Higher‐order finite element modeling of rotational induction heating of nonferromagnetic cylindrical billets

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.

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“…This finding is consistent with those of other studies conducted using 2D models (Lubin et al, 2009;Karban and Mach, 2011).…”

Section: The Temperature Uniformity Along the Radial Directionsupporting

confidence: 93%

Study of the temperature uniformity of aluminium billets heated by superconducting DC induction heaters

Wang

Gao

et al. 2015

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering

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“…There are two unknown potentials in (1), i.e., and . The additional equation combining both potentials follows from the current continuity law inside the conducting object as (2) 2) Moving Frame of Reference: In the moving frame of reference (MF), the global coordinate system is associated with the moving permanent magnet (Fig. 4), i.e., the conducting object moves in the opposite direction along the -axis with velocity .…”

Section: ) Fixed Frame Of Referencementioning

confidence: 99%

“…A keen interest in this area has been demonstrated recently by numerous publications in many fields of research concerning coupled multiphysics problems. They mainly include different types of electromechanical devices in applications such as electrical machine design [1], inductive heating [2], eddy current braking [3], magnetohydrodynamics [4], and nondestructive testing [5]. In the review papers [6], [7], the authors have outlined several methods that can be used in the finite element analysis (FEA) of dynamic electromagnetic systems.…”

Section: Introductionmentioning

confidence: 99%

Finite Element Analysis of Nondestructive Testing Eddy Current Problems With Moving Parts

et al. 2013

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We present the logical expressions (LE) approach that allows fast computation of three-dimensional eddy current problems, including parts in motion. The approach applies time-dependent logical expressions to describe moving parts of the model on a fixed computational grid. The study is motivated by a novel nondestructive testing technique called Lorentz force eddy current testing (LET), which enables the detection of defects lying deep inside a conducting material. Depending on the definition of the frame of reference, we present two different implementations of the LE approach referred to as 1) moving magnet approach, and 2) moving defect approach. In order to demonstrate the advantages of the LE approach, we compare its results with the sliding mesh technique. The validation of the obtained results with experiments is also presented.Index Terms-Eddy current testing, finite element method (FEM), logical expressions, Lorentz force, nondestructive testing.

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“…A challenge arises because the torque of the mechanical driving system can exceed the rated load torque during start up. Typically, the peak torque overload capacity is approximately 200 per cent of the rated torque (Karban and Mach, 2011). In the superconducting DC induction heater for heating aluminium billets ( Φ = 446 mm @ 0.5 T and 20 rpm), the peak load torque of the drive system is 3.6 times higher than the rated load torque during the start-up process based on the simulation.…”

Section: Introductionmentioning

confidence: 99%

Start-up strategy using flywheel energy storage for superconducting DC induction heater

Yang

Wang

Chang³

et al. 2017

COMPEL

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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.

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Higher‐order finite element modeling of rotational induction heating of nonferromagnetic cylindrical billets

Cited by 17 publications

References 4 publications

Study of the temperature uniformity of aluminium billets heated by superconducting DC induction heaters

Study of the temperature uniformity of aluminium billets heated by superconducting DC induction heaters

Finite Element Analysis of Nondestructive Testing Eddy Current Problems With Moving Parts

Start-up strategy using flywheel energy storage for superconducting DC induction heater

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