Induction Heating Process Research Articles

A coupled steady thermo-electromagnetic problem in axisymmetric geometries. Mathematical and numerical analysis

Abstract This paper focuses on the analysis of a steady thermo-electromagnetic problem related to the modeling of induction heating processes. Taking advantage of the cylindrical symmetry, the original three-dimensional problem can be reduced to a two-dimensional one on a meridional section, provided that the current density has only the azimuthal component. A variational formulation is presented in appropriately weighted Sobolev spaces, and the existence of a solution is established by employing a fixed-point argument. Furthermore, uniqueness and additional regularity results are proved under reasonable assumptions on the physical coefficients. A finite element approximation combined with a fixed-point iteration scheme is proposed for the numerical solution of the problem. A priori error estimates are obtained to quantify the accuracy of the approximation. Finally, numerical results are reported to validate the theoretical estimates and assess the performance of the method in a physical application.

Numerical Modeling and Optimization of a Quasi-Resonant Inverter-Based Induction Heating Process of a Magnetic Gear

Numerical Modeling and Optimization of a Quasi-Resonant Inverter-Based Induction Heating Process of a Magnetic Gear

Sub-minute carbonization of polymer/carbon nanotube films by microwave induction heating for ultrafast preparation of hard carbon anodes for sodium-ion batteries

Hard carbons (HCs) are excellent anode materials for sodium-ion batteries (SIBs). However, the carbonization and granulation of HC powders involve complex processes and require considerable energy. Here, we developed a facile method for manufacturing HC anodes for SIBs via a novel microwave induction heating (MIH) process for polymer/single-walled carbon nanotube (SWCNT) films. Numerical simulations solving electromagnetic field and heat transfer problems revealed the MIH mechanism; the electric current induced by the applied microwave enables direct Joule heating of the SWCNT networks in the composite film. Consequently, the composite films could be heated to the target temperatures (800–1400 °C) and free-standing HC/SWCNT anodes could be prepared by applying MIH for only 30 s. Comparative analyses confirmed that ultrafast MIH is a reliable technique for producing HC anodes and can replace conventional carbonization processes which require a high-temperature furnace. Moreover, the HC/SWCNT anodes prepared by the ultrafast MIH were successfully applied to the SIB full cells. Finally, the feasibility of MIH for scalable roll-to-roll production of HC anodes was verified through local heating tests using a circular sheet larger than a resonator.

Influence Law of Electromagnetic Induction Heating Parameters on the Leveling Effect in Thin Plates

Abstract In order to analyze the influence of electromagnetic induction heating parameters on the leveling effect of thin plates after welding, and summarize their influence rules, this paper first introduces the principle of induction heating, further reveals the mechanism of electromagnetic induction heating to control the deformation of thin plates, and discusses the parameters that affect the process of electromagnetic induction heating. Based on this, the electromagnetic induction heating under different gap distances, current intensity, and heating frequency is simulated by finite element simulation software. The experimental verification is carried out, which lays the foundation for selecting the appropriate electromagnetic induction heating-related parameters.

Development of Induction Heating Processing Modes for Melting Corrosion-Resistant Coatings of Steel Components with Taking the Hardening into Account

Development of Induction Heating Processing Modes for Melting Corrosion-Resistant Coatings of Steel Components with Taking the Hardening into Account

An analysis of temperature control for electromagnetic induction heating of CFRP based on sparrow search algorithm

Accurate temperature control during the induction heating process of carbon fiber reinforced polymer (CFRP) is crucial for the curing effect of the material. This paper first builds a finite element model of induction heating, which combines the actual fiber structure and resin matrix, and systematically analyzes the heating mechanism and temperature field distribution of CFRP during the heating process. Based on the temperature distribution and variation observed in the material heating process, a PID control method optimized by sparrow search algorithm is proposed, which effectively reduces the temperature overshoot and improves the response speed. The experiment verifies the effectiveness of the algorithm in controlling the temperature of CFRP plate during the induction heating process. This study provides an effective control strategy and research method to improve the accuracy of temperature control in the induction heating process of CFRP, which helps to improve the results in this field.

