Design Of Thermoelectric Generator Research Articles

Artificial neural network for geometric design and optimization of three-stage segmented thermoelectric generators

The quest for greener power generation is a major driver for the development of thermoelectric generators. Segmented thermoelectric generators are an effective means to significantly improve the efficiency. Given the complexity of multiple geometric parameters in a three-stage segmented thermoelectric generator, the conventional practice is to use software for numerical simulation and geometric optimization before manufacturing. While this method saves time and increases production efficiency, it lacks reproducibility. However, artificial neural networks offer a solution to this problem by further reducing the computational time required. In this work, artificial neural networks are used to replace these processes by using optimization algorithms to guide the neural network in calculating the optimal thermoelectric conversion efficiency. First, a dataset of 3000 three-stage segmented thermoelectric generator configurations is generated using a COMSOL simulation model. A backpropagation neural network is then constructed and trained on this dataset, using particle swarm optimization to adjust the network weights and computational parameters. The trained neural network accurately predicted the conversion efficiency of three-stage segmented thermoelectric generators over various temperature ranges. When compared to COMSOL calculations, the values are generally within the 95% confidence interval of the backpropagation neural network predictions. Finally, genetic algorithms and artificial fish swarm algorithms are used to drive the neural network to calculate the optimal thermoelectric conversion efficiency. Compared to COMSOL, the thermoelectric conversion efficiency increased by 2.48% and 3.61%, respectively. Despite the initial dataset construction time, the artificial neural network can determine the optimal geometric structure and conversion efficiency of a three-stage segmented thermoelectric generator within 5 min. This method is expected to significantly improve the design and production efficiency of three-stage segmented thermoelectric generators.

Design and Simulation of Thermoelectric Generator to Recover Waste Heat of Chimney

Design and Simulation of Thermoelectric Generator to Recover Waste Heat of Chimney

Geometrical Optimization of Segmented Thermoelectric Generators (TEGs) Based on Neural Network and Multi-Objective Genetic Algorithm

In this study, a neural network and a multi-objective genetic algorithm were used to optimize the geometric parameters of segmented thermoelectric generators (TEGs) with trapezoidal legs, including the cold end width of thermoelectric (TE) legs (Wc), the ratios of cold-segmented length to the total lengths of the n- and p-legs (Sn,c and Sp,c), and the width ratios of the TE legs between the hot end and the cold end of the n- and p-legs (Kn and Kp). First, a neural network with high prediction accuracy was trained based on 5000 sets of parameters and the corresponding output power values of the TEGs obtained from finite element simulations. Then, based on the trained neural network, the multi-objective genetic algorithm was applied to optimize the geometric parameters of the segmented TEGs with the objectives of maximizing the output power (P) and minimizing the semiconductor volume (V). The optimal geometric parameters for different semiconductor volumes were obtained, and their variations were analyzed. The results indicated that the optimal Sn,c, Sp,c, Kn, and Kp remained almost unchanged when V increased from 52.8 to 216.2 mm3 for different semiconductor volumes. This work provides practical guidance for the design of segmented TEGs with trapezoidal legs.

Enhanced Heat Transfer in Thermoelectric Generator Heat Exchanger for Sustainable Cold Chain Logistics: Entropy and Exergy Analysis

This study investigates the application of thermoelectric power generation devices in conjunction with cold chain logistics transport vehicles, focusing on their efficiency and performance. Our experimental results highlight the impact of thermoelectric module characteristics, such as thermal conductivity and the filling thickness of copper foam, on the energy utilization efficiency of the system. The specific experimental setup involved a simulated logistics cold chain transport vehicle exhaust waste heat recovery thermoelectric power generation system, consisting of a high-temperature exhaust heat exchanger channel and two side cooling water tanks. Thermoelectric modules (TEMs) were installed between the heat exchanger and the water tanks to use the temperature difference and convert heat energy into electrical energy. The analysis demonstrates that using high-performance thermoelectric modules with a lower thermal conductivity results in better utilization of the temperature difference for power generation. Additionally, the insertion of porous metal copper foam within the heat exchanger channel enhances convective heat transfer, leading to an improved performance. Furthermore, the study examines the concepts of exergy and entropy generation, providing insights into the system energy conversion processes and efficiency. Overall, this research offers valuable insights for optimizing the design and operation of thermoelectric generators in cold chain logistics transport vehicles to enhance energy utilization and sustainability.

