Thermocouple Research Articles

Multiphysical Field Coupling Model for Simulating Thermal Stress and Deformation in Ferronickel Submerged Arc Furnace

To address the issue of thermal expansion and stress concentration in furnace body, a 3D multiphysical field coupling model of electromagnetics, fluid flow, and temperature is developed to predict the interaction mechanisms between temperature, thermal stress, and deformation during submerged arc furnace operation. This model integrates electromagnetism, electrothermal conversion, mass and heat transfer, and multiphase flow within a unified computational framework using user‐defined functions. Additionally, it conducts thermal mechanical coupling analyses to describe the thermal deformation and stress concentration behavior in the furnace body. The results indicate that the multiphysical field exhibits strong coupling and nonuniformity. Due to the high thermal resistance of the furnace body material, the temperature between the inner wall of the furnace lining and furnace shell decreases from 1212 to 467 K. When the electrode insertion depth increases from 1.8 to 2.2 m, the maximum temperature of furnace shell increases from 456 to 498 K, and the maximum deformation of furnace shell gradually increases from 28.0 to 30.1 mm. The maximum deformation position occurs at the height of z = 2.45 m. As the electrode insertion depth increases, the stress concentration phenomena in the rib plates, the bottom of furnace shell, and the central area of furnace bottom are enhanced.

Loss Research and Thermal Analysis of BLDC Hollow-Cup Motor Under Reactor Suppression

In order to avoid overheating of a BLDC permanent magnet (PM) motor at high speeds, this paper focuses on the loss reduction of a 90 W 47,000 r/min BLDC hollow-cup motor. It is proposed to provide an optimizing method for the series reactors and the parameterization of reactors in the motor system. The finite element method (FEM) is used to calculate and analyze the time harmonic of air-gap magnetic flux density, stator core loss, and rotor eddy current loss in two cases: with a series reactor and without a reactor. By parameterizing the inductance value, the optimal resistance value is determined to minimize motor loss. In addition, an electromagnetic–thermal coupling analysis is conducted, and the results show that the temperature distribution of the stator core, winding, and rotor are improved under reactor suppression. Finally, an experimental platform is built to verify the temperature increase and the efficiency of the motor load operation. A clear reference for the research and optimization analysis of motor loss reduction is provided.

Heating Characteristics and Identification Method of Carbonization Defect Composite Insulators Based on Electric–Magnetic– Thermal Coupling

Heating Characteristics and Identification Method of Carbonization Defect Composite Insulators Based on Electric–Magnetic– Thermal Coupling

A Review on High-speed Electric Spindle Dynamics Modeling and Vibration Response Research

Background: One of the main directions of modern technology in the field of precision machining is high-speed operation. The spindle system is commonly utilized in this kind of operation, and the electric spindle is the main preference among high-speed machine tool spindles. Objective: High-speed electric spindle vibration characteristics affect the machining accuracy of the machine tool and the quality of the workpiece, so the research on high-speed electric spindle vibration characteristics has important engineering practical significance. Methods: The research status of high-speed electrospindle at home and abroad has been summarized in this paper. Combined with the patents related to the dynamics modelling of electrospindle, the research on the dynamics modelling of high-speed electrospindle is analyzed. On this basis, the computational and analytical methods for the vibration modelling of the electrospindle, including the transfer matrix method and the finite element method, are investigated, the theoretical foundations of these methods are discussed in depth, and the advantages and disadvantages of the methods are evaluated. The applicability and limitations of the two methods are also compared. Results: The analysis has shown that the current research on the vibration characteristics of highspeed electrospindle is mainly based on mechanical modal analysis and electromagnetic analysis. At present, the dynamic modeling of the electrospindle mainly includes bearing modeling, shaft bearing modeling, spindle-case modeling, electrospindle electromechanical coupling modeling, electrospindle thermal coupling modeling, etc. The correctness of the modelling theory is verified through experimental and simulation results. Although these models tend to be perfected, they are still insufficient in the case of multiple influencing factors coupling and need further development. Conclusion: Finally, through the analysis of the patent and dynamic characteristics related to the high-speed electric spindle, thermal deformation, magnetic tension, material, and other factors should be considered comprehensively, and these factors should be coupled to establish an overall dynamics model for the vibration characteristics analysis. The dynamic modelling, vibration modelling method, and vibration characteristics of the high-speed electric spindle have been summarized in this study, and the outlook is presented.