Numerical simulation study on integral induction heating of backup roll

A finite element model (FEM) of the electromagnetic-thermal coupling is developed to study the integral induction heating of the backup roll. The method of calling different B–H curves of the material at different temperature moments is proposed to consider the change of the relative permeability of the backup roll in the temperature rise process. The magneto-thermal two-way coupling simulation of backup rolls was carried out in ANSYS with consideration of the heating power or current change, and the field test verifies the result. The influence of critical heating process parameters, such as the effective heating length of the coil, the chamfer radial, and the diameter of the backup roll on the temperature distribution, is studied. The results reflect that the length of the induction coil above the roll on one side should be controlled between 100 mm and 200 mm. Temperature near the end of the backup roll increases significantly when the length of one side of the coil exceeds 200 mm. The coils with the same diameter can heat the rolls with different diameters. The diameter difference between the coil to the roll should control around 200 mm to ensure uniformity of temperature distribution along the axial direction. The current value needs to be increased to confirm that the temperature near the end of the roll meets the requirement when the diameter difference between the coil and the roll exceeds 200 mm. The results provide a possibility for pre-evaluating the rationality of induction heating processes in production.

A high-performance multilevel power supply for versatile induction heating processes

Purpose Induction heating processes need to adapt to complex geometries or variable processes that require a high degree of flexibility in the induction heating setup. This is usually done using complex inductors or adaptable resonant tanks, which leads to costly and constrained implementations. This paper aims to propose a multi-level, versatile power supply able to adapt the output to the required induction heating process. Design/methodology/approach This paper proposes a versatile multilevel topology able to generate versatile output waveforms. The methodology followed includes simulation of the proposed architecture, design of the power electronics, control and magnetic elements and laboratory tests after building a 10-level prototype. Findings The proposed converter has been designed and tested using an experimental prototype. The designed generator is able to operate at 1 kVpp and 100 A at 250 kHz, proving the feasibility of the proposed approach. Originality/value The proposed converter enables versatile waveform generation, enabling advanced tests and processes on induction heating system. The proposed system allows for multifrequency generation using a single inductor and converter, or advanced tests for inductive and capacitive components used on induction heating systems. Unlike previous multifrequency proposals, the proposed generator enables a significantly improved versatility in terms of operational frequency and amplitude in a single converter.

Research on the heating effect evaluation of the electromagnetic induction heating system at low temperature based on the electrochemical-thermal coupling model

The extremely fast electromagnetic induction heating system (EIHS) was recently introduced to improve the poor charge and discharge performance of lithium-ion batteries (LiBs) at low temperature. In this work, aimed to investigate the heating effect of EIHS, the accurate electrochemical-thermal coupling model, validated against the charging capacity calibration with various C-rates and HPPC tests at different environments, was developed in depth to reflect the electrochemical and heat transfer behaviors of the LiB exposed to external cool air during the electromagnetic induction heating process. When the copper coil was subjected to a sinusoidal alternating current (SAC) excitation at 10 A, 3 kHz, the LiB can be warmed up to 293.15 K from 243.15 K within 742 s with an even heat generation inside the LiB. The impact of the SAC parameters on the needed heating time was illustrated with time maps, a series of contours suggested that the heating velocity increase with the increase of both the amplitude and frequency. As compared with the low-temperature state, the internal resistance had a more than 3-fold decrease, which can improve the discharging voltage platform and terminal voltage output, thus increasing the pulse power and usable capacity. Neither noticeable capacity retention difference before and after the heating cycles nor obvious capacity loss discrepancy between the normal charge-discharge and heating cycle tests was found at the end of the 200 heating cycles, so the EIHS can achieve a good tradeoff among temperature rising effect, working behaviors and LiB cycle lifespan, which had a considerable potential to enhance the applicability of EVs (electric vehicles) in frigid weather. Moreover, a better heat transfer condition, higher material thermal conductivity and lower specific heat capacity play an important positive role on the improvement of temperature rising performance.