Design and optimal coolant flow rate analysis of an annular water-cooled automotive exhaust-based thermoelectric generator

This paper introduces a design of an annular water-cooled automotive exhaust-based thermoelectric generator (TEG). A comprehensive numerical model of TEG system is established to investigate the relationship between automotive exhaust temperature and coolant flow rate. Through numerical simulations, it is demonstrated that the implementation of this device can effectively enhance the temperature uniformity at the hot side of the heat exchanger, consequently increasing the TEG's power output. After introducing the annular water-cooled radiator, the temperature uniformity of the thermoelectric module increased by 18.8%. By utilizing the numerical simulation outcomes alongside empirical formulas, calculations for the pump power consumption, maximum output power, and maximum net output power of the thermoelectric module (TEM) are conducted. The maximum net output power can be increased by 3.30%–53.24% by controlling the coolant flow rate. As a result, a relationship curve depicting the average temperature difference between the hot and cold ends of the TEM, in relation to the optimum coolant flow rate, is obtained. This relationship curve serves as a valuable tool for adjusting the radiator's coolant flow rate and augmenting the TEG's net output power, ultimately achieving the objective of heightening the power generation efficiency of the TEG.

Impacts of distributed thermal and electric contact resistance on performance and geometric optimization of thermoelectric generators

Thermal and electric contact resistance (TCR/ECR) critically impact performance and geometric optimization of thermoelectric generators (TEGs). However, conventional treatments usually ignored or simplified them as lumped variables, neglecting their actual distributions across the TEG system. In this study, we proposed a multi-physical model to characterize TEG performance with explicitly specifying TCRs/ECRs at different TEG interfaces (locations). The numerical results show that the lumped-variabletreatment led to maximal overestimations of 16.9 % and 24.5 % in the TEG output power and efficiency, respectively, compared to the results with distributed TCR in this article. Importantly, it also reveals that the TEG performance was susceptible to the TCR location—the interfaces on the cold side exerted more negative impacts than those on the hot side. Furthermore, reducing both TCR and ECR could improve TEG performance and reducing TCR is more effective. It is shown that an 80 % reduction in TCR increased the maximum TEG output power by 35.6 %, while the same reduction percentage in ECR only improved it by 8.8 %. As to geometric optimization, an optimal TE leg height equal to 0.6 mm was obtained for the maximum output power. This contrasts with previous studies without considering TCR and ECR, which always favoured shorter heights. As for copper electrodes, their optimal heights were in the range of 0.2–0.4 mm corresponding to the maximum efficiency, far smaller than those (0.7–1.2 mm) obtained when TCR/ECR were neglected. The latter even further resulted in a reduction in the maximum efficiency by more than 1 % compared to its true peak. In this study, all these numerical results clearly elucidate the important impacts of distributed TCR and ECR on TEG performance, and provide a comprehensive and balanced guideline for TEG design.

Mathematical analysis of the solar assisted thermoelectric generator

The direct conversion of solar energy into electrical energy is primarily dependent on the photovoltaic systems. However, in the last few decades, researchers have shown interest to work on the thermoelectric modules for direct conversion of solar thermal energy into electrical energy based on the Seebeck effect. This research paper provides a comprehensive analysis of various Solar Thermoelectric Generator (STEG) designs, focusing on their conversion efficiencies. Despite the comparatively lower efficiency of STEG in comparison to photovoltaic (PV) cells, owing to limitations in the figure of merit value and temperature differences between hot and cold sides of the thermoelectric modules, this study proposes strategies for enhancement. Approaches include the development of materials with higher figure of merit values, design optimization, solar tracking, heat storage systems, and efficient heat sink designs. Also, Mathematical analysis of the power and efficiency calculation of a STEG has been presented on the basis of some fundamental and derived mathematical equations. The overall efficiency of STEG, a product of Opto-thermal Efficiency and thermoelectric module efficiency, is explored, identifying an optimal hot side temperature for maximum efficiency. Module mismatch analyses for series and parallel connections are also derived, underscoring conditions for mitigating power loss. These findings serve as guidelines for designing more feasible and efficient STEG systems, with considerations for economic viability, sustainability and greenhouse gas reduction throughout the life cycle.

