance. The non-thermoelement model takes into account temperature dependence and simulates Joule heat generation, thermal resistances, thermal and electrical interface resistances, and mass for and between the ceramic, copper, and solder. The comprehensive model herein was correlated to experimental data that simultaneously varied electrical current and hot and cold side temperatures with time. Very minimal adjustments to reported thermoelectric properties were required to almost perfectly match the experimental transient power output. The effects of the non-thermoelement model, distributed Thomson effect model and distributed temperature dependent property model were quantified. The model ran very quickly, taking 2.5 real-time seconds to run a 4000 s transient simulation. [ABSTRACT FROM AUTHOR]

• Thermoelectric devices reduce the non-uniformity of chip temperature. • Chip hotspot is cooled by thin thermoelectric in order of tens of micrometers. • Harvested electrical power from chip wasted heat is used for cooling its hotspot. • Chip hotspot is cooled by self-cooling framework with no extra power requirement. Thermoelectric devices are currently being used in the applications of cooling and generating electricity. This study mainly focuses on using these devices for both applications toward cooling down computer chips. An important aspect in designing the cooling system is to minimize the non-uniformity of the temperature distribution in the computer chip so as to reduce the thermal stresses in it. Another aspect in designing the cooling system is to minimize its power requirements. To investigate these two aspects, the temperatures of the cold chip areas can be allowed to increase, but not to exceed a certain temperature threshold, by installing Thermoelectric Generators (TEGs) on these areas that can harvest electrical power from the chip wasted heat. Thereafter, the chip hotspot areas can be cooled down by installing Thermoelectric Coolers (TECs) on these areas that can be powered by the harvested electrical power from the TEGs in order to maintain the temperatures of these hotspots to be less than or equal a certain temperature threshold. This cooling technique is called "sustainable self-cooling framework" for cooling chip hotspots. However, the question is: can the harvested electrical power by the TEGs be enough to power the TECs for cooling chip hotspots? In this study, a 3D model is developed to optimize the performance of both TEGs and TECs. Thereafter, this model is validated against experimental data of TEC and TEG. The results showed that the model predictions were in good agreements with the experimental data to within ±4%. Also, considerations are given in this study to optimize the performance of cascaded and non-cascaded TEGs and TECs for future use them to develop sustainable self-cooling frameworks for cooling chip hotspots at different operating conditions. Finally, a case study is conducted in this paper for a sustainable self-cooling framework in order to address the question above. The results showed that the self-cooling framework can successfully cool down the hotspot at an acceptable temperature with not only no need for additional electrical power requirements but also for reducing the non-uniformity in the chip temperature distribution. [ABSTRACT FROM AUTHOR]

A combined system model consisting of a high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC), a regenerator and a thermoelectric generator (TEG) is proposed, where the TEG is applied to harness the generated waste heat in the HT-PEMFC for extra electricity production. The TEG considers not only the Seebeck effect and Peltier effect but also the Thomson effect. The mathematical expressions of power output, energy efficiency, exergy destruction rate and exergy efficiency for the proposed system are derived. The energetic and exergetic performance characteristics for the whole system are revealed. The optimum operating ranges for some key performance parameters of the combined system are determined using the maximum power density as the objective function. The combined system maximum power density and its corresponding energy efficiency and exergy efficiency allow 19.1%, 12.4% and 12.6% higher than that of a stand-alone HT-PEMFC, while the exergy destruction rate density is only increased by 8.6%. The system performances are compared between the TEG with and without the Thomson effect. Moreover, the impacts of comprehensive parameters on the system performance characteristics are discussed. The obtained results are helpful in developing and designing such an actual combined system for efficient and clean power production. • TEGs are proposed as a waste heat recovery technology for HT-PEMFCs. • Thermal-electrochemical losses within the proposed system are described. • Performance parameters evaluating the proposed system are obtained. • The proposed system is effective for waste heat recovery. • Effects of some design parameter and operating conditions are revealed. [ABSTRACT FROM AUTHOR]