Study on Temperature Field Uniformity of Dynamic Induction Heating for Camshaft of Marine Diesel Engine

This paper focuses on the study of the induction heating process of a camshaft in a marine diesel engine. A three-dimensional finite element model for dynamic induction heating is established using the finite element method of multi-physical field coupling, aiming to investigate the temperature uniformity of the cam during this process. Three elements are analyzed in this study: the moving speed, the gap between the induction coil and the workpiece, and the width of the induction coil. These factors allow for an analysis of the temperature distribution in the thickness direction and contour line direction of the cam under various conditions. On this basis, an equivalent parameter about the temperature uniformity in the thickness direction of the cam is proposed to guide the selection of the camshaft induction heating process parameters.

Revisit: derivation of induction heating power equation for a conductive metal sphere

AbstractCurrently, we are in the research of magnetic induction heating by using conductive metal particles. The technology (comes from a phenomenon known as the “skin effect”) generates heat produced by electrical eddy currents on metal particle’s surfaces. However, till now, the power equation to describe the energy consumption of the eddy current on a single particle surface still remains ambiguous. William R. Smythe derived this equation for metal ball. A minor error was clearly located in his derivation result. Today, similar ambiguous power equation is still adopted by researchers. In order to clarify this ambiguous situation and make our further deep study on particle-based induction heating process, in this paper, I revisit the derivation of the power equation with richful results.

Design and Numerical Study of Induction-Heating Graphitization Furnace Based on Graphene Coils

Induction-heating graphitization furnaces are widely used to produce high-purity graphite products due to their high heating rate, high-limit temperatures, safety, cleanliness, and precise control. However, the existing induction-heating systems based on copper coils have limited energy efficiency. This paper proposes a new induction-heating graphitization furnace based on graphene coils. Due to the excellent high-temperature resistance of the macroscopic graphene material, the coil can be placed closer to the graphite heater, which improves the electromagnetic efficiency; the coil itself does not need to pass cooling water, which reduces the heat loss of the furnace and ultimately results in a higher energy efficiency of the induction furnace. In this paper, a numerical model of the induction-heating process is established and verified, the temperature-field and electromagnetic-field distributions of the heating process are analyzed by using the model, and the energy balance calculations are performed for the original furnace and the new furnace. Through a comparison, it was found that the new furnace possesses an electromagnetic efficiency of 84.87% and a thermal efficiency of 20.82%, and it can reduce the energy consumption by 33.34%, compared with the original furnace. In addition, the influence of the coil parameters on the performance of the induction furnace is discussed. By changing the coil conductivity, the induction furnace can achieve an energy efficiency of 17.76%–18.11%. This study provides new ideas for the application of macroscopic graphene materials in high-temperature induction heating.

An Inductive Method for Comprehensive Estimation of Temperature-Dependent Electrical and Thermal Properties of Conductive Ferromagnetic Materials

Reliable information about the properties of the processed materials has a significant impact on the effects of their processing. In induction heating processes, this also applies to information about the influence of temperature T on these properties. These are both thermal and electro-magnetic properties. Based on previous studies, a comprehensive experimental method is presented for estimating the temperature characteristics of thermal diffusivity, volumetric heat capacity and resistivity on one measurement station, with particular attention to ferromagnetic materials. The estimation process is carried out on an induction heating stand using forcing signals from an inverter generator. In a computer-controlled cycle that changes the base temperature level, basic measurements of thermal and electrical properties are carried out on a material sample in the form of a cylindrical disk. They are the results of the analysis of the temperature and electromagnetic responses of a material sample to short- and long-term step pulses of a sinusoidal excitation signal with a frequency of approximately 40 kHz. The presented estimation method can be treated as a final method or a preliminary procedure for radically narrowing the variability in decision variables inthe optimization process of simultaneous determination of the sought material characteristics.