A Review of Thermoelectric Generators in Automobile Waste Heat Recovery Systems for Improving Energy Utilization

With the progress of modern times, automobile technology has become integral to human society. At the same time, the need for energy has also grown. In parallel, the total amount of waste energy that is liberated from different parts of the automobile has also increased. In this ever-increasing energy demand pool, future energy shortages and environmental pollution are the primary concerns. A thermoelectric generator (TEG) is a promising technology that utilizes waste heat and converts it into useful electrical power, which can reduce fuel consumption to a significant extent. This paper comprehensively reviews automobile thermoelectric generators and their technological advancements. The review begins by classifying different waste heat technologies and discussing the superiority of TEGs over the other existing technologies. Then, we demonstrate the basic concept of and advancements in new high-performance TEG materials. Following that, improvements and associated challenges with various aspects, such as the heat exchanger design, including metal foam, extended body, intermediate fluid and heat pipe, leg geometry design, segmentation, and multi-staging, are discussed extensively. Finally, the present study highlights research guidelines for TEG design, research gaps, and future directions for innovative works in automobile TEG technologies.

Advancements in Thermoelectric Generator Design: Exploring Heat Exchanger Efficiency and Material Properties

This paper presents a comprehensive study on the application and optimization of automotive thermoelectric generators (ATEGs), focusing on the crucial role of heat exchangers in enhancing energy conversion efficiency. Recognizing the substantial waste of thermal energy in internal combustion engines, our research delves into the potential of TEGs to convert engine waste heat into electrical energy, thereby improving fuel efficiency and reducing environmental impact. We meticulously analyze various heat exchanger designs, assessing their influence on the TEG’s output power under different exhaust gas flow rates and temperatures. Furthermore, we explore the impact of TEG material properties on the overall energy conversion effectiveness. Our findings reveal that specific heat exchanger designs significantly enhance the efficiency of waste gas heat exchange, leading to an improved performance of the TEG system. We also highlight the importance of thermal insulation in maximizing TEG output. This study not only contributes to the ongoing efforts to develop more sustainable and efficient vehicles but also provides valuable insights into the practical application of thermoelectric technology in automotive engineering. Through this research, we aim to pave the way for more environmentally friendly transportation solutions, aligning with global efforts to reduce fossil fuel dependence and mitigate environmental pollution.

Development of low-cost micro-fabrication procedures for planar micro-thermoelectric generators based on thin-film technology for energy harvesting applications.

With the rapid proliferation of portable and wearable electronics, energy autonomy through efficient energy harvesting has become paramount. Thermoelectric generators (TEGs) stand out as promising candidates due to their silent operation, high reliability, and maintenance-free nature. This paper presents the design, fabrication, and analysis of a micro-scale TEG for powering such devices. A planar configuration was employed for its inherent miniaturization advantages. Finite element analysis using ANSYS reveals that a double-layer device under a 50 K temperature gradient generates an impressive open-circuit voltage of 1417 mV and a power output of 2.4 μW, significantly exceeding its single-layer counterpart (226 mV, 0.12 μW). Validation against the analytical model results yields errors within 2.44% and 2.03% for voltage and power, respectively. Furthermore, a single-layer prototype fabricated using paper shadow masks and sputtering deposition exhibits a voltage of 131 mV for a 50 K temperature difference, thus confirming the feasibility of the proposed design. This work establishes a foundation for developing highly efficient micro-TEGs for powering next-generation portable and wearable electronics.

