Modeling of three-limb three-phase transformer relates to shunt core using in industrial microwave generators with n=2 magnetron per phase

This paper describes the development and implementation of a digital simulation model of a three-phase transformer relates to shunt core transformer, which used to drive magnetron tubes in the microwave. The focus of this study is based on modeling of a new shell-type of three limbs three-phase transformer. The model uses to feed two magnetrons instead of one magnetron per phase. The proposed model is established on the simultaneous analysis of a duo electromagnetic lumped component equivalent circuit. This latter was implemented in a MATLAB environment under rated conditions. The results obtained from the application of the analytical method are provided results in conformity to the experimental tests in the case of single phase high voltage power supply for one magnetron

Enhanced piezoelectric properties of PVdF-HFP/PZT nanocomposite for energy harvesting application

The use of piezoelectric nanocomposite in detection and actuation applications for the development of electromechanical microsystems (MEMS) has become quite common over the last decade. In this paper, we present a flexible piezoelectric nanocomposite films, composed of lead zirconate titanate (PZT) nanoparticles, embedded in poly(vinylidene-difluoride hexafluoro propylene) (PVdF-HFP) matrix. Piezoelectric and ferroelectric properties evolution is proportional to the evolution of the crystalline β-phase. The evaluation of the interactions between PZT and PVdF- HFP, performed by Fourier transform infrared spectroscopy (FTIR), revealed a dramatic improvement in these characteristics over pure PVdF-HFP, and attributed to a better crystallinity of the PVdF-HFP matrix and uniform distribution of nanoparticles. These films nanocomposites were done by solvent casting method, with various concentrations of PZT. Results of these experiments indicate that the investigated thin films nanocomposites are appropriate for various applications in energy storage and energy harvesting application

Utilisation de la post-décharge d'un plasma micro-ondes d'air ou d'azote pour valoriser le méthane

Valorization of methane is obtained by means of the reaction with a plasma. The plasma is produced in a quartz tube (30 mm in diameter) crossing a wave guide. The energy is supplied by a generator (Thomson CSF, 2 450 MHz, 15 to 1 500 W). Directional couplers followed by an attenuator and thermistor detectors enable forward $\Pi_{\rm i}$ and reflected $\Pi_{\rm r}$ power to be measured. Methane is introduced in the post-discharge zone through five tubes symmetrically arranged around the reactor. Methane consumption $\alpha$, selectivity S$_{\rm X}$ and yield R$_{\rm X}$ are measured as a function of the following parameters : $\beta$ methane/air ratio, $F$ gaz flow, $d$ distance where methane is introduced in the plasma, $P$ pressure, $\Pi$ microwave power absorbed by air or nitrogen. It appears that acetylene is the major hydrocarbon obtained. The corresponding selectivity is increased when $\Pi$ and $P$ are increased or when $d$ and $F$ are decreased. The optimum value of $\beta$ is 4/5. If the best experimental conditions are selected, selectivity of total C$_2$ reaches 44 % with a conversion ratio of 80 %. By decreasing methane/air ratio, carbon monoxide yield is increased. The ratio acetylene/ethylene can by varied without changing the conversion ratio, by introducing a catalyst in the post reaction zone.La valorisation du méthane est réalisée dans la post-décharge d'un plasma microondes (2 450 MHz) d'air ou d'azote. Lorsque la décharge est produite dans l'azote, les principaux produits dosés sont l'acétylène, l'éthylène, l'éthane et l'hydrogène. Lorsque la décharge est produite dans l'air, on dose en outre le monoxyde de carbone. Le taux de conversion du méthane ainsi que la sélectivité des produits ont été déterminés en fonction des paramètres expérimentaux suivants : proportion méthane/gaz plasmagène, flux gazeux, distance d'introduction du méthane dans la post-décharge, pression et puissance micro-ondes. Le procédé expérimenté permet d'obtenir des rendements chimiques importants et d'éviter la formation de sous-produits (charbon, dioxyde de carbone, oxydes d'azote). Une optimisation de l'ensemble des paramètres conduit à un taux de conversion de 80 % et une sélectivité en C$_2$ de 44 %. La puissance micro-ondes, le débit gazeux ou la présence de catalyseur (platine supporté) modifient notablement le rapport acétylène/éthylène