Thermoelectric System Research Articles

General Figures of Merit ZQ for Thermoelectric Generators Under Constant Heat-In Flux Boundary.

The thermoelectric figure of merit ZT bridges the efficiency and material parameters for a thermoelectric device operating under constant temperature of the hot- and cold-source thermal boundary (Type-I TB). However, many application scenarios fall under the constant heat-in flux (qh ) and constant cold-source temperature (Tc ) thermal boundary (Type-II TB), for which a figure of merit is absent for more than half a century. This study aims to fill this gap and propose a figure of merit ZQD for the thermoelectric devices under the Type-II TB condition, defined as , where Z, h, and κ are the traditional figure of merit, leg height, and thermal conductivity, respectively. The effectiveness of ZQD is verified through both numerical calculations and experiments, which are more accurate and practical than ZT. Furthermore, a system-level figure of merit ZQS is suggested after considering the external thermal resistance. Finally, optimization strategies for thermoelectric systems based on ZQS are proposed, showing a 30% enhancement in the efficiency. ZQD and ZQS are expected to be widely used in the thermoelectric field.

A new metaheuristic honey badger-based maximum energy harvesting algorithm for thermoelectric generation system under dynamic operating conditions

A new metaheuristic honey badger-based maximum energy harvesting algorithm for thermoelectric generation system under dynamic operating conditions

Cooling by Coulomb Heat Drag Based on Three Coupled Quantum Dots

We establish a model for a four-terminal thermoelectric system, based on three coupled quantum dots, which consists of a left/right electron reservoir (the source and the drain), two thermal reservoirs and three coupled quantum dots. Based on the master equation theory, we derive the expressions of the electron current and heat flow among the three quantum dots and the corresponding reservoir. We show that the source can be cooled by passing a thermal current between the two thermal reservoirs, with no net heat exchange between the thermal reservoirs and the electron reservoirs. This effect is called the Coulomb heat drag effect. Then, we define the coefficient of performance (COP) and the cooling power. The influence of the main system parameters, such as charging energy, energy level, and temperature, on the performance of the four-terminal thermoelectric system is analyzed in detail. By choosing appropriate parameters one can obtain the maximum cooling power and the corresponding COP. Finally, we also show that the Maxwell demon effect can be realized by using nonequilibrium thermal reservoirs in our four-terminal thermoelectric system.

Preparation, morphology and thermoelectric performance of PEDOT/CuI nanocomposites

Incorporating inorganic nanomaterials into a polymer matrix is one of the most effective ways to create thermoelectric performance for applications where physical flexibility is essential. In this study, flexible thermoelectric nanocomposite films were synthesized by incorporating inorganic copper iodide (CuI) nanosheets as the filler into poly (3,4-ethylene dioxythiophene): poly (styrene sulfonate) (PEDOT: PSS). The process involved the preparation of bulk CuI from precursors and, subsequently, the nanosheet synthesis by dissolving the bulk CuI in dimethyl sulfoxide (DMSO). The morphology of the nanosheets and the nanocomposite films was thoroughly examined, and the film’s thermoelectric performance was evaluated using a standard thermoelectric measurement system, ZEM-3. The morphological observation revealed a triangular nanosheet geometry for CuI, with an average lateral dimension of ~33 nm. The PEDOT/CuI nanocomposite films were prepared by mixing CuI nanosheets with PEDOT: PSS through ultrasonication and filtration on a PVDF membrane. The film with 6.9 vol% of CuI nanosheets exhibited an electrical conductivity and Seebeck coefficient of 852.07 S·cm-1 and 14.95 µV·K-1, respectively. This resulted in an enhanced power factor of 19.04 µW·m-1·K-2, much higher than the individual composite components. It demonstrated a trend of increasing power factor with the nanosheets up to 6.9 vol% due to improved electrical conductivity. The increase in electrical conductivity can be attributed to the screening effect induced by DMSO, which leads to a conformational change in the PEDOT chains. Furthermore, an optimal fraction of CuI nanosheets also contributes to this conformational change, further enhancing the electrical conductivity.Graphical

