Thermoelectric Model Research Articles

Thermal annealing effect on phase evolution, physical properties of DC sputtered copper oxide thin films and transport behavior of ITO/CuO/Al Schottky diodes

Herein, we report on the post-annealing temperature effect on the transport behavior of p-CuO/Al Schottky barrier diodes. In addition, the transformation of phase from Cu4O3 to CuO phase was studied. Copper oxide thin films were grown on soda lime glass substrates, and post-annealing temperature's influence on the films’ structural, chemical, morphological, and electrical characteristics was comprehensively examined. X-ray diffraction study revealed the development of polycrystalline tenorite phase (CuO) on annealing. Raman analysis also confirmed the formation of the tenorite phase (CuO) at higher annealing temperatures (400 °C and 500 °C). XPS study revealed the occurrence of the Cu4O3 phase for room temperature deposited sample and CuO phase at the higher annealing temperature. Using current–voltage analysis, the Chueng model, and the thermoelectric emission model, the Schottky behavior between the metal and semiconductor were investigated. The fabricated diode showed a rectification ratio of 103 at ± 2 V, with the barrier height ranging from 0.84 to 1.12 eV due to different annealing treatments. The attributes of the power law were employed to elucidate space charge-limited conduction and the process of tunneling across the density of interface traps in p-CuO/Al Schottky diodes. This study provides valuable insights into the behavior of the p-CuO/Al Schottky junction, enhancing our understanding of its characteristics.

Multiphysics simulations of uniaxial compression applied to various rock samples subject to microwave pretreatment

PurposeAmong the various applications involving the use of microwave energy, its growing utility within the mining industry is particularly noteworthy. Conventional grinding processes are often overburdened by energy inefficiencies that are directly related to machine wear, pollution and rising project costs. In this work, we numerically investigate the effects of microwave pretreatment through a series of compression tests as a means to help mitigate these energy inefficiencies.Design/methodology/approachWe investigate the effects of microwave pretreatment on various rock samples, as quantified by uniaxial compression tests. In particular, we assign sample heterogeneity based on a Gaussian statistical distribution and invoke a damage model for elemental tensile and compressive stresses based on the maximum tensile stress and the Mohr–Coulomb theories, respectively. We further couple the electromagnetic, thermal and solid displacement relations using finite element modeling.Findings(1) Increased power intensity during microwave pretreatment results in decreased axial compressive stress. (2) Leveraging statistics to induce variable compressive and tensile strength can greatly facilitate sample heterogeneity and prove necessary for damage modeling. (3) There exists a nonlinear trend to the reduction in smax with increasing power levels, implying an optimum energy output efficiency to create the maximum degradation-power cost relationship.Originality/valuePrevious research in this area has been largely limited to two-dimensional thermo-electric models. The onset of high-performance computing has allowed for the development of high-fidelity, three-dimensional models with coupled equations for electromagnetics, heat transfer and solid mechanics.

Study on preparation and properties of silver alloy for Mongolian medicine acupuncture

The Mongolian medical silver needles often encounter issues of bending, fracturing, and blunting in clinical applications. Similarly, Mongolian warm needles can cause burns on patients due to inaccurate temperature control. In this study, we developed an Ag85Cu15 alloy specifically for acupuncture needles based on material preparation. By incorporating appropriate amounts of Mn and Ti elements, we were able to enhance the mechanical properties and biocompatibility of the acupuncture needles. Compared to commercially available silver needles, this alloy exhibited a significant increase in microhardness up to 210.2 Hv0.2 and an improved tensile strength of 880.2 MPa. Furthermore, we designed a thermoelectric effect-based temperature measurement model for precise control of the warm needle's temperature, enhancing the therapeutic effectiveness of the treatment.

Analysis and optimization of effect factors of refrigeration performance of portable micro-refrigerator

