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Thermoelectric coolers (TECs) have a high potential to dominate traditional air conditioning and become the future of HVAC (heating, ventilation, and air conditioning). TECs offer several advantages over traditional air conditioning systems, most notably in terms of zero greenhouse gas emissions, a leak-free environment, and cost efficiency. Despite all these concerns, efficient cooling performance and energy consumption are two major barriers for the rapid adoption of TECs. This article provides a comprehensive literature review of recent developments and challenges in implementing TECs to increase energy consumption and cooling performance. In particular, through the development of components and physical parameters such as thermoelectric material, the effect of fluid flow and the geometry of the heat sink of the thermoelectric cooling system. In addition, the articles will highlight the significant opportunities for thermoelectric applications to achieve economic and environmental benefits. Thermoelectric cooling with the latest conversion efficiency is technically practical and economical for small and micro applications in the current scenario. If thermoelectric cooling is applied on a large and medium scale in commercial practice, it would further develop green technology that improves environmental conditions as well as the energy supply. [ABSTRACT FROM AUTHOR]

In this study, a technique is suggested to enhance the temperature difference for cooling and energy efficiency of thermoelectric cooler (TEC) used in cooled detectors when subjected to high current conditions. Embedding a structure for storing heat during phase change is the basis of this method at the heat sink. A simulation model was created for a common two‐stage series TEC with an asymmetrical design, which is coupled with a structure for storing heat through phase change. The research examined how phase transition heat storage impacts the coefficient of performance (COP) and refrigeration temperature difference across various phase‐change substances, heat transfer coefficients at the hot end, currents, and the height of the phase‐change material (PCM). The findings suggest that the suggested approach of combining PCM with TEC can efficiently lower the cold end temperature of TEC by a maximum of 20 K, enhance the temperature gap by a maximum of 16 K, and preserve the consistency of the optimized quantity across various hot end heat transfer coefficients. During the phase‐change process of PCMs, the COP of TECs integrated with PCM is found to increase by an average of 2%–3% compared to TECs without PCM integration. Under the maximum current operating condition, the cryogenic temperature can be optimized to a minimum of 238 K. In summary, the proposed method of integrating phase‐change heat storage with TECs provides a promising solution for improving their cooling performance and energy efficiency in cooled detectors under high current conditions. Additional investigation can be conducted to explore the practical application of this approach and enhance the design parameters for various uses. [ABSTRACT FROM AUTHOR]

With the development of 5G technology and increasing chip integration, traditional active cooling methods struggle to meet the growing thermal demands of chips. Thermoelectric coolers (TECs) have garnered great attention due to their rapid response, significant cooling differentials, strong compatibility, high stability and controllable device dimensions. In this review, starting from the fundamental principles of thermoelectric cooling and device design, high-performance thermoelectric cooling materials are summarized, and the progress of advanced on-chip TECs is comprehensively reviewed. Finally, the paper outlines the challenges and opportunities in TEC design, performance and applications, laying great emphasis on the critical role of thermoelectric cooling in addressing the evolving thermal management requirements in the era of emerging chip technologies.

In this article, the geometric optimum design of a thermoelectric cooler (TEC) is simulated by Finite Element Analysis. We studied the influence of the geometric structure on TEC parameters including the thermoelectric leg size, the separation distance of P/N legs, the distance from leg edge to copper edge and the copper thickness on the maximum temperature difference, the coefficient of performance (COP) and thermal stress. After optimizing designing, the TEC presented superior cooling performance and high operational reliability. The result demonstrates that the leg height plays the most important role in maximum temperature difference (ΔT max) and thermal stress. At different thermoelectric leg width, by optimizing leg height, the ΔT max can enhance about 9.079 K and the maximum thermal stress can reduce about 72.4 MPa. When the leg height is greater than 0.8 mm, its influence on temperature difference and thermal stress decreases. The separation distance of P/N legs play the most important role in the COP. By optimizing separation distance of P/N legs, the maximum temperature difference and COP all obtain the maximum value of 61.407 K, 0.663. [ABSTRACT FROM AUTHOR]

