Performance Of Thermoelectric Generator Research Articles

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.

Structural optimization of solar thermoelectric generators considering thermal stress conditions

The optimization of the thermoelectric leg (TEL) structure is an effective means which can improve the thermoelectric performance of solar thermoelectric generator (STEG), however, the optimized dimensions may not satisfy the allowed stress and thus prevent the STEG from normal operation properly. To address this issue, we constructed a coupled thermal-electrical-stress multi-physical field model of STEG, and optimized the STEG structure under the condition of allowed stress. The results show that when the allowed stress is not considered, the optimal ratio of cross-sectional ratio (f) to height (h) is 0.03 mm−1 to maximize the thermoelectric conversion efficiency, but then the maximum thermal stress of the STEG far exceeds the allowed stress of the material. When the allowed stress conditions are considered, the critical cross-sectional ratio of the module is much higher than the optimal cross-sectional ratio. The critical output power that can be obtained from the module is 38.5% less than the maximum output power without considering the allowed stress, and the influence of thermal stress on the optimal structural parameters is significant at a high concentration ratio. The critical output power gradually increases with the increase in the concentration ratio, and a greater output performance can be obtained at larger heights, while a greater output power density can be obtained at smaller heights. The outcomes presented by this study have certain guide to the construction of high-efficiency STEG.

Modeling study on the geometric optimization of thermoelectric modules

Abstract The performance of thermoelectric power generators (TEG) primarily depends on the properties of the thermoelectric materials employed. For conventional thermoelectric modules (TEM) utilizing the same material, the geometric parameters also play a significant role in determining TEM performance. As such, optimizing the geometry of TEM can lead to improved performance. In this study, TEM were modeled, designed, fabricated, and tested to investigate the effects of different geometric parameters on their performance. Numerical simulations were conducted under both constant temperature and constant flow boundary conditions, and the results were validated through experimental testing. The simulation results under constant flow boundary conditions exhibited good agreement with the experimental results. The effects of thickness, cross-sectional area, and filling ratio of thermoelectric legs on TEM performance were investigated through numerical simulations and compared with findings from previous studies. It was observed that increasing the cross-sectional area of the thermoelectric legs led to a decrease in the power output of TEM. Conversely, increasing the filling ratio effectively enhanced the TEM's performance. Furthermore, an optimal thermoelectric leg thickness was identified through the numerical simulations that could yield the maximum power output of TEM. The underlying mechanism behind this observation was explained, shedding light on why different reports have identified different optimal thicknesses. Optimizing the thermoelectric leg thickness can help maintain a high effective temperature difference and low internal resistance, which can vary based on the specific type of TEM and the thickness and thermal conductivity of the insulating substrates and copper sheets.

Parametric analysis and potential evaluation of thermoelectric generator driven by solar energy and radiative sky cooling

Solar energy and radiative cooling (RC)-driven thermoelectric generator (TEG) technology, which harnesses the extraterrestrial heat and cold sources from the sun and deep universe, is attracting increasing attention. However, existing studies on solar TEG (STEG) and RC TEG (RCTEG) only focus on either solar spectrum or infrared spectrum. To investigate the TEG performance considering full spectrum’s influence, a thermal-electrical coupled model based on thermal resistance theory is developed. Results indicate the TEG with ideal selective absorber (ISA) provides the best power generation performance, with a power generation of around 2.06 W/m2 and a temperature difference of about 3.18 K. The maximum power generation is 2.89 and 2.87 W/m2 for the ISA and ideal broadband absorber (IBA) systems when the bottom cooling temperature is 275 K, respectively. For every 100 W/m2 increase in solar irradiance, there is a temperature difference increment of about 0.31 K. The IBA and ideal selective absorber and emitter (ISAE) systems are capable of generating electricity continuously, ensuring a 24-hour power supply. Moreover, the radiative cooling capacity provided by the ISAE system is greater than that of the RCTEG system. The proposed STEG system has promising application potential for power generation in view of its carbon footprint features.