• Developed and validated a bifunctional thermoelectric module model. • Four-quadrant operation diagram was developed to present the bidirectional characteristic of module. • Case study of applying a bifunctional thermoelectric generator to a 2 l-diesel engine was carried out. • Faster warm-up effect of engine oil can be obtained by a bifunctional thermoelectric generator. The thermoelectric modules have the bidirectional characteristic, which can work either in power generation mode based on Seebeck effect or in heating-cooling mode based on Peltier effect. In this paper, a feasibility study is performed for a bifunctional thermoelectric generator applied in vehicle engines, which can use Seebeck effect for waste heat recovery and Peltier effect for engine warm-up. To predict the bidirectional behaviours of the thermoelectric module, a dual-mode thermoelectric module model is developed, and the simulation results for the two modes (power generation mode and heating-cooling mode) are both verified with experiments. The four-quadrant operation diagram of thermoelectric module, which clearly presents the cooling, heating and power generation curves, is produced based on the validated model. A case study of applying a bifunctional thermoelectric generator to a 2 l-diesel engine passenger car is then carried out based on a further extended bifunctional TEG model and an engine oil and coolant circuit model. The simulation results shows that the optimal engine oil temperature (100 °C) cannot be reached in the new European driving cycle for the baseline engine without thermoelectric generator, but it can be reached by both applying thermoelectric generator operating in waste heat recovery mode and engine warm-up mode. Compared with the thermoelectric generator only operating in waste heat recovery mode, a 3-min faster warm-up effect of engine oil can be obtained when the bifunctional thermoelectric generator works in engine warm-up mode with electrical current applied. It also finds out that the electric power generated in waste heat recovery mode at vehicle starting and low vehicle speed phrase is limited. However, a faster warm-up effect (engine oil temperature rising 7 °C in the first 100 s) can be obtained by operating thermoelectric generator in engine warm-up mode at vehicle staring. The electric energy used in engine warm-up mode can be regenerated in the later waste heat recovery mode. To compensate all the used electric energy in engine warm-up mode, longer time of thermoelectric generator operating in waste heat recovery mode is needed. [ABSTRACT FROM AUTHOR]

Highlights • All solid-state heat switch. • Under an optimal activation current, switching ratios can exceed 100. • Device geometry can be engineered to trade off switching ratio and speed (currently 10 s). • Operating temperature range 240–410 K. • Device based on Peltier effect. Abstract The switching ratio, the ratio between the thermal conductance in its off and on states, of a thermal switch is a critical design parameter of such a device. Here, we propose Peltier modules as a type of all-solid-state thermal switch that can operate over a wide temperature range and with an adjustable switching ratio. Calculations show that the switching ratio depends only on thermoelectric figure of merit and temperature bounds. A Peltier couple is constructed from Bi 2 Te 3 -based material and characterized by its thermal conductance and response time in the open condition and under an optimal activation current. The switching ratio diverges at small temperature differences with record-high measured values, an order of magnitude larger than achieved by other solid-state devices near room temperature. Materials with a high figure of merit could produce even larger switching ratios over higher temperature differences. [ABSTRACT FROM AUTHOR]

Abstract Thermoelectric cooler (TEC) is a solid-state component that utilizes Peltier effect to dissipate the heat of the electronic packaging system. It shows unique advantages over conventional cooling technology by quiet operation, long lifetime, and ease of integration. However, the internal heat accumulation caused by Joule heat exposes the TEC to the risk of thermal-mechanical failure during long-term operation in realistic thermal environment. In this paper, a heat-generating chip was employed to the cold-end of the module to serve as the finite thermal load while the heat sink at the hot-end was modeled by heat transfer coefficient. Based on the thermoelectric (TE) and thermal stress analyses, we developed a three-dimensional numerical model of a compact TEC, which took into account the temperature dependent TE material properties. It was found that the thermal load attached to Peltier junction can cause extreme high levels of thermal stress, which might cause dislocations and cracks of the material layers. The influences of electrical current, leg length, ceramic plate and bonding layers on the thermal stress levels were examined. These results presented an optimized design with predictive thermo-mechanical performance to realize minimum thermal stress levels, which provided a useful guide to achieve high reliability in a compact TEC. Highlights • Finite element simulations with temperature-dependent properties are carried out. • The effect of thermal load on the thermo-mechanical performance is investigated. • The effects of current, leg length, ceramic plate and bonding layers are examined. • An optimized design to realize minimum thermal stress levels is provided. [ABSTRACT FROM AUTHOR]