• A new thermal management system applied to thermoelectric cooler is proposed. • The system can improve cooling capacity and reduce power consumption. • RSC can be used to passive cooling for TEC at lower power. • There is a reasonable value between the air cooling intensity and the RSC area. • The system is more suitable for use at higher ambient temperatures. In this paper, a new thermal management method applied to thermoelectric cooler (TEC) is proposed by combining radiative sky cooler (RSC) with air cooling, which can improve cooling capacity and reduce power consumption over a standalone air cooling. The system is based on radiative sky passive cooling and supplemented by air cooling for heat dissipation. A steady-state model is developed to analyze the system performance in terms of many parameters, including the input current, the area of RSC, the cold/hot side temperature, ambient temperature and convective coefficient of air. The results show that the system can significantly increase the cooling capacity and reduce the attenuation of heat dissipation capacity at high ambient temperature compared with a standalone air cooling system. It can achieve complete passive cooling by RSC without any energy consumption when the TEC input power is low. Although increasing the RSC surface area and air cooling intensity can further enhance the cooling capacity, there is a reasonable value between the two, depending on the TEC cold and hot side temperatures. Moreover, it has an optimal input power for different target cooling capacity of TEC, which can minimize the required RSC area. [ABSTRACT FROM AUTHOR]

Many worldwide scientists have concentrated on using waste heat recovery technology in automotive applications because of increasingly strict fuel consumption. The thermoelectric generator (TEG) has garnered significant interest in the automobile sector as a viable waste heat recovery solution over the past several decades. A short survey of thermoelectric materials and heat exchangers for TEG systems is initially presented in this paper. To overcome the heat exchanger's current shortcomings, some previous studies designed a variety of the heat exchanger geometry of the TEG system. They suggested concentric cylindrical TEG system utilizes an annular thermoelectric module instead of the traditional square-shaped one. It uses the heat pipe's benefits to improve radial heat transmission. A comparison of the water-inside and gas-inside arrangements indicated that the water-inside concentric cylindrical TEG system provided a greater power output in our simulations to test the performance of the proposed system. [ABSTRACT FROM AUTHOR]

Livelihood improvement in the rural areas is the key parameters to achieve the Sustainable Development Goals. This paper attempts the livelihood improvement in rural areas through green energy technologies. The manuscript comprises a detailed review of electric vehicles with unique features of micro cold storage and vehicle-to-grid technologies. A critical analysis of the intrinsic properties of thermoelectric cooler-based micro cold storage for better material selection, performance, and optimization techniques for effective electric vehicle integration is reported. The manuscript encapsulates the thermoelectric intrinsic parameters like Seebeck coefficient (S), electrical conductivity (σ), thermal conductivity (K), and figure of merit (ZT) parameters with coefficient of performance and cooling capacity (QC) for different types of thermoelectric modules. The review narrows down into suitable parameters for effective combined system design, such as optimal operating voltage (Vopt) and current (Iopt). The manuscript further reviewed and presented the V2G-enabled nanogrid, control, and grid integration techniques for better-integrated operation. This paper reported an experimental investigation on the designed and developed green agro storage integrated V2G enabled nano grid for a rural village in India. The case analysis was carried out by short distance agro produce transportation, decentralized DC–DC control, and phase-locked loop grid synchronization technique. The electrical, thermal and dynamic system characteristics study was carried out and reported. Also, the manuscript highlights the potential strengths, challenges, opportunities and research gaps for the stakeholders to build a sustainable future. The proposed combined system design will pave a sustainable pathway for achieving sustainable development goals. [ABSTRACT FROM AUTHOR]

The present study investigates the performance of solar photovoltaic integrated thermoelectric cooler using MATLAB Simulink. The enhancement of efficiency has been achieved using an effective heat removal mechanism from the hot side heat sink. Since the hot side temperature is a crucial parameter. The intrinsic material properties like Seebeck coefficient, α, thermal conductance, K, and electrical resistance, R, of the thermoelectric module are carefully estimated using analytical method and reported. The MATLAB Simulink Peltier module is developed based on the estimated intrinsic properties. The effect of system voltage (V) and current (A) on the thermal parameters like cooling capacity, QC, and coefficient of performance has been investigated. The simulation study is validated by conducting a series of experimental analysis. The experimental model is equipped with a 100 Wp polycrystalline solar photovoltaic module to integrate and power the 12V/5A of the 60 W thermoelectric cooler. Moreover, the results reveal that there is a significant effect of ambient and hot side temperature on the thermoelectric cooler performance. The fin-type conductive mode of heat transfer mechanism is adopted along with the convective forced air-cooling system to achieve effective heat removal from the hot side. The infrared thermographic investigation is carried out for ascertaining effective heat removal. [ABSTRACT FROM AUTHOR]

