Depleted uranium oxide supported nickel catalyst for autothermal CO_(2)methanation in non-adiabatic reactor under induction heating

Undoped nickel-based catalysts supported on depleted uranium oxide allow one to carry out CO_(2)methanation process under extremely low reaction temperature under atmospheric pressure and powered by a contactless induction heating.By adjusting the reaction conditions,the catalyst is able to perform CO_(2)methanation reaction under autothermal process operated inside a non-adiabatic reactor,without any external energy supply.Such autothermal process is possible thanks to the high apparent density of the UO_x which allows one to confine the reaction heat in a small catalyst volume in order to confine the exothermicity of the reaction inside the catalyst and to operate the reaction at equilibrium heat in-heat out.Such autothermal operation mode allows one to significantly reduce the complexity of the process compared to that operated using adiabatic reactor,where complete insulation is required to prevent heat disequilibrium,in order to reduce as much as possible,the heat exchange with the external medium.The catalyst displays an extremely high stability as a function of time on stream as no apparent deactivation.It is expected that such new catalyst with unprecedented catalytic performance could open new era in the field of heterogeneous catalysis where traditional supports show their limitations to operate catalytic processes under severe reaction conditions.

SIMULATION OF TEMPERATURE FIELD IN ULTRA-HIGH FREQUENCY INDUCTION HEATING AND VERIFICATION

An experimental and numerical study on the temperature field induced in the ultra-high frequency induction heating is carried out.With an aim of predicting the thermal history of the workpiece,the influence factors of temperature field,such as the induction frequency,the dimension of coil and the gap between coil and workpiece,are investigated considering temperature-dependent material properties by using FLUX 2Dsoftware.The temperature field characteristic in ultra-high induction heating is obtained and discussed.The numerical values are compared with the experimental results.A good agreement between them is observed with 7.9% errors.

Zero-voltage switching converter absorbing parasitic parameters for super high frequency induction heating

This paper presents a novel mega-Hz-level super high frequency zero-voltage soft-switching converter for induction heating power supplies. The prominent advantage of this topology is that it can absorb both inductive and capacitive parasitic components in the converter. The switch devices operate in a zero-voltage soft-switching mode. Consequently, the high voltage and high current spikes caused by parasitic inductors or capacitors oscillation do not occur in this circuit, and the high power loss caused by high frequency switching can be greatly reduced. A large value inductor is adopted between the input capacitor and the switches, thus, this novel converter shares the benefits of both voltage-type and current-type circuits simultaneously, and there are no needs of dead time between two switches. The working principles in different modes are introduced. Results of simulation and experiments operated at around 1 MHz frequency verify the validity of parasitic components absorption and show that this convener is competent for super high frequency applications.

Formation and wear behaviors of in-situ Al3Ti/Al composites using aluminum and titanium fibers under electromagnetic induction heating

Under various electromagnetic induction heating powers,different Al3Ti/Al composites were fabricated by in-situ synthesis method from aluminum and titanium fibers.Microstructures and particles distribution of the composites were examined by XRD,SEM and EDS.The results show that no other intermetallic compounds beside Al3Ti can be in-situ synthesized.Around the titanium fibers,the reaction zones and diffusion zones can be obviously found.Due to the stirring of the electromagnetic function,the formation of the micro-cracks inside the reaction zone was conducive to the peeling off of the Al3Ti particles,and ensures the continuous reaction between liquid aluminum and titanium fibers,as well as the diffusion of Al3Ti particles.At the same time,there were secondary splits of Al3Ti particles located in diffusion zones.Two-body abrasion test shows that with the increase of induction heating power,the wear rates of the composites reduced and the number of grooves decreased.