Regulation of Liquid Self-Transport Through Architectural-Thermal Coupling: Transitioning From Free Surfaces to Open Channels.

In this work, the regulation of liquid self-transport is achieved through architectural and thermal coupling, transitioning from free surfaces to open channels. Hierarchical structures inspired by the skin of a Texas horned lizard are designed, with the primary structure of wedged grooves and the secondary structure of capillary crura. This design enables advantages including long-distance self-transport, liquid storage and active reflux management on free surfaces, directional transportation, synthesis and detection of reagents in confined spaces, as well as controllable motion and enhanced heat dissipation in open channels. The regulation capacity can be precisely controlled by adjusting the secondary capillary crura and external thermal gradients. The regulation mechanism is further elucidated through microscopic flow observation and a deduced theoretical model. The proposed structures are expected to introduce a new concept for designing lubrication systems, microfluidic chips, methods for chemical synthesis, and heat transfer in the future.

What makes β-NaYF4:Er3+,Yb3+ such a successful luminescent thermometer?

Luminescence thermometry has emerged as a promising approach for remote, non-invasive temperature sensing at the nanoscale. One of the simplest approaches in that regard is single-ion luminescence Boltzmann thermometry that exploits thermal coupling between two radiatively emitting levels. The working horse example for this type of luminescence thermometry is undoubtedly the green-emitting upconversion phosphor β-NaYF4:Er3+,Yb3+ exploiting the thermal coupling between the two excited 2H11/2 and 4S3/2 levels of Er3+ for this purpose. Within this tutorial article, I would like to give a theoretically motivated account on the underlying reasons for the experimentally recorded success of this material for Boltzmann thermometry referring to time-resolved data on both the bulk and nanocrystalline material. Guidelines are established and both advantages and potential pitfalls in β-NaYF4:Er3+,Yb3+ for luminescence thermometry are given.

Investigation of Welding-Induced Residual Stresses in a Herringbone Column Using the Blind Hole Technique: An Experimental and Numerical Study

The current research investigates the effect of residual stresses from welding on the stability of steel structures, particularly the herringbone column undulating cross-truss structure in the Zhengzhou New International Exhibition Center project. Residual stresses at 30 key points were measured using the blind hole method, and the temperature and stress fields under thermal coupling were analyzed using numerical simulation techniques. The measured residual stresses of the welded herringbone columns are generally higher than the theoretical calculated values, with the relative error of most measuring points being less than 10% and the minimum difference being 0.98 MPa. It was confirmed that the welding quality meets the design and acceptance standards. Through a combination of experimental measurements and numerical simulations, this study provides valuable reference information for the construction of similar projects. The results indicate that the residual stresses in the herringbone columns are controllable, ensuring the overall safety and reliability of the structure.

Coupling adaptation mode and regulation strategy for the wind–thermal climate environment of vernacular dwellings in Jiangnan, China based on regional bioclimatic evaluation

