Thermoelectric Model Research Articles

Preface

Thai Thermoelectric Society, E-mail: actsact2020@gmail.comThe 5th Asian Conference on Thermoelectrics and the 6th Southeast Asia Conference on Thermoelectrics (ACT&SACT2020) were successfully held through a virtual conference platform on 17 December 2020. These conferences were promoted by the Thai Thermoelectric Society, Asian Association of Thermoelectrics, Sakon Nakhon Rajabhat University and Rajamangala University of Technology Isan for favoring the dissemination of scientific and technical progresses in the field of Thermoelectrics in Asia, enhancing the communication between research institutions and industries for promotion of TE applications as well as providing a forum for exchange of information and achievements. Experts, scientists and engineers from Research and Industry around Asia and abroad were all invited and expected for attending the conferences and discussing 1) thermoelectric materials & modeling, 2) thermoelectric characterization and new phenomena, 3) thermoelectric modules and devices, 4) thermoelectric applications: present and future, and 5) other materials and applications.The conferences were initially planned to be held conventionally at Sakon Nakhon. Unfortunately, the outbreak of COVID-19 pandemic leading to the consequent lockdowns and restrictions all over the country at the time, affected traveling to the potential place of the conferences. Hence, the video conference platform, Zoom was introduced to conduct the online conferences hosted at Sakon Nakhon Rajabhat University. Keynote and invited speaker took 45 minutes talk. An individual speaker took 15 minutes for presenting his/her work and answering any question through the platform. Along with the internet communication was good and online platform was perfect, the discussion and commenting for 43 oral presentations and 28 posters were completely accomplished. Thanks to the high capacity ethernet at the hosted university.Eventually, the 27 selected papers were accepted to publish in Journal of Physics: Conference Series (SCOPUS, SJR 0.23), after peer reviewing.Even though all of us did not meet in the presence of each other, we feel confident that everyone enjoyed the online event. The organizing and editorial committee hopes you enjoy the reading of this volume of the JPCS. Furthermore, we wish to thank everyone associated for valuable contributions and made these conferences a truly memorable event at this difficult time for all of us.List of Committee, Sponsors, Photographs are available in this pdf.

The thermal potential of a new multifunctional sliding window

Nowadays, new generations of building envelope need to manage the energy exchange between outdoor and indoor environment responsively and save the building energy. A significant amount of solar heat gain in buildings comes through the windows. The transparent envelope also must answer to visual requirements allowing for external vision but guarantying comfort conditions. In this framework, this article aims to test numerically the thermal performance of a new design of multifunctional glazed window combining the most recent technologies used in building envelopes. Five distinct window designs combing phase change material (PCM), vacuum glazing (VG), photovoltaic (PV), and air cavity were numerically tested for hot weather conditions. The proposed window designs slide inside the wall of the building. A comprehensive transient Multiphysics model coupling the thermo-electric model of the PV, melting and solidification model of the PCM, and the heat transfer mechanisms in the vacuum and air gaps are developed. The model is step by step validated with data in the literature. Various PCM types and PCM thickness are investigated. Among the five investigated window designs, the result showed that the window, including the air gap with PV, PCM cavity, and VG, is the optimal design for the indoor air's thermal isolation. Simultaneously, the PCM with a melting point of 35 ˚C and thickness of 50 mm is the best performance material in a hot arid region in summer at Cairo. The proposed multifunction window generated maximum electrical power intensity of 162 W/m2 at received solar radiation of 1000 W/m2.

Comprehensive investigation on the luminous and energy-saving performance of the double-skin ventilated window integrated with CdTe cells

The PV double-skin windows, as an advancing BIPV technology, possess great potential in developing low-energy consumption buildings. However, the Semi-Transparent PV glasses change the indoor illuminance and spectral distribution. Therefore, quantifying the indoor luminous environment and comprehensively evaluating the luminous and energy-saving performance are of great significance to the promotion of PV double-skin windows. In this work, the thermal-electrical-daylight experiment of a double-skin ventilated window integrated with CdTe cells was conducted. Based on the measured spectral data of the CdTe glasses, the color properties and the daylighting performance were predicted. Then, the overall energy performance of the proposed window was simulated using the validated thermoelectric model. Finally, the comparison between the proposed window and some PV windows in the reported literature was performed. The main results were: (1) The SHGCs of the investigated window in winter and summer were 0.28 and 0.11, respectively. Its U-value and daylight factor were 2.05 W/m2K and 0.6%, respectively. (2) CdTe glass could improve indoor luminous performance and lead to a reduction of annual energy consumption. (3) Compared with the reported PV windows, the CdTe-DSV window could meet seasonal thermal demand while providing better color properties.

