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Article
Publication date: 5 January 2015

Yawei Wang, Hao Gao, Zhuyong Li, Yang Ping, Zhijian Jin and Zhiyong Hong

– The purpose of this paper is to analyse and improve the temperature uniformity of aluminium billets heated by superconducting DC induction heaters.

Abstract

Purpose

The purpose of this paper is to analyse and improve the temperature uniformity of aluminium billets heated by superconducting DC induction heaters.

Design/methodology/approach

A 3D electromagnetic model coupled with a heat transfer model is developed to calculate the heating process of the billets which are rotated in uniform transverse DC magnetic field. A laboratory-scale DC induction heater prototype has been built to validate the model. The results from simulation and measurement have a good agreement. The model is used to investigate the factors affecting the temperature uniformity of aluminium billets.

Findings

The results from simulation show that lower rotation speeds always mean better temperature uniformity along the radial direction, due to the increase in power penetration. However, the situation is very different for the temperature distribution along the axial direction. When the rotation speed is low, the temperature at the ends is lower than other parts. The situation reverses as the rotation speeds increase. This phenomenon is referred to as the “ending effect” in this paper.

Research limitations/implications

Because of the ending effect, a lower rotation speed does not always result in better overall temperature uniformity, especially for billets of smaller sizes.

Practical implications

There is an optimal rotation speed that yields the best overall temperature uniformity. Lower rotation speeds are not always preferred. The results and numerical model developed are very useful in the design of a superconducting DC induction heater.

Originality/value

The temperature uniformity of aluminium billets heated by DC induction heaters is investigated and optimized.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 3 July 2017

Ping Yang, Yawei Wang, T. Chang, H. Ma, Zhuyong Li, Zhijian Jin and Zhiyong Hong

The purpose of this paper is to propose a hybrid driving system that couples a motor and flywheel energy storage (FES) for a megawatt-scale superconducting direct current …

Abstract

Purpose

The purpose of this paper is to propose a hybrid driving system that couples a motor and flywheel energy storage (FES) for a megawatt-scale superconducting direct current (DC) induction heater. Previous studies have proven that a superconducting DC induction heater has great advantages in relation to its energy efficiency and heating quality. In this heater, a motor rotates an aluminium billet in a DC magnetic field and the induced eddy current causes it to be heated. When the aluminium billet begins to rotate, a high peak load torque appears at a low rotation speed. Therefore, driving the billet economically has been a great challenge when designing the driving system, which is the focus of this paper.

Design/methodology/approach

A hybrid driving system based on FES is designed to provide extra torque when the peak load torque occurs at a low rotation speed, which allows the successful start-up of the aluminium billet and the operation of the motor at its rated capacity. The mechanical structure of this hybrid driving system is introduced. A simulation model was constructed using Matlab/Simulink and the dynamic start-up process is analysed. The influence of the flywheel’s inertia and required minimum engagement speed are investigated.

Findings

The results of this paper show that the hybrid driving system that couples FES and a motor can successfully be used to start the aluminium billet rotating. The flywheel’s inertia and engagement speed are the most important parameters. The inertia of the flywheel decreases with an increase in its engagement speed.

Practical implications

The cost of the driving system is significantly reduced, which is very important in relation to the commercial potential of this apparatus.

Originality/value

A novel start-up strategy for driving the aluminium billet of a superconducting DC induction heater at low speed is proposed based on FES.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 7 March 2008

Massimo Fabbri, Antonio Morandi and Pier Luigi Ribani

To analyse the heating process of an aluminum billet rotating in a static magnetic field produced by superconducting coils.

Abstract

Purpose

To analyse the heating process of an aluminum billet rotating in a static magnetic field produced by superconducting coils.

Design/methodology/approach

The idea is to force the billet to rotate in a static magnetic field produced by a DC superconducting magnet. Since, a static superconducting magnet has no losses, the efficiency of the system is the efficiency of the motor used. In order to evaluate the temperature distribution arising from the field profile produced by a given coil configuration, a numerical model, based on an equivalent electric network with temperature‐dependent parameters, is used.

