Thermoelectric Generator System Research Articles

Effects of Multispectral Absorbing Coating on the Generated Voltage of Solar Radiation–Thermoelectric System

The effective utilization of solar energy is an important development direction to realize the exploration of clean energy. Herein, a model of solar radiation–thermoelectric generation (TEG) system is established, which is composed of solar absorbing coating and TEG component. Five different microscopic structures of coating are designed and the spectral absorption properties are numerically analyzed with the finite‐difference time‐domain method. Then, the absorbed solar energy and produced open‐circuit voltage with different coating structures are compared, with the coupling calculation of temperature field and electromagnetic field achieved. Additionally, the effects of structural size parameters on the output voltage performance are discussed. It can be observed that the absorbing coating can effectively improve the performance of TEG component, and the multilayer structure with appropriate gold particle diameter chosen is an optimization research direction for more efficient energy conversion.

Multiphysics performance evaluation of thermoelectric generator arrays

Thermoelectric generators (TEGs) are widely used nowadays in heat recovery and power generation applications. TEGs are connected in series and/or parallel configurations in an array to meet the voltage and/or current requirements of electric load. Therefore, it is necessary to examine the electrical performance of different TEG array configurations employed in TEG systems. In the present study, a hydro-thermoelectric Multiphysics computational model is experimentally validated by integrating the computational fluid mechanics (CFD) model with the TEG model to test the electrical performance of various TEG array configurations in terms of load voltage, current, associated power, and conversion efficiency. Each TEGs array configuration’s performance is evaluated by varying the hot water temperature from 27 °C to 42 °C and hot/cold water flowrate from 0.5 L/min to 2 L/min. Three various configurations including series and a combination of series and parallel connections were designed. The findings show that the series configuration of the TEGs array generates higher electric power than series and parallel combined configurations whereas the latter achieves the maximum power point at a higher electric current than the series configuration. The comparative analysis of CFD model with the experimental results indicates a maximum discrepancy of 7 %. For thermoelectric power-generating systems, the proposed model might serve as a benchmark for optimizing TEGs array configurations according to the electric load requirements.

Thermoelectric power generation system intelligent Runge Kutta control: A performance analysis using processor in loop testing

As an emerging source of clean electrical power, Thermoelectric generation (TEG) finds its applications in heat removal and electricity generation as an efficient improvement tool for thermal devices utilizing fossil fuels. TEG exhibits low power density and its temperature distribution is usually non-uniform over thermal conductive surfaces. Due to the non-uniformity of heat flow and loose surface contact, non-uniform temperature distribution (NTD) appears on TEG surfaces and the TEG control problem becomes complex, multi-solution, nonlinear, and highly sensitive to operating conditions. The bypass diode activation of TEG systems streamlines the power flow in a string of series-connected modules, generating multiple peak points. Classical techniques fail to address these issues of multiple maxima and lose efficiency. To solve this problem, a novel SI-based optimization algorithm, Runge Kutta Method (RUN), is applied as MPPT control. To gauge the performance of the proposed controller several distinct case studies are used, including varying temperatures gradient, NTD, 24-hour thermal profile stochastic temperature, and experimental verification. Additionally, MPPT rating analysis, economic assessment, and statistical studies are done for comparison with other state-of-the-art control techniques. The minimum tracking and settling times have been improved by RUN to 180 ms. For the additional hardware implementation, the maximum levelized cost of energy (LCOE) is about 0.16 $kWh1.07¥kWh. The power tracking efficiency of RUN can be above 99 % with energy harvest improvements of 6.3 %.

Multiple thermoelectric cogeneration system in an industrial thermal peeling press machine – Thermal modeling, case studies, and parametric analysis

Cogeneration systems, exploiting waste heat sources, have emerged as crucial solutions in decreasing energy consumption and mitigating CO2 emissions across diverse industrial domains. This study delves into the innovative integration of multiple waste heat recovery (MWHR) mechanisms with thermoelectric generators (TEGs) within industrial contexts, with a specific emphasis on harnessing exhaust gas heat. Through meticulous investigation, six distinct configurations of TEG placement covering three unique systems were examined to expose their influence on overall system efficacy. Findings clarify a deep correlation between TEG positioning and system performance, with TEGs strategically positioned in close to heat sources, particularly along the inner walls of exhaust pipes, demonstrating the most auspicious outcomes in terms of power generation. Furthermore, the study reveals notable metrics, including a maximum power efficiency of 0.11 W per TEG and a water heat flow rate peaking at 5114 W. However, a comprehensive analysis underscores the imperative for interpreting the primary mechanisms governing TEG placement's impact on system performance, alongside defining the practical implications of the observed power efficiency and water heat flow rate. These empirical insights underscore the transformative potential of WHR-TEG interactions in optimizing energy utilization within industrial ecosystems, highlighting the request for further research actions aimed at implementation strategies and sustainability benchmarks.