We report about the modelling of spark plasma sintering of a line of thermoelectric materials. A significant difference of sintering temperature ΔTs from 15 K to 110 K was found in the samples studied. The Peltier effect on the graphite-thermoelectric interfaces results in such temperature difference. The rise of sintering temperature leads to the ΔTs increase. ΔTs in the vertical direction is 2-3 times higher than in the radial one. Electric insulation modelled in the horizontal graphite-thermoelectric interfaces reduced ΔTs in all the types of numerically studied samples by 59-92%. [ABSTRACT FROM AUTHOR]

In thermoelectric coolers (TECs) applied external voltage potential is generated to a temperature difference based on the Peltier effect. Main and basic structure of TECs is in the form of single stage device. Due to the low efficiency, especially low coefficient of performance (COP) of thermoelectric coolers, optimal design of geometrical parameters of such devices is vital. For this purpose, usually optimization algorithms are used. Therefore, in this research, chemical reaction optimization algorithm (CRO) is used in order to optimal design of structure of single stage thermoelectric cooler. CRO algorithm is a novel optimization scheme inspired form chemical reaction mechanisms. The results of the research are compared with previous data obtained using other optimization algorithm. Comparison of the results shows that application of CRO algorithm results in enhancement of COP of the system. Therefore, CRO algorithm proposed in this research could be used for better design of single stage TECs to achieve higher efficiency and coefficient of performance of the system. [ABSTRACT FROM AUTHOR]

This paper introduces a low-cost electronic circuit to control and monitor an Atmospheric Water Generator (AWG) system based on thermoelectric cooling. The study evaluates water collection by a specific AWG device in a Hydroponic Green Fodder (HGF) production environment to explore the feasibility of using this technology as a supplementary method for crop irrigation. The proposed circuit measures key parameters of an AWG prototype, including temperature in the cold and hot zones of the Peltier cell, relative humidity, and ambient temperature. Based on this data, a control algorithm enhances water collection and reduces energy consumption for moisture condensation by regulating energy delivered to the Peltier cell and heat sink subsystems. The control and monitor circuit is programmable and adaptable for different AWG prototypes. Tests showed variable water collection rates from 3.01 mL/h to 4.93 mL/h. Under conditions of 84.1% relative humidity and 19.5 °C ambient temperature, the system produced 4.93 mL/h with a power consumption of 34.6 W. Conversely, at 68.3% relative humidity and 19.6 °C ambient temperature, the collection rate decreased to 3.01 mL/h, with a power consumption of 34.7 W. This water volume represents a significant proportion, ranging from 16% to 55%, of the irrigation needed to produce one kilogram of hydroponically grown fodder, assuming HGF cultivation requires between 1.5 to 3.0 liters of water per kilogram of forage produced. • A low-cost electronic circuit for controlling and monitoring an AWG is introduced. • The proposed prototype enhances water sustainability in hydroponic fodder cultivation. • The resulting harvesting capacity is 16% to 55% of the water required for 1 kg of hydroponic green fodder. • The prototype is adaptable to various Peltier cell-based AWG systems. [ABSTRACT FROM AUTHOR]

• We presented a method to rapidly and in-situ extract the Seebeck coefficient of thermopile IR sensors over a wide temperature range (300–600 K). • The effectiveness of this method is evaluated by a thermopile IR sensor. The maximum relative error between the results obtained from this method and specialized instrument (NETZSCH SBA 458 Nemesis) does not exceed 9%. The Seebeck coefficient of thermopile infrared (IR) sensors is a crucial parameter. The ability to rapidly and in-situ extract the Seebeck coefficient across a wide temperature range is advantageous for assessing the impact of temperature on sensor's performance. In this study, specific sets of current excitations are used, the exothermic and endothermic temperature changes caused by Peltier effect are offset, and the Seebeck coefficient of sensor over a wide temperature range (300–600 K) is extracted from Joule heat by measuring the resistance of sensor. The effectiveness of this method is evaluated by a thermopile IR sensor. The maximum relative error between the results obtained from this method and specialized instrument does not exceed 9 %. [ABSTRACT FROM AUTHOR]