Performance of Single Cell and Double Stacked Thermoelectric Generator Modules for Low Temperature Waste Heat Recovery

Thermoelectric generator (TEG) is an energy conversion technology that is capable of converting temperature difference into electrical output. This manuscript focused on different design setups of TEG module in recovering waste heat captured from hydrogen fuel cell vehicle (FCV) into useful electrical energy. Effects of single cell (SC) and double stacked (DS) TEG configurations were analysed before an additional heat sink (HS) was installed in the heating section for heat transfer enhancement. The performance of all design setups was tested under waste heat temperature (Twh) of 53°C and 58°C. Under Twh of 58°C, the maximum power point (MPP) was enhanced from 0.23mW/cm2 (SC TEG design setup) to 2.8mW/cm2 (DS TEG configuration with HS addition design setup), by approximately 92%. Rapid increase in MPP was obtained as HS was applied in the TEG module due to higher rate of waste heat capturing. The installation of HS is proved to be a successful add-on to the TEG module for WHR from low temperature waste heat.

Increase in the efficiency of electricity production with a thermoelectric generator (TEG)

Currently used TEG modules have low efficiency of about 5%. The energy generated by the TEG module depends on the temperature difference between the module surfaces. Heat exchange between the heat source and the module surface takes place through the contact between two rough solid surfaces. This creates contact resistance. It can be reduced by using a substance filling the empty spaces between the contact surfaces and applying pressure. During the tests, the efficiency of electricity generation with a thermoelectric generator was measured (TEG) at various pressure forces. The tests were carried out at a pressure force of 250 N, 500 N, 750 N and 1000 N. The selected values of pressure do not exceed the limit value arising from the thermoelectric generator (TEG) design. A copper element constituting the heat source was heated in a furnace. Next, it was pressed at an adequate force to the generator, which was placed on a water cooler. The impact of conductive materials placed between the faces of the heat source and the TEG on the generation of electricity was examined. At low forces, the use of a thermal pad as an intermediary substance does not result in improved heat transfer in the heat source—TEG generator system. Better filling of voids is provided by thermally conductive paste due to its properties.

Optimization of Building integrated photovoltaic and thermoelectric hybrid energy harvesting system for different climatic regions

As energy saving emerges as a critical factor for the sustainable development of humankind, the importance of Zero-Energy Buildings (ZEB) is gradually increasing. Therefore, much research is being conducted on high-efficiency renewable energy technologies that can be applied in urban areas. However, increasing the efficiency of BIPV were proposed and studied because of the need for the renewable energy source. Such as using phase change material (PCM), heat fin, wavelength selection, PV surface temperature decreasing or using a thermoelectric generator (TEG), and convection cooling utilizing the waste heat from the PV. In most previous studies, the performance when each method was analyzed through experiments or simulations. However, the design analysis for maximum performance still needs to be conducted. Therefore, a BIPV combined with a PCM and TEG (BIPV-TEG-PCM) design is analyzed in this study. Herein, the three variables (phase change temperature of the PCM, heat fin spacing in the PCM container, and TEG arrangement) were analyzed through computational fluid dynamics (CFD)-based simulations. Moreover, through multi-objective optimization, the BIPV-TEG-PCM system of the optimal design was derived. Analysis results of the appropriate melting temperature of PCM, heat fin interval, and arrangement of TEG for the proposed system are 40 °C, 12.4 mm, and 187 mm, respectively.