Prediction of the effect of load resistance and heat input on the performance of thermoelectric generator using numerical and artificial neural network models

The load resistance in the thermoelectric generators (TEGs) is crucial for optimizing power output, and managing load resistances and operating conditions are integral elements of TEG system design. In this context, it is very important to predict the performance of TEGs at variable operating conditions. This research addresses an important problem in TEG by predicting the effects of load resistance and heat input on performance using both numerical and ANN models. The three-dimensional finite volume methods applied by employing ANSYS software, and the results were compared with experimental and ANN results in terms of voltage, current, power output and efficiency. In case of ambient temperature values of 17 °C, the average absolute errors of ANN and numerical model were calculated as 2.09 % and 4.22 % for voltage output, 0.79 % and 7.73 % for current output, 5.35 % and 12.09 % for power output, 4.14 % and 12.09 % for efficiency, respectively. As a result, it was observed that the ANN model gives better results compared to the numerical model. The highest power output was obtained at load resistance of 5.4 Ω and hot surface temperature of 150 °C, with the value of 0.827 W experimentally, 0.905 W numerically, and 0.824 W with ANN models. Besides, to evaluate the effect of ambient temperature, two additional temperatures (10 °C and 25 °C) were tested and it was found that decreasing the ambient temperature increased the TEG performance. The results showed that significant improvements on power and efficiency performance of the TEG can be achieved with optimised operating conditions.

TEG and TEC Battery Cooling System

Abstract: In various industries and applications, maintaining optimal operating temperatures for batteries is important to ensure performance, longevity, and safety. Traditional methods of battery cooling often involve complex and energy-intensive systems. In this paper, we propose a Thermoelectric Generator (TEG) and Thermoelectric Cooler (TEC) battery cooling system as an innovative solution to address this challenge. By harnessing the thermoelectric effect, this system offers a compact, efficient, and environmentally friendly approach to regulate battery temperatures. Through a comprehensive review of relevant literature and the design and implementation of our TEG and TEC cooling system, we explore its potential advantages and limitations. Experimental results demonstrate the system's effectiveness in maintaining desired battery temperatures while highlighting opportunities for further optimization. This research contributes to the advancement of battery cooling technology and opens avenues for future research and practical applications in various fields, including electric vehicles, renewable energy systems, and portable electronics.

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.

Numerical Investigation of Performance Enhancement for Thermoelectric Generator System Optimization of HX Fin Shape

This paper presents a performance analysis and optimization of heat exchanger fin shapes in a thermoelectric power generation system for ship waste heat recovery. It proposes a new curved fin design aimed at enhancing heat transfer efficiency and maximizing thermoelectric power generation capacity. Numerical analysis and response surface methodology (RSM) focused on 225 parameters to identify the optimal fin shape. Computational analysis using CFX was conducted on the thermoelectric module system with curved fins. The methodology was verified by comparing and analyzing CFD and PIV experimental results for a curved fin. The paper comprehensively compares the fluid dynamics of curved fins and straight fins, highlighting how curved fins improve heat exchange by creating a tip leak vortex. The results demonstrate the superiority of the curved fin design in terms of heat transfer efficiency and net power generation over the conventional straight fin design.

Experimental study of optimization of thermoelectric modules’ number and layout for waste heat recovery

A thermoelectric system should be designed in such a way that it harvests as large water heat as possible while using the least modules. To seek an optimal module number, the present study investigates the effect of source temperature, mass flow rate, turbulator, module number and layout on performance of a thermoelectric generator (TEG) system. The experimental results show the optimal module number isn't a fixed value and turbulator has a significant influence on the whole performance of the thermoelectric system. For compact configuration of TEG, using six modules is the best choice without a turbulator, while using eight modules has the best performance with turbulator. The study shows that module layout has a great effect on the thermoelectric system performance. Compared to compact configurations, all separate ones can harvest more power from the hot air except for 32 modules, enhancing by 10–50% whether the turbulator exists or not. In this situation, eight modules are optimal number. The net output power achieves a maximum value of 16.93W and the maximum net efficiency is 3.85% under present experimental parameters. Meanwhile, a new index called power uniformity coefficient is introduced to assess the distribution of output power among TEGs.