• Ratiometric method was proposed to measure the Peltier coefficient. Compared with other approaches, only one additional AC measurement was required. • The accuracy of the temperature measurement is not critical to the final calculated Peltier coefficient. • The thermophysical and geometrical properties of the sample are no longer part of the proposed measurement equation under optimal thermal and geometrical conditions. We present a novel ratiometric approach to independently measure the Peltier coefficient, without using Kelvin's relation, using the ratio of two temperature signals induced by the Peltier and Joule effects, in addition to readily obtained electrical quantities: electrical resistance and current. One major advantage is that the accuracy of the temperature measurement is not critical to the calculated Peltier coefficient, primarily because of the ratiometric measurement. Crucially, the thermophysical and geometrical properties of the sample are no longer part of the proposed measurement equation under optimal thermal and geometrical conditions. As a demonstration, the Peltier coefficient of a polycrystalline n-type Bi 2 Te 3 sintered sample is measured. The use of an AC current with an amplitude equal to the DC current intensity precisely separates the Joule heating from Peltier heating. The obtained Peltier coefficient agrees well with that calculated from Kelvin's relation within 3%. Compared with other approaches, the proposed approach requires only one additional AC measurement, which is an accurate and a comparably effortless undertaking. This study aims to significantly advance the development of highly accurate thermoelectric metrology. [ABSTRACT FROM AUTHOR]

• A new hybrid vaccine freezer system equipped with thermoelectric is presented. • The hybrid system consists of the freezer and cooler compartment. • The proposed hybrid refrigeration system is experimentally evaluated. • The hybrid system achieved temperatures of −40 °C in the freezer compartment. • The COP of the hybrid vaccine freezer system of 1.05 is achieved. Recently, the demand for refrigeration globally has been increasing in the fields of vaccine storage, medical services, food preservation, and cooling for electronic components. This has resulted in the generation of more electrical power and thus releasing more CO 2 around the world which has led to many climatic changes, such as global warming. The vapour compression refrigeration cycle (VCC) is the most common as it has a high coefficient of performance (COP), although it only operates down to temperatures of around −20 °C. The thermoelectric cooler (TEC) modules offer a featured method for cooling technology, which is not mainly considered by energy efficiency but offers distinctive merits in specific applications. Although the TEC system is not conventionally known for incomparable energy efficiency, it offers a range of exceptional attributes that make it a desirable option for certain scenarios. Therefore, this work aims to assess the performance of the innovative hybrid vaccine freezer system depending on how well the VCC system and the TEC work together. Also, the temperature distribution within the freezer compartment has been investigated under various operating conditions. The newly developed hybrid vaccine refrigerator system consists of four pieces of TEC-12706 modules that function well at low temperatures. The results indicate that the best coefficient of performance (COP) of 1.05 is achieved with a total power consumption of 172.8 W when the TEC is operating at 5.5 V and the fan is running at 12 V. The cooling capacities of the freezer and cooler compartments are 9.2 W and 165 W, respectively. Furthermore, the best distribution and lowest temperatures were obtained, with temperatures in the lateral area of −40 °C compared with −37 °C in the central area. [ABSTRACT FROM AUTHOR]

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 Φc′/Φc $\varPhi_{{\text c}}'/\varPhi_{{\text c}}$ 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.

Introduction: No one can cast a shadow of doubt on the fact that temperature is a key element in dentistry. Temperature control enable dentists in a variety of clinical fields to perform more convenient. Frozen slab is a known method for manipulating temperature before mixing cements. But lack of precise temperature and infection control is bolded. Clinical innovation: The present apparatus determines a method for temperature control in routine dentistry tasks; namely restorative dentistry, prosthesis and even injections. This device is capable of whether heating or cooling materials using low voltage electricity. Peltier or thermoelectric effect is the mechanism behind this device. As operator sets a temperature, device would provide it via metal pads arranged on it in seconds. Discussion: Other common methods used in dentistry have some issues regarding power usage, infection control, size and etc. However, this device is small, cost effective, simple to use and has fast action. Infection control can be actively be maintained with it. This device is a promising alternative for this purpose. Present manuscript summarizes device properties and its potential utilities in dentistry.