ABSTRACT With the increasing reliance on mechanical devices and the diminishing connection with climate and region, architecture is falling into a paradigm of “isolation” from the environment. As native building types, vernacular dwellings present the mode of human – environment mutualism, which is an important reference for responding to low-carbon and sustainable development of buildings and reshaping regional architectural styles. This study choses vernacular dwellings in Jiangnan, China as the research objects, focusing on the wind – thermal climate environment coupling adaptation mode and regulation strategy under the hot-summer and cold-winter zone. First, by using bioclimatology methods, the theoretical range of passive climate control zones in Jiangnan area during the summer and winter seasons was anatomically analyzed with the actual range of passive climate conrrtrol zones of Jiangnan dwellings. Second, the wind-thermal climate adaptation mechanism was comprehensively interpreted from climatological situation, space configuring type, climate space gradient and climate regulation interface four perspectives. Finally, from the perspective wind – thermal environments are respectively synergistic and contradictory in summer and winter, the coupling adaptation mode and strategy of Jiangnan residential climate adaptation are proposed, as well as a passive building regulation paradigm for hot-summer and cold-winter climate type, which provides an important way to promote climate-responsive sustainable development.

Performance analysis of superconducting motors for electrical aircraft propulsion using electromagnetic–thermal coupling method

The aviation industry is focusing on the development of low-carbon emission technologies, with hydrogen-powered aviation hybrid technology being an important area of interest. Superconducting motors (SCMs) play a crucial role in these aviation hybrid systems due to their high power-to-weight (PTW) ratio. However, SCMs face challenges such as strong coupling of the electric field, magnetic field, and temperature field within the motor. Conventional electromagnetic–thermal coupling analysis methods are not suitable for SCMs, as they are slow to perform calculations that are also less accurate. This study proposes an electromagnetic-thermal coupling analysis model for SCMs, taking into account the constraints of critical current, critical magnetic field, and critical temperature of superconducting (SC) materials. The study analyzes the impact of the critical current of SC tapes, permanent magnet remanence, convection heat transfer coefficient between SC coils and cooling medium, AC loss reduction of SC coils, and motor speed on the ultimate power of SCMs. The results show that an optimal permanent magnet remanence can maximize the ultimate power, and the other parameters have been found to be positively correlated with the ultimate power of the SCM. To enhance the PTW ratio of SCMs, future research directions include increasing the critical current of SC materials, reducing the AC loss of SC coils, and improving the cooling effectiveness of SC coils.

Application of physics-informed neural networks (PINNs) solution to coupled thermal and hydraulic processes in silty sands

The accurate modeling of water and heat transport in soils is crucial for both geo-environmental and geothermal engineering. Traditional modeling methods are problematic because they require well-defined boundaries and initial conditions. Recently, physics-informed neural networks (PINNs), which incorporate partial differential equations (PDEs) to solve forward and inverse problems, have attracted increasing attention in machine learning research. In this study, we applied PINNs to tackle hydraulic and thermal transport coupling forward problems in silty sands. A fully connected deep neural network was utilized for training. This neural network model leverages automatic differentiation to apply the governing equations as constraints, based on the mathematical approximations established by the neural network itself. We conducted forward problems and compared the solutions derived from PINNs with those from Finite Element Method (FEM) simulations. The forward problem results demonstrate the PINNs model’s capability in predicting hydraulic transport, heat transport, and thermal–hydraulic coupling in silty sands under various boundary conditions. The PINNs exhibited great performance in simulating the thermal–hydraulic coupling problem. The accuracy of the PINNs solutions shows its potential for simulation in geotechnical engineering.

Influence and regulation of photon de-excitation on thermal energy coupling characteristics and dynamic stability boundary of single-doped thulium ion laser

Influence and regulation of photon de-excitation on thermal energy coupling characteristics and dynamic stability boundary of single-doped thulium ion laser

Abnormal temperature rise and discharge characteristics of decay-like composite insulators

Abstract In recent years, there have been multiple incidents of fracture faults caused by the deterioration of composite insulators in China, seriously threatening the safe operation of the power system. This article takes a 500 kV decay-like composite insulator collected from the operation site as the research object, conducts visual inspection and analysis of its shed and core rod degradation status, and tests its infrared temperature rise and ultraviolet discharge distribution under power frequency operating voltage and related electrical parameters. Finally, an electric thermal coupling finite element model is established to analyze its discharge and tem-perature rise mechanism. The research results found that the infrared temperature rise characteristics and ultraviolet discharge characteristics of decay-like composite insulators can reflect their degradation status. As the testing distance increases, the measured infrared temperature rise gradually decreases. The distortion of dielectric parameters and the decrease in insulation resistance have caused partial discharge and abnormal temperature rise of decay-like insulators. In addition, compared to ultraviolet imaging detection, infrared temperature measurement can better reflect the internal defects of decay-like composite insulators and is less susceptible to interference from unrelated discharges around them.

