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Performance Analysis of a conducting MHD pump with a superconducting magnet by means of a lumped-parameter model
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Application of 3D lumped parameter model in MHD generator design
No full textMagnetohydrodynamic (MHD) energy conversion consists of electrical energy generation directly from high enthalpy of ionized gas. MHD generators are devices having a channel in which ionized gas (plasma) is blown, where a high magnetic field is present. The interaction between the conductive gas and the magnetic field makes the conversion. To describe and to design the MHD plants, circuital models of MHD generators are advantageous for an easier investigation approach to the interface between generators and power plants; they become extremely useful when a 3-D analysis is necessary for easier computation taking into account 3-D effects due to spatial distribution of electromagnetic fields. In this paper we describe some design applications of the three-dimensional (3-D) lumped parameter model for MHD generators
Performance evaluation of MHD generators: the lumped parameter model and its validation
No full textThe authors present a stationary model of MagnetoHydroDynamic (MHD) linear and disk generators. The active region of the device has been modelled by a 3D lumped parameter network which takes into account both the electrical characteristics of ionized gas and the external load apparatus. The 3D equivalent electrical network of the generator has been realized by subdividing the plasma into many elementary volumes, each of which is modelled by composite branches placed along the axes of a suitable Cartesian or cylindrical inertial coordinate system. These branches simulate all local characteristics and physical phenomena which influence the plasma behaviour around the centre of gravity of each brick. Then, in order to complete the stationary model of the device, the equivalent electrical network of the external load apparatus is attached to the previously defined network. The proposed model has been validated comparing the results of the simulation both with experimental data coming from measurements on various test facilities and with numerical values obtained by other researchers using sophisticated analytical models. The main advantage in using this model comes both from its 3D nature, which allows an accurate simulation of the device, and from the circuit approach, which allows to attainment important information on generator behaviour with small computational resources
MHD linear generator modelling
No full textThe performance of typical magnetohydrodynamic (MHD) linear generators are evaluated as function of the excitation magnetic field profile. Using a three dimensional (3D) lumped parameter model, able to simulate all major physical MHD energy conversion phenomena, a parametric analysis has been pointed out for various saddle shaped superconducting (sc) coils. For each type of MHD linear generator (Faraday, Hall and diagonal connected generator) the output electrical power has been correlated to the magnetic field characteristics and it has been compared with an ideal flat magnetic field profile in order to quantify the decay of the energy conversion efficiency
Displacement eddy current computation in magnetic laminates
No full textThe paper presents an equivalent circuit model of small magnetic laminated objects. The responses in the frequency domain of these laminates are significantly influenced by eddy currents which can exist even if the thickness of the magnetic films is smaller than the skin depth. These currents can circulate within the laminates because of the capacitive coupling across the dielectric layers separating the magnetic films. Using this model the effective permeability of the thin multilayer films has been computed also taking into account the displacement eddy currents. The results presented are in agreement with numerical and experimental tests available in literature. The authors have developed this model using the circuit theory because this approach has the major advantage of being simple to understand and easy to implement with a calculation code
Two-dimensional eddy current computation on the dewar's thermal shields for a superconducting magnet in a magnetohydrodynamic device
No full textNon-linear behaviour of ground electrodes under lightning surge currents: computer modelling and comparison with experimental results
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