Bernard Paya

Eddy currents in thin plates modelled as surface regions

This paper analyses the conditions for which the results of eddy currents computation in thin regions modelled by surface regions are concordant with those obtained using volume finite elements. The concepts of geometrically thin or thick region, electromagnetically thin or thick region, 2D or 3D problem, transverse or longitudinal flux problem are used to characterise the limits of the surface model. The computation of eddy currents in sheets heated in transverse flux inductors and of the eddy current losses in metallic casing of an induction furnace highlights the surface finite element applicability.

Magnetic field dependence of nonlinear surface impedance: which field to choose?

The aim of this paper is to determine the best choice of magnetic field to use in a nonlinear surface impedance calculation. Due to boundary relations, a normal component exists and must be generally taken into account. But it can be neglected if we use the metallic side magnetic field for the surface impedance evaluation unless steel is too saturated or the incident field is near to the normal direction. This method has been implemented in the three-dimensional software FLUX3D and validated by comparison with a two-dimensional computation.

3D magneto‐thermal computations of electromagnetic induction phenomena

This paper presents the results of a series of tests made in order to validate the magneto‐thermal module of the new FLUX3D v3.40. The tool was conceived to solve the coupled problems of electromagnetic and thermal phenomena. The solving method of the program considers a thermal‐transient problem during a certain period of time and it solves, at each time step, the thermal and electromagnetic equations (in quasi‐stationary magneto‐harmonic formulation), alternatively. We have modelled the inductive longitudinal welding of steel pipes. The results of 3D simulations are compared with measurements on a laboratory device.

Medium frequency induction‐heated chemical reactor with cooling metallic envelope of the tank

Purpose – Analysis and development of a high efficiency, induction heated chemical reactor, medium frequency supplied (1,000‐2,000 Hz), able to be equipped with efficient cooling circuits.Design/methodology/approach – The numerical investigations of the technical solutions proposed in this paper are based on 3D finite element models that are experimentally validated.Findings – Solutions to increase the transparency of the cooling envelope of the reactor tank with respect to magnetic field. The positions of envelope regions characterized by high values of power losses are experimentally confirmed by infrared temperature measurements.Practical implications – The numerical analysis and the experimental investigations, show the possibility to implement efficient cooling circuits in chemical reactors without affecting the performances of the induction heating process. By designing properly the metallic envelope of the tank the global efficiencies of the chemical reactors increase at around 90 percent with redu...