Electrothermal Method Research Articles

Fast electrothermal coupling calculation method for supporting digital twin construction of electrical equipment

AbstractThe failure of electrical equipment directly or indirectly caused by overheating has become one of the main reasons for equipment accidents. The real‐time condition monitoring method of electrical equipment based on digital twin (DT) has received extensive attention and is considered as a technology with great engineering values and excellent application prospects. However, the current calculation of DT mostly relies on the traditional finite element method (CFEM). This method becomes less computationally efficient as the size of the DT increases, especially for electrical equipment with high complexity. It is difficult to meet the requirements real‐time calculation in DT. Therefore, starting from the algorithm optimization and parallel architecture, based on the weighted residual method and stabilised conforming nodal integration, a novel discrete method of electrothermal coupling equation is proposed and the data storage structure of the algorithm from the bottom layer is redesigned, and the corresponding GPU and multi‐core CPU parallel framework are proposed. Finally, taking the high voltage bushing as an example, the correctness of the method in this paper is verified by the CFEM code and commercial software ABAQUS. Under the same grid and accuracy requirement, the calculation time is shortened by at least five times than ABAQUS. And the method is easy to extend to other types of multi‐physics calculations.

Electrothermal Analysis of System in Package for Aerospace Application

Abstract Aiming at the failure problem of aerospace electronic product at the complex space environment, the electrothermal coupling method has been used to analyze the reliability of the ten channels independently adjustable voltage conversion system in package (SIP) module based on integrated forming package, which has supplied the voltage to the remote sensing camera detector. First, the electromagnetic model and thermal model have been made based on the SIP module; second, the electrothermal coupling simulation of three working conditions at normal environment have been made, and the maximum temperature of the SIP has been calculated; then, the maximum temperature of the SIP has been also calculated at vacuum and 45 °C to analyze the performance of this SIP in the space environment; at last, some test have been made of the SIP product. Compared with the measured results, the electrothermal coupling method has much more accurate than traditional thermal method. At normal environment, the simulated temperature relative error is 2.8%. At vacuum and 45 °C environment, the simulated temperature relative error is 9%. This method ensured the performance and accuracy of the design of the SIP, which has verified the reliability of aerospace SIP module at early stage.

Dried Wild-Grown Mushrooms Can Be Considered a Source of Selected Minerals.

Dried mushrooms might be a source of mineral components, which are indispensable for human health. The aim of this study was to determine the contents of calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), and selenium (Se) in dried wild-grown mushrooms (Boletus edulis and Xerocomus badius) available for sale, and to evaluate these mushrooms’ contribution to the daily reference intake of the studied bioelements. The concentrations of mineral components in the mushroom samples were determined by the flame method (Ca, Mg, Fe, Zn, Cu, Mn) and the electrothermal (Se) atomic absorption spectrometry method. The mean Ca, Mg, Fe, Zn, Cu, Mn (in mg/kg), and Se concentrations (in µg/kg) in B. edulis were 82.1, 964.1, 233.4, 97.9, 25.3, 22.1, and 6501.6, respectively, whereas in X. badius: 67.5, 1060.2, 87.8, 197.2, 33.9, 19.8, and 282.4, respectively. We have shown that dried B. edulis can be considered a source of Se. In the case of the other microelements, the tested mushrooms may serve only as additional supplements. Therefore, the studied species of mushrooms cannot be regarded as potential nutritional sources of the macroelements in question. Consumers should be properly informed about this, which should be guaranteed by appropriate legal regulations.