Liquid metal-enhanced thermoelectric generator for high-temperature thermal harvesting

It is a challenge to achieve high output power of the thermoelectric generator (TEG) for high-temperature waste heat recovery due to the working fluids with low thermal conductivity (such as air) or low tolerance of temperature (water or oil). In this paper, the gallium-based liquid metal (LM) with a high boiling point (>1000 ℃) and thermal conductivity (>20 W/mK) are introduced to significantly enhance heat charging and discharging at the hot/cold sides of TEG. We also developed an electromagnetic induction pumping method for the effective LM-driven flow at high temperatures. A three-dimensional coupling multi-parameter optimization simulation model of LM-based TEG was developed to reveal the internal heat transfer and power generation mechanism for clarifying the impact factors of the performance. The results have shown that the power generation capacity can be effectively improved by increasing the inlet temperature (Thot-in). It is worth noting that the temperature difference (ΔT) of the TEG module is severely limited by the thermal resistance (Rcapacity) of the LM heat capacity, such as, when the flow rate of 2 L/min, the Rcapacity accounts for 90.6 % (0.020 ℃/W). It is easier to achieve a larger open circuit voltage by increasing the height of the thermoelectric leg, but the Pmax is constantly weakened. Compared with Xceltherm 600 and Solar salt, LM heat transfer fluid has more obvious advantages in enhancing the power generation performance of the system. The LM-based TEG experiment platform was established to study heat transfer and power generation characteristics. The results have demonstrated that good consistency was proved by comparing experimental and numerical data. And the Pmax of the LM-based TEG system is 0.16 W/cm2 at ΔT of 136 ℃. LM-based TEG can open new perspectives for broad applications in high-temperature waste heat recovery.

Evaluation of energy efficiency of thermoelectric energy generator system with heat pipes, solar tracker, Fresnel lens and nano-particle fluids

This study investigated the limits of electrical energy production from a thermoelectric generator in a high thermal efficiency system using pure water and nanofluids called aluminum oxide and titanium dioxide. It was aim to provide efficient thermal performance by using a Fresnel lens, solar glass tube, heat pipe and tracking system. Experimental measurements were made between 10:00 and 14:00 on July 26 and 27 in 2023. On each measurement day, the system containing pure water and a nanofluid was compared. The values of parameters such as temperature, solar radiation, wind speed and Thermoelectric Generator (TEG) open circuit voltage were measured instantaneously during the measurements. These data were used to calculate thermal resistance, electrical efficiency and output power. The results showed that the open circuit voltage increased with increasing solar radiation and, therefore, hot side temperature. The calculations showed that the highest open circuit voltage of 2.76 V was obtained with the mechanism using pure water as the working fluid. However, the obtained electrical efficiency ηe and output power Pmax values remained at 1.06 % and 1.058 W, respectively. Numerical and Artificial Neural Network (ANN) models are widely used to save time and cost in determining the optimal operating conditions of the TEG. Therefore, in addition to the experimental study, a numerical model consisting of TEG and a cooling system, and an Artificial Neural Network (ANN) model were also developed in this study. The average absolute errors for Computational Fluid Dynamics (CFD) and electrical results were obtained in the numerical model as 3.47 % and 2.97 %, respectively. In addition, the average absolute errors in the ANN model were obtained as 0.6 %, 0.5 % and 0.27 % for water, Al2O3 and TiO2 nanofluids, respectively.

Multi-scale CuS-rGO pyramidal photothermal structure for highly efficient solar-driven water evaporation and thermoelectric power generation

Integrated water evaporation and thermoelectric power generation system (IWETPGS) has been recognized to be a promising strategy for the utilization of solar energy. Herein, we developed a new type of IWETPGS with multi-scale pyramidal photothermal structures. They featured three-dimensional pyramidal structures with microscale gradient porous copper foams, as well as micro/nanoscale CuS nanowires and reduced graphene oxide (rGO) composite materials. They combined the merits of efficient multiple refraction and absorption of light, broad-spectrum absorption capabilities of rGO and high near-infrared extinction coefficient of CuS, as well as fast water transportation by gradient porous matrix. These photothermal structures induced a photothermal conversion efficiency of 97.6%. An IWETPGS integrating these structures with a thermoelectric generator (TEG) and microchannel heat sink was developed, and outstanding evaporation and output power performance were obtained simultaneously with an evaporation rate of 2.29 kg/m2h and maximum output power of 1.32 W/m2 under 1 sun illumination. Outdoor tests showed that an average daily water production of 12.1 kg/m2 and a maximum power generation of 5.55 W/m2 was obtained. This work provides a high-performance multi-scale CuS-rGO pyramidal photothermal structure to achieve freshwater and thermoelectric power co-generation, which provides potential opportunities for freshwater and electricity supply in remote areas.

