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Predictive computer simulation of the temperature field control system of an induction heated object encounters difficulties associated with the nonlinearity of system on the one hand, and the time of calculation on the other hand, during numerical analysis of the magneto-thermal field of the object, especially in 3D. The paper presents a methodology for the fast simulation of temperature field for a completed induction heating system of calender rolls. The method of 3D calculations of rotating calender rolls with a moving web of wet paper can be connected easily with a simulation of the temperature field controller, for simulation of complex control systems. [ABSTRACT FROM AUTHOR]

Soft-switching technologies can effectively solve the problem of switching losses caused by increasing switching frequency of grid-connected inverters. As a branch of soft-switching technologies, load-side resonant soft-switching is a hotspot for applications of high-frequency inverters, because it has the advantage of achieving soft-switching without using additional components. However, the traditional PI control strategy based on the linear model is prone to destabilization and non-robust dynamic performance when large signal perturbation occurs. In this paper, a novel Passivity-Based Control (PBC) method is proposed to improve the dynamic performance of load-side resonant soft-switching grid-connected inverter. Besides, the model based on the Port Controlled Hamiltonian (PCH) model of the soft switching inverter is carried out, and the passivity-based controller is designed based on the established model using the way of interconnection and damping assignmentpassivity based control (IDA-PBC). Both stable performance and dynamic performance of the load-side resonant soft-switching inverter can be improved over the whole operating range. Finally, a 750 W load-side resonant soft-switching inverter simulation model is built and the output performance is compared with the traditional PI control strategy under stable and dynamic conditions. The simulation results show that the proposed control strategy reduces the harmonic distortion rate and improves the quality of the output waveforms. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this paper, a Cr coating was prepared by induction heating and pack-cementation chromizing on AISI 304 austenitic stainless steel. Then, the cold-rolling deformation and annealing treatment were introduced to refine the coarse matrix grains caused by pack-chromizing and improve the overall performance of 304 austenitic stainless steel. The phase composition, element distribution, and microstructure of the coating were carefully characterized. The microhardness, wear resistance, and corrosion resistance of the coating were tested. The results show that the Cr coating with a thickness of 100 μm is mainly composed of a (Cr,Fe)23C6, (Cr,Fe)7C3, and α-Fe-Cr solid solution. After the cold-rolling deformation and subsequent annealing treatment, the grains are significantly refined and the Cr coating is divided into two layers, consisting of carbon-chromium compounds such as Cr23C6, Cr7C3, Cr2C, and Cr3C2 in the surface layer and a Fe-Cr solid solution in the subsurface layer. The cold-rolling deformation and annealing treatment significantly improved the microhardness and wear resistance of the coated sample, and the corrosion resistance was also better than that of the uncoated sample. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive analysis of a novel control approach to improve the efficiency of parallel LLC resonant inverters using a combination of a current controlled variable inductor (VI) and phase shift (PS). The proposed control aims to reduce the Root Mean Square (RMS) current, thereby reducing conduction and switching losses, and improving power transfer efficiency, while considering zero-voltage-switching (ZVS) operation, output power variations and load changes. Furthermore, a design methodology for the variable inductor is proposed, and design considerations relevant to this application are discussed. The effectiveness of the proposed approach is evaluated through mathematical modeling and experimental results. The mathematical modeling results show that the proposed approach, utilizing SiC MOSFETs, maintains a maximum efficiency of 98.5% for a 20 kW inverter over a wider range of output power, which is a significant improvement over existing approaches. The experimental results also confirm the effectiveness of the proposed control in improving the efficiency of parallel LLC resonant inverters. [ABSTRACT FROM AUTHOR]

Induction surface hardening (ISH) processes are widely used in the heat treatment of numerous industrial components, especially in the automotive industry. Since this industry operates under very demanding quality standards, it is crucial for these heat treatment processes to meet rigorous specifications to ensure the safety and reliability of the produced components. This implies the precise and repeatable control of certain parameters throughout the manufacturing process of each of the parts treated, through precise and reliable instrumentation in electromagnetically harsh environments. The main objective of this work is to define the monitoring process for an industrial IHS application, determining the control needs and the methods of measurement, recording, and verification of the parameters that ensure the quality of the process. This paper describes the monitoring process of induction surface hardening, emphasizing the use of sensors and modern measurement and control systems. A comprehensive monitoring system supported by a programmable logic controller (PLC) and mixed acquisition and instrumentation systems (analog and digital) implemented with a high-performance Field Programmable Gate Array (FPGA) will be presented. [ABSTRACT FROM AUTHOR]

This paper proposes a single-stage direct AC to high-frequency (HF) AC resonant converter based on LLC configuration for induction heating (IH) systems or HF applications. Unlike conventional converters for IH systems, the proposed topology converts the utility frequency to HF AC in a single stage without using a DC link inductor and capacitors and takes the advantages of LLC configuration. Additionally, it improves the power factor to 0.9–1, lowers the THD (3.2% experimentally), and protects against the high-frequency components. An embedded control scheme was designed to keep the HF current oscillating at a resonant frequency, ensuring zero-voltage switching. The operating principle of the proposed topology was investigated using mathematical equations and equivalent circuits. Finally, it was verified using computer simulation, and an experimental prototype of 1.1 kW was developed to demonstrate the proposed topology's uniqueness. [ABSTRACT FROM AUTHOR]