The objective of this study was to ascertain an efficient portable cold container, considering the constrained space, low airflow velocity, and uneven heat distribution of a micro-refrigerator, which lead to in insufficient heat dissipation and low refrigeration efficiency. A thermoelectric micro-refrigerator model with a volume of 9083.8 cm3 was established under forced convection heat transfer conditions. Through single-factor and response surface experiments, the impact of thermoelectric elements configuration on refrigeration efficiency was identified. These elements include the input current of the Thermo Electric Cooler (TEC), the derating factor (actual power) of the cooling fan, and the height of the heat sink fin.The results indicate that optimizing the refrigeration conditions significantly enhances the refrigeration efficiency of the micro-refrigerator. At an ambient temperature of 25℃, with a fan derating factor of 0.77 (corresponding to an actual power of 0.8218 W), a heat sink fin height of 59.15 mm, and a TEC input current of 5.09A, under stable conditions,the cold side temperature can reach −11.3 ℃. The hot side temperature is 38.2 ℃, consistent with the response surface experiment result. Numerical simulation under these conditions reveals a cold side temperature of −12.4 ℃ and a hot side temperature of 41.9 ℃, showing a 9.7 % difference from the experimental results. The simulation data further demonstrate that the vertical arrangement of the cooling fan and heat sink can achieve a cold side temperature of −12.9 ℃, effectively maintaining the hot side temperature below 40 ℃. The thermoelectric system investigated in this paper holds promising potential for applications in portable fresh-keeping and refrigeration.

Analysis and Verification of Heat Dissipation Structures Embedded in Substrates in Power Chips Based on Square Frustums Thermal through Silicon Vias.

A novel heat dissipation structure composed of square frustums thermal through silicon via array and embedded in P-type (100) silicon substrate is proposed to improve the heat dissipation capacity of power chips while reducing process difficulty. Based on theoretical analysis, the heat transfer model and thermo-electric coupling reliability model of a power chip with the proposed heat dissipation structure are established. A comparative study of simulation indicates that the proposed heat dissipation structure, which can avoid problems such as softness, poor rigidity, fragility and easy fracture caused by thinning chips has better heat dissipation capability than thinning the substrate of power chips.

Simulation of High Thermal Conductivity Polyurethane DC Support Capacitor

In the field of energy storage, capacitors are receiving more and more attention due to their high power density, long life cycle, lack of maintenance, etc. We have developed a thermoelectric coupling model to simulate the temperature rise of DC support capacitors under normal operating conditions at room temperature and to obtain accurate results. Boundary conditions are established under this model and the temperature rise of the capacitor is shown by iteration as well as solving the partial differential equation. The temperature rise condition of the capacitor is shown by iteration and solving partial differential equations and the actual situation is predicted and investigated. The results show that the capacitor can operate steadily under normal working conditions.

Computer simulation-based nanothermal field and tissue damage analysis for cardiac tumor ablation.

Radiofrequency ablation is a nominally invasive technique to eradicate cancerous or non-cancerous cells by heating. However, it is still hampered to acquire a successful cell destruction process due to inappropriate RF intensities that will not entirely obliterate tumorous tissues, causing in treatment failure. In this study, we are acquainted with a nanoassisted RF ablation procedure of cardiac tumor to provide better outcomes for long-term survival rate without any recurrences. A three-dimensional thermo-electric energy model is employed to investigate nanothermal field and ablation efficiency into the left atrium tumor. The cell death model is adopted to quantify the degree of tissue injury while injecting the Fe3O4 nanoparticles concentrations up to 20% into the target tissue. The results reveal that when nanothermal field extents as a function of tissue depth (10mm) from the electrode tip, the increasing thermal rates were approximately 0.54362%, 3.17039%, and 7.27397% for the particle concentration levels of 7%, 10%, and 15% compared with no-particle case. In the 7% Fe3O4 nanoparticles, 100% fractional damage index is achieved after ablation time of 18s whereas tissue annihilation approach proceeds longer to complete for no-particle case. The outcomes indicate that injecting nanoparticles may lessen ablation time in surgeries and prevent damage to adjacent healthy tissue.

Thermoelectric properties of TaVO5 and GdTaO4: An experimental verification of machine learning prediction

Advancements in materials discovery tend to rely disproportionately on happenstance and luck rather than employing a systematic approach. Recently, advances in computational power have allowed researchers to build computer models to predict the material properties of any chemical formula. From energy minimization techniques to machine learning-based models, these algorithms have unique strengths and weaknesses. However, a computational model is only as good as its accuracy when compared to real-world measurements. In this work, we take two recommendations from a thermoelectric machine learning model, TaVO5 and GdTaO4, and measure their thermoelectric properties of Seebeck coefficient, thermal conductivity, and electrical conductivity. We see that the predictions are mixed; thermal conductivities are correctly predicted, while electrical conductivities and Seebeck coefficients are not. Furthermore, we explore TaVO5’s unusually low thermal conductivity of 1.2 Wm−1K−1, and we discover a possible new avenue of research of a low thermal conductivity oxide family.