Copyright of Problems of Friction & Wear is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Thermoelectric coolers (TECs) have been used for cooling electrical elements of high dissipating energy to provide a fixed temperature, with the advantages of being reliable, noiseless, tightly packed, with no moving parts as well as no harmful gases. As high performance of TECs is required, developed emerging thermoelectric (TE) materials can be employed to enhance their performance. Hence, this study provides an experimental investigation to study the effect of different operational parameters on the performance of the TE cooling system including the system coefficient of performance (COP) and the rate of heat transfer. The parameters investigated are the applied input power, inlet working fluid velocity, and the arrangement of utilized TECs modules. The used test rig consists of two attached horizontal ducts, and the interface surface between them contains three TE modules, each of power 48 W. The applied input power and the working fluid flow rate range from 16 to 48W and from 0.0025 to 0.01 L/min, respectively. Results show that the maximum COP occurs at lower values of applied input power. A noticeable enhancement in the COP is found when all TEC modules are in use. A new correlation of the COP of the TEC system is obtained. [ABSTRACT FROM AUTHOR]

The systems maintaining thermal regimes are a necessary component of thermally-loaded radio-electronic equipment, without which its operation is impossible. The uneven distribution of heat emitted by components such as semiconductor lasers, receivers of intense infrared radiation predetermines the preference of thermoelectric coolers for them. The joint application of a cooler and a heat-loaded element significantly tightens the requirements for the reliability indicators and the dynamic characteristics of the cooler. The cause is the influence exerted by the temperature gradients in the soldered joints between different materials of thermoelements and the electrode of the substrate. The main parameters of thermoelectric coolers are the number of thermoelements and the value of the working current. When targeting the design of thermoelectric systems for ensuring thermal regimes based on reliability indicators, the optimization of the problem for the following set has been proposed: the number of thermoelements, the working current, and the relative intensity of failures. At the fixed branches’ geometry, decreasing the number of thermoelements leads to a decrease in the heat load, which can be compensated for by increasing the working current of the thermoelectric cooler. A ratio has been derived for the relative working current corresponding to the minimum size of the set. Using the set makes it possible to choose the required working current, for which there is an extremum, which optimizes the process of control over the cooler. The win in the refrigeration factor, compared to the mode of maximum cooling capacity, is 15 %. This demonstrates the advantage of a comprehensive indicator, which allows the development of systems enabling thermal modes for practical application, in particular, on-board systems for which energy consumption is critical. The originality of the results obtained is related to a comprehensive criterion for the basic performance indicators, which has a minimum. [ABSTRACT FROM AUTHOR]

In the present work, a novel technique has been developed to enhance the thermal performance of a thermoelectric cooler (TEC) by integrating with phase-change material (PCM). The PCM has been integrated at the hot side of the thermoelectric cooler to maintain constant and relatively low temperature. The study has been carried out with variable geometric parameters of the heat sink, variable cooling load conditions, variable input currents to the TEC and with different PCMs. The results show that there is a significant reduction in both hot and cold side temperatures of the thermoelectric cooler with the use of PCM. For a typical operating condition in the TEC with two thermocouples (2 mm × 2 mm × 3 mm each) under cooling load of 0.03 W and convective heat transfer coefficient of 5 Wm−2 K−1, the hot and cold side temperatures of the TEC have been reduced from 52 to 30 °C and 25 to 12 °C, respectively, with the use of PCM. The coefficient of performance of the TEC integrated with PCM has been estimated and it has been found to be 30% higher than the TEC without PCM for a cooling load of 0.05 W. Moreover, the thermal performance of TEC has been studied with variable fill volume of PCM in the heat sink. It has been found that the increase in fill volume of PCM increases the thermal performance of the TEC. This study has been carried out with different PCMs and similar performance enhancements have been observed. [ABSTRACT FROM AUTHOR]