In this paper, the influence of bismuth content and heating rate on the morphology of MnS inclusions in bismuth-containing free-cutting steel during heating was investigated through in situ observation experiments and 3D electrolytic corrosion experiments. By observing the microscopic morphology of inclusions in the original sample, it was found that MnS inclusions in the sample were rod-shaped, spherical, irregular, small in size, and mostly clustered at the grain boundary in the form of chains and divergences. With the addition of bismuth, MnS inclusions of a larger size appear in the steel, and the inclusions distributed at grain boundaries are also reduced. When bismuth (0.010~0.020%) is added to the steel, MnS is mainly spherical and uniformly dispersed in the steel matrix. If the bismuth content is too high, the inclusions aggregate. Through in situ observations of the inclusions in the sample, it was found that the addition of bismuth in the heating process delays the appearance of ferrite grain boundaries and contributes to the spheroidization of MnS inclusions. Mn and S elements can fully diffuse slowly in the matrix with a heating rate below 1 °C/s and a long holding time (300 s), which provides the possibility for the spheroidization of MnS inclusions. [ABSTRACT FROM AUTHOR]

This paper presents new resonant inverter topologies for dual-frequency induction heating (IH). These 2T1C and 3T topologies combine the advantageous features of two- and one-inverter solutions. An analytical description of the load impedance of a dual-frequency series-parallel circuit has been made. Using manufacturer datasheets and LTspice models of selected transistors, a MATLAB model was parameterized. Based on it, power losses are determined as a function of the following parameters: nominal power, frequency and DC bus voltage. The obtained results allowed for determining the data necessary in the design process. The research has been experimentally verified. Tests were carried out for pulsing and simultaneous operation. Power control characteristics as a function of frequency are determined. The possibility of operating the inverter with high efficiency (>97%) in the proposed 2T1C and 3T systems at nominal power is demonstrated. [ABSTRACT FROM AUTHOR]

This paper focuses on analytical methods of a finite-element method (FEM)-based edge heating system. The edge heating system plays a role in maintaining the temperature in the hot rolling process of carbon steel. Carbon steel moves along the production line and maintains the temperature by the edge heating system in the process. Power-of-the-edge heating system is transmitted to carbon steel during the process. Eddy currents are generated in carbon steel by Faraday’s law of electromagnetic induction, and eddy current loss serves as a heat source to increase the temperature. Thus, there is a need for accurate electromagnetic-field analysis and thermal analysis because the eddy current path generated in carbon steel greatly affects the heat distribution in carbon steel. This multiphysics analysis requires high reliability. Accordingly, this paper presents a coupling analysis method using an FEM-based coordinate mapping method as a more accurate analytical method. This paper also established an analytical approach to the edge heating system using the ductility analytical method of this coordinate mapping method. [ABSTRACT FROM AUTHOR]

Drying various materials constitutes an essential component of several industrial processes, e.g., paper production. Typically, rotating cylinders heated internally by water steam are used for drying tape-shaped material in paper-making machines. Such an approach remains very energy-consuming, while the whole process is expensive and in conflict with the global policy of reducing energy consumption in heavy industry. One promising alternative method of drying fibrous tapes is the induction heating of drying cylinders. In this paper, we propose a drying system based on a set of inductors (electromagnetic field sources) that generate energy in the mantle of the cylinder and dry the running tape. By enabling the movement of the inductors, the system provides a high level of flexibility in terms of reacting to the varying humidity of the tape. Additionally, imaging the temperature field on the cylinder surface provides a supplementary source of information, enabling the temperature profile to be controlled. Two types of humidity control systems, a one-loop feedback control and a cascade control, were designed and analyzed. Simulation analysis and experimental verification performed using a semi-industrial setup proves that using the proposed cascade control ensures more than 30% faster response of the whole dryness control system. [ABSTRACT FROM AUTHOR]

To quickly repair the inner-surface damage to the hydraulic support cylinder caused by frequent scratches, corrosion, and wear in the process of fully mechanized coal mining, this paper proposes a method of high-frequency induction cladding (HIC) copper alloy on inner-wall of cylinder (IWC) to improve the corrosion, sealing and pressure retention performance of hydraulic cylinders combined with numerical simulation and experimental study. Firstly, a numerical temperature field model for HIC of copper alloy on the IWC is established to investigate various distribution patterns and influencing factors including frequency of induction heating, gap between coil and cladding, power supply rating, cladding thickness and side length of square section of induction coil, etc. Subsequently, an HIC test experiment is conducted to rigorously validate the numerical temperature field model and the experiment employs a meticulously collected dataset of temperature measurements, confirming the model's accuracy and consistent alignment with anticipated changing trends. In addition, the experiment results were verified through microstructure observation, microhardness testing, friction-wear testing, and electrochemical corrosion parameters, which shows that the factors of induction heating frequency and others have obvious effects on the temperature field distribution of HIC copper alloy on the IWC. Under these working conditions (cladding thickness 1.5 mm, power supply rating 120 kW, heating frequency 120 kHz, gap between the cylindrical workpiece and the induction coil 3 mm, induction coil cross-sectional side length of 10 mm), the thermal impact on the cylinder barrel matrix is minimal, the metallurgical bonding between the cladding layer and the matrix is good, and there are no over burning and porosity defects. [ABSTRACT FROM AUTHOR]