Efficient design optimization of a miniaturized thermoelectric generator for electrically active implants based on parametric model order reduction.

This research focuses on the design of a miniaturized thermoelectric generator (TEG) for electrically active implants. Its design optimization is performed using the finite element method. A simplified TEG model is obtained by replacing the thermocouple array with a single representative thermopile, which considers the number and fill factor of the thermocouples as parameters. Instead of rebuilding the geometry of a detailed model with multiple thermocouples, the simplified model adapts the material properties of its representative thermopile, facilitating design optimization. We extend the model by integrating the simplified TEG together with a housing inside a human tissue model for thermoelectric analysis. For computation efficiency and applicability of model order reduction (MOR), a thermal model is derived from the thermoelectric one, with the Peltier effect being considered through an effective thermal conductivity. Through parametric MOR, two parametric reduced-order models are generated from the full-scale thermoelectric and thermal model, respectively. Furthermore, we demonstrate the design optimization of TEG both in full-scale and reduced-order model for maximal power output and sufficient voltage output.

Disorder-induced Anderson-like localization for bidimensional thermoelectrics optimization

Disorder-induced Anderson-like localization for bidimensional thermoelectrics optimization

Quantification of the Flexibility of Residential Prosumers

Balancing in a distributed generation network is an increasingly difficult task because of the increasing number of residential prosumers on the power network. This paper proposes a framework for the estimation, as well as the prediction of the power flexibility of residential prosumers. In order to quantify the residential buildings’ demand flexibility, a thermoelectric simulation model of a typical residential house was developed based on first engineering principles. Based on the calculated flexibility values, a simple prediction method was used to give a short-term forecast of the prosumer flexibility. The results were validated by simulation experiments incorporating real data for four different scenarios.

Thermoelectric model of the Earth's magnetic field

A variant of the thermoelectric model of the Earth's dipole magnetic field is considered. It is based on geothermoelectric currents present in the planet's core. The currents cyclically change their direction, which leads over time either to warming on the Earth, if their movement is directed towards the Earth's crust, or to cooling, when moving towards the inner core. With each change in the direction of movement of the thermal currents, the poles of the Earth's magnetic field are inverted simultaneously. The inversion process is instantaneous (on the scale of planetary time) and is not the result of a gradual reversal on the 180° Earth's magnetic axis. At the moment of inversions of thermal currents in the core, the total geomagnetic field decreases to the level of 4.6∙10-6 T, which is constantly supported by thermal currents of semi-conducting rocks of the lower mantle. The considered version of the thermoelectric model of the Earth's magnetic field may be promising for studying the magnetic fields of planets in the Solar system.

Experimental Validation of a Thermo-Electric Model of the Photovoltaic Module under Outdoor Conditions

An operating temperature of the photovoltaic (PV) module greatly affects performance and its lifetime. Therefore, it is essential to evaluate operating temperature of the photovoltaic module in different weather conditions and how it affects its performance. The primary objective of this paper is to present a dynamic thermo-electric model for determining the temperature and output power of the photovoltaic module. The presented model is validated with field measurement at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor, Slovenia. The presented model was compared with other models in different weather conditions, such as clear, cloudy and overcast. The evaluation was performed for the operating temperature and output power of the photovoltaic module using Root-Mean-Square-Error (RMSE) and Mean-Absolute-Error (MAE). The average RMSE and MAE values are 1.75 °C and 1.14 °C for the thermal part and 20.34 W and 10.97 W for the electrical part.