Conversion of induction heating temperature from ANSYS to DEFORM

In the production of hot extrusion pipes, the billet will be heated in an induction furnace, before piercing or extrusion,to a certain temperature. The induction heating temperature field profile in the billet will exert an influence on the deformation processes. The study has developed an data conversion program to convert the temperature data from induction heating by ANSYS to deformation simulation software DEFORM; therefore, not only the relatively accurate temperature field can be made available, compared with the usually assumed uniform temperature field, but also the connection between induction heating and deformation can be established, which is essential to evaluate the processing parameters. Numerical simulation of the piercing processes of different temperature fields by induction heating was carded out, and the results have shown that the different initial temperature fields in the billet can lead to different deformation curves, which indicates that the conversion program is necessary to study the production process of hot extrusion pipes.

Mathematical modeling of induction heating of discard substitution block for billet hot extrusion process

A magnetic and temperature field-coupled mathematical model is proposed to calculate the induction heating process of a discard substitution block for billet hot extrusion process. The mathematical model is validated by comparing simulation results with temperature measurements recorded during physical modeling. Based on systematical analysis of calculation results, a quantitative sawtooth induction power curve was proposed to realize the aim of achieving the best distributed temperature field in the block within the shortest induction time.

Progress on research of induction heating in Baosteel

Owing to the development of new products and higher requirement of product properties, the current existing induction heating technology of Baosteel can no longer satisfy the new requirements of the product line. Control of the induction heating temperature to an appropriate value is a key consideration in induction heating technology. To obtain acculturated temperatures, investigations were focused on the parameters of an induction heating system, including those of induction heating equipment and heating processes. In these investigations, computer simulation was used to model the induction heating process, followed by physical experimentation to verify and improve the simulation model; finally, optimized induction heating parameters were suggested. The use of computer simulations dramatically decreased physical experimental times, and the computed heating parameters were used to guide the physical experimentation and design of the product line ; this increased the efficiency of subsequent investigations. This study focuses on the development of induction heating technology in Baosteel, which includes the overall induction heating technology used in manufacturing backup rollers and in the thermomechanical control process.

Experimental study of induction heating for steel plates

The temperature distribution of steel plates is affected by heating rates and heating curves in the process of induction heating.The magnetic flux density inside the induction furnace was measured,the distribution of magnetic flux density was analyzed and the uniform area of the induction heating temperature distribution was ascertained.The locations for measuring temperature were set and the temperature in different processes was measured.The influence of heating rates and heating curves on the temperature difference of steel plates was studied.The experimental results showed that the steel plates’ temperature difference increased with the increase of the heating rate.The temperature difference was obviously affected by different heating curves when the heating rate was the same.A suitable heating curve would be beneficial to reduction of steel plates’ temperature difference.

Effects of induction heating temperature fields on 321 stainless tubes during the expansion process

Expansion is an important operation in the hot extrusion production line of seamless steel tubes, which is to produce proper hollow billets for extrusion. The billet goes through induction heating before expanded to acquire a proper temperature. In this study, the effects of three types of inhomogeneous temperature fields on 321 stainless tubes during the expansion process were simulated. The results have indicated that it was an optimum temperature filed for expansion, where the temperature varied linearly along radial direction and the temperature was lower on the inner surface. This temperature field is beneficial to improving the stability of expansion and ensuring dimensional accuracy and increasing the utilization rate of tubular billet material.

Numerical simulation of multistage induction heating of coated steel tubes in Baosteel

The electromagnetic and temperature fields in the multistage intermediate-frequency induction heating of coated steel tubes were calculated using a numerical simulation.The influence of the voltage and frequency on the parameters of power circuit and heating temperature of the steel pipe was also analyzed.The results indicate that:(1) the electromagnetic field of induction heating is concentrated between the induction coil and steel tube and dissipated more at both ends of the coil;(2) during the induction heating,the temperature difference between the outer and inner walls of the steel pipe is approximately 3040 K,and the two temperatures rapidly tend to be the same after exiting the induction heater;(3)during the natural cooling,the temperature drop of the steel tube in the low-temperature section is approximately 10 K,and that in the high-temperature section is approximately 20 K;(4)the appropriate induction heating frequency and matching capacitance should be selected,so that the temperature of the steel pipe,especially at the outer wall,meets the coating process requirements,and as to achieve a synchronous improvement of the power efficiency and heating efficiency.This study is beneficial to building a more low-consumption and high-efficiency coating line of large-diameter steel pipes in Baosteel.