Integrated heating and mechanical rolling forming (IHMRF) has recently been introduced for manufacturing complex curvature hull plates. It fabricates the target curved plate by sequential loading along the multipath. Accurate and efficient prediction of the deformation of the plate is the basis for developing the process planning and ensuring the quality of the forming. The inherent-strain method is ideal for this purpose, but its prediction accuracy needs to be improved. This paper proposes a multipath process-based inherent-strain method (MPISM), which considers the effect of the sequential loading process of the multipath on plate deformation. First, the effect of loading paths near the plate edge was investigated, which in turn clarified the rationale for obtaining the inherent strain only in the plate center. Secondly, a strain correction strategy was established by analyzing the variation pattern of the inherent strain caused by the crossing or proximity of the previous path and the subsequent path. This allowed the effects of the loading process to be taken into account in the elastic analysis. Based on the plate-and-shell theory, the idea of an equivalent inherent strain distribution is also presented. This makes the loading of inherent strains more accurate in the elastic finite-element model. MPISM predictions and experimental results show good agreement. Compared with the thermo-elastic–plastic finite element method, the MPISM substantially improves efficiency while maintaining accuracy. Compared with the original inherent-strain method, the MPISM is more accurate in terms of deformation magnitude prediction. [ABSTRACT FROM AUTHOR]

In this paper, the appropriate channel design and operating conditions for the simultaneous operation of the inclusion removal and the induction heating of the molten steel by imposing the A.C. magnetic field around the circular channel have been studied. (1) The effect of the lift force and the turbulence force on the inclusion in the transition zone of the channel has been computed; the results show that when the diameter of the inclusion is not less than 0.1 mm, both forces can be neglected because they are less than the electromagnetic pinch force, especially when the shielding parameter is not less than 5.0. (2) The minimal channel length to remove the inclusions out of the dead zone was computed without the lift force and the turbulence force; the shielding parameter of 10.0~15.9 is optimal to obtain the shortest channel length. Furthermore, the slow velocity of the molten steel is desirable. (3) The molten steel temperature increase per unit channel length by the induction heating can be controlled by the A.C. magnetic field frequency; a high frequency condition is better for the efficient thermal supply in this calculation condition. (4) When the flow velocity of the molten steel in the channel with a length of 1 m and a radius of 0.075 m is 0.1 m/s, the shielding parameter of 15.9 is the optimal parameter to simultaneously remove the inclusions and heat up the molten steel in the circular channel. And when the non-dimensional magnetic field intensity of the A.C. magnetic field is 31.7, the removal rate of the 0.1 mm inclusion in the channel can reach more than 95% and the molten steel temperature can be heated over 10 K. [ABSTRACT FROM AUTHOR]

In this paper, an experimental and numerical study of a novel heating strategy is shown for thin profiled workpieces using induction and convective heating at the same time. A characteristic of induction heating is its potential for achieving efficient local heating due to the direct conversion of electromagnetic fields to thermal energy. One disadvantage of this is the high temperature gradients that occur on the workpiece and, therefore, the uneven distribution. This is even more significant for thin workpieces or workpieces made out of sheet metal due to the lighter mass and, therefore, less conduction away from the heating zone. This paper presents the idea of combining induction heating with convection to obtain a more even distribution of the temperature but with considerable energy savings compared to pure convective heating. The combination of both heating methods has been analysed both experimentally and numerically with different geometries. The multiphysic simulation included both the induction heating and also the convective heat transfer for temperature-dependent material properties. The results of the simulations and the experiments were in good agreement, and both showed that there is a huge potential for energy savings when convective heating is supported by induction heating (up to 53%). This study provides a reference for future industrial applications for heating sheet metal workpieces, e.g., for drying paint. [ABSTRACT FROM AUTHOR]

In this article, an efficient die-bonding technology based on silver sintering due to induction heating is presented. By using this technology, the heat for the sintering reaction is locally limited to the bonding area and heating of the entire power module is avoided. Furthermore, the sintering reaction is promoted due to current flow between the silver particles, and the sintering time is drastically reduced. Next to the experimental trials presented in this paper, finite element (FE) simulation methods were applied to develop a suitable induction coil geometry for the bonding of a diode to a direct bonded copper (DBC) substrate. Additional heating and sintering tests verified the reliability of the simulation model as well as the technological approach. Diodes were successfully bonded during the experiments and were analyzed by means of scanning electron microscopy (SEM) and function tests to qualify the inductive bonding technology. The results presented in this paper demonstrate that induction heating has high potential for cost-effective production in the field of die attach and can drastically increase the output in power-electronics production. [ABSTRACT FROM AUTHOR]

Nowadays, multilevel inverter (MLI)-based induction heating (IH) technology is the best-suited option in many domestic, commercial and medicinal applications because of its higher efficiency, low cost, fast heating and lower electromagnetic interference (EMI). This paper presents reduced components count high-frequency (HF) single phase five-level (5-L) MLI for IH applications. The working methodology of the proposed system has been analyzed in the multicarrier phase disposition pulse width modulation (MC-PD-PWM) method in high switching frequency i.e., 10 kHz. In addition, the proposed topology can produce output voltage twice of input voltage without any external source. Moreover, the detailed power loss and reliability analysis have been evaluated for the proposed system. In terms of switch count and efficiency, the single-phase 5-L inverter architecture is compared to some conventional and current topologies. Finally, to validate and justify the operation of the proposed system, the simulation and experimental results of five-level inverter are presented. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental study of the interaction of a candidate sacrificial material (SM) for a light water reactor melt trap with corium at the Lava-B test-bench. The candidate sacrificial material is a combination of aluminum oxide and a lead layer. The idea of using such a combination of SM is based on the fact that when the lead layer interacts with corium, there will be an increase in the intensity of heat removal from the corium, as well as the chemical interaction between the corium and SM due to the high heat-conducting properties of lead. This approach will improve the efficiency of corium localization in the melt trap compared to the current set of sacrificial material. Experiments have shown active melting and boiling of lead during its interaction with corium. This is confirmed both by the readings of thermocouples and by the X-ray diffraction phase analysis of the deposit material formed on the walls of the melt receiver (MR) of the Lava-B bench, sampled after the experiment. The experiment results show that the lead layer reduces the rate of increase in the temperature of the corium and increases the rate of erosion of the ceramic part of the SM. With these circumstances, it is possible to conclude that the use of aluminum oxide with a lead layer is promising in practice. [ABSTRACT FROM AUTHOR]