Investigating the modified thermoelectric generator system performance

AbstractIt is essential to enhance the performance of the thermoelectric generator as lower efficiencies are obtained recently. This could be achieved by changing its dimensions in addition to copper strip thickness. The present study is performed to obtain the best dimensions of the P–N legs considering the interaction between all variables. To do this, a comprehensive TEG model is achieved in addition to utilizing the single-objective optimization technique. The main performance metrics, including electricity production and conversion efficiency, are assessed, and contrasted with the conventional TEG system since the simulation. The length of the legs and their cross-sectional area were shown to significantly affect power production. The thickness of the conducting plate, in contrast, barely matters. For instance, a P–N pair with legs that have a 2 mm2 cross-sectional area generates 0.4 W and 1.3 W for temperature differences of 480 °C and 980 °C, respectively. Furthermore, the equivalent efficiencies are 4.41% and 6.73%, respectively. Using the genetic algorithm revealed that the ideal values for the leg cross section, leg length, and conducting plate thickness are 1.84 mm2, 0.5 mm, and 0.44 mm, respectively. Once compared to the conventional system, using the optimization method results in an improvement in power production and conversion efficiency of about 247% at a temperature differential of 980 °C.

Effect of filter material and porosity on the energy storage capacity characteristics of diesel particulate filter thermoelectric conversion mobile energy storage system

The thermal energy generated by the diesel particulate filter (DPF) is converted into electrical energy through the thermoelectric generator (TEG) and stored in a mobile battery power energy storage (MBPE) system. The filter material and porosity directly affect the regeneration temperature of the DPF, which in turn affects the thermoelectric conversion capability of the thermoelectric module (TEM). This study explores the energy storage capacity characteristics for the DPF-TEG of the MBPES system at a regeneration temperature of 923 K. The filter materials considered are cordierite, mullite and SiC with porosities of 0.4, 0.45, 0.5, 0.55, 0.6, 0.65 and 0.7. The maximum output power and thermoelectric conversion efficiency are analyzed. The thermal input power for the SiC filter is approximately 2.4 times and 1.8 times than that of the cordierite filter and the mullite filter. As the porosity increases from 0.4 to 0.7, the output current for the DPF-TEG of the MBPES system with the 3 filter materials ranges from 0.66 A to 2.11 A. The output voltage changes from 50.62 V to 161.98 V. The maximum output power varies from 33.36 W to 341.59 W and the conversion efficiency rises from 0.88% to 2.72%.

Design and Power Generation Characteristics Analysis of a Self-adaptive Thermoelectric Power Generation System Based on LTspice

Design and Power Generation Characteristics Analysis of a Self-adaptive Thermoelectric Power Generation System Based on LTspice

Mechanism of Thermoelectric Performance Enhancement in CaMg2 Bi2 -Based Materials with Different Cation Site Doping.

Chemical bonds determine electron and phonon transport in solids. Tailoring chemical bonding in thermoelectric materials causes desirable or compromise thermoelectric transport properties. In this work, taking an example of CaMg2 Bi2 with covalent and ionic bonds, density functional theory calculations uncover that element Zn, respectively, replacing Ca and Mg sites cause the weakness of ionic and covalent bonding. Electrically, Zn doping at both Ca and Mg sites increases carrier concentration, while the former leads to higher carrier concentration than that of the latter because of its lower vacancy formation energy. Both doping types increase density-of-state effective mass but their mechanisms are different. The Zn doping Ca site induces resonance level in valence band and Zn doping Mg site promotes orbital alignment. Thermally, point defect and the change of phonon dispersion introduced by doping result in pronounced reduction of lattice thermal conductivity. Finally, combining with the further increase of carrier concentration caused by Na doping and the modulation of band structure and the decrease of lattice thermal conductivity caused by Ba doping, a high figure-of-merit ZT of 1.1 at 823 K in Zn doping Ca sample is realized, which is competitive in 1-2-2 Zintl phase thermoelectric systems.

Electrothermal transport of water conveying copper, silver and alumina nanoparticles through a vertical wavy microchannel

This study emphasizes the significance of optimizing heat transmission, energy conversion, and thermal management in electronic devices, renewable energy systems, and emerging technologies like thermoelectric devices and energy storage systems. The aim is to enhance heat transfer efficiency for improved performance and lifespan of electronic equipment. The research utilizes a mathematical flow analysis to study a water-based ternary nanofluid’s flow and thermal characteristics in a vertical microfluidic channel driven by peristalsis and electroosmosis. The ternary-hybrid nanofluid (THNF), comprising copper, silver, and alumina nanoparticles dissolved in water, is examined considering induced magnetic fields. The study delves into fluid flow, heat absorption, and mixed convection, using Debye–Hückel, lubrication, and long wavelength approximations. Results show that THNF exhibits superior heat transmission compared to pure water. Increasing solid volume fraction of nanoparticles decreases THNF’s temperature. Induced magnetic fields impact the system. This research could influence thermal pipe heat sinks and bioengineered medical devices design.