Influence of Microgreens Biofortification with Selenium on Their Quantitative and Qualitative Parameters

The study monitored the effect of differentiated mineral nutrition of microgreens species by solution of sodium selenate (2 mg Se/L) on the content of Se, chlorophylls, and other minerals. Chlorophylls were measured spectrophotometrically, Se by electrothermal atomic absorption method (ETAAS) with Zeeman-effect background and elements’ concentration was performed by a dual Inductively coupled plasma atomic emission spectroscopy (ICP-OES) iCAP7600 instrument. The content of selenium in fresh weight moved on average from 0.013 to 12.556 μg/g. Selenisation increased the content of Se in all tested species significantly (p < 0.05) without impacting yield. The content of chlorophyll a moved from 249.9 mg/kg (Mizuna) to 604.4 mg/kg (Arugula) with significant differences between the species, without significance (p ≤ 0.05) between tested variants. The influence of selenisation on other minerals significantly differed (p < 0.05) due to the genetic variability. A significant (p ≤ 0.05) increase in Ca was observed in green basil (10.7%) and cress (20.9%); of Fe in green basil (1.6%) and cress (40.9%); of K in arugula (1.6%), green basil (3.9%) and cress (2.8%); of Zn in arugula (2.6%), green basil (8.6%), cress (2.7%) and radish (5.9%); and of Ba in green basil (5.6%) and cress (23.9%).

Improved finite element method based on radial point interpolation method (RPIM) for electro-thermal coupling

Efficient electro-thermal coupling calculation is of great significance to the monitoring and structural design of power equipment. Finite element method (FEM) is one of the powerful tools of electro-thermal analysis and is widely used in various fields. However, the finite element method itself cannot solve the first-order discontinuity, which causes the deterioration of accuracy. For example, in the electro-thermal coupling calculation, Joule heat is often used as the only heat source of the thermal field, and the calculation of Joule heat depends on the first-order variable field strength of the electric field. The calculation error of is further amplified in the thermal field solution, and the performance is more obvious in strong electromagnetic environment. Therefore, this paper proposes a finite element (RFEM) electrothermal coupling method based on the radial point interpolation method (RPIM). The idea of this method is to use the first-order continuous RPIM method to interpolate the variables in the overall solution domain to obtain continuous and smooth solution results. Examples show that RFEM has a higher solution efficiency than FEM, and it is better at capturing local high gradient changes in an electromagnetic environment.

Arsenic in Groundwater Sources from Selected Communities Surrounding Taal Volcano, Philippines: An Exploratory Study

Arsenic (As) is a highly toxic, carcinogenic trace metal that can potentially contaminate groundwater sources in volcanic regions. This study provides the first comparative documentation of As concentrations in groundwater in a volcano-sedimentary region in the Philippines. Matched, repeated As measurements and physico-chemical analyses were performed in 26 individual wells from 11 municipalities and city in Batangas province from July 2020 to November 2021. Using the electrothermal atomic absorption spectrometric method, analysis of the wells revealed that in 2020, 23 out of 26 (88.46%) had As levels above the WHO limit of >10 ppb while 20 out of 26 wells (76.92%) had persistently high As levels a year later. Using a Wilcoxon signed-rank test, levels of As were found to be statistically elevated compared to the national safe limit of 10 pbb in the 26 matched sampling sites in both 2020 (p-value < 0.001) and 2021 (p-value = 0.013). Additionally, a two-paired Wilcoxon signed-rank test revealed that As levels were statistically higher in 2020 than in 2021 (p-value = 0.003), suggesting that As levels may be higher in years when there is more volcanic activity; however, this remains to be further elucidated with suitable longitudinal data, as this study is still in its preliminary stages. The data was also analyzed using a bivariable regression, which showed no evidence of a significant relationship between As levels and distance from the danger zone (Taal volcano crater); however, results showed an inverse but statistically insignificant relationship between As levels and elevation. Due to the toxic profile and persistence of As in groundwater in Batangas Province, continuous groundwater As monitoring, timely public health risk communication, and the provision of alternative water sources to affected populations are recommended.