Findings

The main heating parameters, i.e. heating time, total power injected and temperature difference, are evaluated for different values of angular velocity and magnetic field. The field profile suitable to meet the specifics of an industrial heating process in terms of temperature homogeneity and heating time is determined. Starting form this profile the layout of the magnet is arrived at and some considerations on the operating condition of the superconducting windings are reported.

Research limitations/implications

The mechanical stress in the billet due to weight, centrifugal effects, applied torque and resonance is examined by taking into account the weakening of the material properties with the increase of temperature and the practical limits of the heating process are evaluated.

Practical implications

DC induction heating of aluminum billet using superconducting magnets can be done fulfilling the specifics of the industrial processes.

Originality/value

A high‐efficiency induction heater for aluminum billets using superconducting coils in a novel scheme is investigated.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 1 March 2005

Massimo Fabbri, Antonio Morandi and Francesco Negrini

To investigate the feasibility of a novel scheme of high‐efficiency induction heater for nonmagnetic metal billets which use superconducting coils.

Abstract

Purpose

To investigate the feasibility of a novel scheme of high‐efficiency induction heater for nonmagnetic metal billets which use superconducting coils.

Design/methodology/approach

The idea is to force the billet to rotate in a static magnetic field produced by a DC superconducting magnet. Since a static superconducting magnet has no losses, the efficiency of the system is the efficiency of the motor used. In order to evaluate the temperature distribution arising from the field profile produced by a given SC coil configuration, a numerical model, based on an equivalent electric network with temperature‐dependent parameters, is developed.

Findings

A substantial independence of the shape of the temperature profile on the angular velocity and the value of the uniform magnetic field applied, is observed. A strong temperature gradient is observed in the radial direction in the proximity of the penetration front and in the axial direction at the top and bottom surface of the billet. Small temperature gradient was observed in the central part of the billet.

Research limitations/implications

The reported temperature profile is inadequate for an actual extrusion process which is desired to happen at a constant temperature. The appropriate profile along the billet length can be achieved by a suitable axial shaping of the magnetic field, through the optimization of the coil layout, whereas the undesired radial gradient can be reduced by interspacing the rotation with temperature smoothing intervals.

Practical implications

The investigation of the profile of applied magnetic field and the heating procedure which allow to achieve the distribution of temperature suitable for the extrusion process can be carried out by using the present model.

Originality/value

A high‐efficiency induction heater for nonmagnetic metal billets using superconducting coils in a novel scheme is investigated.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 24 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 13 September 2011

Massimo Fabbri, Antonio Morandi and Pier Luigi Ribani

The purpose of this paper is to analyse the heating process of an aluminum billet rotating in a static magnetic field produced by optimized supercoducting coils.

Abstract

Purpose

The purpose of this paper is to analyse the heating process of an aluminum billet rotating in a static magnetic field produced by optimized supercoducting coils.

Design/methodology/approach

In order to meet the technical specifications of industrial heating, many processes with low speed in the given high magnetic field have been simulated. The mechanical stresses in the billet are examined by taking into account the temperature dependence of the mechanical properties.

Findings

The main heating parameters, i.e. heating time, average temperature and temperature homogeneity, are evaluated for different values of angular velocity. The simulation results show that an optimal angular speed can be chosen with respect to the heating time.

Research limitations/implications

The mechanical stress in the billet due to weight, centrifugal effects, applied torque and resonance is examined by taking into account the weakening of the material properties with the increase of temperature. The practical limits of the heating process are evaluated; while resonance does not seem to be a concern, the safety against yielding, in order to avoid plastic deformation of the billet during the heating, seems to be a constraint.

Practical implications

DC induction heating of aluminum billet using superconducting magnets can be done fulfilling the specifics of the industrial processes.