Design and Fabrication of Solar-Powered Portable Thermoelectric Refrigeration System for Thermolabile Pharmaceuticals

Abstract: In order to maintain the therapeutic efficacy of thermolabile medicine and vaccines, electrical energy must be continuously supplied. For remote areas lacking access to electrical electricity, this poses a serious dilemma. The potency level of thermolabile medications and vaccines is decreased, particularly during last-mile delivery, which causes significant financial loss. In this study, we designed and developed a portable active refrigeration system that runs on solar photovoltaic cells for the refrigeration of thermolabile pharmaceuticals to be utilized in rural areas without access to electricity, especially to facilitate last-mile vaccination delivery. The system makes use of a thermoelectric refrigeration system that, when given electrical power, causes a temperature difference based on the Peltier effect. It will be demonstrated that a solar panel with a peak power of roughly 50W and batteries with a storage capacity of 10Ah are needed for a typical application for vaccine refrigeration. The developed refrigeration system has a 3-liter volume capacity and can store 150 vaccine ampules, each with a 10ml capacity, at temperatures between 2°C to 8°C using a Peltier cell (TEC), that consumes 66 W at 12V

Thermal Analysis to Achieve Low Temperature with Thermoelectric Cooling System

Thermal Analysis to Achieve Low Temperature with Thermoelectric Cooling System

Heavy pnictogens-based perovskite-inspired materials: Sustainable light-harvesters for indoor photovoltaics

The need for self-powered electronics is progressively growing in parallel with the flourishing of the Internet of Things (IoT). Although batteries are dominating as powering devices, other small systems, such as piezoelectric, thermoelectric, and photovoltaic systems, are attracting attention. These last ones can be adapted from their classical outdoor configuration to work preferentially under indoor illumination, i.e., by harvesting the spectrum emitted by LEDs and/or fluorescent lamps. However, crystalline silicon, the classical photovoltaic material for solar panels, has a bandgap not suitable for ensuring good efficiency with such spectra. With wider bandgaps, other semiconductors can come into play for this task. Still, the materials of choice, having to be integrated within households, should also satisfy the criterion of non-toxicity and maintain low-cost production. While lead-based halide perovskites cannot represent a valuable solution for this scope, due to the strong environmental and health concerns associated with the presence of Pb, analogous compounds based on the heaviest pnictogens, i.e., bismuth and antimony, could work as sustainable light-harvesters for indoor photovoltaic devices. In this Review, we focus on reporting the most recent developments of three compounds of this class: The double perovskite Cs2AgBiBr6 is first chosen as a model system for the other two, which are emerging perovskite-inspired materials, namely, Cs3Sb2I9−xClx and bismuth oxyiodide. We show the potential of these semiconductors to play a crucial role in the future market of self-powering IoT devices, which will become a large class of devices in the electronics industry in the upcoming years.

PRELIMINARY DESIGN OF THERMOELECTRIC COOLER BOX FOR MUD CRAB (SCYLLA)

Mud Crab (Scylla) is a species of crab that is popular seafood that can be easly found in Indonesia, especially in Sumatera Island. Unlike crab, mud crab can preserve at fishing spot before transportes and distributed. Conventional preservation of mud crab uses block ice to reach -20oC temp in cooler box which is heavy and contribute most on fishing boat. Block ice load is more than 60% of a cooler box and can be easly melt due to inproper handling. Therefore, a more modern method which lighter and lower energy consumption is needed. Preliminary cooler box design with thermoelectric module is conducted. Thermoelectric based system, which is light, saves electricity and does not require a large area on this cooling technology design is expected to provide data and analysis results that help cooler box designers to produce the best performance. The designed cooler box has the need to use it to store seafood such as mud crabs (Scylla). By using a thermoelectric cooling system, the power that can be generated by the thermoelectric module (TEC1-12706) is 56.27 W, the maximum power that generate is 272.5 W, and the power required if the object being cooled is mud crabs (scylla) of 3186 W and requires 17 thermoelectric modules to cool a cooler with a capacity of 30 liters

A Thermoelectric System for Thermal Treatment of the Anterior Segment of the Eye in Humans

A Thermoelectric System for Thermal Treatment of the Anterior Segment of the Eye in Humans

Hybridization of energy systems for air conditioning application in an educational building

