Thermoelectric Power Generation Device Research Articles

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.

Thickness-dependent thermoelectric properties of ultrathin polymer film on self-assembled monolayers

Conductive polymers have attracted attention for wearable and implantable thermoelectric devices due to their lightweight, flexibility, and solubility. With the development of microsystems, thermoelectric power generation devices are trending toward miniaturization, flexibility, high integration, and lightweight thin films. Therefore, the study of the thickness of thermoelectric materials has become increasingly important. In this study, we prepared ultrathin polymer thermoelectric (TE) films with different thicknesses (14–52 nm) by modifying the substrate with self-assembled monolayers (SAMs). The thickness-dependent thermoelectric performances on SAMs are investigated. It is found that SAMs regulate the carrier concentration in polymer ultrathin TE films, and a smoother surface contributes to the improvement of carrier mobility, thus optimizing the thermoelectric performance. The maximum modulation of thermoelectric performance is observed at a film thickness of approximately 35 nm, which contains nine molecular layers.

Promoted Na Solubility and Modified Band Structure for Achieving Exceptional Average ZT by Extra Mn Doping in PbTe.

Na doping strategy provides an effective avenue to upgrade the thermoelectric performance of PbTe-based materials by optimizing electrical properties. However, the limited solubility of Na inherently restricts the efficiency of doping, resulting in a relatively low average ZT, which poses challenges for the development and application of subsequent devices. Herein, to address this issue, the introduced spontaneous Pb vacancies and additional Mn doping synergistically promote Na solubility with a further modified valence band structure. Furthermore, the induced massive point defects and multiscale microstructure greatly strengthen the scattering of phonons over a wide frequency range, leading to a remarkable ultralow lattice thermal conductivity of ∼0.42 W m-1 K-1. As a result, benefiting from the significantly enhanced Seebeck coefficient and superior thermal transports, a high peak ZT of ∼2.1 at 773 K and an excellent average ZT of ∼1.4 between 303 and 823 K are simultaneously achieved in Pb0.93Na0.04Mn0.02Te. This work proposes a simple and constructive method to obtain high-performance PbTe-based materials and is promising for the development of thermoelectric power generation devices.

Flexible p-n thermoelectric power generation device using SWCNT film with high heat dissipation effect

Flexible p-n thermoelectric power generation device using SWCNT film with high heat dissipation effect

Influence and comprehensive evaluation of porous metal foam filled fins on the performance of power cable surface waste heat recovery thermoelectric power generation device

Cables are essential components in power systems. Certain amount of heat is generated during the energy transfer process. Effective recovery and utilization of waste heat generated by cables is a helpful proposition. In this study, a cable waste heat recovery thermoelectric generation device (CTEG) is proposed. By installing cooling fins and thermoelectric generation devices on the cable surface, the waste heat on the cable surface is converted into electric energy. To improve the power generation efficiency of the device, a method of filling porous metal foam material in the fin teeth gap is used. The results demonstrate that filling the fin teeth gap with porous metal foam material with high porosity and low pore density (PPI) can significantly increase heat transfer efficiency and benefit the output power of the thermoelectric generation device. The flow field in the pipeline of thermoelectric generation device is also analyzed in this study. A comprehensive evaluation method is proposed to consider the power generation efficiency and heat transfer efficiency of the thermoelectric generation device. It is shown that filling porous metal foam material with high porosity and low pore density can maximize the power generation efficiency of the thermoelectric generation device, and at the same time, the pipe pressure drop loss can be compensated by the improvement of heat transfer. This research is significant because it provides useful information for enhancing the energy conversion efficiency of thermoelectric generation devices that recover waste heat from cable surfaces and generate electrical power.

Efficient Separation and Purification Method for Recovering Valuable Elements from Bismuth Telluride Refrigeration Chip Waste.