Originality/value

The operational and mechanical constraints on a high‐efficiency DC induction heater for aluminum billets using superconducting coils are investigated.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 6 March 2017

Massimo Fabbri and Antonio Morandi

This study aims to investigate the feasibility of saturated AC heating of magnetic metals. In AC heating of magnetic steel below the Curie temperature, because of the high…

Abstract

Purpose

This study aims to investigate the feasibility of saturated AC heating of magnetic metals. In AC heating of magnetic steel below the Curie temperature, because of the high magnetic permeability, the penetration depth is in the order of 1-6 mm at 50 Hz. Surface heating is then obtained, in practice, if large slabs are processed. The necessity to provide the required surface-to-core temperature uniformity (about 25°C) at the end of the heating process, avoiding excessive thermal stresses which can lead to cracks, thus implies a long heating time.

Design/methodology/approach

The penetration depth can be increased if the material is brought to saturation by applying an external DC magnetic field, and a faster in-depth heating can be obtained. The DC saturating field can be produced with no losses over large volumes by means of superconducting (SC) coils.

Findings

The feasibility of in-depth induction heating of a 200 × 1,000 × 5,000 mm magnetic steel slab with an applied 2 T DC saturating field is numerically investigated. The results show that the use of a DC saturating field leads to shorter processes which fulfil the heating objectives.

Practical implications

A DC saturating field cannot be produced by means of copper coils because of the large amount of material and the unaffordable power required. However, this field can effectively be produced by means of SC magnets based on state-of-the-art materials.

Originality/value

Superconductivity may be the enabling technology for fast and efficient induction heating of magnetic steel slabs if the increase in productivity can balance the additional costs due to the SC magnet.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 1 June 2000

P.Di Barba

Introduces the fourth and final chapter of the ISEF 1999 Proceedings by stating electric and magnetic fields are influenced, in a reciprocal way, by thermal and mechanical…

Abstract

Introduces the fourth and final chapter of the ISEF 1999 Proceedings by stating electric and magnetic fields are influenced, in a reciprocal way, by thermal and mechanical fields. Looks at the coupling of fields in a device or a system as a prescribed effect. Points out that there are 12 contributions included ‐ covering magnetic levitation or induction heating, superconducting devices and possible effects to the human body due to electric impressed fields.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 19 no. 2
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 7 March 2008

R. Araneo, F. Dughiero, M. Fabbri, M. Forzan, A. Geri, A. Morandi, S. Lupi, P.L. Ribani and G. Veca

The paper aims to deal with the induction heating of metal billets rotating in a DC magnetic field.

Abstract

Purpose

The paper aims to deal with the induction heating of metal billets rotating in a DC magnetic field.

Design/methodology/approach

The induced power distributions are analysed and the main heating parameters are estimated with reference to an infinitely long Al billet 200 mm diameter. The paper refers to the activity developed in the frame of a National Italian Project carried out by research groups of the Universities of Bologna, Padua and Roma “La Sapienza.”

Findings

The main process parameters have been evaluated for the heating up to 500°C of an Al billet 200 mm diameter.

Practical implications

This innovative technology appears to be very promising for improving the efficiency of the through heating of high‐conductivity metals (e.g. copper, aluminum) before hot working, by using superconducting magnets.

Originality/value

The paper analyses the induction heating of a infinitely long billet rotating in a uniform DC magnetic field.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 8 October 2018

Ammar Abdi, Youcef Ouazir, Georges Barakat and Yacine Amara

This work aims to study a new design of linear permanent magnet transverse flux induction heating devices of nonmagnetic parallelepipedic workpiece. In these topologies…

Abstract

Purpose

This work aims to study a new design of linear permanent magnet transverse flux induction heating devices of nonmagnetic parallelepipedic workpiece. In these topologies, the permanent magnet inductor produces a static magnetic field, and the workpiece to be heated is subjected to a linear movement. To study the magnetothermal process, a new analytical coupling method between the magnetic and thermal phenomena is developed. This analytical model described in this study takes into account the variation of the physical properties of the heated workpiece. The analytical results are compared with good agreement to those issued from finite elements simulations, as well as those issued from measurements on an actual prototype.