The powder metallurgy (PM) route for the production of closed-cell metallic foams has recently received a significant amount of attention. One of the major issues is the non-uniform and non-spherical nature of the cells produced, which can negatively affect the mechanical behavior. The current paper uses the PM route to process metallic foams for the first time using novel Al-TiH2 foamable precursor "particles" (FPPs). The effect of FPP content (0–10 wt.%) on the developed foam structure of aluminum and its mechanical properties is investigated. An increase in FPP content results in a decline in product density by forming uniform and near-spherical cells. The main advantage of the FPPs is the localization of the blowing agent TiH2 particle content within Al-TiH2 composite particles (i.e., giving rise to a higher local TiH2 content), which has led to the production of pores with relatively high circularities even at very low overall TiH2 contents. The foams produced displayed energy absorption capacities of 10–25 MJ/m3 at 50% strain, and maximum energy absorption efficiencies ranging from 0.6–0.7 (for 40–60% closed cell content) [ABSTRACT FROM AUTHOR]

This paper describes the use of cold and hot composite forming technology to produce pointed curtain wall profiles. An electromagnetic–temperature coupling model was constructed using ANSYS to study the temperature and electromagnetic field distribution during the forming process. Numerical simulation was used to optimize the process parameters to obtain the optimum heating parameters with a current of 4000 A, a frequency of 35 kHz, and a duration of 2 s. The accuracy of the model was also verified through experiments. The simulation results show that the use of a conductive magnet can improve the induction heating efficiency, increasing the heating frequency and the temperature peak; however, it also increases the temperature difference. Sharp-corner curtain wall profiles were successfully produced using the optimized process parameters. The temperature of the heating zone was measured using an infrared thermal imager, and the relative errors between the maximum heating temperature obtained from the simulation and the actual measured values were 5.37% and 5.02%, respectively, indicating that the finite element model performs well in terms of prediction. [ABSTRACT FROM AUTHOR]

Induction heating (IH) technology is widely recognized and utilized in residential applications due to its high efficiency and safe operating characteristics. Resonant inverter circuits are widely used in IH systems because of their high efficiency and ability to perform soft switching. Among the various resonant inverters used in IH systems, the single-switch quasi-resonant (SSQR) inverter topology is typically preferred for low-cost and low-output-power applications. Despite its cost advantage, the SSQR topology has a relatively narrow soft-switching range, which can be unstable depending on the electrical parameters of the load and the resonant converter circuit. Accurately determining the capacitance value of the resonant capacitor and the inductance value of the induction coil, which are the key circuit elements of the SSQR induction cooker, is crucial for designing a reliable, efficient, and durable cooking system. In other words, there exists a critical relationship between the resonant converter circuit parameters, load characteristics, and safe operating conditions. Additionally, when considering closed-loop control methods used for power control and safety, selecting appropriate resonant circuit elements becomes vital in ensuring both reliable and efficient operation. This paper focuses on a novel and simplified design method for the SSQR inverter utilized in household appliances. The proposed method and its advantages in terms of the safe operating area of the switch are theoretically investigated and verified through simulations and prototype circuits. [ABSTRACT FROM AUTHOR]

Induction heating offers numerous advantages over conventional methods for heating high-pressure fluids in hydraulic testing applications. It simplifies complex processes, mitigates the risks associated with high-pressure environments, and enhances overall safety. The design of an efficient induction heating system requires a clear understanding of its key components, including the resonant tank circuit, impedance matching and isolation stage, high-frequency inverter, driver circuitry, and controller. The configuration of the resonant circuit plays a crucial role in device ratings and control methods. To meet the demanding requirements of switching devices like IGBTs, the driver circuit must ensure high immunity to interferences and failure. Effective system design allows the heating circuit to operate close to resonant switching, minimizing switching losses and cooling requirements. This paper presents the design and development of a 4-kW induction heater specifically tailored for inline heating of aviation fuel under high pressure. The system aims to achieve a precise temperature profile for testing line-replaceable units (LRUs) used in aircraft. The design methodology encompasses the selection of the resonant tank circuit configuration, impedance matching and isolation stage, high-frequency inverter, driver circuitry, and control strategies. Through extensive simulations in LTspice and experimental measurements, power losses in different components of the power conversion circuits are assessed, and overall system efficiency is evaluated. The results demonstrate the proposed induction heating system's remarkable energy efficiency, reduced switching losses, and improved reliability. Furthermore, a comprehensive comparison with existing designs and industry norms is presented, highlighting the distinct advantages of the proposed system in terms of cost-effectiveness, energy efficiency, material utilization, and processing time. This research contributes valuable insights into the design and optimization of induction heating systems for high-pressure fluid heating applications, providing a practical and efficient solution for the aviation industry. [ABSTRACT FROM AUTHOR]