This study reports the hybridization of energy systems for an air conditioning (AC) application in an educational building, using the Faculty of Engineering Lecture Theaters at Rivers State University, Port Harcourt, Nigeria as case study. It includes conceptual design of a hybrid energy system of thermoelectric and solar energy, analysis of cooling load to select suitable air conditioning system for the building using Carrier’s Hourly Analysis Program (HAP) software, analysis of the required energy to drive the air conditioning system, and techno-economic analysis of the system. The analysis carried out shows that a total of 4 packaged rooftop air conditioners each of 10.6kW (30,000 Btu/h) capacity would be required to handle the building’s cooling load of 38.28kW, and would require 344.5kWh of energy per day, out of which 249kWh/day would be generated from the thermoelectric generator (TEG) modules, and the remaining 95.5kWh/day would be generated from the photovoltaic (PV) modules. The 249kWh/day of energy required from the thermoelectric energy system would require a total of 1600 TEG modules of 26W each, and the 95.5kWh/day of energy required from the solar system would require a total of 65 PV modules of 330W each. The energy generated would be stored in a 679kWh capacity battery storage system which contains 72 batteries of 48V and 200Ah capacity each, which are wired into 3 parallel strings, which would supply the AC system. The techno-economic analysis carried out shows that the system designed can be implemented at a cost of ₦98,558,000, with a payback period of 9years, and would mitigate 72,050.5kg of CO2 emissions annually.

Popular strategies for constructing polymer gel thermoelectric materials

AbstractPolymeric thermoelectric materials utilizing the Soret effect have the advantages of high Seebeck coefficient, non‐toxicity, light weight, and excellent mechanical properties that make them shine in the field of thermoelectrics. However, ionic thermoelectric systems based on polymer gels are still in their infancy and research is relatively limited, and there is an increasing interest in how to prepare high performance polymer thermoelectric materials. In this paper, we review some of the existing polymer TE materials based on the Soret effect and discuss the different approaches to achieve high Seebeck coefficient and enhanced thermoelectric properties from the perspective of material design strategies. Moreover, we highlight the popular strategies of the construction of thermoelectric materials and provide a brief outlook on the development of the polymer thermoelectric field for its future research.

Air-Stable Semiconducting Ionic Polymers for Thermoelectric Applications

Thermoelectric (TE) devices that interconvert heat and electricity are the promising tools to harvest waste heat and solve energy problems. The current TE market is dominated by inorganic materials such as Bi2Te3 due to their excellent TE performance; however, the issues of inorganics that involve material toxicity, rigidity, heavy weight and energy-intensive processing techniques are limiting the wide applications of TE devices. Choosing organic materials that are light weight, mechanically flexible, abundant and require low-temperature processing, as in our research focus, is paving the path to sustainability and opening up opportunities for a variety of applications such as electronic wearables and sensors.In our study, we aim to design and develop sensors that can detect high electric-field utilizing air-stable ionic polymer TE systems, a novel type of organic semiconductors, via a facile, solution-processing technique. We selected two n-type chloride-based ionic polymers, MADQUAT and PDADMAC as our starting materials because they have relatively low yet reliable ionic conductivities and intrinsically high Seebeck Coefficients under dry condition. The key challenge was that chloride-based polymers were extremely unstable due to their sensitivity to air/moisture and polymer relaxation. We adopted a solution-processable anion exchange technique and successfully created new systems with the same cationic polymer chain but various anions such as tetrafluoroborate (BF4 -) and hexafluorophosphate (PF6 -), that are more hydrophobic, increasing the system stability. Currently, we are investigating our stable ionic polymer TE performance by applying high voltages (500V-2000V) laterally across the samples through a pair of electrodes thermally evaporated on top. The change in TE properties after the high E-field application will help us probe further into the ionic movement of the polymeric systems thermodynamically and kinetically and understand what determines the p/n-type behavior. The thermoelectric sensor for high E-field detection can be incorporated into devices that can detect planetary objects in the outer space as well as microscale biological systems.

