1,721,197 research outputs found
Selected papers from HES-2016 conference
No full textSelected papers from the Heating by Electromagnetic Sources Conference 2016 (HES-2016
Numerical modelling of silicon melt purification in induction directional solidification system
Full text linkSolar 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
A numerical evaluation of electromagnetic fields exposure on real human body models until 100 kHz
No full textPurpose - The purpose of this paper is to describe how numerical models of human body have been applied for the evaluation of current density induced by strong magnetic field, to verify the respect of the basic restriction proposed by International Committee Non Ionizing Radiation Protection (ICNIRP) guidelines.
Design/methodology/approach - Finite element method has been used in order to compute the induced current density in a suitable human body model and a simplified model a homogeneous cylinder due to a time-varying magnetic field.
Findings - In the practical case of a resistance welding equipment, the implemented computational technique has been used in order to evaluate both the magnetic flux density and the induced current density in different tissues. Their values have been also compared with the ones obtained in a homogeneous cylinder.
Practical implications - The proposed method can be used in order to evaluate the compliance of the magnetic field produced by resistance welding equipments with ICNIRP limits.
Originality/value - A realistic model of human body has been used. In the paper, the difference on magnetic flux density and corresponding current density values is pointed out for various source positions using a heterogeneous tetrahedral human body model
Switch of design variables: a cost-effective identification of the Pareto front in inverse magnetics
No full textA new optimization method, combining design of experiments with evolutionary computing, is proposed: it handles a set of design
variables, the size of which changes during the process: initially, most sensitive variables are activated; subse
quently, the whole set of variables is activated. The optimal synthesis of a magnetic field for magneto-fluid treatment is considered as the case study
Pulsed electric field applied to biological tissue: measurement set-up to evaluate electrical resistivity
No full textIn this paper we present the design of a measurement set-up to evaluate electrical resistivity of biological tissues
Electrically enhanced plastic deformation of duplex stainless steel UNS S32750
No full textIt is well known that increasing the temperature softens the materials and increases formability. This could be done in many ways, one of which is by joule heating. In the late fifties it has been observed an enhancement of formability for certain alloys when heated by electrical current, compared to traditional heating method. This led the researcher to investigate the effect of electrical current on the plastic flow of metallic materials discovering a new effect called Electroplastic Effect (EPE). EPE is used in the so called Electrically Assisted Manufacturing processes (EAM). The stacking fault energy (SFE) describes the dislocation dynamics of metallic materials and it has been hypothesized an a-Thermal effect which is caused by direct interaction between dislocations and electrical current. High SFE materials show an increase of formability while low SFE materials reach the fracture prematurely. In this work, duplex stainless steel (DSS) UNS S32750 has undergone uniaxially tested with the aid of continuous and pulsed electrical current in order to study the EPE of a metallic material that presents two different phases, high SFE (ferrite) and low SFE (austenite). Different current densities (continuous and pulsed) were tested while to separate the EPE from the effect of temperature some thermal tensile counterpart tests has been conducted. The DSS was then characterized through optical microscopy, scanning electron microscopy and x-ray diffraction. The DSS tested shows an increase in the elongation at rupture, either for the continuous current set-up and much more evident in the case of the pulsed current compared to the thermal tests, while the ultimate tensile strength and the yield strength were barely affected
Electroplastic Effect
No full textRealization of final products frequently involves severe bulk deformation steps and, therefore, methods aimed to improve and increase the materials formability are required. In industry, for bulk material forming, a commonly used method is hot working, where deformations are observed at or above recrystallization temperature of the material; alternatively, incremental forming can be employed, in which intermediate cold deformation steps are followed by annealing to restore the material workability [1]
Investigation on the induction stirring effect in a laboratory scale crucible with the variation of electrical supply parameters
No full textPurpose: This paper aims to study the possibility of controlling the electromagnetic stirrer (EMS) is fundamental in a continuous casting line to achieve the desired properties of homogeneity and mechanical strength in the solidified cast. Design/methodology/approach: Coupled electromagnetic (EM) and fluid dynamic (FD) simulations allow to predict the mixing effect on molten metal, in terms of velocity amplitude and shape of the flow. This paper describes the numerical results of EMS effect within a cylindrical crucible, surrounded by a solenoidal inductor, filled with a low melting temperature alloy, i.e. GalInStan. Findings: Induced forces and resulting velocity distribution of the flow of the liquid metal have been calculated depending on varying amplitude and frequency of the supplied current. As expected, at a given amplitude of the current supply, the velocity distribution shows a maximum at a certain frequency while the intensity of electrodynamic forces monotonically increase as the frequency increases Originality/value: The paper deals with simply models and experiments applied to coupled EM and FD problem, to assess the applied methodology
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