This paper focuses on the effect of rapid annealing on Non-Grain Oriented Electrical Steel (NGO) in terms of microstructure, mechanical properties, and magnetic properties. The Ultra-Fast Heating (UFH) tests were performed by a transversal induction heater on NGO electrical steel samples (cold rolled down to 0.5 mm), varying the heating power (80 kW and 90 kW) and the speed of the strip through the induction heater. This allowed us to exploit heating rates (HR) in the range of 200–300 °C/s and targeting peak temperature (Tpeak) up to a maximum of 1250 °C. The comparison between the microstructure as obtained by conventional annealing and the ultra-fast heating process highlights a clear effect in terms of grain size refinement provided by the UFH. In particular, the average grain size as obtained by UFH ranges two/three times lower than by a conventional process. The results show the possibility of applying UFH to NGO steels, targeting mechanical properties such as those obtained by the standard process, combined with the benefits from this innovative heat treatment in terms of green energy and the minimization of CO2 emissions. Magnetic characterization performed by a single sheet tester (30 × 90 mm) showed that the values of core losses are comparable with conventional NGO grades. [ABSTRACT FROM AUTHOR]

The paper presents a universal computational model of heating curves for walking beam furnaces, which allows to determine the temperature distribution along the length of the furnace during heating of the steel charge. The model was made based on analytical dependencies regarding transient heat conduction, taking into account the temperature variability of all thermo-physical properties. The methodology of calculations and examples of heating curves for selected cases are presented. [ABSTRACT FROM AUTHOR]

The paper describes the physical aspects of modelling a moving heat source on the outer surface of a steel ring. The work concerns numerical modelling of thermal and structural phenomena in spiral laser heating and cooling in any coolants. The numerical analysis performed in the Abaqus/FEA software was developed to predict the size and quality of the hardened zone. The power distribution and spiral motion of the moving heat source are implemented in an additional DFLUX subroutine (Fortran). The results of the numerical simulation include the temperature field and the predicted zone hardened at different cooling rates. They are the starting point for the analysis and selection of parameters when modelling the hardening process, taking into account phase transformations in the solid state. [ABSTRACT FROM AUTHOR]

Industrial induction heating (IH) is a key manufacturing process due to its benefits in terms of efficiency, accurate output power control, and high performance. These features have made possible the extension of this technology to a wide range of industries from automotive to aeronautic, domestic, or renewable energies. One of the main challenges still present is the design of a high-performance and cost-effective process for those induction targets with complex geometries exposed to the magnetic field, being the most representative example gears present in most mechanical systems. Usually, in order to optimize the heating process, multifrequency IH systems are used, being often expensive and/or difficult to tune and control. The aim of this paper is, consequently, to propose a family of power converters able to supply the inductor system with two simultaneous frequencies in order to improve the heating process of the induction target. The proposed converter takes advantage of a multiresonant network allowing full control of the output power delivered at each frequency and, at the same time, a compact and cost-effective implementation. The proposed converter is analyzed, designed, and implemented, and experimental verification of its operation is provided in this paper. [ABSTRACT FROM AUTHOR]

This paper presents an analysis and design strategy for a half‐bridge series resonant induction heating (HB SR‐IH) cooker powered by a rectified sinusoidal DC. The simplified equivalent circuit of an induction cooker is modelled by a train of rectified sinusoidal DC pulses chopped at the switching frequency. An average root‐mean‐square (RMS) method is proposed to calculate the RMS resonant voltage and current extrapolated to the power line frequency period. The stability of the cooker is achieved by properly setting the damping ratio in the root‐locus plane to keep the system running quasi‐resonantly at the required power. The power control of the SR HB‐IH cooktop is performed by forced commutation above the resonance frequency. A prototype of a 3 kW HB SR‐IH cooker was designed and implemented to validate the estimated results. Various waveforms from low power to high power are discussed and verified by damping ratio control. The SR HB‐IH cooktop achieves a high‐power factor of 0.95 to 0.995 when generating 300W to 3kW due to less filtered DC power. The power quality assessment showed that the total harmonic distortion (THD) of the line current and voltage measured at 3 kW was 4.1% and 3.5%, respectively. [ABSTRACT FROM AUTHOR]

In induction heating processes, knowledge of the charge material parameters, i.e., thermal conductivity and volumetric heat capacity, as well as resistivity and magnetic permeability, is important both at the stage of preparatory process simulations and during their implementation. The paper presents a measurement method for estimating the thermal diffusivity, volumetric heat capacity, and resistivity of the charge material as a function of temperature on a single measuring setup, using a generator for induction heating as the source of signals. The method is based on the study (for forced temperature levels) of the temperature responses of cylindrical samples of the test materials and the voltage induced in the designed measuring coil after short- or long-term step excitation impulses. The presented approach enabled the dedicated computer-controlled system to obtain the initial values of the searched parameters with an accuracy of several percent. The procedure constitutes an introductory step in the simultaneous determination of a set of searched characteristics, and, by performing measurements, significantly narrows the range of variability in the decision variables of the optimization process. [ABSTRACT FROM AUTHOR]

A dual output direct AC–AC series resonant converter is presented in this paper, to meet the requirements of modern domestic induction heating. To address the significant limitations of the classic induction heating system, a hybrid control approach comprising pulse frequency modulation and asymmetrical duty-cycle control is developed. A single source is connected to multiple loads with this control technique to achieve minimum switching losses; power controllability of two loads is achieved independently and simultaneously. The power controllability of two loads is achieved independently and simultaneously. This research presents an induction heating system that can heat both ferromagnetic and non-ferromagnetic materials, such as steel and aluminum. A prototype is developed to use switching frequencies of 30 kHz and 150 kHz for steel load and aluminum load, respectively. The experimental setup resulted in an efficiency of 97.5% under wide load resonant condition. The suggested hybrid control approach allows the converter to regulate a wide range of output power while increasing efficiency, making it suitable for practical induction heating. [ABSTRACT FROM AUTHOR]