Effect of thermal and electric coupling on the multifield response of laminated shell structures employing higher-order theories

Effect of thermal and electric coupling on the multifield response of laminated shell structures employing higher-order theories

Investigation of Coaxial Surface Junction Thermocouples Under Different Materials on Thermal Measurement

Coaxial surface junction thermocouples (CSJTs) are commonly applied to transient thermal measurements. Based on the measurement principle of CSJT, one-dimensional analytical inversion is applied for obtaining surface heat fluxes. However, with the thermophysical properties difference between the wall material and CSJT, transverse thermal conduction occurs that leads to a measurement error of surface temperature by CSJT. Hence, conventional temperature data processing methods can lead to surface heat flux measurement error. Therefore, quantitative analysis of lateral structural heat transfer should be carried out in the junction region and the interface between the sensor and the wall. In this paper, the multidimensional transmission of heat between three types of CSJTs and wall material under transient and long duration was investigated by numerical simulations. And the derivation of the axisymmetric heat transfer government equation was obtained by the improved Crank–Nicolson discrete scheme. We found the best wall materials for thermal matching with E-, J-, and K-type CSJTs, respectively. And the stainless steel tube can maintain a stable heat flux curve within a certain period. The conclusions of this study offer practical guidance for the selection of wall material and design improvement of CSJTs.

Failure Mechanism Investigations of Bond Wires Lifting-Off and Die-Attach Solder Aging Considering the Thermal Coupling Effects

Failure Mechanism Investigations of Bond Wires Lifting-Off and Die-Attach Solder Aging Considering the Thermal Coupling Effects

COMPUTATIONAL ANALYSIS OF FLUID-STRUCTURE INTERACTION AND HEAT TRANSFER IN EXTRUSION PROCESSES

The extrusion process is integral to manufacturing, enabling the production of continuous profiles with precise cross-sections for various industries, including automotive, construction, and aerospace. This study focuses on the computational analysis of material flow and heat transfer during the extrusion of an L-type section under steady-state conditions. Finite element analysis is used to model the extrusion process.The research evaluates the impact of key parameters such as container temperature, ram velocity, and friction coefficients on the billets thermal profile and exit temperature. The study incorporates non-Newtonian flow dynamics, and thermal coupling to provide comprehensive insights into optimizing process efficiency, die design, and material flow uniformity. The results demonstrate the critical role of thermal and frictional parameters in enhancing extrusion quality and preventing material defects.

A general thermodynamical model for finitely-strained continuum with inelasticity and diffusion, its GENERIC derivation in Eulerian formulation, and some application

A thermodynamically consistent visco-elastodynamical model at finite strains is derived that also allows for inelasticity (like plasticity or creep), thermal coupling, and poroelasticity with diffusion. The theory is developed in the Eulerian framework and is shown to be consistent with the thermodynamic framework given by General Equation for Non-Equilibrium Reversible-Irreversible Coupling (GENERIC). For the latter we use that the transport terms are given in terms of Lie derivatives. Application is illustrated by two examples, namely volumetric phase transitions with dehydration in rocks and martensitic phase transitions in shape-memory alloys. A strategy toward a rigorous mathematical analysis is only very briefly outlined.