Numerical investigation of a thermoelectric generator system with embedded sickle-shaped fins

To enhance the utilization efficiency of exhaust gas in thermoelectric generator (TEG) systems, a polygonal heat exchanger with embedded sickle-shaped fins was proposed in this study. A coupled fluid-thermal-electric multiphysics numerical model was developed to analyze the impact of different fin variables on system performance. Subsequently, the established model was validated on a test bench. The results indicate that embedded sickle fins significantly improve the TEG performance. Higher fins enhance the system's output power and temperature uniformity, albeit with increased pressure drop. Conversely, elongated linear fins and increased arc fin radius decrease pressure drop but reduce its output power. Additionally, increasing the end angle of the arc improves temperature uniformity with minimal effect on output power and pressure drop. Moreover, the TEG system exhibits optimal performance when the linear fin length is 180 mm, the height is 45 mm, the radius of arc fins is 305 mm and the end angle is 8°. At the inlet air temperature of 600 K and the velocity of 40 m/s, the TEG output power, temperature uniformity coefficient and pressure drop for this configuration are 116.59 W, 0.99 and 845 Pa, respectively. This work contributes a theoretical reference for the structural optimization of low-backpressure TEG systems in future automotive exhaust applications.

Hierarchical hybrid heat sink material for thermo-electric generators

This short communication focuses on the impact of enhancing heat sink effectiveness of thermoelectric generators (TEG) by attaching covalently bonded carpet-like arrays of carbon nanotubes on prefabricated copper structures. Structural hierarchy of heat sinks are important for synergizing the thermal conductivity of materials with fin architectures tailored for active or passive electronic cooling components. We investigated strategic integration of carefully aligned carpets of carbon nanotubes (CNTs) on heat sink fins to simultaneously enhance conductive, convective, and radiative heat transfer pathways. Carbon nanotubes (CNT) combine ultra-high thermal conductivity along their axial directions with high surface area and radiative heat transfer coefficients. While CNTs are known to enhance nanofluidic coolants and thermal interface composites, their full potential can only be utilized if they are aligned normal to heat sink fins, and strongly anchored to retain the fin/radiator architecture in service conditions. This study focused on measuring the direct impact of CNT carpet on TEG performance under ambient passive cooling conditions without adding any noticeable weight or volume to the heat sink. It was seen that this single step of CNT attachment on the surface could increase the open circuit voltage of TEG modules by over 50% in the passive mode with respect to original untreated heat sink, and over 100% with respect to no heat sink. This improvement may be enhanced even further by introducing forced coolants. These results therefore show significant promise in using the surface nanocarpet approach for development of compact, lightweight, robust and reusable solid-state heat sinks in future.

Consideration of Thomson effect in multi-objective optimization of thermoelectric generator using metaheuristic techniques

This paper proposes the performance estimation of a multi-parameter multi-objective optimization problem of a thermoelectric generator (TEG) considering the Thomson Effect using metaheuristic techniques. The hot and cold side temperatures, load resistance, length of thermoelectric legs, and fill factor of the TEG are varied simultaneously to optimize the output power and efficiency of the TEG. Thirteen-metaheuristic algorithms have been used to perform single and multi-objective optimization of TEG system with multi-variable space and obtained the best performing algorithm among them for TEG model with and without considering the Thomson effect. In terms of accuracy and speed, moth flame optimization (MFO) and cuckoo search (CS) algorithms are found to be the most suitable for the models with and without considering the Thomson effect. Cuckoo search, genetic algorithm (GA), and moth flame optimization (MFO) algorithms gave consistent results for the model considering the Thomson effect. The TEG performance of both models with and without considering the Thomson effect is also compared. For single-objective optimization, CS and MFO produced optimal power output and efficiency of 16.99325 W & 2.0696 % and 19.20837 W & 2.4427 % respectively for models with and without considering the Thomson effect respectively. For multi-objective optimization, the optimal power outputs of 16.993 W & 19.20837 W and efficiencies of 1.9583 % & 2.25932 % are obtained on the Pareto front for models with and without considering the Thomson effect respectively. These optimal points are determined using the Shannon entropy decision-making approach which is found to be the best technique.

A multi-objective optimization energy management strategy for marine hybrid propulsion with waste heat recovery system

To improve the efficiency of marine hybrid propulsion systems (HPS) and make full of the potential of the waste heat recovery system, this paper presents a powerplant scheme which includes marine HPS with thermoelectric generator (TEG) and organic rankine cycle (ORC) system. The original energy management strategy (EMS) based on the multi-objective optimization algorithm is proposed, which considers the objectives of minimum total energy consumption, maximum output energy of TEG and ORC, and the optimal engine efficiency. The EMS is validated with different initial states of charge of the battery, and the influence of weight factors in the EMS on the system performance is also investigated. Additionally, the interactions between various ship driving cycles and performance of TEG and ORC system are analyzed. Compared with the traditional engine propulsion, the maximum energy saving of the HPS is 13.74%, while the efficiency of the engine and ORC system has been improved by 1.53% and 1.17%, respectively. This paper provides a new algorithm of waste heat recovery system regulation and gives a valuable reference for EMS optimization in marine HPS.