This paper investigates an induction heating problem in a multi-component system containing a moving non-magnetic conductor. The electromagnetic process is described by the eddy current model, and the heat transfer process is governed by the convection-diffusion equation. The two processes are coupled by a restrained Joule heat source. A temporal discretization scheme is introduced to numerically solve the corresponding variational system. With the aid of the Reynolds transport theorem and a density argument, we prove the convergence of the proposed scheme as well as the well-posedness of the variational problem. Some numerical experiments are also performed to assess the performance of the numerical scheme. [ABSTRACT FROM AUTHOR]

This paper describes a new method for the online parameter estimation of an induction heating system. Simulations and experiments are presented in order to measure its impedance matrix for more exact control in closed loop. In previous papers, various parameter identification methods including offline methods were introduced and compared for current inverters. It has been demonstrated that parameter identification is necessary to achieve good control of the inductor currents. A “pseudoenergy” method for a simple and fast implementation is compared to a classical “ $V/I$ with phase shift” method. They are experienced on a reduced-power three-phase coupled resonant system supplied with voltage inverters with satisfying results. [ABSTRACT FROM PUBLISHER]

To analyze the heating phase of an induction heated injection molding tool precisely, the temperature-dependent magneticproperties, B–H curves, and the hysteresis loss are necessary for the molding tool materials. Hence, injection molding tool steels, corematerials among other materials have, in this paper, been characterized for their temperature-dependent magnetic properties. Theproperties have been measured using a vibrating sample magnetometer, able to reach to 350 °C. The established material databasecomprises the B–H loops, from which the mean B–H curve, relative permeability versus magnetic flux density, and hysteresis lossversus magnetic flux density have been extracted and are presented. [ABSTRACT FROM AUTHOR]

In recent years, SiC single crystal growth technology has been developed toward larger size and thickness to reduce the cost of SiC-based power devices. Resistance heating has gradually become a hot spot for research because the crystals grown by the induction heating display the disadvantages of high stress and defect density. In this paper, the design of resistance heaters for SiC crystal growth was thoroughly investigated via numerical simulation. A simulation of the thermal field generated by different resistive heater arrangements was performed. The stress and dislocation distribution in crystals under different growth conditions were studied. Based on the comprehensive requirements of a small radial temperature gradient and a large growth rate, the arrangement and length of the resistance heater were proposed. This study would serve as a useful guidance for the study of SiC growth by resistive heating. [ABSTRACT FROM AUTHOR]

In general, it can be concluded that the emerging thermal food processing technologies are subject to fundamental and applied research in many countries, and the strong industry demand for employing new processing techniques highlights the need for further research in this area, in particular for addressing the well-reported upscaling hurdles. Ohmic heating, as one of the most interesting emerging thermal processing technologies, was explored in one of the accepted papers in this Special Issue, entitled "Application and Effects of Ohmic-Vacuum Combination Heating on the Quality Factors of Tomato Paste" [[2]]. [Extracted from the article]

In the present paper, we compare the activity, selectivity, and stability of a supported nickel catalyst in classical heating conditions and in magnetically activated catalysis by using iron wool as a heating agent. The catalyst, 5 wt% Ni supported on titania (Degussa P25), was prepared via an organometallic decomposition method and was thoroughly characterized by using elemental, microscopic, and diffraction techniques. In the event of magnetic induction heating, the % CO2 conversion reached a maximum of ~85% compared to ~78% for thermal conditions at a slightly lower temperature (~335 °C) than the thermal heating (380 °C). More importantly, both processes were found to be stable for 45 h on stream. Moreover, the effects of magnetic induction and classical heating over the catalyst evolution were discussed. This study demonstrated the potential of magnetic heating-mediated methanation, which is currently under investigation for the development of pilot-scale reactors. [ABSTRACT FROM AUTHOR]

This paper aims to study the application feasibility of steel slag powder (SSP) in replacing limestone powder (LP) to enhance the heat release and self-healing properties of asphalt and an asphalt mixture. First, the microwave-heating characteristics of SSP and LP asphalt mortar were analyzed, and the differences in the microstructure and chemical composition between SSP and LP were compared. Secondly, through the DSR frequency sweep test, the optimal healing temperature of the two asphalt mortars was determined. Finally, asphalt mixtures with different SSP contents were prepared by replacing part of LP in the mixture in a gradation with SSP. Under microwave radiation, the temperature distribution of the mixture was explored, and the self-healing properties and factors affecting the healing were analyzed. Results demonstrated that there are metal oxides with high electromagnetic parameters such as Fe2O3 and CaO in SSP, therefore, asphalt and a mixture containing SSP were seen to have excellent microwave absorption capacity. The healing temperature of the two kinds of asphalt mortar was between ~50 °C and 60 °C. Under microwave radiation, the temperature of the asphalt mixture increased with the increase in SSP content, and the temperature difference decreased with the increase in SSP content. Asphalt mixtures with an LP content of 30%, 40%, 50%, 60%, and 70% replaced by SSP increased the healing index by 8.7%, 17.3%, 22.1%, 26.9%, and 27.7% compared with conventional asphalt mixtures. Temperature is the most important factor affecting the healing behavior of the asphalt mixture. With the increase in the damage times of the asphalt mixture, the overall healing index of the asphalt mixture showed a downward trend. However, the healing index of an asphalt mixture containing SSP can still be maintained at more than 50% after repeated mechanical damage. [ABSTRACT FROM AUTHOR]