Study on the Influence of Geological Parameters of CO2 Plume Geothermal Systems

At present, there are relatively few studies on the exploitation of geothermal resources in depleted high-temperature gas reservoirs with carbon dioxide (CO2) as the heat-carrying medium. Taking the high-temperature gas reservoir of the Huangliu Formation in the Yingqiong Basin as the research object, we construct an ideal thermal and storage coupling model of a CO2 plume geothermal system using COMSOL6.2 software to conduct a sensitivity analysis of geological parameters in the operation of a CO2 plume geothermal system. The simulation results show that, compared with medium- and low-temperature reservoirs, a high-temperature reservoir exhibits higher fluid temperature in the production well and a higher heat extraction rate owing to a higher initial reservoir temperature but has a shorter system operational lifetime; the influence of the thermal conductivity of a thermal reservoir on the CO2 plume geothermal system is relatively minor, being basically negligible; and the thinner the thermal reservoir is, the faster the fluid temperature in the production well decreases and the shorter the thermal breakthrough time. These findings form a basis for selecting heat extraction areas for CO2 plume geothermal systems and also provide a theoretical reference for future practical CO2 plume geothermal system projects.

Rapid Screening of Etomidate and Its Analogs in Seized e-Liquids Using Thermal Desorption Electrospray Ionization Coupled with Triple Quadrupole Mass Spectrometry.

The growing popularity of e-cigarettes has raised significant concerns about the safety and potential abuse of these products. Compounds originally used in the medical field, such as etomidate, metomidate, and isopropoxate, have been illegally added to e-liquids, posing substantial risks to consumer health, and facilitating the misuse of illicit drugs. To address these concerns, this study developed a rapid and efficient method for detecting etomidate, metomidate, and isopropoxate in e-liquids using thermal desorption electrospray ionization coupling triple quadrupole mass spectrometry (TD-ESI/MS/MS). The TD-ESI/MS/MS method exhibits high sensitivity, with detection limits for etomidate, metomidate, and isopropoxate reaching 3 ng/mL. Screening of 70 seized e-liquid samples from 12 cases using TD-ESI/MS/MS revealed that 46 samples contained only etomidate, 13 samples contained only isopropoxate, and 11 samples contained both etomidate and metomidate. The qualitative results obtained from TD-ESI/MS/MS were in complete agreement with those of GC-MS. Moreover, the TD-ESI/MS/MS method requires no pre-treatment steps and has a detection time of only 1 min, thereby saving experimental consumables and significantly reducing detection time. The method demonstrated high sensitivity, accuracy, and reproducibility, making it suitable for high-throughput screening in forensic and regulatory settings.

Impact of cold fluid injection on caprock integrity

In Brazilian pre-salt fields, the extracted carbon dioxide (CO2) is reinjected with lower temperatures into the reservoirs to maintain reservoir pressure, improve oil recovery and reduce greenhouse gas emissions. The cold CO2 injection can alter the mechanical and hydraulic properties of the subsurface and induce variations in formation stresses. Stress changes can be sufficiently high to generate undesirable fracture propagation, damage the caprock, and activate natural fractures or geological faults. Consequently, they can induce seismicity, leaks, and contamination of shallower aquifers and CO2 release into the atmosphere. This work investigates the thermo-hydro-mechanical effect of cold fluid injection on caprock integrity. To this end, a fully coupled thermo-hydro-mechanical (THM) finite element model governs the rock formation behavior. The proposed model considers poroelasticity, fluid flow, and convection/diffusion heat transfer within the permeable rock formation under single-phase fluid flow conditions. The temperature diffusion, pore-pressure buildup, and stress variation under isothermal or non-isothermal injection scenarios are investigated. The results show reservoir expansion in the isothermal scenario due to fluid injection, which is expected in the pressurization process. In the non-isothermal scenario, the thermally disturbed region throughout the reservoir resulted in compaction rather than expansion, even though it was subjected to injection. The instantaneous drop in temperature induces a hard drop in pore pressure and plastic deformations in the reservoir. The lower interval of the caprock presents critical horizontal tension stresses compromising its integrity. Finally, the study adds valuable insight to better understand the complex cold fluid injection process, considering hydraulic, mechanical, and thermal coupling.