Electrothermal response optimization of nozzle structure for multi-material rapid prototyping based on fuzzy adaptive control

PurposeMost rapid prototyping (RP) relies on energy fields to handle materials, among which electricity has been much more utilized, resulting in distinctive responsiveness of non-linear, overshoot, variable inertia, etc. The purpose of this paper is to eliminate the drawbacks of array nozzle clogging, stringing, melt sagging, particularly in multi-material RP, by focusing on the electrothermal response so as to adaptively distribute thermal more accurate, rapid and balanced.Design/methodology/approachThis paper presents an electrothermal response optimization method of nozzle structure for multi-material RP based on fuzzy adaptive control (FAC). The structural, physical and control model are successively logically built. The fractional order electrothermal model is identified by Riemann Liouville fractional differential equation, using the bisection method to approximate the physical model via least square method to minimize residual sum of squares. The FAC is thereafter implemented by defining fuzzy proportion integration differentiation control rules and fuzzy membership functions for fuzzy inference and defuzzification.FindingsThe transient thermodynamic and structural statics, as well as flow field analysis, are conducted. The response time, mean temperature difference and thermal deformation can be found using thermal-solid coupling finite element analysis. In physical experimental research, temperature change, together with material extrusion loading, were measured. Both numerical and physical studies have revealed findings that the electrothermal responsiveness varies with the three-dimensional structure, materials and energy sources, which can be optimized by FAC.Originality/valueThe proposed FAC provides an optimization method for extrusion-based multi-material RP between the balance of thermal response and energy efficiency through fulfilling potential of the hardware configuration. The originality may be widely adopted alongside increasing requirements on high quality and high efficiency RP.

Temperature-Dependent Characterization of Power Amplifiers Using an Efficient Electrothermal Analysis Technique

In this paper, we propose an efficient methodology for the electrothermal characterization of power amplifier (PA) integrated circuits. The proposed electrothermal analysis method predicts the effect of temperature variations on the key performances of PAs, such as gain and linearity, under realistic dynamic operating conditions. A comprehensive technique for identifying an equivalent compact thermal model, using data from 3-D finite element method thermal simulation and nonlinear curve fitting algorithms, is described. Two efficient methods for electrothermal analysis applying the developed compact thermal model are reported. The validity of the methods is evaluated using commercially available electrothermal computer-aided design (CAD) tools and through extensive pulsed RF signal measurements of a PA device under test. The measurement results confirm the validity of the proposed electrothermal analysis methods. The proposed methods show significantly faster simulation speed comparing to available CAD tools for electrothermal analysis. Moreover, the results reveal the importance of electrothermal characterization in the prediction of the temperature-aware PA dynamic operation.

Electro-Thermally Actuated Non-Volatile Mechanical Memory With CMOS-Level Operation Voltage and Low Contact Resistance

A non-volatile mechanical memory device with CMOS-level operation voltage and low contact resistance is proposed utilizing electro-thermal actuation method for the first time. Unlike the most widely used electrostatic actuation method in microelectromechanical systems (MEMS) devices, electro-thermal actuation is known to produce large actuation force and displacement with low operation voltage, which are preferable attributes of a mechanical memory. In addition, stiction, one of the most notable failure mechanisms of MEMS devices referring to the inadvertent permanent adhesion between two surfaces, can be exploited to significantly improve the energy efficiency of mechanical memory by retaining the ON-state without power. We devised a non-volatile mechanical memory device capable of performing multiple cycles of write and erase operations with CMOS-level voltage by utilizing electro-thermal actuation and stiction. The fabricated electro-thermally actuated mechanical memory successfully performed 200 repeated cycles of write and erase operations at 0.9V and 1.0V, respectively. Thanks to the high contact force generated by electro-thermal actuation, the fabricated device achieved the contact resistance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$17 \boldsymbol {\Omega }$ </tex-math></inline-formula> . Lastly, we confirmed that the fabricated device successfully retained both ON and OFF states upon removal of power beyond 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> seconds. [2021-0178]

Modification and Characterization of Interfacial Bonding for Thermal Management of Ruthenium Interconnects in Next-Generation Very-Large-Scale Integration Circuits.