Model predictive control for automatic operation of space nuclear reactors: Design, simulation, and performance evaluation

Space nuclear reactors possess the inherent benefits of independence from solar energy and the capability to withstand intricate external circumstances. Distinguishing themselves from terrestrial reactors, space nuclear reactors function within the realm of outer space, operating autonomously throughout their entire operational cycles. Consequently, the establishment of a dependable automatic control system assumes utmost significance. In this paper, a high-fidelity nonlinear space thermionic nuclear reactor model is established, encompassing neutron physics, thermal–hydraulic, and thermoelectric conversion system models. An automatic control system with a model predictive controller (MPC) is designed based on the system. A simplified state-space model is established based on system identification as the internal model for the MPC controller, demonstrating good agreement with the dynamic response of the nonlinear system model. The deployment of the MPC controller for system control simulations exhibits excellent control performance under various operating conditions. In the case of a nuclear power step response, the MPC controller achieves an overshoot of 0.07 % and a settling time of 0.65 s. For an electric power step response, the MPC controller yields an overshoot of 0.28 % and a settling time of 36.6 s. These control performances are significantly better than those achieved by the PID controller. In power tracking control, the MPC controller demonstrates virtually error-free tracking performance. When external reactivity disturbances are introduced, the MPC controller outperforms the PID controller in swiftly compensating for the disturbances, maintaining the system's operating state at the desired level.

Fast Coupled Thermoelectric and Magnetic Model to Simulate the Transient Behavior of Inductive and Resistive Superconducting Fault-Current Limiters

Fast Coupled Thermoelectric and Magnetic Model to Simulate the Transient Behavior of Inductive and Resistive Superconducting Fault-Current Limiters

Performance prediction and optimization of annular thermoelectric generators based on a comprehensive surrogate model

A traditional system-level thermoelectric model requires enormous computing power and time for simulation analysis, especially when multiple optimization algorithms are combined. This paper initially proposed a comprehensive surrogate mode for the accurate modeling, field analysis, and fast optimization of thermoelectric generators. The surrogate model is made up of an artificial neural network (ANN) and a conditional generative adversarial network (cGAN), which can achieve a prediction accuracy of 97 % and a structural similarity (SSIM) of 0.954. Using a twisted tape annular thermoelectric generator (TT-ATEG) as an example, the generalization capability of the comprehensive surrogate model is demonstrated by studying the change of the twisted tape geometry parameters on the output performance and field distribution of the annular thermoelectric generator. The combination of the surrogate model and NSGA-II achieves fast optimization of key parameters under different working conditions, and the computational efficiency is improved by 99.97 %. Meanwhile, the cGAN part can predict the pressure and heat flow fields within 5s to provide intuitive visual feedback. The trained surrogate model requires less computer arithmetic power compared to the traditional multi-physics field simulation software. The successful application of the comprehensive surrogate model in this work provides a new solution idea and an optimization method for system-level TEG.

Radial Thermoelectric Model for Stranded Transmission Line Conductors.

Bare-stranded conductors play a critical role in the efficiency and safe operation of transmission lines. The heat generated in the interior of the conductor is conducted radially to the outer surface, creating a radial thermal gradient. The radial temperature gradient between the core and the surface depends on multiple factors, such as stranding, number of layers, current level, electrical resistance and the effective radial thermal conductivity. Therefore, the radial temperature model must be considered when developing accurate conductor models. Such models are particularly important in the development of dynamic line rating (DLR) approaches to allow the full current carrying capacity of the conductor to be utilized while ensuring safe operation. This paper develops a radial one-dimensional thermoelectric model for bare-stranded conductors used in transmission lines. The accuracy of the proposed model is determined by experimental tests performed on three conductors.

A novel thermoelectrical model for dye-sensitized solar cells for consideration of the effects of solar irradiation, wavelength, and surface temperature

The present study aims to provide an innovative model to simulate the behavior of dye-sensitized solar cells, considering their advantages and the emerging technology of cells. The new model uses carrier particle continuity equations and the Butler-Volmer equation to examine the effects of solar radiation, wavelength, and temperature on cell performance. Power Conversion Efficiency (PCE) is studied for sunny and cloudy days (7 am to 6 pm) based on input and output power. Parametric changes, including fill factor, open circuit voltage, and short circuit, are calculated in this regard. The good agreement observed between the outcomes of previous studies and the results obtained here emphasizes the reliability of the proposed model. As a striking novelty, the impact of transparent conductive oxide (TCO) recombination current on cell performance parameters is also examined using the Butler-Volmer equation under normal and diffuse radiation (low light). The results reveal that the effect of recombination current is more significant for diffuse radiation conditions than the clear sky (sunny day). For example, the efficiency and voltage drop are higher for the cloudy mode. The sunny weather has a reduction of about 0.2 % in efficiency, while the same state for the cloudy weather is about 1.8 %.