Bismuth telluride and its alloys are widely utilized in thermoelectric refrigeration and power generation devices. Waste bismuth telluride-based cooling chips contain valuable elements; however, recycling processes for these materials remain underdeveloped due to their complexity. In this study, we developed a concise and efficient chemical method that does not require expensive reagents or equipment, enabling the separation and purification of tellurium, bismuth, selenium, and antimony from waste bismuth telluride-based cooling chips. Initially, the waste was leached with HCl and NaClO3 to dissolve primary elements and recover 99.9% of selenium using hydroxylamine hydrochloride. Subsequently, Na2S and NaOH were employed for precipitation and leaching, resulting in a solution containing tellurium. The precipitated residue was treated with HNO3 to oxidize antimony into insoluble SbOHN and dissolve bismuth completely. 99.8% of the bismuth telluride waste was dissolved via oxidative leaching through hydrolysis. A small amount of sodium sulfide reduced the precipitation percentage of tellurium from 11.9% to 7.5% in an alkaline solution, and the direct recovery percentage of tellurium in the form of TeO2 exceeded 90%, while the purity of TeO2 reached 99.9%. By adjusting the pH of the bismuth solution to 0.15, 98.9% of the bismuth was able to precipitate and be recovered as BiOCl, with the purity also reaching 99.9%. In summary, this study presents an efficient hydrometallurgical method for treating bismuth telluride waste and provides theoretical guidance for reagent dosage, demonstrating the significant potential for industrial applications.

Effects of Installing Different Types of Cooling Fins on the Cold Side of a Thermoelectric Power Generation Device on the Thermal Efficiency and Exergy Efficiency of Power Cable Surface Waste Heat Recovery.

This study investigates the thermal efficiency and exergy efficiency of a thermoelectric power generation device for recovering power cable surface waste heat. Numerical simulations are conducted to analyze the impact of different types of cooling fins on the system's performance. The results demonstrate that the installation of cooling fins improves heat transfer efficiency and enhances the thermoelectric power generation device's output power. Among the various fin designs, the system equipped with cooling fins with 17 teeth exhibits the highest performance. These findings highlight the importance of fin design in optimizing the system's thermal efficiency and exergy efficiency. This study provides valuable insights for the development and improvement of thermoelectric power generation systems for power cable surface waste heat recovery applications.

Gibbs Adsorption and Zener Pinning Enable Mechanically Robust High-Performance Bi2 Te3 -Based Thermoelectric Devices.

Bi2 Te3 -based alloys have great market demand in miniaturized thermoelectric (TE) devices for solid-state refrigeration and power generation. However, their poor mechanical properties increase the fabrication cost and decrease the service durability. Here, this work reports on strengthened mechanical robustness in Bi2 Te3 -based alloys due to thermodynamic Gibbs adsorption and kinetic Zener pinning at grain boundaries enabled by MgB2 decomposition. These effects result in much-refined grain size and twofold enhancement of the compressive strength and Vickers hardness in (Bi0.5 Sb1.5 Te3 )0.97 (MgB2 )0.03 compared with that of traditional powder-metallurgy-derived Bi0.5 Sb1.5 Te3 . High mechanical properties enable excellent cutting machinability in the MgB2 -added samples, showing no missing corners or cracks. Moreover, adding MgB2 facilitates the simultaneous optimization of electron and phonon transport for enhancing the TE figure of merit (ZT). By further optimizing the Bi/Sb ratio, the sample (Bi0.4 Sb1.6 Te3 )0.97 (MgB2 )0.03 shows a maximum ZT of ≈1.3 at 350 K and an average ZT of 1.1 within 300-473 K. As a consequence, robust TE devices with an energy conversion efficiency of 4.2% at a temperature difference of 215 K are fabricated. This work paves a new way for enhancing the machinability and durability of TE materials, which is especially promising for miniature devices.