Electro-thermal modeling of an induction heating process of 42CrMo4 steel probe

This paper describes the procedure of electromagnetic and thermal modeling of an induction hardening load of 42CrMo4 steel. In addition to the temperature and field level dependent physical properties of the material, the magnetic behavior of the load is captured by means of some kind of non-linear impedance boundary condition which simplifies the computational cost of the simulation. The numerical results show the critical behavior around Curie temperature. Finally, a comparison between several simulation results and experimental measurements are provided to assess the usefulness of the proposed electro-thermal simulation.

Non-contact heating methods of carbon fiber thermoplastic composites based on Joule thermal properties: Optimization and validation

Carbon fiber matrix composites have garnered significant attention due to their exceptional properties, finding wide-ranging applications in industries such as aerospace, transportation, and military. In this study, a novel approach involving the addition of nickel was explored to fabricate carbon fiber-reinforced thermoplastic polymer composites and composite materials filled with nylon 12, utilizing nickel foam as matrix. Subsequently, electromagnetic-thermal multiphysics coupling models were established to analyze the induction heating process. The study investigated the effects of nickel content, spatial location of the main heat source, coil current, and coil frequency on the temperature rise and heat generation. Additionally, a linear fit was applied to determine the material surface temperature and related factors during induction heating. Furthermore, a theoretical formula was derived for induction heating under ideal conditions, elucidating the heat transfer mechanism and the influence of various factors on heat generation. The findings of this research serve as a reference for optimizing the utilization of Joule heat in composites, thereby expanding the application of carbon fiber-reinforced polymer composites in temperature regulation and operational control.

Neural metamodels and transfer learning for induction heating processes (TEAM 36 problem)

The authors explore the possibility of applying a convolutional Naeural Network (CNN) to the solution of coupled electromagnetic and thermal problem, focusing on the classical problem of induction heating systems, traditionally solved by resorting to Finite Element (FE) models. In fact, FE modelling is widely used in the design of induction heating systems due its accuracy, even if the solution of a coupled nonlinear problem is expensive in terms of computational time and hardware resources, notably in 3D analysis. A model based on CNN could be an interesting alternative; in fact, CNN is a learning model selected for its excellent ability to converge, even when trained with a limited dataset. CNNs are able to treat images as input and they are used here as follows: given a temperature map in the workpiece, identify the corresponding vector of current, frequency and process heating time; this mapping is a model of the inverse induction heating problem. Specifically, we consider as an example the induction heating of a cylindrical steel billet, made of C45 steel, placed in a solenoidal inductor coil exhibiting the same axial length of the billet (TEAM 36 problem). A thorough heating process is usually applied before hot working of the billet, as in an extrusion process, but this methodology can be applied also in the design of induction hardening processes. First, a CNN has been trained from scratch by means of a dataset of FE solutions of coupled electromagnetic and thermal problems. For the sake of a comparison, a transfer learning technique is applied using GoogLeNet, i.e. a Deep Convolutional Neural Network able to classify images: starting from the pre-trained GoogLeNet, its training has been subsequently refined with the dataset of solutions from FE analyses. When the training dataset contains a limited number of samples, GoogleNet shows good accuracy in predicting the process parameters; in the case of a high number of samples in the training set, namely beyond a threshold like e.g. 1500, both CNNs show good accuracy of the result.

Prediction model for heating rate of section steel during the induction heating demolition process of steel reinforced Concrete：Experimental and numerical analysis

Traditional demolition techniques face challenges in effectively separating steel and concrete components of steel-reinforced concrete (SRC) structures. To address this issue, our research group has developed induction heating demolition (IHD) technology, a method allowing for environmentally sustainable and recyclable separation of section steel and concrete. To clarify the underlying mechanisms of the induction heating (IH) process applied to section steel, we undertook experiments on 32 samples of section steel. Our investigations focused on delineating the roles of two key parameters: the heating power (P) and the size of the sections involved. We found the heating rate (V) of the section steel to be significantly influenced by P, in conjunction with the flange and web plate thicknesses. To further unravel the transformations occurring in the steel's internal physical properties throughout the IH process, we devised a numerical simulation approach capable of faithfully replicating the IH process as it applies to section steel. This analysis revealed a diminishing IH efficiency for the section steel, with values declining from 0.7 to roughly 0.4 as the temperature escalated. Utilizing both experimental and numerical data, we formulated a predictive model for the section steel's V, aiming to facilitate the planning stage of IHD implementations. The model exhibits a predictive deviation maintaining a margin within 10 %, demonstrating its substantial reliability. This investigation provides novel strategies to curtail construction waste emissions in building demolition endeavors, thereby presenting a promising avenue toward more sustainable practices in the industry.