Effect of operating conditions on the output performance of a compact TEG for low-grade geothermal energy utilization

Thermoelectric generators (TEGs) offer a promising solution for harnessing low-grade heat sources including geothermal energy. However, the limited ZT values of current thermoelectric materials and the absence of advanced material-to-system integration technology result in suboptimal performance compared to conventional power generation methods, thereby constraining their large-scale applications in practice. This study has developed a compact TEG, featuring mini-channel liquid–liquid heat exchangers, to simulate low-medium temperature geothermal fluid utilization. The TEG performance was experimentally investigated and the cause of the degradation in module-to-system performance was revealed. The impacts of operational conditions and several beneficial strategies for optimizing thermoelectric performance were systematically analyzed. The results showed that the primary factor contributing to the reduction in module-to-system conversion is attributed to a decrease in internal effective temperature difference, resulting in a 12% decline in open-circuit voltage and a 26% drop in TEG power performance. The implementation of strategies, such as optimizing the flow rate of cooling water, adjusting assembly pressure, and utilizing appropriate thermally conductive pads, resulted in significant increases in net power output by 7.07%, 27.9% and 24.3%, respectively. The economic analysis also suggests that our TEG design can achieve a competitive cost and higher power performance compared to other designs, showcasing its potential for large-scale application in geothermal energy utilization.

Performance enhancement of segmented annular thermoelectric generator based on multi-parameter and multi-objective optimization

The excellent performance of annular thermoelectric generator (ATEG) is crucial for its commercial application, and it has been validated that the segment configuration can effectively enhance the ATEG performance. Nevertheless, owing to the limitations in conventional optimization methods which fail to simultaneously consider the co-influence of multiple parameters, further exploration is required for achieving optimal design of segmented annular thermoelectric generator (SATEG). In this study, we present a novel approach combining multi-objective genetic algorithm (MOGA) with finite element method to implement the multi-parameter and multi-objective optimization of SATEG. This approach not only reduces the computational cost but also ensures precise control on SATEG temperature below its maximum acceptable operation temperature. Furthermore, the optimization results highlight the importance of emphasizing diversity between p- and n- type TE legs as well as recognizing the different optimal geometrical structures for two types of TE legs, which have been always overlooked in previous researches. By adopting the optimal geometrical structure at a hot end temperature of 600 K, significant improvements in output power of 32.839 % and efficiency of 61.915 % are achieved for SATEG.

Design of Thermoelectric Generators and Maximum Electrical Power Using Reduced Variables and Machine Learning Approaches

This work aims to contribute to studies on the geometric optimization of thermoelectric generators (TEGs) through a combination of the reduced variables technique and supervised machine learning. The architecture of the thermoelectric generators studied, one conventional and the other segmented, was determined by calculating the cross-sectional area and length of the legs, and applying reduced variables approximation. With the help of a supervised machine learning algorithm, the values of the thermoelectric properties were predicted, as were those of the maximum electrical power for the other temperature values. This characteristic was an advantage that allowed us to obtain approximate results for the electrical power, adjusting the design of the TEGs when experimental values were not known. The proposed method also made it possible to determine the optimal values of various parameters of the legs, which were the ratio of the cross-sectional areas (Ap/An), the length of the legs (l), and the space between the legs (H). Aspects such as temperature-dependent thermoelectric properties (Seebeck coefficient, electrical resistivity, and thermal conductivity) and the metallic bridge that connects the legs were considered in the calculations for the design of the TEGs, obtaining more realistic models. In the training phase, the algorithm received the parameter (H) and an operating temperature value as input data, to predict the corresponding value of the maximum power produced. This calculation was performed for conventional and segmented systems. Recent advances have opened up the possibility of applying an algorithm for designing conventional and segmented thermocouples based on the reduced variables approach and incorporating a supervised machine learning computational technique.

High-performance flexible thermoelectric generators with tunable in-plane and out-of-plane architectures