Ruthenium may replace copper interconnects in next-generation very-large-scale integration (VLSI) circuits. However, interfacial bonding between Ru interconnect wires and surrounding dielectrics must be optimized to reduce thermal boundary resistance (TBR) for thermal management. In this study, various adhesion layers are employed to modify bonding at the Ru/SiO2 interface. The TBRs of film stacks are measured using the frequency-domain thermoreflectance technique. TiN and TaN with high nitrogen contents significantly reduce the TBR of the Ru/SiO2 interface compared to common Ti and Ta adhesion layers. The adhesion layer thickness, on the other hand, has only minor effect on TBR when the thickness is within 2-10 nm. Hard X-ray photoelectron spectroscopy of deeply buried layers and interfaces quantitatively reveals that the decrease in TBR is attributed to the enhanced bonding of interfaces adjacent to the TaN adhesion layer, probably due to the electron transfer between the atoms at two sides of the interface. Simulations by a three-dimensional electrothermal finite element method demonstrate that decreasing the TBR leads to a significantly smaller temperature increase in the Ru interconnects. Our findings highlight the importance of TBR in the thermal management of VLSI circuits and pave the way for Ru interconnects to replace the current Cu-based ones.

Upcycling of photovoltaic silicon waste into ultrahigh areal-loaded silicon nanowire electrodes through electrothermal shock

Upcycling of photovoltaic silicon (Si) waste to produce high-energy-density energy storage materials represents an effective way to achieve carbon neutrality. However, at present, photovoltaic Si waste (WSi) can only be suitable for degraded utilization because WSi recycling processes are limited by deep oxidation, entrainment of trace impurities, and structural reconstruction difficulties. Here, we propose an electrothermal shock method to convert photovoltaic WSi directly into ultrahigh areal-loaded (4.02 mg cm−2) silicon nanowire (SiNW) electrodes. High-gradient thermal fields (∼104 K s−1) are produced to drive the formation and deposition of gaseous Si molecules using the easy oxidation characteristics of the WSi powder. Carbon fiber cloth is used as both a heater and an in-situ growth substrate for the SiNWs to construct SiNW-carbon cloth self-supporting electrode (SiNWs@CC) structures. When used as a binder-free anode for lithium-ion batteries, it exhibits ultra-high areal capacity (3.2 mAh cm−2 for 600 cycles, capacity retention rate >83%) and long-cycle stability (1706.2 mAh g−1 at 1 A g−1 after 1800 cycles). A full battery assembled using a commercial LiFePO4 cathode also demonstrates stable cycling performance (>91.2% initial capacity maintained at 0.5 C for 250 cycles). Such an upcycling strategy will help to promote environmentally friendly, economical, and sustainable development of the photovoltaic and energy storage industries.

Investigation of the machining performance of ferritic ductile cast iron in WEDM using response surface methodology

Wire electrical discharge machining (WEDM) technology is a special electrothermal processing method that can precisely production of parts with variable stiffness with sharp edges or production of complex geometric parts which are difficult to produce by traditional manufacturing methods. It has an important place in production sector in terms of low energy consumption. In this study, the relationship between processing parameters on surface quality on the ferritic ductile cast iron (GGG-40) material in WEDM process with molybdenum wire was investigated by Response Surface Methodology (RSM). The aim of this study is to determine the optimum process parameters for low-cost production of GGG-40 material with sharp-edged and complex geometry parts using the WEDM method. In experimental works, surface roughness, and process time were investigated using table feedrate, pulse on time, and pulse space as cutting parameters. The surfaces obtained as a result of the experiments were evaluated in terms of surface quality with Scanning Electron Microscopy (SEM), and surface roughness device. According to the findings, it has been observed that the surface roughness has increased with increasing table feedrate, and pulse on time, and surface roughness decreased with pulse space increasing. Also, it is understood that pulse on time is the most important factor effecting surface quality. It has been found that the process time depends on only the table federate where they are inversely proportional. As result of RSM analysis, optimum cutting parameters were obtained in terms of lowest surface roughness, lowest process time and best time/performance condition on both parameters for ferritic ductile cast iron in WEDM process.