In this study, the performance of a thermoelectric cooler (TEC) as a simple and easy-to-assemble freezing instrument has been evaluated. Experiments were carried out using samples with different viscosity ranging from 44.07 to 16 965.80 MPa. The analysis of sodium component of the samples by direct laser irradiation of frozen samples showed emission enhancement and higher signal-to-noise ratio compared to that of liquids. This work also focused on using chemometrics methods such as principal component analysis (PCA) to compare the principal component score separation and clustering pattern between frozen and liquid samples. The PCA was constructed by dividing the samples into two different categories: (i) type (paste, cream, gel, and oil) and (ii) viscosity (more than and less than 10 000 MPa). The frozen samples showed a more established separation and clustering compared to that acquired from the liquid samples. However, poorer clustering pattern of some frozen samples could be due to the heat transfer during laser–sample interaction inducing surface melting and splashing. The average laser-induced breakdown spectroscopy (LIBS) spectra were taken at as many different surface areas as possible to ensure the sample surface always maintain similar freezing temperature. This work showed that the TEC pre-treatment method had improved the LIBS measurement of the liquid samples. [ABSTRACT FROM AUTHOR]

Thermoelectric devices are currently being used in cooling and generating electricity applications. This study mainly focuses on using thermoelectric devices for both applications towards cooling down computer chips; especially, that the very large scale integration technology has reached high advancement where more than 100 million transistors can be fabricated in 1 mm2. Reducing the non-uniformity of the chip temperature is important so as to decrease the induced thermal stress in this chip and consequently reduce its failure rate. To simultaneously reduce both the non-uniformity of the temperature distribution in the chip and the power requirements for the cooling system, thermoelectric generators can be installed on the cooler chip areas to harvest electrical power from the chip wasted heat. Thereafter, the chip hotspot areas are cooled down using thermoelectric coolers that are powered by the harvested electrical power from the thermoelectric generators in order to maintain the temperatures of these hotspots to be less than or equal a certain temperature threshold. Because no additional electrical power requirement is needed to cool down the hotspots, this cooling technique is called in this paper as "sustainable self-cooling framework for cooling chip hotspots". However, the question is that can the harvested electrical power by the thermoelectric generators be enough to power the thermoelectric coolers for different computer chips at a given operating condition? As such, one of the objectives of this paper is to develop a three-dimensional numerical and optimization model to predict the thermal and electrical performance of cascaded and non-cascaded thermoelectric generators and cascaded and non-cascaded thermoelectric coolers for cooling chip applications. Then, validate the developed model against experimental data. The results showed that the predictions of the developed model were in good agreement with the experimental to within ± 4%. After gaining confidence in the developed model, it was used for a given chip operating condition to conduct a case study for a sustainable self-cooling framework in order to answer the raised 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]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper develops three dimensional numerical models of a two-stage series-connected TEC model and a two-stage parallel-connected TEC model. NSGA-II is used to optimize their electric current, height of lower stage and ratio of channel width and thickness of fin in the case of constant thermoelectric material volume. Two objectives, exergy efficiency and irreversibility are considered simultaneously. The optimal values one Pareto front are obtained by three decision making methods, Shannon's entropy, TOPSIS and LINMAP, while deviation index is a criterion for evaluating three decision making methods. Sensitive analysis has been carried out to investigate the influence of three variables to be optimized. And TEC with and without plate-fin heat exchanger have been compared. The results show that solution selected by LINMAP is the most compromising solution. The parallel connected TEC saves about 50% of the power consumption compared to the series connected TEC under the same temperature difference. Optimal variables are discussed to obtain the most energy efficient solution with optimal configuration and plate-fin heat exchanger. • NSGA-II are used to optimize structure, configuration and load resistance of a 2-stage TECs. • Optimal values one Pareto front are obtained by three decision making methods. • LINMAP is the most compromising for selecting the optimized solution. [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]

