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Article

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

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

Massimo Fabbri, Pier Luigi Ribani and Davide Zuffa

A conveyor device is studied with the aim to reduce the friction between the inner surface of the beam and the chain. The lower is the friction between the chain and the…

Abstract

Purpose

A conveyor device is studied with the aim to reduce the friction between the inner surface of the beam and the chain. The lower is the friction between the chain and the beam, the lower is the surface wear. The magnetic repulsion force among permanent magnets (PMs) placed on the beam and on the chain is utilized to reduce friction. The paper aims to discuss these issues.

Design/methodology/approach

The considered magnetic suspension is realized with PMs in repulsive configuration; it is designed by solving a constrained optimization problem, with reference to the geometry of the 90° horizontal bend FlexLink WL322 conveyor. Flux density field and its gradient are evaluated using volume integral equation method, allowing to calculate the forces acting on the chain and the stiffness of the magnetic suspension.

Findings

The magnetic suspension prototype was manufactured and tested. The experimental and calculated values of the forces acting on the chain compares well. A stable horizontal equilibrium of the chain was obtained during both static and dynamical tests.

Research limitations/implications

The quasi-static model used neglects the dynamical interactions among the elements of the chain, the PMs and loads weight during motions and the eddy current losses in the aluminium beam. However the dynamical tests on the prototype show that the chain motion is regular up to the nominal velocity all along the conveyor with the exception of the trailing edge of the 90° curve.

Practical implications

The tests on the prototype show the possibility of a removal or at least a reduction of the friction force between the chain and the inner side of the beam by means of a passive magnetic suspension. As a consequence a reduction of noise and vibrations and an increase of the mean-time-to-failure is expected.

Originality/value

Prototype testing shows that the unavoidable vertical instability of the magnetic forces has no practical consequence since, reducing the allowed vertical gap, the chain is stabilized by the gravitational force.

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

Chiara Caterina Borghi, Yoko Akiyama, Massimo Fabbri, Shigehiro Nishijima and Pier Luigi Ribani

The aim of this paper is the study of the magnetic separation of pollutants from water by means of a magnetic filter. A magnetic activated carbons nanometric powder that…

Abstract

Purpose

The aim of this paper is the study of the magnetic separation of pollutants from water by means of a magnetic filter. A magnetic activated carbons nanometric powder that combines the well-known pollutants absorbent capacity of activated carbons with the magnetic properties of magnetite (Fe3O4) is used.

Design/methodology/approach

The considered magnetic filter is made of stainless steel spheres, magnetized by an external flux density field provided by permanent magnets. Flux density and fluid velocity fields are evaluated using volume integral equation method. The modelling of the particles trajectories inside the filter allows calculating its capture efficiency.

Findings

The results of the model are tested on the experimental data obtained using two different setups. A removal of the powder larger than 90 percent is achieved in both cases. The pollutant removal efficiency is checked on surfactants (water diluted). Their adsorption on magnetic activated carbons leads to residual concentration below the limit for the reuse in agriculture (according to the Italian legislation) for all the tested surfactants.

Originality/value

The proposed process combines efficiently a physico-chemical phase of adsorption and a magnetic phase of filtration due to the particular properties of magnetic activated carbons.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 1/2
Type: Research Article
ISSN: 0332-1649

Keywords

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