Transient numerical simulations in innovative thermoelectric power: A comprehensive study on material segmentation and cross-section design for multi-facetted excellence

In the pursuit of sustainable energy innovations, this study investigates the transformative potential of material segmentation and non-uniform cross-sections in the field of thermoelectric power generation. By analyzing four distinct thermoelectric models under varying optical concentration ratios (OCRs), our research is dedicated to optimizing exergy efficiency, economic viability, and thermo-mechanical performance. Model 3, representing a uniform cross-section segmented thermoelectric generator (TEG), emerges as the frontrunner in our study. The significance of this research lies in its potential to revolutionize thermoelectric power generation, offering a fresh perspective on sustainable energy production. Our primary aim is to elucidate the impact of innovative design strategies on thermoelectric performance. To achieve this, we employ numerical simulations and transient analyses to explore the dynamic behavior of these models under changing OCRs. Our key findings reveal the remarkable superiority of Model 3, which achieves a peak power output of 624.60 mW, exergy efficiency of 10.27 %, and CO2 savings of 1.08 kgyr−1, all under an OCR of 700. Notably, Model 3 outperforms conventional systems by 300.45 % in power output and 75.76 % in CO2 savings. Conclusively, our research provides valuable insights into the capacity of material segmentation and non-uniform cross-sections to reshape the realm of thermoelectric power generation, highlighting their potential in propelling sustainable energy solutions.

Effect of Shunt Resistor Value on the Performance of Resistive Superconducting Fault Current Limiters

Resistive-type superconducting fault current limiters (r-SFCLs) have generated great interest for research and technical applications. This is attributed to their superior features, which include self-action, fast response, and simple operation. In low line impedance systems, r-SFCLs are seen as a viable protective mechanism for limiting high-magnitude fault currents. However, overcurrent caused by faults results in an increased temperature of the r-SFCL, possibly damaging the coils. Thus, the r-SFCL must be appropriately engineered to protect it while still allowing for effective fault current limitation. To achieve this goal, an appropriately sized shunt resistor must be used. Adding a shunt resistor benefits the r-SFCL in several ways, from lowering its maximum temperature to speeding up its recovery. Additionally, the shunt resistor protects the r-SFCL from excessive surges in temperature by giving the current an alternative path to flow down, thus saving it from further damage. A multilayer thermoelectric model was developed to examine the thermoelectrical behavior of the r-SFCL coil throughout a fault occurrence and the subsequent recovery period using three shunt resistors ranging from 4 to 16 Ω. MATLAB®/Simulink was used as the simulation platform in this study. The dependence of the current limitation capability and the voltage profile on the shunt resistor value was studied compared to the basic case without an r-SFCL. Increasing the shunt resistor value led to an enhanced ability to limit fault currents, although at the cost of higher temperatures and a longer recovery time. This study also presents guidance for optimizing the design parameters of r-SFCLs.

Modelling and model-based tracking control of soft twisted and coiled actuators

Soft twisted and coiled actuators (STCAs) have promising prospects for application in the field of soft-bodied robots. However, the STCA has a complex energy conversion mechanism and a rate-dependent hysteresis nonlinearity, which brings great difficulties to its modelling and control. To solve these difficulties, this paper proposes modelling and model-based tracking control methods to realize the high-precision output-force tracking control of the STCA. First, a dynamics model framework is constructed, which consists of a thermo-electric model and a thermo-mechanical model, to describe the current-to-force process of the STCA. Among which, the thermo-mechanical model is established by combining the Bouc–Wen model and the linear dynamic system in series, which can accurately describe the rate-dependent hysteresis nonlinearity of the STCA. Then, a double closed-loop control architecture with a hysteresis inverse compensation controller is proposed, which can realize the timely control of the temperature and the compensation for the rate-dependent hysteresis nonlinearity of the STCA. Next, controller parameters are adjusted in the simulation environment to reduce the risk of the damage of the STCA and to obtain a satisfactory control effect. Finally, practical experiments are conducted, and root mean square errors of all experiment results are all less than 5.01%, which verifies the effectiveness of the proposed modelling and control methods.