In this paper, an inductive power transfer (IPT) system without compensation elements is presented for small house appliances. The proposed system's transmitter side is an independent induction heating cooktop. IPT can be achieved when the kettle with the receiving coils is placed on the transmitter coil. The coils are designed with a high coupling coefficient. The magnetic system model consisting of aligned transmitter and receiver coils is created in the Maxwell program. In the created model, the analysis depends on the air gap and frequency, which are the variables that affect the wireless power transfer. The electronic circuit simulation uses the coil model to examine the system's dynamic behavior. The design of the transmitter/receiver coils of the IPT system is made with a cylindrical coil with a diameter of 145 mm, taking into account that it is compatible with the dimensions of the existing kettle and induction heating cooktops coil. A half-bridge series resonant converter circuit is used to adjust the power transferred to the load. To verify the simulation results and test the designed system, an experimental circuit using a 2200 W kettle is carried out. In the experiments, the air gap between the coils is kept constant at 7 mm, and measurements are taken for different powers. Experimental results confirm the magnetic model and simulation results. As a result, wireless power transfer is realized in a wide range without loss of performance in the kettle. System efficiency is greater than the 90% specified in the Ki cordless kitchen standard, and the harmonic currents drawn from the mains are lower than the values determined by the IEC 61000-3-2 standard. [ABSTRACT FROM AUTHOR]

This paper presents a novel single-phase modified Vienna rectifier (MVR) for the harmonic mitigation and power factor improvement of an induction heating (IH) system. The latter employs a high-frequency resonant inverter that is responsible for the generation of high-frequency harmonics, which, in turn, deteriorates the power quality. This mitigation must be done in accordance with harmonic regulations such as IEEE Std. 519-2014,IEC-555, and EN 61000-3-2, etc. Consequently, an MVR is placed between the power supply and the IH system. The proposed novel MVR topology overcomes the limitations of conventional Vienna rectifiers, such as their unbalanced voltage across output capacitors, high ripple at the output DC bus, and high THD in the supply current, etc. The efficacy of the proposed model has been verified by a series of simulations in PSIM. It is followed by a hardware validation using an Arduino Uno ATmega328 digital controller on a 1.2 kW experimental prototype of the IH system. The simulation and experimental results of the power quality indices comply with the IEEE-519 standards. [ABSTRACT FROM AUTHOR]

The paper introduces spatially stable Ni-supported bimetallic catalysts for CO2 methanation. The catalysts are a combination of sintered nickel mesh or wool fibers and nanometal particles, such as Au, Pd, Re, or Ru. The preparation involves the nickel wool or mesh forming and sintering into a stable shape and then impregnating them with metal nanoparticles generated by a silica matrix digestion method. This procedure can be scaled up for commercial use. The catalyst candidates were analyzed using SEM, XRD, and EDXRF and tested in a fixed-bed flow reactor. The best results were obtained with the Ru/Ni-wool combination, which yields nearly 100% conversion at 248 °C, with the onset of reaction at 186 °C. When we tested this catalyst under inductive heating, the highest conversion was observed already at 194 °C. [ABSTRACT FROM AUTHOR]

Based on the multi-physical field coupling analysis method, a finite element meso model of an induction heating circular tube containing carbon fiber texture and resin matrix is established, and the change law of the temperature field and stress of the circular tube is verified by experiments in order to study the distribution and change law of each physical field of induction heating technology in the heating process of a carbon fiber composite (CFRP) circular tube. This paper's electro-magnetic thermal mechanical coupling analysis model is shown to be accurate. The temporal and spatial variation laws of the temperature field, curing degree, and stress field in the process of multi-coil heating in a CFRP circular tube are investigated using the analytical model. The induction heating method of magnetic field superposition and coupling is proposed to improve the forming quality of carbon fiber circular tubes. The coupling state between magnetic fields changes with time, resulting in the dynamic change of eddy current and heat generation in the material and improving the uniformity of heat distribution in the periodic range which can effectively improve the uniformity of the temperature field, curing degree, and stress distribution of circular tubes and improve the quality of CFRP circular tubes in the forming process. [ABSTRACT FROM AUTHOR]

This paper presents the results of computational and physical studies on the production of corium and its retention in an MR's melt trap of the Lava-B facility. A feature of the Lava-B facility used in the IAE NNC RK to study the processes occurring during a severe accident at a nuclear reactor, is the separation of the stages of the reactor core corium formation and its interaction with structural materials. The melting of materials takes place in an induction furnace with a hot crucible, after which it moves to a melt receiver (MR) in which the test object is located. In the case of studies of processes occurring outside the reactor vessel, this is a special trap, which is placed in the inductor to simulate decay heat. However, based on the conservative computational estimates, it was found that the inductor power in the MR can be sufficient to directly produce, melt, and, subsequently, maintain the corium in the liquid phase. In this regard, in order to optimize the experiments under controlled conditions, the authors came up with the idea to experimentally test the possibility of producing corium by induction heating directly in the MR's melt trap. In addition, according to the authors, this method would obviate the problem of corium contact with the carbon environment of the melting furnace of the Lava-B facility. Previously, burden heating simulating corium was modeled on the computer using available parameters of the MR's induction heater. Based on the numerical experiment, the conditions for physical modeling of the corium production in the MR's melt trap were established. An analysis of the physical modeling showed that during the burden heating in the melt trap, its metal components became liquid, thus, forming a melt pool. However, in terms of this design of the trap, there were problems associated with the complete melting of all corium components, as well as with the integrity of the experimental device when forming the corium pool and during the actual physical modeling. [ABSTRACT FROM AUTHOR]