TURBOŞARJLI BİR TRAKTÖR İÇİN BİR TERMOELEKTRİK SOĞUTUCUNUN OPTİMİZASYONU

This work covers a numerical analysis of the design and optimization of a thermoelectric cooler (TEC) operated by a thermoelectric generator (TEG). The aim of the work was to design the optimum mini refrigerator for tractors and also to provide cooling using the energy produced in the TEG used in the tractor. Thanks to the TEC powered with the TEG system, farmers will be able to preserve their food during working hours without additional fuel consumption. When the literature is examined, no study has been found in which cooling is done by using the compressor air of turbocharged systems. Therefore, this work will make an important contribution to the literature. According to the numerical results obtained, while the electrical power requirement was 34.78 W at an outdoor temperature of 30 °C, it was 26.54 W at an outdoor temperature of 15 °C. In other words, while the coefficient of performance was obtained as 0.301 at 15 °C, it was determined as 0.219 at 30 °C. In addition, while the electrical power value produced by the TEG system used in the tractor for an outdoor temperature of 15 °C was 50.71 W, it was 38.84 W at an outdoor temperature of 30 °C.

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.

Parametric study and design optimization of a thermoelectric generator system for waste heat recovery

This article proposes a transient simulation based on Comsol software to investigate the behavior of a segmented thermoelectric device (S-TEG) exposed to a pulsed heat flux. It is found that thermoelectric generators (TEG) incorporating segmented materials have offered greater thermal and electrical performance. An increase in the electrical output power and efficiency of 60% and 40% were reached respectively. Furthermore, the effect of segmentation is most noticeable for short TE leg lengths and large cross-sectional areas. For the S-TEG with a leg length of 2 mm, there is a 104% increase in output power compared to the TEG with a leg length of 3 mm. The effect of asymmetric TE legs on the improvement of the performance of the segmented TEG was carried out. It was found that when a pulsed heat source is applied, the performance of S-TEGs are maximum when the N-leg area is lower than the P-leg area (AN/AP <1). Therefore, to attain the highest TEG performance, an asymmetric shape of AN < AP is required.

Experimental investigation of the external load effect on thermoelectric generator discharge time in a low power energy harvesting system

Thermoelectric generator systems are often evaluated and studied in open circuit and close circuit modes. In the open circuit case, minimum heat flux passes across the thermoelectric module and the module does not have any thermal losses. Moreover, in the close circuit system, the external consumer is connected to the module and higher heat is pumped from its hot side to cold side. Hence, investigating the effect of external load resistance as the consumer connected to the module on its response is a significant issue in thermoelectric systems. In this study, to evaluate the effect of various consumers (4, 8, 10, 15, 20 and 30 Ω) over the module on discharge time, output voltage and temperature on both sides of the module, thermoelectric systems lacking and containing phase change material as the useful means for energy storage and thermal management of thermoelectric system were designed and exposed to constant heat loads. Results of this study show that the power consumption of the internal resistance of the module (connected to the consumer) led to an increase in the temperature of both sides of the module compared to open circuit systems. Therefore, the thermal balance and temperature distribution over the module changes and more affected. The maximum output power and discharge time were obtained at the external resistance of 4 Ω (close to the average internal resistance of the module) in the studied systems. The phase change material prevented excessive temperature on the hot side during the charging process and provided proper thermal management to enhance voltage generation and discharge time. The thermoelectric generator is an effective technology in starting consumers with low resistance, such as light bulbs and remote controls.

Unidirectionally Structured Magnetic Phase-Change Composite Based on Carbonized Polyimide/Kevlar Nanofiber Complex Aerogel for Boosting Solar-Thermo-Electric Energy Conversion.