Energy and exergy analysis of a new calcium carbide production process

Energy and exergy analysis is very useful to optimize the design, operation and evaluation of calcium carbide production process. In this paper, a new calcium carbide production process of coal-coke-electricity grading substitution method (GSM) is proposed and evaluated by inter grating the first and second laws of thermodynamics according to the actual operation data from an actual calcium carbide production enterprise. Three typical calcium carbide production processes of GSM, electro thermal method (ETM) and oxygen thermal method (OTM) are compared based on the comprehensive energy and exergy consumption indexes of multiple products. The results show that, for the GSM, the mixed pellet brings into the highest proportion of energy and exergy of 69.36% and 71.85%, while the calcium carbide brings out the highest proportion of energy and exergy of 71.97% and 69.09%. Among the various heat losses, calcium carbide furnace gas takes the most heat, accounting for 15.9% of the total heat output. The power consumption per unit product of GSM is only 2.48 kWh/kg-CaC2, which is 23.93% lower than 3.26 kWh/kg-CaC2 of ETM. According to the energy and exergy analysis, when CaC2 is the only target product, the GSM has the lowest comprehensive energy consumption of 10.22 kWh/kg-CaC2 and the lowest comprehensive exergy consumption of 9.15 kWh/kg-CaC2. Compared with the traditional ETM and OTM, the GSM has obvious advantages.

Millisecond Conversion of Photovoltaic Silicon Waste to Binder‐Free High Silicon Content Nanowires Electrodes (Adv. Energy Mater. 40/2021)

Waste to Electrodes In article number 2102103, Junhao Liu, Yanan Chen, Zhi Wang and co-workers propose an electrothermal shock method that directly converts photovoltaic silicon waste to Si nanowire (SiNW) electrodes in milliseconds. The SiNW electrode has a Si content of 76% and exhibits an ultrahigh initial Coulombic efficiency (89.5%) and stable half/full cell cycle performance. Successful application of this method opens a new pathway for promotion of sustainable development of renewable energy.

Thermal computer modeling of laser gyros at the design stage: a promising way to improve their quality and increase the economic efficiency of their development and production

In the paper, we consider the ways to improve the quality and economic efficiency of development and production of complex innovative electronic devices, among which are laser gyros (LGs). Development, manufacturing and testing of high-tech LG are relatively expensive. The accurate thermal modeling at the early stages of LG designing is an effective way to reduce overall costs owing to noticeable savings of expenses on multiple-laboratory tests of the LG under development and its re-design due to overheating. Use of the inexpensive Russian computer system ASONIKA for thermal modeling provides yet another boost to cost efficiency. In the paper, details of application of the electro-thermal analogy method, finite difference method, grid method, graph method in ASONIKA are described. The developed algorithm of creation of LG thermal model with the procedure of step-by-step disaggregation (zooming technique) is presented. The process of LG modeling by ASONIKA computer system is explained; the created LG thermal model in graphic view and the obtained thermal field of one of PCB in colored view are demonstrated. Electronic components prone to overheating are specified. The paper also presents the results of empirical verification of modeling with actual measurement of temperature by the thermal sensors installed in places corresponding to the model nodes; those measurements confirmed high accuracy of ASONIKA-based simulation.

Electrodynamic Apparatuses for Concentration of Solutions

The results of complex research of electrodynamic vacuum evaporators are presented. The scientific and technical concept of the directed energy action technology applicable to apparatuses of the electrodynamic type is substantiated. A system analysis of the energies of traditional dehydration equipment is given. Their technological and energy problems are determined by the electrothermal analogy method. It is shown how these problems are solved in the electrodynamic type apparatuses. A physical scheme and a mathematical model of a electrodynamic continuous operation vacuum evaporator are developed. Assumptions that take into account the specifics of evaporation in an electromagnetic field are formulated. A system of differential equations that defines the solution interaction with an electromagnetic field in vacuum is presented. A nonstationary model is transformed into relations in dimensionless variables using the methods of similarity theory and the “dimension analysis”. The tasks of experimental modeling are defined. The results of complex experimental studies of microwave vacuum evaporators are presented. The influence of the electromagnetic field power, the solution type and concentration, and the pressure level on the steam output is established. Constants of the equation in generalized variables, which, with an error within 8%, establishes the relationship of the number of energy actions with dimensionless complexes that characterize the technological parameters, are defined.