Numerical simulation of key factors influencing sparking during edge induction heating

To address the phenomenon of sparking during the edge induction heating process in hot strip mills,this paper uses numerical simulation to systematically investigate the key factors influencing sparking and their effects.The distribution of induced current density in the steel plate above roller conveyor table during the heating process is calculated and compared under different conditions,including the relative positions of the steel plate and induction coil,the width of the steel plate,and changes in load. The results show that when a narrow steel plate is heated or the steel plate shifts to the side of the induction coil,sparking between the steel plate and roller conveyor is more likely to occur.

Temperature distribution of boron-manganese sheet metal blank by induction heating in application for hot stamping

In order to speed up the production and save more energy in hot stamping process,the induction heating technology as a new effective heating method is considerable.Finite element(FE)-simulation and a series of experiments are carried out to research the temperature homogenization of induction heating with the face inductor.It is found the edge effect has a notable influence on the temperature distribution.Results concerning the mechanical properties of the stamped part as well as surface characteristics will be presented and discussed.

Magnetic flux leakage during longitudinal magnetic flux induction heating

A three-dimensional electromagnetic thermal coupled model of a 45#steel strip during longitudinal magnetic flux induction heating was established in this study.The influence of different power levels,frequencies,and electromagnetic shielding on the magnetic induction intensity and the heating of parts of different materials around the inductor was analyzed by calculating the magnetic induction intensity around the longitudinal flux induction heater under different conditions.The results show that leakage flux can be reduced up to 49%by electromagnetic shielding.The higher the frequency,the greater the electromagnetic shielding effect,and the lower the magnetic leakage around the inductor.Conversely,the higher the power,the greater the magnetic induction around the inductor.By adding electromagnetic shielding to reduce magnetic leakage of the inductor and replacing the metal part material around the inductor with stainless steel,the heat generation of the parts around the inductor can be greatly reduced.

Effect of induction heating and tempering on properties and microstructures of quenched and tempered pipes

In this study,a C-Mn quenched steel tube was quickly tempered by induction heating,and the influence of the tempering temperature on its performance was studied and compared with that by traditional tempering. The results show that the yield strength of both is quite strong with regular changes in the tempering temperature,but that the tensile strength of the tube tempered by induction heating is higher than that tempered by traditional tempering by about 25 MPa,and the elongation after induction tempering is significantly higher than that after traditional tempering. The differences in the microstructures of tubes after induction and traditional tempering were compared by metallographic microscope,scanning electron microscopy,and transmission electron microscopy.Theoretical analysis was also performed. Compared with traditional tempering,a fine dispersion of precipitated carbides occurs after induction tempering,which is the main reason for the performance differences.

Investigation of Thermal Losses in a Soft Magnetic Composite Using Multiphysics Modelling and Coupled Material Properties in an Induction Heating Cell

The complex interaction between material properties in an induction heating circuit was studied by multi physics simulation and by experimental verification in a full-scale laboratory heater. The work aims to illustrate the complexity of the system of interacting materials, but also to propose a method to verify properties of soft magnetic composite materials in an integrated system and to identify which properties are the most critical under different circumstances and load cases. Heat losses at different loads were primarily studied, from DC currents to AC currents at 15, 20 and 25 kHz, respectively. A FE model for magnetic simulation was correlated with a corresponding model for heat simulation. The numerical model, as well as the established input material data, could be verified through the experimental measurements. In this particular study, the current loss in the litz wire was the dominant heat source, thus making the thermal conductivity of the SMC the most important property in this material.

Improving the Efficiency of Induction Heating in the Air Gap of the Magnetic Circuit

Improving the efficiency of induction heating of parts in the air gap of the magnetic circuit is associated with the use of surface and edge effects.Through modeling in ANSYS Electromagnetics Suite 19.2 and experimental studies identified patterns of edge effect in the heated parts.To ensure the uniformity of induction heating of small parts and reduce the soldering time,the electrical switch of soldered parts is used,which with the help of device controller forms a secondary circuit with low electrical resistance and high density of eddy currents.