Real-time Monitoring Method of Insulation Status of Photoelectric Composite Submarine Cable based on Thermoelectric Coupling

The existing approach for monitoring the insulation state of photoelectric composite submarine cables primarily relies on detecting the current of the cable protection layer. However, this conventional method suffers from limited monitoring accuracy due to the absence of parameter identification processing for the cable. As a result, there is a need to improve the monitoring methodology by incorporating robust parameter identification techniques to enhance the accuracy of insulation state evaluation. In this regard, a real-time monitoring method based on thermoelectric coupling is proposed to monitor the insulation status of the photoelectric composite submarine cable. By constructing an equivalent composite circuit model and a thermodynamic function, a thermoelectric coupling model is constructed and used to identify the parameters of the submarine cable; by extracting the frequency extremes in the spectral values of the submarine cable current signal, an equivalent insulation characteristic function is constructed to realize the determination of the insulation state. The proposed method is verified for the insulation state monitoring effect in the experiment. The experimental results show that when the proposed method is used to monitor the insulation state of the photoelectric composite submarine cable, the calculated partial discharge quantity has a small error, and the monitoring accuracy is high.

Structural Optimization of Annular Thermoelectric Module Applied to Liquefied Natural Gas Cold Energy Recovery

The gasification of liquefied natural gas (LNG) is characterized by a substantial release of cold energy, which can be utilized for power generation via thermoelectric generator (TEG). Employing a gasifier integrated with a thermoelectric generator for LNG gasification allows for the recovery of cold energy and its conversion to useful power, a process that holds significant potential for widespread application. In the study, a thermoelectric model has been developed for an annular thermoelectric module, which formed a new category of gasifier tube. The influence of the module’s structure as well as the heat transfer parameters on the thermoelectric performance was examined. The results revealed that an optimum height of the thermoelectric leg, specifically 2 mm, maximized the output power while allowing the thermoelectric conversion efficiency to reach a peak of 3.25%. Another noteworthy finding is that an increase in the central angle of the thermoelectric leg leads to a concomitant rise in output power but a decrease in conversion efficiency. Furthermore, when the heat transfer coefficients at the hot and cold ends of the module achieved 4000 W/(m2·K) and 10,000 W/(m2·K), respectively, the conversion efficiency can be elevated to 6.98%. However, any additional enhancement in power generation performance derived from further augmenting the heat transfer is marginal. These findings can serve as a valuable reference in the design and optimization of TEG intended for the recovery of cold energy from LNG.

Construction and simulation analysis of lithium‐ion batteries thermoelectric coupling model based on digital twin

AbstractWith the rapid development of energy storage technology, it is significant to evaluate the operating status of lithium‐ion batteries efficiently and accurately, so as to ensure their safe operation and reduce the probability of accidents. For the problems of long simulation time and low accuracy in existing models, this paper proposes a construction method of lithium‐ion batteries thermoelectric coupling model based on digital twin. First, the digital twin structure system of lithium‐ion batteries is proposed. Second, considering the coupling effects of the thermodynamic model and the equivalent circuit model, the thermoelectric coupling model is constructed based on the digital twin platform ANSYS TwinBuilder. The thermodynamic model is reduced in order and the simulation time is reduced to second level, which improves the simulation efficiency and meets the real time simulation requirements of the digital twin. Furthermore, considering that the operating parameters of lithium‐ion batteries are variable, the parameters of the equivalent circuit model are identified online based on the variable forgetting factor recursive least squares algorithm. It updates parameters of the model and improves the simulation accuracy. Finally, the efficiency and accuracy of the model are verified through simulation analysis.

Multi-source-data state estimation for integrated electricity–heat-building networks

Building heating systems (BHS) play a major role in integrated electricity and heat systems (IEHS). To capture the real-time dynamic operating state of IEHS based on multi-source measurement data, this paper develops a comprehensive state estimation (SE) framework for IEHS with BHS fleets. First, a thermo-electrical SE model integrating BHS, electric power grid (EPG), and district heating network (DHN) is developed. Then, to jointly estimate the state variables of IEHS with different time scales of dynamics, a holistic SE algorithm is proposed based on the partial equivalence between the Weighted Least Squares (WLS) estimation problem and the correction stage of the Iterative Extended-Kalman Filter (IEKF). It also includes a data anomaly processing algorithm to combat data corruptions from sensing and communication processes. Simulation results show that the proposed framework can accurately track the thermo-electrical states of the system both in the presence of measurement noise and anomalies during various dynamics in IEHS.