In this work, it was examined mechanisms that control internal cooling device (nano-homojunction diode)depending on thermoelectric Peltier effect, resulting in structures that are optimized thermal management. Peltier coefficient for short-length diode is theoretically investigated. It is found that the cooling power is governed by the carrier concentration, current density and the ratio of n-type region width to p-type region width. It has been determined the optimum value of the cooling power at the junction of ZnO in the optimum density at doping symmetrically on a certain value.The cooling power, temperature difference (temperature between the contact and the junction) and dimensionless figure of merit are found in this material for different thicknesses, then comparing between them. It has been simulated the homojunction diode using a MATLAB software with numerically calculated the Peltier coefficient for each layer in these diodes.It has been found that nano-homojunction introduce a significant improvement in the internal cooling performance.

We propose thermopile structures for the anisotropic magneto-Peltier effect (AMPE) to enhance its heating/cooling power. The cross-shaped thermopile, one of the representative AMPE-based thermopile structures, consists of four L-shaped ferromagnetic metals arranged in a cross-shaped configuration, which allows the concentration of the AMPE-induced temperature modulation at the center of the cross structure. The AMPE-based thermopile does not require the use of any complicated junctions comprising different materials, enabling the design of compact and versatile temperature controllers for nanoscale devices. [ABSTRACT FROM AUTHOR]

Abstract The necessity for renewable energy sources is on the increase all around the world because of the negative consequences of burning fossil fuel to produce energy. Recently, Saudi Arabia has decided to become the world's largest producer of solar energy by the vision of Kingdom of Saudi Arabia in 2030. This study mainly focuses on developing a solar photovoltaic cell based thermoelectric refrigerator (compressor less refrigerator) which can function as the refrigerator system in houses. The design was going to be equipped with the controller and sensors to reach the required minimum temperature which is around 6°C that is almost similar to the commercial refrigerators. [ABSTRACT FROM AUTHOR]

Abstract Thermoelectric materials can be utilized to generate electricity from a temperature gradient, thereby recycling the nowadays abundant waste heat, as well as for cooling applications by creating a temperature gradient from electricity. The former is based on the Seebeck effect, and the latter on the Peltier effect. Noticing the continuously declining fossil fuel resources and mankind's increasing need for energy, the importance for clean thermoelectric energy generation continues to climb. Traditional thermoelectric materials were based on the binary tellurides Bi 2 Te 3 and PbTe, which have been utilized for decades. The focus on tellurium as the heaviest non-radioactive chalcogen stems from the observation that heavier elements are advantageous for a reduced thermal conductivity, which is essential for the thermoelectric energy conversion. Moreover, tellurides are less ionic than sulfides or selenides, which leads to an enhanced carrier mobility that is advantageous for the desired high electrical conductivity. This review presents these traditional routes to low thermal conductivity, as well as alternatives based on the lighter analogues of tellurium, namely sulfur and selenium. Graphical abstract In special cases like in these binary copper chalcogenides, sulfides and selenides can outperform the more traditional thermoelectric tellurides. fx1 Highlights • Recent progress in thermoelectric materials is presented. • Outstanding thermoelectric performance depends strongly on the thermal conductivity. • Heavy elements are not required to achieve the required low thermal conductivity. • Stereochemically active lone pairs may result in low thermal conductivity. • Ion mobility also leads to low thermal conductivity, but may be detrimental to device stability. [ABSTRACT FROM AUTHOR]

Many machines around us continue to age over time. This aging of machines affects experimental results, and the accuracy of experimental results may be reduced or not fully achieved. To prevent this problem, we decided to predict the lifetime of a machine to help us analyze experimental results. Thus, we carried out a polymerase chain reaction (PCR) experiment, which is an experiment to amplify the gene information stored in DNA to the amount required for gene analysis experiments, to determine the temperature change of a thermoelectric module (Peltier). The Peltier was used to determine the reliability of the results by learning how it affects the lifetime of the device. As a method of measuring aging, we used deep learning technology. In this study, we expect to learn how machines age. By learning the machine's own aging data of important parts, the reliability of test results can be greatly improved. [ABSTRACT FROM AUTHOR]