Latent and controllable doping of stimuli-activated molecular dopants for flexible and printable organic thermoelectric generators

Conjugated polymers (CPs) are a promising class of materials for organic thermoelectric generators (OTEGs); however, achieving high electrical conductivity through molecular doping while maintaining compatibility with thin-film printing processes remains a huge challenge. In this paper, we present a novel doping strategy using stimuli-activated molecular dopants (SAMDs) based on photoacid generators (PAGs) that can be activated by light of a specific wavelength. We demonstrate that this approach can effectively control the doping efficiency and optoelectronic properties of CP-PAG-blended thin films, resulting in a wide range of electrical conductivities. Our selected PAG molecules enabled efficient printing of the CP-PAG mixed solution and yielded a high thermoelectric figure of merit. To elucidate the mechanism behind this high thermoelectric performance, we systematically investigated the morphologies, microstructures, and energy structures of the PAG-doped CP thin films and performed various comparative tests. We also demonstrate the feasibility of using SAMDs to print flexible OTEG modules on thin polyimide substrates. We believe that our work represents a significant step toward the development of efficient, scalable, and sustainable thermoelectric devices for power generation and waste heat recovery, and highlights the advantages of PAG-based SAMDs for printable organic thermoelectrics.

Experimental Study on the Efficiency of Dynamic Marine Thermal Energy Generator Based on Phase Change Compensation

Miniaturized detection devices in the ocean generally experience problems such as short endurance and unreliable power supplies. This article aimed to develop a dynamic ocean temperature difference energy collection device to capture ocean temperature difference energy and provide objective electricity for stable detection devices. The main focus was to conduct experimental research on the effectiveness of a dynamic ocean temperature difference energy power generation device. During the research process, the fact that ammonia gas in a working fluid is easy to liquefy and vaporize was utilized. By utilizing the increase in seawater temperature during the floating process of the device, it vaporized and drove the turbine to rotate for power generation. In the structural design, multiple sets of small air chambers were creatively proposed, which could effectively control the air pressure and improve the stability of the airflow. By charging the airflow to impact the turbine, multiple sets of power generation fans were used to form a stable current. Further, the buoyancy of the device could be changed by adding phase change materials between the air chamber and the device shell, and the temperature difference between the two ends of the phase change materials could be used to change the electron density of the material to form a weak current. In this experimental study, concepts such as the structural design of multiple small gas chambers, miniaturization of energy collection devices, compensation power generation of phase change materials, and application scenarios of devices combined with Argo buoys were all proposed for the first time. The results of this experimental study indicate that the overall power generation of the device is about 2A, and its maximum output power amplitude is about 22 W. The cyclic thermal efficiency of the power generation device can be increased from +0.19% to +0.88%. The development of this thermoelectric power generation device can provide a considerable stable power supply for ocean observation devices, especially the buoy device represented by Argo, which can extend the endurance of deep-sea exploration devices.

Maximizing energy generation: A study of radiative cooling-based thermoelectric power devices

In the present study, a continuous thermoelectric power generation device (CTEGRC) has been fabricated by combining the recently proposed radiative cooling paint with a commercially available thermoelectric generator (TEG) to achieve continuous power generation throughout the day. The CTEGRC has been modeled and the results have been verified through experiments, and then the effects of structural and environmental parameters on the performance of the CTEGRC have been discussed in detail. The annual performance of the CTEGRC has been evaluated for five different weather conditions (five cities in China) based on the established model. It has been shown that an annual power generation of 241.46 Wh/m2-423.86 Wh/m2 can be achieved for the applications of the CTEGRC in the five climate zones of China based on an optimal area ratio of 11 for the radiative cooling module to the TEG.