Simulation of Induction Heating Process of Continuous Casting Slab

Induction heating of steel in continuous casting/rolling process is an important means to reduce energy consumption, decrease cost and improve efficiency, thus becoming an attractive research direction. A mathematical model with Finite Difference Method （FDM） was developed to describe the electromagnetic field and predict the temperature distribution in the steel slab for the whole induction heating process. To validate feasibility of the model, computational results were compared with the ANSYS simulation results. According to the comparing results, the temperature distributions of the slab cast under different technical parameters were investigated, which may provide useful information to optimize the parameters of technology in heating process.

A General Approach for Direct Conversion of Single Phase AC to AC Converter for Induction Heating System

This paper signifies the study of modeling and simulation of a single phase matrix converter for induction heating system. The working principle and the control method, using PID are revealing in detail. The performance of the system is carried out in MATLAB/Simulink environment with pulse width modulation switching strategy by varying the duty cycle. PID control is employed to obtain the better performance for a specified input supply for various output frequencies. The proposed control strategy of AC to AC converter has been discussed with a wide range of operating frequencies and results in low Total Harmonic Distortion.

The rapid densification behavior of powder metallurgy Ti alloys by induction heating sintering

Micropores are decisive to mechanical properties and thermal deformation capabilities of powder met-allurgy(P/M)Ti alloys sintered compacts.As a result,achieving express densification is of prime im-portance and has attracted increasing attention recently.Induction heating owns the merits of high effi-ciency,short process,and low cost,and thus has huge potential to be used as a sintering approach for the fabrication of P/M Ti alloys.Nevertheless,the facilitated densification behavior associated with induction heating sintering remains unclear so far.To address it,powder metallurgy Ti6Al4V is manufactured via induction heating sintering with which the underlying sintering mechanism is investigated in-depth.It is found that induction heating could generate a fully densified compact in a remarkably shortened time,demonstrating its superior sintering efficiency as compared with conventional resistance furnace heat-ing.COMSOL finite element analysis reveals that the maximum current density during induction heating can reach 10^(6)A m^(–2)though the magnetic field strength is solely 0.02 T,leading to a slight tempera-ture difference of approximately 30℃between the interior and exterior of the billet.Furthermore,the rapid heating essentially starts at sharp corners of particles due to the potent current concentration ef-fect,which facilitates the cracking of the particle surface oxide film and thus enhances the direct contact between them.Moreover,the electromigration effect caused by induction current promotes the diffusion capability of elements,giving rise to expedited densification,alloying,and chemical homogenization.This work provides not only critical insight into the sintering mechanism of induction heating sintering but also significant guidance for low-cost powder metallurgy materials preparation.

Induction heating enables efficient heterogeneous catalytic reactions over superparamagnetic nanocatalysts

Most catalytic processes are achieved by heating the whole reaction systems including the entire reactor,substrate and solvent,which leads to energy loss and obvious heat transfer limits.In this study,induction heating was employed to boost the catalytic Suzuki-Miyaura cross-coupling reactions by using conductive superparamagnetic microspheres with loaded Pd nanoparticles as heterogeneous catalysts.It was found that,at the same apparent reaction temperatures,the reactions by adopting the induction heating all exhibit better catalytic performance with higher conversion and yield,as compared to the reactions using conventional joule heating.The improvement is mainly attributed to the localized heating effect endowed by high efficiency of the heat transfer from the heat source to catalytic sites,which dissipates the electromagnetic energy through Néel relaxation mechanism.Moreover,it has be found that the reactions have been largely accelerated,resulting in much shorter reaction time required to approach a given value of reactant conversion.These results indicate that the unique heating method based on the superparamagnetic nanomaterials as both the inductive component and catalyst support holds a promising application for fast and efficient heterogeneous catalytic process,and exhibits potential for improving energy transfer efficiency and reducing the side reactions attributed to the uneven temperature profile.