The problem of the optimal integration of thermoelectrically cooled optoelectronic components into an electronic housing is studied with the emphasis on practical implementation. The lines of 2-stage and 3-stage thermoelectric coolers (TECs) compatible with TO8 housing have been developed, and their parameters are measured in a wide range of heat sink temperatures. The TECs are optimized to receive a temperature difference of 100-110 K under a heat load from 70 mW to 100 mW with minimal power consumption. To fit into a standard housing interior, all the TECs have the same overall dimensions, regardless of the number of stages. Details of the TEC configurations and their performance characteristics are presented and discussed. [ABSTRACT FROM AUTHOR]

A thermodynamic model of a thermoelectric cooler driven by thermoelectric generator (TEG-TEC) device is established considering Thomson effect. The performance is analyzed and optimized using numerical calculation based on non-equilibrium thermodynamic theory. The influence characteristics of Thomson effect on the optimal performance and variable selection are investigated by comparing the condition with and without Thomson effect. The results show that Thomson effect degrades the performance of TEG-TEC device, it decreases the cooling capacity by 27 %, decreases the coefficient of performance (COP) by 19 %, decreases the maximum cooling temperature difference by 11% when the ratio of thermoelectric elements number is 0.6, the cold junction temperature of thermoelectric cooler (TEC) is 285 K and the hot junction temperature of thermoelectric generator (TEG) is 450 K. Thomson effect degrades the optimal performance of TEG-TEC device, it decreases the maximum cooling capacity by 28% and decreases the maximum COP by 28% under the same junction temperatures. Thomson effect narrows the optimal variable range and optimal working range. In the design of the devices, limited-number thermoelectric elements should be more allocated appropriately to TEG when consider Thomson effect. The results may provide some guidelines for the design of TEG-TEC devices. [ABSTRACT FROM AUTHOR]

This work examines the validity of formulating the effective thermoelectric material properties as a way to predict thermoelectric module performance. The three maximum parameters (temperature difference, current, and cooling power) of a thermoelectric cooler were formulated on the basis of the hot junction temperature. Then, the effective material properties (Seebeck coefficient, electrical resistance, and thermal conductivity) were defined in terms of the three maximum parameters that were taken from either a commercial thermoelectric cooler module or the measurements. It is demonstrated that the simple standard equation with the effective material properties predicts well the performance curves of the four selected commercial products. Normalized parameters over the maximum parameters were also formulated to present the characteristics of the thermoelectric coolers along with the normalized charts. The normalized charts would be universal for a given thermoelectric material. [ABSTRACT FROM AUTHOR]

• Steady- and transient-state simulations were studied to capture the supercooling phenomenon. • A model of a two-stage thermoelectric cooler system was developed. • In-series and parallel thermal connections of modules were investigated. • The influence of the thermal capacity of internal reservoir on supercooling was determined. • Various current-shaping methods and the number of module legs were optimized to achieve the best cooling performance. The paper discusses issues related to the modelling of a cooling system equipped with thermoelectric modules to achieve the lowest possible temperature of the cooled space. Considerations were made for both the steady state and the momentary capability to reach the lowest possible temperatures. The analysis concerns modules arranged as the in-series thermal connection in a sandwich configuration and the parallel connection in a single layer. It was assumed that in each case the modules worked with identical heat exchangers. Optimal sizes were found for the modules in each of the analysed configurations, both considering and omitting in the model the thermal resistance between the system elements. Taking resistance into account results in an almost 50% increase in the module dimensions to 90/250, compared to 60/170, and also in the minimum temperature rise by even up to 20 K. Inducing higher currents in the circuits of the modules can cause momentary supercooling of the cold heat reservoir significantly below the temperature achievable in the steady state. The highest values of momentary drops in temperature can be achieved through current pulse in the circuits, and also for higher thermal capacities of the upper and additional internal reservoir in a sandwich system. To determine optimal supply currents for the modules, optimization was carried out. In the considered configurations this made it possible to achieve momentary supercooling temperatures by about 18 K lower compared to the steady state. The most essential design variables are the number of thermoelectric legs, the shape of the thermal capacity of the current pulse shape and the internal reservoir. [ABSTRACT FROM AUTHOR]