Effect of post-annealing treatment on the thermoelectric properties of Ag2Se flexible thin film prepared by magnetron sputtering method

Flexible thermoelectric power generation devices can help solve the power supply problem of wearable electronic devices. Herein, single-phase Ag2Se films with a thickness of less than 500 nm were deposited on flexible polyimide substrates via magnetron sputtering. The microstructure, chemical composition, and thermoelectric properties of the films were investigated at different annealing temperatures (523 K–673 K). After annealing, the X-ray diffraction (XRD) test showed that the film had obvious preferential growth in the (002) and (004) crystallographic directions. Scanning electron microscopy (SEM) showed that with increasing annealing temperature, the size of the grains initially increased and subsequently decreased. Finally, after annealing at 623 K for 20 min, the film obtained a peak power factor of 526.86 μW∙m−1∙K−2. A six-leg flexible generator comprising Ag2Se films has a maximum power density of 7.52 W∙m−2 (50 K temperature difference). After 1000 bending times, the resistivity of the device changed by only 14.11 %, and the actual application test revealed an output voltage of 12.3 mV and a power of 23.49 nW under a temperature difference of 22.2 K. This work demonstrates that thermal treatment of thin films prepared by magnetron sputtering is a remarkable approach to increase thermoelectric performance, providing an efficient fabrication scheme for the development of environmentally friendly and wearable flexible thermoelectric devices.

Enhancement of electrical transport properties in CrSi2-NbSi2 composite synthesized by the AM-SPS technique

Waste heat can be harnessed into electrical energy by employing thermoelectric power generation devices. Chromium disilicides are being considered as p-type thermoelectric material which is used in thermoelectric devices for waste heat recovery applications in the mid-temperature regime owing to their low cost, stability and constitute of earth-abundant elements. In the current work, spark plasma sintering was used to develop CrSi2-NbSi2 composite materials via arc melting. The surface morphology of all the synthesized samples was examined using a field emission scanning electron microscope and the elemental mapping confirms the homogenous distribution of both the CrSi2-NbSi2 phases. The phase structure of each sample was identified using X-ray diffraction. The Seebeck coefficient and the resistivity was determined for all the samples between 300 K and 800 K. A significant power factor value of ≃ 1.44 × 10-3 W/mK2 was achieved at 423 K in an optimized composition of CrSi2/2 wt% NbSi2 material in comparison to pristine ≃ 0.92 × 10-3 W/mK2 sample. It is primarily caused by the metallic NbSi2 phase that was incorporated into the CrSi2 matrix, which increased electrical conductivity and leads to the enhancement of thermoelectric performance of CrSi2.

High-Efficiency Power Generation Device of Magnetic Declination Thermoelectric Material and Multisource Coordination Optimization of Distribution Network

The first-order phase transition compounds have attracted widespread attention from refrigeration enterprises and scientists due to their giant magnetocaloric effect and refrigeration temperature region spanning room temperature. Magnetic substances are crystal structures composed of magnetic ions or atoms with a certain thermal motion or vibration. This research mainly discusses the multisource coordination optimization of magnetic declination thermoelectric material efficient power generation device and distribution network. In this study, large doses of MnFe(P,Si) compounds with different ratios were prepared. The reason for choosing a large dose is that the properties and structures of the samples prepared in a large amount and a small amount will be more or less the same for the samples fired in the same proportion and in the same process. At the same time, mass production also prepares for future mass production. Thermomagnetic power generation described in this study is a form of power generation that converts thermal energy directly into electrical energy. The conversion of thermal energy to electric energy is realized by the change of magnetization in the closed coil by the thermomagnetic material in the magnetic field environment, and then, the change of the magnetic flux in the closed coil is realized. The distribution network refers to the power network that receives electrical energy from the transmission network or regional power plants and distributes it locally through distribution facilities or distributes it to various users step by step according to the voltage. It is composed of overhead lines, cables, towers, distribution transformers, isolating switches, reactive power compensators, and some ancillary facilities. A network that plays an important role in distributing electrical energy in the power grid. This research starts with the active distribution network scheduling priority and the distribution network scheduling coordination control framework. Combined with the scheduling and operation characteristics of each component in the distribution network, the coordinated optimization scheme of the distribution network and the source-network load-storage coordinated control framework are investigated and analyzed. The scheduling resources of the model include the power of the substation flowing into the distribution network, the output of the adjustable distributed power source, the output value of the energy storage element, the closing status of the tie switch, and the section switch. In the study, it was found that when the Fe content was 0.63, the Curie temperature of the compound could reach 273 K at the highest. Scientifically designing a thermomagnetic power generation demonstration device is an important part of the realization of thermomagnetic power generation. The magnetic declination thermoelectric materials designed in this study will help to improve the power generation efficiency.