Inductive Heating and Quenching of Planetary Shafts for Diesel Engine Starters

High mechanical and temperature cyclic loading of the final products for automotive, transport, construction and agriculture mechanization industry, demands sufficient mechanical properties of all of their components during its exploitation. Majority of the components is made of steel, by different cold forming processes. Their main demanded characteristics are surface wear resistance and fatigue strength under pulsating stress in combination with cyclic temperature loading, which could be achieved only by appropriate heat treatment. The efficiency of the combined inductive heating and water quenching heat treatment and quality of the planetary shafts were analyzed, with the use of thermographic analysis, hardness measurements, and metallographic examination. Combination of inductive heating and water quenching is the most effective heat treatment process of carbon steel planetary shafts for the diesel engine starters. Long life span of carbon steel planetary shafts it’s essential for their economical production. The replacement of starter is expensive from both: money and working time point of view. Surface temperature measurements during the inductive heating process were performed in the industrial environment. The intensity and homogeneity of the planetary shaft surface temperature field was measured by thermographic camera. On the base of theoretical knowledge and measurements, a mathematical model for temperature conditions determination in the shaft during the entire process of heating and quenching was carried out, and used for analyses and optimization of planetary shafts induction hardening process.

Latent heat effects in inductive heating of shape memory alloy fibers

AbstractMotivation of the present work is an inductive heating process, used in manufacturing a new kind of improved ultra‐high performance concrete. In this novel material, fibers made out of shape memory alloys are used to increase the maximum possible fiber volume fraction, or to create an internal state of compressive stress. In contrast to other works, the underlying microstructure transformation from martensite to austenite is highlighted based on thermal analysis. Dynamic scanning calorimetry measurements are adapted as basis for development of a phenomenological phase transformation model. It relates local temperature and temperature rate to the rate of change of the phase indicator, modeling the transformation of martensite to austenite. Latent heat is considered by an enthalpy method, the inductive heating process is considered by a phenomenological model. Study results for a purely thermodynamic process of heating a single fiber embedded in concrete are presented. They show that latent heat effects delay phase transformation and the process of fiber activation is very sensitive to the induced heat. Furthermore, it is discovered that latent heat causes a strongly inhomogeneous state of transformation in radial direction of the fiber, which is of great importance for thermomechanical processes and the interpretation of experimental results.

Uncovering the hidden structure: A study on the feasibility of induction thermography for fiber orientation analysis in CFRP composites using 2D-FFT

The induction heating process elicits a heating response in a carbon fiber reinforced polymer (CFRP) composite distinctly different from those in metal. Prior work in our lab and elsewhere has established that the intensity and spatial distribution of the heating patterns are governed by the fiber orientations in each layer and the degree of electrical contact between layers. Based on more extensive work on this non-conventional heating behavior, we show that the analysis of induction heating patterns enables the characterization of the fiber orientations and stacking order within the material. In the first step, 2D Fast Fourier Transform (2D-FFT) is used to extract the fiber orientations from the spatial characteristics of the heating pattern recorded with an infrared camera. In the next step, the extracted fiber orientation is used to design bandpass filters to carry out the inverse 2D-FFT and obtain the layer stacking order. Our findings demonstrate that this approach can accurately identify the layer orientations (maximum error of 6o) and the stacking sequence in quasi-isotropic CFRP laminates with up to 12 layers. We believe that the proposed approach has the potential as a valuable nondestructive, non-contact tool for large-area inspection and quality control in manufacturing fiber-reinforced composites.