• Digital image correlation based on laser speckle proves suitable for thermomechanical diagnostics of TEC pillar. • Direct observation of full-court pillar-level deformation is achieved • Thermally induced global displacement and strain fields of TEC pillar are obtained. • Maximum shear stress exceeds the fracture limit. Fatigue-induced fracture of B i 2 T e 3 pillars in a thermoelectric cooler (TEC) due to thermal stress is a prevailing occurrence in the device during dynamic operation, which has been a major reliability concern from manufacturing perspectives. However, it remains a crucial challenge to explore global pillar-level deformation of TEC with simple experiment methodology. Herein, digital-image-correlation-based thermomechanical diagnostics is introduced to experimentally characterize the in-plane thermal deformation of B i 2 T e 3 pillars. Highly contrasted surface pattern generated by He-Ne laser was utilized, exempted from extra speckle fabrication while simultaneously guaranteeing high experimental accuracy. By imposing different thermal loadings to specimen, corresponding full-court pillar-level displacements are respectively observed. Furthermore, shear strain and stress distribution and their dependence on Δ T are studied with stress concentration region identified. The maximum in-plane shear stress at around Δ T = 60 K is indicated to exceed material fracture limit, resulting in high probability of fracture. The good agreement of experimental results and empirical simulation indicates the viability of the proposed technique. Due to its capability of direct observation of thermomechanical behavior of B i 2 T e 3 pillars, the approach employed in this study is of significant practical appeal and notable potential for thermal reliability prediction of thermoelectric device. [ABSTRACT FROM AUTHOR]

Abstract: Whole-cell bacterial bioreporters await miniaturized photon counting modules with high sensitivity and robust compatible hardware to fulfill their promise of versatile, on-site biosensor functionality. In this study, we explore the photon counting readout properties of the silicon photomultiplier (SPM) with a thermoelectric cooler and the possibilities of detecting low-level bioluminescent signals. Detection performance was evaluated through a simulated LED light source and the bioluminescence produced by the genetically engineered Pseudomonas fluorescens bacterial bioreporter 5RL. Compared with the conventional photomultiplier tube (PMT), the results revealed that the cooled SPM exhibits a wider linear response to inducible substrate concentrations (salicylate) ranging from 250 to 5000ppb. Although cooling of the SPM lowered dark count rates and improved the minimum detectable signal, and the application of a digital filter enhanced the signal-to-noise ratio, the detection of very low light signals is still limited and remains a challenge in the design of compact photon counting systems. [Copyright &y& Elsevier]

Warming poses a significant threat to the utility of deep-sea samples. This study developed an active temperature-preserving deep-sea water sampler to use at full ocean depths. The most important component of the sampler is the pressure-adaptive thermoelectric cooler module; laboratory experiments validated its high-pressure resistance and waterproof capability under 110 MPa water conditions. The overall structure of the sampler was then designed, and computational fluid dynamics modeled the samples' temperature distribution. The simulation results were consistent with experimental data. Finally, a sampler prototype was constructed and then tested in the Mariana Trench zone at a large depth of up to 6000 m. Preliminary results indicated that it functioned well during sea trials. The developed sampler should help preserve the in situ temperature of deep-sea samples throughout the recovery process and thus improve the sample quality. • The special-designed pressure-adaptive TEC module could be used at full ocean depths. • The active temperature-preserving sampler can maintain the water sample at in situ temperature without temperature rise. • A custom-made pressure-adaptive temperature probe is used for generating the temperature feedback signal. [ABSTRACT FROM AUTHOR]

The present study proposes a unified numerical approach to the problem of optimum design of the thermoelectric devices for cooling electronic components. The standard mathematical model of a single-stage thermoelectric cooler (TEC) with constant material properties is employed. The model takes into account the thermal resistances from the hot and cold sides of the TEC. Values of the main physical parameters governing the TEC performance (Seebeck coefficient, electrical resistance, and thermal conductance) are derived from the manufacturer catalog data on the maximum achievable temperature difference, and the corresponding electric current and voltage. The optimization approach is illustrated with several examples for different design objective functions, variables, and constraints. The objective for the optimization search is the maximization of the total cooling rate or the performance coefficient of the cooling device. The independent variables for the optimization search are as follows: The number of the thermoelectric modules, the electric current, and the cold side temperature of the TEC. Additional independent variables in other cases include the number of thermoelectric couples and the area-to-height ratio of the thermoelectric pellet. In the present study, the optimization problems are solved numerically using the so-called multistart adaptive random search method. [ABSTRACT FROM AUTHOR]