Fabrication of ultrafine powder using processing control agent, and investigation of its effect on microstructure and thermoelectric properties of p-type (Bi, Sb)2Te3 alloys

Low-dimensional materials can significantly enhance the efficiency of thermoelectric devices for power generation and cooling applications. In the present work, ultra-fine powders of p-type (Bi, Sb)2Te3 alloys are fabricated through high energy ball milling using stearic acid as a process control agent (PCA). The influence of the PCA addition on powder characteristics, microstructure and thermoelectric transport properties are studied. Further, the ultra-fine powder is subjected to calcination (Cal-PCA) and subsequently consolidated all powders using spark plasma sintering (SPS). The PCA, Cal-PCA, and non-PCA powder morphological effects on the microstructure and thermoelectric properties are systematically investigated and elucidated thoroughly. The electron beam scattering diffraction (EBSD) results confirmed that the PCA sample exhibited very fine grains (average grain size of ∼800 nm) compared to the non-PCA (average grain size of about 2.6 µm), while the grains were distributed randomly for all samples. Formation of fine grains and partial existence of the stearic acid (carbon and oxygen phases) in the matrix were strongly inhibiting the transport of the carriers that severely decreased the carrier mobility, reflecting the severe reduction in electrical conductivity for PCA sample compared to Cal-PCA and non-PCA. The lowest thermal conductivity (κ) of 0.745 W/mK was achieved for the PCA sample, which is 19%, 12% lower than that of non-PCA, and Cal-PCA samples. The strong reduction in κ was mainly attributed to the dramatic decrease in the phonon thermal conductivity owing to phonon scattering at numerous grain boundaries and oxide phases. The obtained high electrical conductivity with balanced thermal conductivity in Cal-PCA sample is attributed to the significant improvement in ZT of 1.1, which is 27%, and 47% higher than that of the Non-PCA sample at room temperature, and 350 K, respectively.

Effect of cooling condition on the performance of thermoelectric power generation system coupling with PCM module

In this study, a thermoelectric power generation (TEG) system coupling with PCM module for thermal control and storage has been fabricated. Bismuth Telluride (Bi2Te3) TEG devices were applied to convert heat into electricity and Sn- Ag-In alloy PCM was employed for heat storage. A cooling channel with pure water and graphene nanofluids as heat exchange media was attached tightly with the cold-sides of the TEG devices. The effects of the flow rate of cooling water and the mass fraction of graphene nanofluids on the heat transfer process and the performance of the as fabricated TEG-PCM coupling system have been investigated. It is found that increasing the heat exchange capability of the cooling channel would help the PCM module to enhance the heat absorption and utilization of thermal energy from heat source, which in turn brings about the improvement of efficiency of TEG system. The output voltage of TEG system by using pure water for cooling is improved by 6.6%-13.1% with the acceleration of flow rate. Using graphene nanofluids as heat exchange media, the TEG system could achieve 7.2%-18.5% enhancement in output voltage with an increase in the mass fraction of the used nanofluid.

Optimal Design and Performance Analysis of Thermoelectric Power Generation Device Based on Multi‐Objective Genetic Algorithm

AbstractThe combined use of flue gas waste heat resources and thermoelectric generators (TEGs) is considered to be a relatively reliable method to generate electricity. The focus of this study is on the optimization and improvement of the hot‐end heat collection pipe. This paper aims to increase the temperature difference between hot and cold ends of TEG and enhance uniformity of temperature distribution, thereby improving the output power of the TEG system. To balance the temperature difference between the cold and hot ends of the TEG, the pressure drop from the inlet to the outlet and the mass of TEG hot end pipes, a finite element simulation model is constructed. Meanwhile, a multi‐objective genetic algorithm is applied to optimize the structure of four dimensions: fin bottom length, fin height, fin thickness, and outlet diameter. Three optimization objectives, namely, average temperature difference, total pressure drop from inlet to outlet, and pipeline mass are globally optimized to determine the best size, based on which the accuracy of the simulation model is verified by conducting experiments.