The development of energy-efficient Power-to-Heat (PtH) technologies with high power density on a utility scale is a key element in the future of flexible energy systems. Although existing solutions for electric flow heaters (EFH) based on resistance heating have a high efficiency, the process outlet temperature and power output are limited by the lifetime of the contact heating elements. Inductively heated packed bed heaters can achieve higher gas outlet temperatures with a higher power density, which is essential for an efficient process. This paper focuses on the modeling, experimental validation and numerical analysis of inductively heated pebble bed gas heater. Foremost, a model that is based on a 3D finite volume method approach is introduced. After that, an experimental setup for different sphere arrangements is used to obtain results for concept verification and model validation. With the model validated, the design space for the PtH concept is investigated by varying the heat transfer area and material properties of the pebble bed. Design solutions with high energy efficiency above 90% and power density over 5.5 MW/m3 are presented for magnetic as well as non-magnetic materials at laboratory and utility scale. [ABSTRACT FROM AUTHOR]

This paper deals with the setting-parameter optimization procedure for a multiphase induction heating system considering transverse flux heating. This system is able to achieve uniform static heating of different thin/size metal pieces without movable inductor parts, yokes, or magnetic screens. The goal is reached by the predetermination of the induced power-density distribution using an optimization procedure that leads to the required inductor supplying currents. The purpose of the paper is to describe the optimization program with the different solution obtained and to show that some compromise must be done between the accuracy of the temperature profile and the energy consumption, with the calculation of the losses. [ABSTRACT FROM PUBLISHER]

The effect of magnetic fields on the water remains a highly controversial topic despite much research focused on this topic in the past decades. However, the improvement of water heating in a magnetic field is less controversial. The mechanism underlying this phenomenon was studied in prior works. In this paper, use solar electric induction to study the heating of water in magnetic fields; one distinction between induction heating and magnetic field heating is that the convection in the water heater is varied due to the different heating locations. Using computational fluid dynamics, it was possible to examine the heat load in the heater during induction heating and magnetic field heating, determine its temperature distribution, and flow rate. The heat flow in magnetic field heating was measured over the heater base at the bottom. In induction heating, the analysis was conducted using the distribution of heat production as determined by electromagnetic field analysis. Simulation shows differences in convective flow in the heater during induction heating and magnetic field heating, particularly in the early stages of heating. [ABSTRACT FROM AUTHOR]

This paper proposes a new way to remove salt from water at home by using electricity to heat it. The process involves heating a metal rod using copper coils that are energized by magnets. The metal rod is placed in a tank of salt water. This study examines how water is stabilized and how water flows are represented using numbers and then tested in real life. Testing showed that when a strong electric current of 20 amps is applied to the surface of a steel rod, it boils, reaching boiling temperature. In simpler words, using an induction heating system can heat a water heater to 157°C. By changing the number of rods, the temperature is 21°C for one rod and 37°C for three rods connected in series. In an environment where objects were placed next to each other, the highest temperature reached was 28°C. If the temperature of the heating coil goes up from 55°C to 60°C, the amount of freshwater produced and the efficiency of the system increase. The amount of freshwater goes up from 1.589 liters to 2.403 liters and the efficiency goes up from 56.87 percent to 60.49%. This means that the increase in the quality of freshwater is 39.9%, while the improvement in thermal efficiency is 6.36%. These numbers show that the improvement gets less as the heater temperature goes up. In this model, the highest level of effectiveness in using heat and the amount of clean water produced can both reach 70.44% and 5.65 liters, respectively. Data indicates that the system's performance depends on the evaporator's maximum temperature. This innovative method of heating salt water to turn it into fresh water might be a good, low-cost way to obtain clean water. [ABSTRACT FROM AUTHOR]

This paper proposes a shunt active filter (SAF) for harmonic mitigation and reactive power compensation in an induction heating (IH) system. The high-frequency switching in the resonant inverter of the IH system generates a considerable number of high-frequency harmonics. The latter flow back to the supply side and causes a wide variety of problems. The predominant ones are the deterioration of the power quality, distortion in the grid voltage, and malfunctioning of the protective equipment. These harmonics need to be attenuated as per the IEEE 519-1992 and IEEE 519-2014 standards. To overcome these problems, an SAF based on the modified version of instantaneous power theory was placed between the power supply and the IH equipment. Moreover, the proposed model could work in unbalanced and non-sinusoidal input voltage conditions, as well as dynamic conditions with changing reference currents. The feasibility of the proposed SAF-based IH system was verified by a series of simulation results and a comparative analysis of the THD of the input currents. The power quality issues were successfully addressed, which signifies the ability and effectiveness of the proposed model to mitigate the problems caused by harmonics and enhance the power factors. [ABSTRACT FROM AUTHOR]

A new magnetic pole is designed and proposed for the transverse flux induction heating (TFIH) device, since the TFIH device with the original magnetic pole has the deficiencies of uneven temperature distribution on the strip surface at the outlet of the heater and large magnetic resistance of the alternating magnetic field through the magnetic circuit. Using the magnetic–thermal coupling calculation method proposed in this paper, the eddy current field and temperature field of the TFIH device with the original and new magnetic poles are calculated and analyzed under the same excitation. At the same time, the temperature distribution on the strip surface of the TFIH device with the new magnetic pole is calculated under different excitation parameters, and the magnitude and frequency are obtained when the uniformity of the temperature distribution is best. [ABSTRACT FROM AUTHOR]