Abstract: This work has two parts. The first part details the thermal analysis of a thin-film thermoelectric cooler under the influence of the Thomson heating, the Joule heating, and the Fourier''s heat conduction. A constant Thomson coefficient, instead of traditionally a constant Seebeck coefficient, is assumed. The influence of the Thomson effect on the cooling power, the achievable temperature difference and the optimum operating current density is then explored. It is found that the Joule''s heat and the conduction heat flowing to the cold junction can be significantly reduced if thermoelectric materials with properly designed Thomson coefficients are employed. A modified thermal conductance and a modified electric resistance are resulted. The second part of this paper details the analysis of the thermal stresses existing in the layered structure and induced by the temperature difference via a non-coupled thermal elastic theory. The results provide a preliminary knowledge to judge whether the thin-film structure is destroyed by the thermal stresses or not, especially by the shear stresses between adjacent layers. [Copyright &y& Elsevier]

A general staging model is developed to optimize multistage exo-reversible refrigeration systems affected solely by internal irreversibilities. Under some reasonable assumption, the same high to low temperature ratio is found at each stage so as to maximize the coefficient of performance of a multistage combined refrigeration system, where each stage is subjected to an independent refrigeration subcycle. This model is then applied to the optimum staging of two configurations of multistage thermoelectric coolers, which are the ones with different and identical electrical current flowing through each stage, respectively. For both the two cases, the optimum stage temperatures are numerically proved to follow from the ideal staging well. Detailed optimum staging parameters of both types of thermoelectric coolers are calculated with commercially available thermoelectric (TE) materials. The temperature dependence of TE properties has been taken into account. [Copyright &y& Elsevier]

The worldwide energy crisis and environmental deterioration are probably humanity's greatest challenges. Thermoelectricity, which allows for the mutual conversion between thermal and electrical energy, has become a promising technology to alleviate this challenge. Increasingly more research focuses on how to fabricate and apply thermoelectric materials for harvesting energy and regulating the indoor thermal environment. However, only a few studies have focused on cementitious materials with thermoelectric potential. Thermoelectric cement is a composite material in which particular additives can enhance the thermoelectric performance of ordinary cement. By potentially replacing traditional construction materials with thermoelectric cement in building applications, electricity could be generated from waste heat, reducing the use of fossil fuels, and supplementing other renewable energy sources like solar and wind. This article presents a review of fundamentals, fabrication, characterization, composition, and performance, as well as modeling methods and opportunities for thermoelectric cement composites. The literature reviewed covers the period from 1998 to 2020 related to thermoelectric cement. It also presents the challenges and problems to overcome for further development and provide future research directions of thermoelectric cement. • Fabrication, characterization, and performance of TE cement are summarized. • Existing studies measured TE properties of cement composites separately. • Most TE cement composites exhibit ZT lower than 10−3. • ZT of graphene and Al-doped ZnO enhanced cement was improved to 10−2. • Atomistic and macroscale modeling for TE composite materials are reviewed. [ABSTRACT FROM AUTHOR]

• An experimental study has been performed on trapezoid-shaped legs for TEC application. • Microstructural characteristics of synthesized TE materials have been investigated. • A comparison of performance analysis between TEC prototypes has been studied. • Analytical analysis has been carried out and validated with experimental results. • Lower area ratio shows better performance at lower current for the proposed design. The zero emission and chlorofluorocarbons (CFC) free thermoelectric cooling systems have the potential to limit the adverse effect on our climate due to the greenhouse gas emission from traditional cooling technologies. In this paper, a new configuration of thermoelectric cooling system is proposed, which includes trapezoidal-shaped solid-state thermoelectric legs, bismuth-antimony-telluride-selenium alloy, and it is manufactured using environmentally friendly handheld dispenser fabrication method. The synthesized thermoelectric materials are characterized using x-ray powder diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscope (SEM) technologies in order to study the morphology of the materials. Both theoretical and experimental studies are performed on trapezoidal and rectangular prototypes. It is identified that the trapezoidal-shaped leg requires less material (nearly 25% less) and exhibits lower thermal conductance (around 27% less) in comparison with the rectangular-shaped TE leg. Experimental results further show that a maximum temperature difference of 79.4 °C can be achieved from the trapezoidal-shaped prototype at 5A input current which is 10% higher than the rectangular prototype. Besides, an experimentally validated analytical model is used to investigate further the cooling capability, temperature difference, and coefficient of performance of both trapezoidal and rectangular-shaped TEC. A range of area ratio of the hot surface to the cold surface of the TE leg varying from 0.33 to 3 has been studied. In addition, the maximum COP of the trapezoidal-shaped prototype is approximately 32.5% higher than the rectangular prototype. The maximum obtainable cooling rate and temperature difference are almost the same but require nearly 50% less input current to achieve this maximum output with a hot to cold surface area ratio of 0.33. [ABSTRACT FROM AUTHOR]

