International Journal of Applied Electromagnetics and Mechanics - Volume 53, issue S1

Authors: Kichigin, V. | Nacke, B. | Poznyak, I.

Article Type: Research Article

Abstract: A distinctive feature of induction furnaces with cold crucible is the skull melting without introducing any impurities in the melt and overheating of the melt over 3000°C at air. Therefore the technology of induction melting in cold crucible is suitable for high temperature synthesis of oxide materials. This paper describes a new technology for continuous melting and pouring of oxide melts. A new type of cold crucible with two chambers is used for this application. In the first chamber the charged oxide is melted and transferred via a barrier to the second chamber where the oxide is superheated before pouring …over a discharging hole. During the transfer of the melted oxide from the melting zone into the superheating zone the transport of non-melted oxide particles has to be avoided. This transport is mainly influenced by the hydrodynamics of the melt flow and the temperature field during melting and pouring. Numerical simulation is used to investigate the heat and mass transfer during the melting and pouring processes in the cold crucible furnace. Both forced and free convections are taken into account in the simulation. Apart from the melt flow inside the cold crucible special attention is also paid to the behavior of the pouring stream. The numerical results are compared with experimental data of melting and pouring experiments in the skull melting installation at the Institute of Electrotechnology. The paper presents a description of the cold crucible setup, the results of the numerical simulation and comparison of them with experimental data. Show more

Keywords: Skull melting, oxide melting, oxide pouring

DOI: 10.3233/JAE-162247

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 53, no. S1, pp. S89-S94, 2017

Authors: Djambazov, G. | Bojarevics, V. | Pericleous, K. | Forzan, M.

Article Type: Research Article

Abstract: Solar grade silicon production is an energy intensive and harmful to the environment process. Yet 40% of this valuable product material is lost into sawdust (kerf loss) during wafering. The kerf waste from Fixed Abrasive Sawing of PV silicon wafers is pelletized and then remelted in an induction furnace. The furnace has a square cross-section quartz crucible, surrounded by graphite susceptors and heated by an induction coil that enables directional solidification of the new ingot. Top and bottom `pancake' coils provide additional temperature control. Once melted, silicon becomes electrically conductive and subject to stirring by induction. To recycle the silicon, …particulate impurities (due to the sawing, condensed silicon oxides or carbides) need to be removed. Flow control and the electromagnetic Leenov-Kolin force are used to expel particulates, through a novel dual frequency induction scheme. Three-dimensional, multi-physics numerical modelling captures the electromagnetic, fluid-flow and heat-transfer effects in this process. The presented results show it is possible to retain the impurity particles on the sides of the solidified ingot where they can be sliced off and removed. Show more

Keywords: Silicon recycling, electromagnetic separation, dual frequency induction melting

DOI: 10.3233/JAE-162248

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 53, no. S1, pp. S95-S102, 2017

Authors: Rognin, Etienne | Rossa, Guillaume Barba | Brun, Patrice | Sauvage, Emilien | Lacombe, Jacques

Article Type: Research Article

Abstract: In this article, we report 3D numerical simulations of highly conductive non-magnetic particles dispersed in a moderately conductive matrix, subject to an AC magnetic field in a range of several hundred kHz. We address the issue of the scaling of current loops and heating power with respect to the volume fraction of the dispersed phase. Simulations are performed in two steps. First, a static electric potential gradient is imposed between two opposite faces of the simulation domain and an effective conductivity is computed in good agreement with percolation models. Second, the particles are constrained in a spherical sub-region and an …AC magnetic field is imposed at the boundary of the domain. For small volume fractions, the induced Joule power is in good agreement with an analytical model of dilute dispersions. As the volume fraction increases, wider current loops form, until the percolation threshold is reached. Then the induced power in the spherical aggregate is well described by the power induced in an equivalent sphere with a volume-fraction-dependent conductivity. Show more

Keywords: Particles, eddy currents, heating power, effective conductivity

DOI: 10.3233/JAE-162241

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 53, no. S1, pp. S103-S110, 2017

Authors: Fehling, T. | Steinberg, T. | Baake, E.

Article Type: Research Article

Abstract: In our modern society hydrogen is an important alternative energy source for current and future applications in fuel cells as well as coolants or hydrogenation of coal. To achieve an environmentally compatible production of hydrogen, another method of thermal decomposition, is discovered. In this process methane is injected with an orifice at the bottom of an bubble column reactor that is filled with liquid tin. While rising up in the reactor, the methane bubbles do a chemical decomposition reaction into hydrogen and carbon, which is depending on the tin temperature. In this article a numerical model for the methane bubble …flow inside the tin melt is described. For that case residence times and flow structures are discovered depending on different heating systems of the melt - heating coil and electromagnetic field. In the following studies different inlets types as well as installations like packed beds are discovered to view their influence on higher residence times and efficiency of the reaction. Show more

Keywords: Numerical simulation, bubble dynamics, thermal decomposition, magnetohydrodynamics

DOI: 10.3233/JAE-162242

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 53, no. S1, pp. S111-S120, 2017

Authors: Kozuka, T. | Sigit, W.P. | Fukuda, S. | Iihoshi, C. | Kawahara, M.

Article Type: Research Article

Abstract: Metal anodizing process is now widely applied to not only usual commercial products but also advanced materials like a photo-catalyst or some nano-materials. In these applications, micro-pore or nano-pore structure in the anodized oxide film, e.g. pore arrangement or straightness, is considered to be important to improve the performance of electric devices etc. In this research, in order to obtain good arrangement and straightness and control of pore size, strong magnetic field and strong electric field imposition during anodization are conducted for Al and Ti under intense electric field and intense magnetic field imposition. Strong electric field can control the …pore size and its distribution. Strong magnetic field can promote the metal substitution reaction and it also increase the metal anodizing. Furthermore, magnetic field has the possibility of ordering the pore arrangement in the anodized film. Show more

DOI: 10.3233/JAE-162243

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 53, no. S1, pp. S121-S128, 2017

Authors: Lope, I. | Carretero, C. | Acero, J. | Serrano, J. | Burdío, J.M.

Article Type: Research Article

Abstract: Cost-effective solutions for domestic induction heating appliances have become a priority in recent years. With this purpose, the implementation of Printed Circuit Board (PCB) inductors has entailed important research efforts. A proper litz structure is essential to achieve high-efficiency PCB inductors. This structure requires routing the traces by using vias in a double layer PCB to obtain the appropriate transposition pattern. In this paper, the optimal number of vias has been analyzed to minimize the power losses in the coil. This analysis has been carried out based on numerical calculations whose results have been experimentally verified.

Keywords: Home appliances, induction heating, magnetic devices

DOI: 10.3233/JAE-162244

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 53, no. S1, pp. S129-S137, 2017

Authors: Di Barba, P. | Mognaschi, M.E. | Lowther, D.A. | Dughiero, F. | Forzan, M. | Lupi, S. | Sieni, E.

Article Type: Research Article

Abstract: In the paper, a benchmark in the area of induction heating is presented in order to test methods and codes of field analysis in a comparative way. In particular, the transient thermal analysis of a magnetic steel cylindrical billet is considered: the coupled-field problem is characterized by a twofold non linearity, i.e. the dependence of magnetic permeability on both field strength and temperature.

Keywords: Induction heating, multiphysics problem, magnetic-steel billet, finite element analysis, benchmark problem

DOI: 10.3233/JAE-162249

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 53, no. S1, pp. S139-S149, 2017