Design/methodology/approach

The research methodology is based on analytical development of coupled problem, including the electromagnetic and thermal boundary problems. A strongly coupled magneto-thermal analytical model is developed; the time dependent magnetic problem is first solved by using the separation of variables method to evaluate the induced currents in the nonmagnetic plate and the resulting power density loss distribution. The plate temperature profile is then obtained, thanks to strong involvement of this magnetic model in a new analytical thermal model based on a synergy of separation of variables method and Green’s function transient regime analysis method.

Findings

The results show that an efficient transient magneto-thermal analytical model was developed allowing fast analysis of permanent magnet induction heater for deep heating of parallelepipedic workpieces. Developed model allows also fast and precise simulations of nonlinear and transient magneto-thermal phenomena for different types of permanent magnet induction heating devices.

Practical implications

The developed magneto-thermal analytical model can be used for fast designing of permanent magnet linear induction heating devices for moving parallelepipedic nonmagnetic workpiece.

Originality/value

A new analytical coupled model, including the electromagnetic and transient thermal boundary problem with additional algebraic equations and taking into account the nonlinearity, has been developed. The developed model accuracy was validated with a permanent magnet linear induction heating device. Developed coupled analytical model allows fast analysis and designing of such permanent magnet linear induction heating devices.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 9 June 2020

Mohammed Messadi, Larbi Hadjout, Youcef Ouazir, Hakim Bensaidane, Noureddine Takorabet, Thierry Lubin and Smail Mezani

This paper aims to propose a new 3D electromagnetic model to compute translational motion eddy current in the conducting plate of a novel linear permanent magnet (PM…

Abstract

Purpose

This paper aims to propose a new 3D electromagnetic model to compute translational motion eddy current in the conducting plate of a novel linear permanent magnet (PM) induction heater. The movement of the plate in a DC magnetic field created by a PM inductor generates induced currents that are at the origin of a heating power by Joule effect. These topologies have strong magnetic end effects. The analytical model developed in this work takes into account the finite length extremity effects of the conducting plate and the reaction field because of induced currents.

Design/methodology/approach

The developed model is based on the combination of the sub-domain’s method and the image’s theory. First, the magnetic field expressions because of the PMs are obtained by solving the three-dimensional Maxwell equations by the method of separation of variables, using a magnetic scalar potential formulation and a magnetic field strength formulation. Then, the motional eddy currents are computed using the Ampere law, and the finite length extremity effects of the conducting plate are taken into account using the image’s method. To analyze the accuracy of the proposed model, the obtained results are compared to those obtained from 3D finite element model (FEM) and from experimental tests performed on a prototype.

Findings

The results show that the developed analytical model is very accurate, even for geometries where the edge effects are very strong. It allows directly taking into account the finite length extremity effects (the transverse edge effects) of the conducting plate and the reaction field because of induced currents without the need of any correction factor. The proposed model also presents an important reduction in computation time compared to 3D finite element simulation, allowing fast analysis of linear PM induction heater.

Practical implications

The proposed electromagnetic analytical model can be used as a quick and accurate design tool for translational motion PM induction heater devices.

Originality/value

A new 3D analytical electromagnetic model, to find the induced power in the conducting plate of a novel translational motion induction heater has been developed. The studied heating device has a finite length and a finite width, which create edge effects that are not easily considered in calculation. The novelty of the presented method is the accurate 3D analytical model, which allows finding the real power heating and real distribution of the induced currents in the conducting plate without the need to use correction factor. The proposed model also takes into account the reaction field because of induced currents. In addition, the developed model improves an important reduction in the computation time compared with 3D FEM simulation.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 39 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

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