The temperature-dependent material property effects, including the thermal conductivity, Seebeck coefficient, and electrical resistivity, on the thermoelectric element (TE) temperature profiles are assessed in this study. The nonlinear partial differential equation governing energy transport within a one-dimensional TE is solved using a finite difference method. The solution of the TE temperature field is obtained by solving the resulting finite difference equation in the form of a third-order polynomial. The effects of key variables on the cooling process are discussed using a practical example. Results indicate that internal constrictive resistance and Joule heat generation can be reduced with conical elements when compared to conventional free-standing elements. The cooling efficiency can be improved by incorporating a temporarily transient current pulse before it reaches a steady-state condition. This additional transient cooling and steady-state recovery time strongly depend on the magnitude of the current pulsed, duration, and pulse shape, as well as material properties. Strategies for cooling are investigated in this study; the knowledge gained from this study can be utilized by engineers in the thermoelectric industry for design optimization. [ABSTRACT FROM AUTHOR]

• Detailed review of thermoelectric geometry and structure optimization are presented. • Thermal stress studies on thermoelectric generators and coolers are reviewed. • Three-dimensional and multi-objective optimization studies are reviewed. • Future research directions on thermoelectric geometry optimization are presented. Thermoelectric geometry and structure optimization are vital research areas which are being explored extensively in recent years due to significant performance enhancement achieved. However, the lack of a single review paper on this key area is a huge gap identified. Therefore, this review presents a first of its kind in-depth analysis of the start of art in thermoelectric geometry and structure optimization. The four main parameters including leg length or height, cross-sectional area, number of legs and leg shape which are paid attention to during optimization of thermoelectric geometry are discussed in detail. In addition, a review of the different thermoelectric structure available in literature such as flat plate, annular, segmented, cascaded, corrugated, concentric, linear, flexible and micro thermoelectric generators and coolers is presented. Furthermore, special attention is paid to both electrical and mechanical performance enhancement obtainable from thermoelectric geometry and structure optimization. A review of thermal stress optimization is presented alongside other optimization including contact resistance, heat pipe, pulsed heating and cooling. Geometry and structure optimization methods including three-dimensional finite optimization and multi-objective optimization are discussed in detailed and the most significant results obtained from the literature review are presented. This comprehensive review will be a valuable and essential reference literature on all issues relating to thermoelectric geometry and structure optimization. [ABSTRACT FROM AUTHOR]

• Analytical modeling on how to calculate thermoelectric effective material properties. • Effective material properties obtained from the manufacturer maximum parameters. • The accuracy of model is validated experimentally as well as manufacturers' data. • Effective material properties improve thermoelectric ideal equations' accuracy. • Contact resistances and Thomson effects analysis aren't needed to improve accuracy. Non-standardized forms of performance data is an issue designers encounter when dealing with thermoelectric module manufacturers. To assess a product's performance, experimental methods can be used as well as analytical modeling by using the material properties that are not usually revealed. The latter investigates theories using the guidelines given by the manufacturers. After analyzing the theories, the values are used to assess the performances of the thermoelectric modules. The samples then go through experimental testing to insure their validity. Finally, the analytical, experimental, and manufacturer-provided results are compared to find a common ground. The results shows good agreement where the most of the errors are less than 1%. [ABSTRACT FROM AUTHOR]