Development of thermo-electrical model of photovoltaic panel under hot-spot conditions with experimental validation

This work was focused on development of thermo-electrical numerical model for circumstance of free-standing photovoltaic (PV) panel exposed to hot-spot effect. The model was developed for partial hot-spot situation and for serial cell connection. The developed 3D model uses a novel approach via two-way coupling of thermal and electrical models. The model was experimentally validated for geographical location of Mediterranean climate, using the readings from temperature sensors, as well as thermal imaging data. The comparison of results between measured and simulated values were shown to be well matched, with deviation not more than 1.5 °C. The model could be useful for optimization of the bypass diodes and better understanding of hot-spot coupled with other thermal effects. Also, the model can be used for examinations in the case of building integrated photovoltaics (BIPV), since hot-spot effects could be utilized as additional heat sources that could be properly managed. The effect of temperature non-uniformity could be also examined with herein proposed modelling approach and which is beneficial in the case of cooled PV panels.

Comprehensive Regulation of the Threshold Oscillation for Neuromorphic Systems Based on Cryogenic Performance of NbO₂ Device

In this study, an oscillating neuron based on the Pt/ NbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> / TiN device with high performance was demonstrated. The temperature dependence of NbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> threshold switching devices were well studied at cryogenic environment (100 K), where the reaction intensity is cut down and thus facilitates the observation of the performance and mechanisms of the device. To lucubrate these results, the thermoelectric coupling model was simulatively realized and validated based on cryogenic electrical experiments, guiding the influence factors of NbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based oscillation system. Ulteriorly, the NbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> threshold switching device as oscillating neuron was simulated and its comprehensive regulation was presented. Ambient temperature, switching time and threshold voltage are found to affect the oscillation frequency, while threshold voltage can also change the amplitude of the frequency affected by other factors. This work performs a systematically cryogenic study of NbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and oscillation system, and simultaneously provides a deep understanding of performance regulation mode of the oscillating system.

Preparation of CuO1-x-Mnx (x= 0.03, 0.05, 0.07) and MATLAB modelling for sustainable energy harvesting applications

A different Mnx(x= 0.03, 0.05, 0.07) doped on CuO1-x has been successfully synthesised by a co-precipitation method by maintaining a pH-12. The nature of Mn doped CuO nanoparticles has been characterized with the help of X- Ray Diffraction (XRD). The Mn in the lattice sites of CuO gives the monoclinic crystal structure with C2/c space group which has been confirmed through JCPDS card no: 05-0661. The morphology variations with Mnx doping have been examined with the help of field emission scanning electron microscope (FESEM) and Energy Dispersive X-Ray Spectroscopy (EDS). Additionally, band properties have also been noticed via Ultraviolet-Visible (UV) Spectroscopy. The band gap of material has been calculated as 2.39 eV, 1.96 eV and 2.25 eV for energy harvesting modelling through MATLAB with temperature difference behaviour of material. The thermodynamic modelling has been used for energy harvesting application with the help of MATLAB and the Seebeck coefficient has been calculated for thermoelectric modelling of CuO-Mnx.

A Lightweight Soft Gripper Driven by Self-Sensing Super-Coiled Polymer Actuator

This study proposes a soft gripper driven by a simple, lightweight, low-cost, self-sensing super-coiled polymer (SCP) actuator with a high power-to-weight ratio. SCP generates an untwisting motion when heated, and therefore, is suitable for designing the actuator. The actuator is fabricated with a multifilament sewing thread woven by the self-coiling method and yields a high output force. To enhance the accuracy of the actuator in measuring higher temperatures, we propose an improved temperature self-sensing method that uses a dedicated metal wire wound around the SCP. To provide a theoretical basis for the control of the actuator, we construct through experiments a thermoelectric model and a thermomechanical model for the SCP. The resulting kinematics of the soft gripper are analyzed, and a nested control system is established to realize a precisely control of the soft gripper. Finally, we build a prototype to test the grasping ability of the soft gripper.

Superconducting Power Filter for Aircraft Electric DC Grids

A new device, referred to as Superconducting Power Filter (ScPF), is introduced to improve the stability of aircraft electric DC grids. This device is made of a non-inductive superconducting coil connected in series with a conventional RLC filter. The superconducting coil behaves as a nonlinear current-dependent resistance. By design, the superconductor does not undergo a full transition to the normal-resistive state and remains in the current-sharing regime. Thus, a quick response and recovery of the superconductor to transients can be achieved. In the present work, the thermo-electric model of the device incorporates a refined description of the transition from the superconducting state to the normal-resistive state of the superconductor. To check the feasibility of passive stabilization of embedded DC grids using ScPF, different widths and lengths of commercially available 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> generation High Temperature Superconducting (2G HTS) tapes were considered. We chose a case study simulating an equivalent circuit of a More Electric Aircraft (MEA) with an EPS-A3 architecture. For this particular case study, it is shown that the stability limit of the DC grid can be significantly increased, while preserving the reliability (no quench) and low cost (only a few meters of superconducting tape) of the ScPF.