A comprehensive comparison of micro heterojunction thermoelectric generators based on a carrier transport model

To be a crucial aspect in the performance of thermoelectric generators, carrier transport in thermoelectric materials cannot be captured by existing multiphysics models. In this work, a carrier transport model for heterojunction thermoelectric generators (TEG) is developed with the drift-diffusion equation comprehensively considering the effect of carrier mobility on the current density. Subsequently, based on the concept of inverse- and homo-heterojunction, three micro TEG are designed considering Si and Si0.7Ge0.3 bases with the doped boron and arsenic and compared with the original design for revealing the effects of load resistance and temperature difference on the thermoelectric performance. It has been demonstrated that for homo-heterojunction, the thermoelectric power and conversion efficiency are significantly improved at hot temperatures from 600 to 1000 K, with a maximum improvement of 18.09% compared to the conventional TEG. For inverse-heterojunction, the optimal temperature of the thermoelectric performance is 1100–1300 K, and its efficiency is 23.50% higher than that of the conventional TEG. Both the doping impurity ionization and intrinsic carrier excitation contribute to a high density of majority carriers and are responsible for the better performance of homo-heterojunction at low working temperatures. For inverse-heterojunction, a high working temperature can significantly promote the excitation of minority carriers because of the built-in electric field and leads to better performance. Finally, we propose a novel heterojunction by combining both homo- and inverse-heterojunction which can improve thermoelectric efficiency by up to 27.72%.

Energy Conversion Performance and Optimization of Wearable Annular Thermoelectric Generators

Energy Conversion Performance and Optimization of Wearable Annular Thermoelectric Generators

Thermo-economic and performance analysis of a novel tubular hybrid high-temperature proton exchange membrane fuel cell and thermoelectric generator

This paper proposes a novel tubular design for a hybrid high-temperature proton exchange membrane fuel cell (HT-PEMFC) and thermoelectric generator (TEG) system. The wasted heat from the fuel cell is captured by a thermoelectric generator to generate more electricity. Hence, the primary objective of the research is to determine the waste heat recovery performance of the TEG for thermal management of the tubular HT-PEMFC. A validated 3D numerical approach was employed to evaluate the performance of the tubular hybrid system with a tubular TEG integrated into the HT-PEMFC. A parametric study evaluates the impact of various TEG geometrical configurations and operational parameters on the system's performance. The results indicate that boosting the cell voltage improves the fuel cell efficiency, while decreasing the thermoelectric sizing has a notable impact on the TEG's performance. The TEG's conversion efficiency and output power are significantly impacted by changes in the angle ratio and the temperature of the cold side. Increasing the inlet temperature has a positive impact on thermoelectric power generation but leads to a reduction in fuel cell power and efficiency. Overall, the study highlights the importance of optimizing the operating conditions of hybrid tubular HT-PEMFC/TEG to achieve optimal performance and provides valuable insights for the design and development of hybrid energy systems that can potentially contribute to meet the increasing demand for sustainable energy solutions.

Effects of Performance and Normalized Parameters on Various Materials Based Multistage Thermoelectric Generator

Abstract Multi-staging and variable cross section greatly improve the performance of thermoelectric generators. Hence, the present theoretical study analyzes a multi-stage-variable-shaped thermoelectric generator (MVS-TEG) for a combination of dissimilar materials. Effects on voltage, power, conversion efficiency, normalized constraints (voltage, power, and conversion efficiency), and second law efficiency with a row number, exhaust inlet temperature, and the coolant flowrate have been investigated. Results reveal that the row number is the most critical input parameter followed by exhaust inlet temperature and coolant flowrate. Also, the work gives optimum values of rows for voltage and power as Nx = 19 for MVS TEG-1, MVS TEG-3, and MVS TEG-4 while Nx = 18 for MVS TEG-2. The exhaust inlet temperature variation increases the voltage and power output by 54–59% and by 53–58% respectively. The coolant flow variation has a greater impact on the conversion efficiency and the average improvement in the efficiency is about 9.23% in the present study. The second law efficiency decreases with the increase in all the input parameters.