Although thermoelectric generators (TEGs) based on organic/inorganic composite films have made great achievements in recent years, rational design of flexible TEGs with tunable in-plane or out-of-plane architecture still remains a great challenge. Herein, flexible films of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/single-walled carbon nanotube (PEDOT:PSS/SWCNT) composite with an optimized power factor of 97 ± 2.4 μW m−1 K−2 are prepared by a facile solution mixing, followed by vacuum filtration and sequential solvents post-treatment. The effects of geometric parameters of thermoelectric (TE) legs on the generator output performance were investigated. Subsequently, the designed TEG prototypes, assembled in a "back-to-back" pattern with 5 or 10 p-n couples (TEG-5pn or TEG-10pn), can effectively utilize both in-plane and cross-plane temperature gradients. The out-of-plane TEG-10pn exhibits a higher output power density (337.4 μW cm−2 or 0.069 μW cm−2 K−2 at temperature difference of 70 K). Furthermore, the designed TEGs displayed versatile applications, efficiently achieving heat-to-electricity conversion by harvesting both in-plane and cross-plane temperature gradients induced by hot water in a cylindrical beaker, human body, or a hot plate. This work provides a convenient and practical strategy for the development of film-based TEGs, considering device architecture design, packing density and the geometric parameters of the TE legs.

Structural Optimization of Annular Thermoelectric Module Applied to Liquefied Natural Gas Cold Energy Recovery

The gasification of liquefied natural gas (LNG) is characterized by a substantial release of cold energy, which can be utilized for power generation via thermoelectric generator (TEG). Employing a gasifier integrated with a thermoelectric generator for LNG gasification allows for the recovery of cold energy and its conversion to useful power, a process that holds significant potential for widespread application. In the study, a thermoelectric model has been developed for an annular thermoelectric module, which formed a new category of gasifier tube. The influence of the module’s structure as well as the heat transfer parameters on the thermoelectric performance was examined. The results revealed that an optimum height of the thermoelectric leg, specifically 2 mm, maximized the output power while allowing the thermoelectric conversion efficiency to reach a peak of 3.25%. Another noteworthy finding is that an increase in the central angle of the thermoelectric leg leads to a concomitant rise in output power but a decrease in conversion efficiency. Furthermore, when the heat transfer coefficients at the hot and cold ends of the module achieved 4000 W/(m2·K) and 10,000 W/(m2·K), respectively, the conversion efficiency can be elevated to 6.98%. However, any additional enhancement in power generation performance derived from further augmenting the heat transfer is marginal. These findings can serve as a valuable reference in the design and optimization of TEG intended for the recovery of cold energy from LNG.

Design and optimization of thermoelectric generators for harnessing geothermal anomalies: A computational model and validation with experimental field results

Thermoelectric generators have been recently proved to be a feasible alternative to harness hot dry rock fields with very promising results transforming the geothermal heat into electricity. This research deepens in the study of these generators, developing a versatile computational model that serves as a tool to design and optimize this type of thermoelectric generators. This tool is important to develop this thermoelectric technology on a large scale, to produce clean and renewable electrical energy especially in the Timanfaya National Park, in Lanzarote (Spain), where some of the most important shallow geothermal anomalies in the world are located, in order to promote self-consumption in this zone. However, it could be employed in other areas with different boundary conditions. The model, based in the finite difference method applied to the thermal-electrical analogy of a geothermal thermoelectric generator, has been validated with the experimental field results of two thermoelectric generators installed in two different zones of geothermal anomalies. It has achieved a relative error of less than 10% when predicting the power and between 0.5–1.6% in the annual energy generation, what makes it a very reliable and useful computational tool. The developed model has been employed for the first time to estimate the electrical energy that could be generated if harnessing the characterized area of anomalies in Lanzarote. Here, given the continuity of geothermal energy, 7.24 GWh per year could be generated, which means annually 1.03 MWh/m2.

Enhanced output voltage of thermoelectric generators driven by alternate triboelectric charges

Here, we report a novel thermoelectric generator (TEG) design aimed at boosting output voltage through the incorporation of ionic materials (perfluoroalkoxy and Ni) with alternating triboelectric charges. The ionic materials are attached to the cooling part of p-type BiSbTe and n-type BiTeSe TEGs, respectively. This significantly increases the electric potential difference inside the p-n junction TEG from 7.14 to 12.12 mV at the temperature difference of 20 K and the enhanced output voltage is maintained over 24 h. Finally, a TEG consisting of 11 p-n junction legs generates an output voltage of 0.167 V and the charged energy of 10 mF-capacitor is also boosted within 21 s.