Design and evaluation of a high power density and high energy efficiency fuel element for space nuclear reactors

• A novel fuel design with dual-cooling was proposed based on TOPAZ-II fuel. • Thermionic-thermoelectric models were developed and fuel analysis was conducted. • Power density could be increased by 120%, while fuel temperature was decreased. • The system conversion efficiency was increased from 9.2% to 13.4%. • The system utilization efficiency was increased from 6.6% to 10.2%. The enhancement of the power density and efficiency of space nuclear reactors is of great value for space exploitation and exploration. Based on a TOPAZ-II space nuclear reactor, a novel fuel element design was proposed for power density and energy efficiency improvements in this study. In addition to an external thermionic generator in the original fuel design, a heat pipe thermoelectric generator (HPTEG) was implemented on the inside of the fuel ring. This novel design allowed for a significant power density increase while lowering the fuel temperature. Thermionic and thermoelectric simulation models were developed and then implemented in a thermo-mechanical analysis program for a space nuclear fuel element. With this program, the thermo-mechanical, thermionic, and thermoelectric performances during long-term operation were investigated. The results indicated that the maximum allowable power density could be increased by 120% while substantially reducing the fuel temperature in the new design. Compared with a thermionic generator, the HPTEG exhibited the characteristics of high output voltage and low current, which could reduce the joule dissipation and improve the energy utilization efficiency. Due to the high power density, the system energy conversion efficiency was increased from 9.2% to 13.4% and the system energy utilization efficiency was increased from 6.6% to 10.2%.

C band microwave damage characteristics of pseudomorphic high electron mobility transistor* *Project supported by the Foundation Enhancement Plan and the National Natural Science Foundation of China (Grant No. 61974116).

The damage effect characteristics of GaAs pseudomorphic high electron mobility transistor (pHEMT) under the irradiation of C band high-power microwave (HPM) is investigated in this paper. Based on the theoretical analysis, the thermoelectric coupling model is established, and the key damage parameters of the device under typical pulse conditions are predicted, including the damage location, damage power, etc. By the injection effect test and device microanatomy analysis through using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), it is concluded that the gate metal in the first stage of the device is the vulnerable to HPM damage, especially the side below the gate near the source. The damage power in the injection test is about 40 dBm and in good agreement with the simulation result. This work has a certain reference value for microwave damage assessment of pHEMT.

Exploration of Thermal Management Issues in the Battery Life Cycle

In order to comprehensively track and monitor battery performance across time domains and perform efficient thermal management. This article first summarized the research progress and status quo of battery aging models, and then coupled it with thermoelectric models to obtain the evolution of battery characteristic parameters during battery decay. From the perspective of the battery life cycle, it explored the thermal safety control and overheating prevention technology of power batteries, proposed a feed-forward heat management strategy, and took cooling measures in advance to prevent the increase in heat production caused by aging. The results show that the feed-forward thermal management strategy can ensure the cooling effect of the cooling system on the battery in the later stage of aging.

Simulation and experimental investigation of tool wear rate in dry and near-dry EDM process

Purpose Many engineering applications in this era require new age materials; however, some classic alloys like spring steel are still used in critical applications such as aerospace, defense and automobile. To machine spring steel material, there exist various difficulties such as rapid tool wear rate, the rough surface formation of a workpiece and higher power consumption. The purpose of this paper is to address these issues, various approaches in addition to electrical discharge machines (EDM) are used such as dry EDM (DEDM) and near dry EDM (NDEDM). Design/methodology/approach This study focuses on these two approaches and their comparative analysis with respect to tool wear during machining of spring steel material. For this study, current, gap voltage, cycle time and dielectric medium pressure are considered input variables. This study shows that the near dry EDM approach yields better results. Hence, the thermo-electrical model for this approach is developed using ANSYS workbench, which is further validated by comparing with experimental results. This thermo-electrical model covers spark radius variation and formation of temperature profile due to electric discharge. Transient thermal analysis is used to simulate the electric discharge machining. Findings It is observed from this study that discharge environment parameters such as debris concentration and fluid viscosity largely influences the dielectric fluid pressure value. Experimental results revealed that NDEDM yields better results in comparison with DEDM as it shows a 25% lesser tool wear rate in NDEDM. Originality/value The range of predicted results and the experimental results are in close agreement, authenticating the model.