EFEK LAJU PEMANASAN (HEATING RATE) TERHADAP DISTRIBUSI TEMPERATUR DAN KINERJA MODUL THERMOELECTRIC GENERATOR SP1848 SA

Thermoelectric Generator (TEG) is an energy conversion technology that converts heat energy into electrical. There are several factors that affect the performance of TEG, one of which is the heat source. This research will investigate the use of waste heat by varying the heating rate on the performance of TEG in generating electricity and the temperature distribution profile through experimental studies on a laboratory scale. The heating plate is used to heat the hot surface of the TEG. There are three variations of the heating rate used, namely: Low (0.355°C/min), Middle (0.933 °C/min) and High (1.558 °C/min). Temperature measurements were carried out on the hot surface (Th), the cold surface (Tc) of the TEG module, and the ambient temperature (Ta) using Arduino temperature data logger. Meanwhile, to measure the electrical output in the form of voltage (V) generated by the TEG module, using the Arduino voltage data logger. The results show when the heating rate used is high (high heating rate) then the average electrical output of the TEG module produces a voltage of 5.34V. The heating rate on the hot surface of the TEG module will affect the difference in surface temperature and the performance of the TEG module in generating electricity.

Study of Diverse Leg Geometry Effect on the Performance of Segmented Thermoelectric Generator with the Same Leg Volume

When developing any product, one of the factors that determine its price is the volume of the product. In this paper, the effect of various geometrical forms on the performance of a segmented TEGs with the same leg volume was performed. For this purpose, a numerical study was performed using the finite element method (FEM) for different geometrical shapes by considering 3 following forms: Rectangular-leg, Pin-leg, and Cone-leg. In each region, Bismuth Telluride was deposited on the cold side while Lead Telluride was placed on the hot side. Two cases were studied. In the 1st case, the 2 regions’ the same length, for n and p types, which constitute the leg was taken. While in the 2nd case, all forms of the same volume were evaluated by taking a variable leg length and a fixed cross-sectional area of the hot side. The optimal ratios of the Bismuth Telluride lengths in and regions for the Rect-leg, Pin-leg, and Cone-leg were studied. The obtained results showed that the Rectangular-leg model in the 1st case presents the highest output power and efficiency with about 0.3019 watt and 12.47 % with leg length values of ( and ) 1 and 4.5 mm, respectively. Based on the simulation results, we conclude that the leg form and the length ratio influence the performance of the segmented TEGs. The findings indicate that the Rect-leg model presents the best performance. HIGHLIGHTS Difference of the internal temperature distribution with the variable leg geometry The effect of the segmented thermoelectric leg length ratios on internal resistance and thermal conductance In the segmented TEGs Efficiency decreases with increasing the length ratio of materials in lower temperature range Increasing the performance in the segmented TEGs compared to the traditional TEG GRAPHICAL ABSTRACT

Experimental Study on the Influence of Wind Speed on the Start-Up Characteristics and Thermoelectric Generation Characteristics of Gravity Heat Pipe in Gangue Dump

As an efficient heat exchange component, the gravity heat pipe can effectively control the accumulated temperature inside gangue dumps and enable reuse of transferred heat. This study establishes a similar simulation experimental platform for gravity heat pipes to control gangue dumps and thermoelectric generation. The influence of wind speed on the start-up performance and isothermal performance of gravity heat pipes is analyzed, along with the impact of wind speed on their thermoelectric generation performance. Initially, the optimal working fluid height and heating height are determined, followed by a comparison and analysis of the isothermal performance, start-up performance, and thermoelectric generation performance of the gravity heat pipe under different wind speeds. The results indicate that at a wind speed of 1.0 m/s, the gravity heat pipe exhibits better start-up and isothermal performance. At a wind speed of 2.0 m/s, the thermoelectric power generation reaches its peak. In the range of 1.0~2.0 m/s wind speeds, the curve of thermoelectric generation exhibits the most fluctuations.

Effects of material doping on the performance of thermoelectric generator with/without equal segments

Thermoelectricity is a clean energy source that has garnered attention worldwide. Improving the performance of thermoelectric devices to convert waste heat into electricity efficiently is currently a priority for many researchers. One way to do this is by improving the thermoelectric performance of the materials used in thermoelectric generators (TEGs). In recent years, doping different materials into thermoelectric materials to enhance TEG's performance has attracted attention. This study analyzes the improvement of TEGs by performing 3D numerical simulations of thermoelectric devices using a series of SnTe with different doping levels. The results show that the undoped SnTe-AgSbSe2 composite has the highest output power compared with the doped case. In terms of conversion efficiency, the composite AgSbSe2 doped with 3% SnTe achieves the highest conversion efficiency. Furthermore, the performance comparison with conventional TEG shows that the equal segmented thermoelectric generator (STEG) has higher output power and conversion efficiency at all doping ratios. In addition, the SnTe-AgSbSe2 composite with 3% doping concentration has the best thermoelectric performance with an output power of 64.49 mW and an efficiency of 14.17% at a temperature difference of 500 K (a hot side temperature of 800 K and a cold side temperature of 300 K). Accordingly, it is summarized that the combination of doped SnTe thermoelectric material and equal-STEG design can efficiently enhance the thermoelectric module's (TEM) performance.