Comparative analysis of photovoltaic thermoelectric systems using different photovoltaic cells

The photovoltaic-thermoelectric (PV-TE) system has emerged as a focal point in research endeavors aimed at harnessing the full spectrum of solar energy and enhancing the efficacy of solar power generation. Owing to the variations in bandgap and inherent material properties across diverse photovoltaic cells, the capacity to utilize the solar spectrum of PV-TE systems can be significantly affected when using different photovoltaic cells. Historically, investigations into the influence of photovoltaic cells on PV-TE systems have been predominantly rooted in theoretical simulations. These examinations have primarily concentrated on the holistic system efficiency under varying temperature conditions. In this study, we integrated three distinct types of photovoltaic cells into PV-TE systems. Both simulation and experimental methodologies were employed to evaluate the impact of these photovoltaic cell types on the PV-TE systems' performance. Additionally, we compared the back temperatures of standard PV systems with those of PV-TE systems. The average photovoltaic conversion efficiencies of PV-TE systems equipped with CIGS, CdTe, and a-Si photovoltaic cells were 21.9%, 19.7%, and 12.7%, respectively. Meanwhile, the average efficiencies of TEG were 0.256%, 0.102%, and 0.083% respectively, with average backplate temperatures of 39.3 °C, 44.0 °C, and 40.5 °C. The temperature disparities between the back of standard photovoltaic systems and PV-TEG-PCM systems stood at 4.70 °C, 2.32 °C, and 3.43 °C, respectively. Notably, CIGS photovoltaic cells, which harness a specific range of the solar spectrum more effectively, showcased superior performance. Furthermore, a broader usable solar spectrum band for a PV cell doesn't always translate to enhanced performance. These findings offer valuable insights for optimizing the power generation capabilities of photovoltaic-thermoelectric systems leveraging full-spectrum solar energy.

Investigations of microstructures and thermoelectric properties of TiNiSn half-Heusler compounds with micro- and nano-scale copper additions

The TiNiSn-based half-Heusler compounds have been considered as a promising thermoelectric material system for waste heat recovery applications. There have been numerous studies dedicated to improving its intrinsic low thermoelectric performance, and one strategy is to incorporate certain types of metal dopants into the host materials. Only a few research works have been focused on the effects of the dimensions of metal particles on the thermoelectric properties of materials. In this study, we investigate the roles of micro- (M) and nano-scale (N) Cu powders in affecting the microstructures and thermoelectric properties of TiNiCuxSn (x = 0−0.1) compounds. Owing to the ease of oxidation of Cu nanoparticles and the tedious preparation procedure, TiNiCux, NSn shows lower carrier concentration and electrical conductivity compared to the TiNiCux, MSn with the same nominal Cu content. The high-temperature Seebeck coefficient of TiNiCux, NSn gradually deteriorates as the temperature rises, partly due to the impurities-induced bandgap narrowing effect. The maximum power factor achieved for TiNiCux, NSn is about 20.2% lower than that for TiNiCux, MSn. Even though the reduced contribution of electronic component leads to a lower total thermal conductivity at low temperatures, the highest zT obtained in TiNiCux, NSn is markedly lower than that in the corresponding TiNiCux, MSn. These findings highlight the importance of investigating the dimensions of metal dopants in studies of the thermoelectric properties of materials.

Efficient energy valley optimization approach for reconfiguring thermoelectric generator system under non-uniform heat distribution

A thermoelectric generator (TEG) suffers from low conversion efficiency, especially when it has been operated under non-uniform temperature distribution. Dynamic reconfiguration is an effective method to enhance the TEG overall efficiency although it requires many electrical switches that make the process more complex. This paper proposes a new approach of energy valley optimizer (EVO) to optimally reconfigure the TEG array operated at non-uniform temperature distribution and enhance the harvested electrical energy. The selection of EVO is due to fast convergence rate, parameter-free, and avoiding stuck in local optima. Minimization of absolute error between the TEG system current at maximum power and the actual one is the proposed fitness function. The analysis is performed on small 9 × 9 TEG array and large 15 × 15 TEG array. Eight temperature distribution patterns of non-uniform row, non-uniform column, short wide, long wide, diagonal, external, internal, and random are analyzed. The proposed EVO is assessed via comparing to reported immune genetic algorithm (IIGA) and other programmed approaches of osprey optimization algorithm (OOA), chef-based optimization algorithm (CBOA), artificial hummingbird algorithm (AHA), and northern goshawk optimizer (NGO). Moreover, statistical investigation is implemented via performing Kruskal-Wallis test, Friedman test, ANOVA test, and Wilcoxon rank test. The fetched results revealed that, the best enhanced power from small 9 × 9 array is 9.143% compared to the original arrangement occurred at long wide temperature distribution. Regarding large 15 × 15 TEG array, the best enhanced power happened during diagonal pattern with 3.359%. The results confirmed the preference of the proposed EVO in solving the TEG system reconfiguration problem with great efficiency.