Thermoelectric Response of Ion‐Selective Membranes: Modelling and Experimental Studies

AbstractThermoelectricity of ion‐selective membrane refers to the phenomenon that the membrane potential is generated in the presence of a temperature gradient, which plays a crucial role in low‐grade heat energy harvesting. Here, a new thermoelectric model is proposed, in which the entire membrane is divided into the intra‐membrane region and two diffusion boundaries. Simulated results suggest the thermally inducted membrane potential is composed of the diffusion potential inside membrane and two Donnan potentials at the membrane boundaries. The effects of the membrane charge density, electrolyte concentration, and solution temperature are theoretically explored in detail. This model is confirmed experimentally with cation‐selective hybrid nanochannels and a commercial cation‐selective polymer membrane. We believe the new thermoelectric model is beneficial to understanding the mechanism of thermoelectric response and promoting practical applications of thermal energy conversion.

Numerical and Experimental Study of Lightning Stroke to BIPV Modules

Building Integrated Photovoltaic (BIPV) modules are a new type of photovoltaic (PV) modules that are widely used in distributed PV stations on the roof of buildings for power generation. Due to the high installation location, BIPV modules suffer from lightning hazard greatly. In order to evaluate the risk of lightning stroke and consequent damage to BIPV modules, the studies on the lightning attachment characteristics and the lightning energy withstand capability are conducted, respectively, based on numerical and experimental methods in this paper. In the study of lightning attachment characteristics, the numerical simulation results show that it is easier for the charges to concentrate on the upper edge of the BIPV metal frame. Therefore, the electric field strength at the upper edge is enhanced to emit upward leaders and attract the lightning downward leaders. The conclusion is verified through the long-gap discharge experiment in a high voltage lab. From the experimental study of multi-discharge in the lab, it is found that the lightning interception efficiency of the BIPV module is improved by 114% compared with the traditional PV modules. In the study of lightning energy withstand capability, a thermoelectric coupling model is established. With this model, the potential, current and temperature can be calculated in the multi-physical field numerical simulation. The results show that the maximum temperature of the metal frame increases by 16.07 °C when 100 kA lightning current flows through it and does not bring any damage to the PV modules. The numerical results have a good consistency with the experimental study results obtained from the 100 kA impulse current experiment in the lab.

Superconducting protector against electromagnetic pulses based on YBCO film prepared on an Al2O3 substrate with a CeO2 sublayer

The electric and magnetic properties of microbridges made from 440 nm thick Y–Ba–Cu–O films prepared on Al2O3 substrates with CeO2 sublayers by the pulsed injection metal organic chemical vapor deposition (MOCVD) method were studied in temperatures ranging from 20 K to 300 K in order to investigate the possibilities of using these microbridges as fast fault current limiters. The application of an external magnetic field () causes the flux flow induced magneto-resistive effect, which is proportional to and to at low and high temperatures, respectively. The experimentally obtained S-shaped I–V characteristic and the change of the microbridge resistance over time when affected by a step-like magnetic field can be well explained using a thermo-electrical model based on Joule heating and the flux flow nature of the resistive state (RS). The transition from the superconducting to the RS, studied using ns duration rectangular waveform electrical pulses able to create up to ≈2106 A cm−2 current densities without rises of microbridge temperatures, demonstrated that the I–V characteristics of the RSs consisting of an assembly of straight lines corresponding to the different pinning centers. At temperatures close to the critical temperature of superconductivity, the number of these lines increases, and the I–V characteristics can be described with high accuracy by a power law. It was concluded that microbridges made from these films can be used as protectors against complicated waveform electromagnetic pulses having short rise times, high voltage peak amplitudes and long low-value over-current ‘tails’.