Transport properties of RuV-based half-Heusler semiconductors for thermoelectric applications: a computational study

A systematic study of electronic structure, mechanical and transport properties of RuV-based half-Heusler alloys (RuVZ, Z = As, P, Sb) have been presented using ab initio density functional and Boltzmann transport theory. The electronic structures are obtained using generalized gradient approximation with Perdew–Burke–Ernzerhof functional. All the compounds are crystallized in face centered cubic phase with space group #216. Our preliminary electronic structure simulations reveal that all the alloys are non-magnetic semiconductors. Additionally, the phonon dispersion and elastic constants (along with the related elastic moduli) also verify mechanical stability of the alloys. Due to strong dependence on the electronic bandgap in thermoelectric materials, we have estimated bandgap using more accurate hybrid functional i.e. Heyd–Scuseria–Ernzerhof. The transport coefficients (e.g. Seebeck, electrical conductivity, thermal conductivity due to electrons) are calculated by solving the Boltzmann transport equation for charge carriers as implemented in BoltzTraP software under constant relaxation time approximation. The lattice thermal conductivity due to phonons is calculated using more reliable shengBTE code based upon the Boltzmann transport equation for phonons. We have calculated the more reliable value of the thermoelectric figure of merit, ZT (related to the conversion efficiency) for all the compounds. The obtained ZT for RuVAs, RuVP and RuVSb is 0.41(0.32), 0.21(0.16) and 0.70(0.61) for p(n)-type behavior at 900 K. The corresponding carrier concentrations are also predicted. High value of ZT is obtained for RuVSb alloy due to low lattice thermal conductivity. Among these compounds, RuVSb emerged out as a most suitable candidate for thermoelectric power generation device. Minimum lattice thermal conductivity in theoretical limit along with the corresponding maximum value of ZT is also predicted in these alloys.

Parametric study of asymmetric thermoelectric devices for power generation

Parametric study of asymmetric thermoelectric devices for power generation

Al-Si Alloy as a Diffusion Barrier for GeTe-Based Thermoelectric Legs with High Interfacial Reliability and Mechanical Strength.

To build high-performance thermoelectric (TE) devices for power generation, a suitable diffusion-barrier layer between the electrodes and the TE materials in a TE device is generally required for achieving good interfacial connection with high reliability, high mechanical strength but low electrical and thermal contact resistivities. GeTe-based materials have attracted great attention recently due to their high TE performance in the mid-temperature range, but studies on their TE devices are still limited. Here, we selected the Al66Si34 alloy as a diffusion barrier for GeTe-based TE legs based on the matching test of the coefficient of thermal expansion. The good connection between Al66Si34 and Ge0.9Sb0.1TeB0.01 is realized by the interfacial reaction, where the randomly distributed Al2Te3 and Ge precipitates are formed at the interface of the joint. The as-prepared interfacial electrical contact resistivity can be as low as 20.7 μΩ·cm2 and only slightly increases to 26.1 μΩ·cm2 after 16 days of aging at 500 °C. Moreover, the shear strength of the joints can be as high as 26.6 MPa and unexpectedly increases to 41.7 MPa after 16 days of aging. The thickness of the reaction layer tends to be stabilized after 8 days of aging and nearly does not change after further aging to 16 days, which may be ascribed to the drag effect from Si and the secondary Ge phases. These results demonstrate the great potential of the Al-Si alloy as a diffusion barrier for GeTe-based TE devices with high performance.