A thermal contact model encompassing near-field effects of multi-interface TEGs in hypersonic conditions

High efficiency heat harvest of hypersonic vehicles claims elaborate design of thermoelectric (TE) conversion process. A thermoelectric generator (TEG) contains multi-interfaces in the heat transfer path and the interfacial thermal contacts with certain amount of nanoscale effects have significant influence on its TE conversion process. In this paper, a thermal contact model encompassing near-field thermal radiation (NFTR) effects of TEGs with heterogeneous interfaces between substrates, electrodes and TE legs is established and experimentally validated in hypersonic conditions. First, a real-topology-based thermal contact resistance (TCR) prediction model is developed and the far- and near-field radiative heat transfer at heterogeneous interfaces is considered by the fluctuational electrodynamics, and the model is validated by direct and indirect experimental measurements. Second, the effects of average interfacial temperature, clearance distance and opposite heat transfer paths on the thermal radiation are analyzed, and the influences of average interfacial temperature, loading pressure and clearance mediums on the TCR are then clarified. Third, the TCR is equivalently considered in a TEG performance evaluation model and the NFTR effects is quantitatively counted. The result shows that: with the consideration of the NFTR, the TCRs between TE legs and electrodes, substrates and electrodes decrease by about 3.90% to 17.0% and 0.510% to 6.40% under vacuum clearance, 1.30% to 5.50% and 0.220% to 2.00% under air clearance, respectively; and the maximum output power of the TEG increases by about 8.02% and 1.29% under vacuum and air clearance (0.1 MPa, 650 K), respectively.

Exhaust heat recovery performance analysis of a Bi-fuel engine utilizing a thermoelectric generation kit and fuel economy evaluation

The internal combustion engine (ICE) exhaust gas temperature depends on fuel energy and combustion characteristics. The exhaust gas temperature of compressed natural gas fuel (CNG) is more than gasoline fuel and consequently, affect the thermoelectric generation (TEG) performance. This study evaluates how CNG and gasoline fuels affect exhaust temperatures, TEG power output and the brake specific fuel consumption (BSFC). In test setup, the engine exhaust channel is modified to support a thirty thermoelectric unit (TEM) in upper and lower of exhaust muffler; the TEM is clamped between exhaust mufflers and the cooling system to control the cold surface temperature of the TEM. The maximum power output and open circuit voltage of the TEG are described as functions of temperature difference. The electrical power output of the TEG is evaluated in terms of changing engine speed and load for both fuels. The result indicates that the CNG fuel has better temperature distribution of TEG Kit hot surface which can generate a maximum peak power output. The TEG kit can reach 178.3 W, while the gasoline fuel was 164.4 W. The average saving BSFC for a bi-fuel engine was (2.71%:3.20%) with TEG kit for both fuels.

Design and optimization of thermoelectric generators

Thermoelectric generators (TEGs) are gaining significant traction as they are capable of converting waste heat into electrical energy without requiring any moving mechanical parts. Although TEGs are less efficient than other power-generating equipment, they find wide applications in diverse industries such as biomedical, aerospace, automotive, and power generation. To enhance the efficiency, figure of merit, and power output of thermoelectric generators (TEGs), certain aspects need to be addressed. The present work mainly focuses on the impact of design factors, including cross-sectional area and height of the semiconductor, and semiconductor materials, namely SiGe, PbTe, and Bi2Te3, on the TEG's performance. Parametric studies are conducted using the COMSOL Multiphysics program to optimize the TEG's efficiency and power output. The results show that employing Bi2Te3 at an operating temperature of the hot side at 410 °C and the cold side at 20 °C increases TEG efficiency by nearly 10% compared to the SiGe semiconductor whereas the design factors have a marginal impact on the TEG's efficiency. However, the power output maximum is achieved by increasing the TEG cross-sectional area and decreasing the semiconductor height.