To realize highly efficient solar-thermo-electric energy conversion for clean electricity power generation, we have developed a new type of unidirectionally structured magnetic phase-change composite comprising a carbonized polyimide (C-PI)/Kevlar nanofiber (KNF) complex aerogel as a 3D carbon skeleton porous supporting material, CoFe2O4 nanoparticles as a magnetic additive, polyethylene glycol (PEG) as a phase-change material, and polypyrrole as a photothermal absorption coating layer. The as-fabricated C-PI/KNF complex aerogel exhibits a unidirectional microstructure, high porosity, robust skeleton frame, ultralight weight, and high thermal conductance. Featured with such unique structure and characteristics, the complex aerogel can offer an effective heat and electron transfer method to ensure highly efficient solar-thermal conversion and photothermal energy storage of the developed composite. The developed composite exhibits a high latent heat capacity of over 150 J g-1, outstanding shape stability along with a low leakage of 0.2 wt %, good thermal cycling stability, and high photothermal conversion efficiency of 84.8%. Based on the Seebeck effect, a solar thermoelectric generation system (STEGS) was constructed with the hot side coupled with the developed composite and the cold side immersed in air and ice water. Under 2.0 kW m-2 solar irradiation, the developed STEGS in ice water obtained maximum output voltage and current of 259.7 mV and 27.1 mA, respectively, which are significantly higher than those in air. The output power of the developed STEGS in an ice water environment is 50.6% higher than that in air under 4.0 kW m-2 solar irradiation. More importantly, the developed STEGS in ice water continuously generated output voltage and current for about 810 s without solar irradiation thanks to the latent heat release by the PEG component within the developed composite. In addition, the introduction of magnetic CoFe2O4 can accelerate solar-thermal conversion through periodic electron motion by the Néel relaxation or Brownian relaxation. This resulted in an increase in the maximum output voltage and current by 13.7 and 11.5%, respectively, under an alternating magnetic field as a result of the magnetism-accelerated solar-thermo-electric conversion. This study offers an innovative approach for developing PCM-based advanced functional materials for solar energy utilization in clean and sustainable electricity generation.

Impact of internal connections and heat loss on simulated large-scale low-temperature thermoelectric generation system

Thermoelectric generator (TEG) has been demonstrated as a desirable technology for deeply harvesting low-temperature waste heat discharged from industrial processes. Due to the multilayer hollow structure, the internal connection-and-contact (ICC) effects and heat loss can cause considerable performance degradation in TEGs. In this study, a two-dimensional thermal-electrical model is established to realize multi-parameter optimization of large-scale plate TEG systems including the ICC layers and heat transfer coefficient on the TEG surfaces. The ICC effects are identified for different side-surface heat transfer coefficient, by using gradient search method to match with the experimental data. The results show that, the ICC effects have significant impact on maximum output power and optimal design parameters in the TEG, while impact of the side-surface heat transfer coefficient is not significant. In the model without ICC effects and heat loss, when the thermoelement length increases, the maximum output power changes negligibly, and corresponding cost-to-power ratio increases monotonously. However, when the ICC effect is coupled with the side-surface heat transfer coefficient, the maximum output power increases significantly while the cost-to-power ratio varies non-monotonously. Therefore, considering the real ICC effects is crucial for optimum design of large-scale TEG systems operating at low temperatures.

Effect of an Exhaust Heat Exchanger with Inserts on the Performance of Thermoelectric Generators

A thermoelectric generator is used as a waste heat recovery system for generating electric power. The thermoelectric generator system consists of an exhaust heat exchanger, a thermoelectric module, and a water heat exchanger. The aim of the current work is to explore different types of inserts used in the test section of the exhaust heat exchanger and power generation of thermoelectric generators at different operating conditions. An experimental setup has been developed for conducting experimental investigation on thermoelectric generators to find the effect of the exhaust heat exchanger (EHE) with inserts on the performance of thermoelectric generators. The cone (G-type test section) and cone-cylinder (H-type test section) type inserts were introduced to enhance the performance of the thermoelectric generator. Compared with an insert-free (empty, F-type) thermoelectric generator with cone and cone-cylinder type inserts in terms of the output power, the average heat transfer rate and convection heat transfer coefficient of F-type, G-type, and H-type test sections of the EHE are 358, 468, and 459 W and 76, 100, and 97 W/m2K, respectively. It shows that the G-type test section of EHE exchanges more heat from engine exhaust to the hot surface of the thermoelectric module through the wall of the EHE. The G-type test section created more temperature difference; obviously, it generated more power output. It was observed that the G-type and H-type test sections of exhaust heat exchangers improved average maximum output power by 29.49% and 26.11% than that by the F-type test section of heat exchanger, respectively. The F-type, G-type, and H-type test sections of exhaust heat exchangers showed a maximum average efficiency of 0.80, 0.78, and 0.70%, respectively.