Electro-thermal comprehensive analysis method for defective bushings in HVDC converter transformer valve-side under multiple-frequency voltage and current harmonics

The insulation failure mechanism of the resin impregnated paper (RIP) valve-side bushings of HVDC converter transformer under high ambient temperature and strong electromagnetic field conditions is explored in this study via a novel electro-thermal comprehensive analysis method. Considering that the bushings are operating under Multiple-Frequency Voltage and Current Harmonics, a superposition analysis method is established for voltage and current with five frequencies based on a Fourier spectrum analysis of the rated voltage waveform and full-load current waveform. Calculation methods for the heat loss, temperature field, and electric field of RIP bushings at the converter transformer valve-side are then established under two defect conditions: (1) overheating defect caused by an abnormal spring contact at the copper-aluminium conductive tube transition joint and (2) electric potential suspension caused by disconnection between the outmost condenser’s foil layer and grounded flange. An overheating defect in a valve-side bushing with spring contact at the conductive tube is successfully identified by the proposed method to prove its effectiveness. This method can be used to optimize bushing insulation and current-carrying structures as well as to diagnose insulation failures in RIP valve-side bushings.

Lithium-Ion Battery Thermal Runaway Electro-Thermal Triggering Method and Toxicity Analysis

In high temperature condition, lithium-ion batteries have a greater risk of thermal runaway. Lithium-ion batteries may be exposed to smoke, combustion, or even explosion, which poses a greater threat to humans and the environment. In this paper, the electro-thermal triggering method is used to induce thermal runaway of the lithium-ion batteries. The most representative ternary polymer lithium-ion battery (NMC), lithium cobalt oxide battery (LCO), lithium iron phosphate battery (LFP) in the market were selected as experimental samples, all using 18650 batteries, and then the state of charge of battery samples were adjusted to 0%, 30%, 50%, 100%. The thermal runaway reaction phenomenon of lithium-ion batteries and the surface temperature of the batteries were recorded. The positive electrode samples of the batteries were characterized by X-ray diffraction and electron microscopy, and the thermal runaway reaction products were analyzed. The results show that with the increase of the state of charge, the thermal runaway reactions of the batteries are more severe. Thermal runaway reaction products contain a large amount of toxic substances, and prevention and protection are necessary.

Design, Implementation, and Validation of Electro-Thermal Simulation for SiC MOSFETs in Power Electronic Systems

Silicon carbide (SiC) mosfets are getting popular in high-frequency power electronic (PE) applications. More and more concerns for system efficiency and reliability are growing due to the increasing switching losses and thermal stress. In this article, an electro-thermal simulation method for SiC mosfets in modern PE systems is proposed. In the device simulation, a behavioral transient model of SiC mosfets is developed and used for generating a multidimensional power loss table in a wide range of operating conditions. The effects of parasitic elements, temperature-dependent parameters, and reverse recovery effect of the diode are taken into account. Furthermore, the power loss look-up table is integrated into the PE system simulation with an additional Cauer-based dynamic thermal model considering heatsink impact. In this way, the instantaneous power losses and junction temperature can be obtained, respectively, with fast simulation speed, reasonable accuracy, and improved simulation convergence. The proposed approach is implemented in PSCAD/EMTDC and further validated by the experimental results of a double pulse test setup and a power factor correction system.

Millisecond Conversion of Metastable 2D Materials by Flash Joule Heating.

Controllable phase engineering is vital for precisely tailoring material properties since different phase structures have various electronic states and atomic arrangements. Rapid synthesis of thermodynamically metastable materials, especially two-dimensional metastable materials, with high efficiency and low cost remains a large challenge. Here we report flash Joule heating (FJH) as an electrothermal method to achieve the bulk conversion of transition metal dichalcogenides, MoS2 and WS2, from 2H phases to 1T phases in milliseconds. The conversions can reach up to 76% of flash MoS2 using tungsten powder as conductive additive. Different degrees of phase conversion can be realized by controlling the FJH conditions, such as reaction duration and additives, which allows the study of ratio-dependent properties. First-principles calculations confirm that structural processes associated with the FJH, such as vacancy formation and charge accumulation, result in stabilization of the 1T phases. FJH offers rapid access to bulk quantities of the hitherto hard-to-access 1T phases, a promising method for further fundamental research and diverse applications of metastable phases.