Couplage multiphysique à l’aide d’électret application à la récupération d’énergie

In the last decades, direct energy conversion devices for medium and low grades waste heat have received significant attention due to the necessity to develop more energy efficient engineering systems. A great deal of research has in recent years been carried out on harvesting energy using piezoelectric, electrostatic, electromagnetic , and thermoelectric ,transduction, with the aim of harvesting enough energy to enable data transmission. For this purpose, piezoelectric elements have been extensively used in the past; however they present high rigidity and limited mechanical strain abilities as well as delicate manufacturing process for complex shapes, making them unsuitable in many applications. Thus, recent trends in both industrial and research fields have focused on electrostrictive polymers for electromechanical energy conversion. This interest is explained by many advantages such as high productivity, flexibility, and processability. Hence, electrostrictive polymer films are much more suitable for energy harvesting devices requiring high flexibilities, such as systems in smart textiles and mobile or autonomous devices. Electrostrictive polymers can also be obtained in many different shapes and over large surfaces. . In the last years, electrostrictive polymers have been investigated as electroactive materials for energy harvesting. However for scavenging energy a static field is necessary, since this material is isotope, there is no permanent polarization compare to piezoelectric material. A solution for avoid this problem; concern the hybridization of electrostrictive polymer with electret. Finally, the implementation of electrostrictive materials is much simpler for small-scale systems (MEMS). Hence, several studies have analyzed the energy conversion performance of electrostrictive polymers, both in terms of actuation and energy harvesting.Les matériaux actifs, tels que les matériaux piézoélectriques et électrostrictifs, sont couramment utilisés dans la conception de dispositifs exploitant leurs propriétés respectives. La propriété principale de ces matériaux réside dans le fort couplage entre les comportements électrique et mécanique (piézoélectricité). Dans la majorité des cas, ces matériaux sont utilisés séparément. L’utilisation combinée de ces matériaux permet la réalisation de dispositifs innovants basés sur l’effet électrostrictifs: l’apparition d’une polarisation électrique induite par une contrainte mécanique et réciproquement l’apparition d’une déformation mécanique sous l’action d’un champ électrique. Les applications « support » concernent les capteurs et les actionneurs. L’étude de ce couplage passe par la caractérisation de ces matériaux, puis par la mise en place de modèles décrivant finement leurs comportements et enfin par le développement d’outils pour la conception. L’objectif de la thèse est de remplacer le matériau céramique, rigide et à faible déformation, par un film polymère nanocomposite électroactifs, présentant des grandes déformations et forces d'actionnement sous champ électrique modéré grâce à l'incorporation dans la matrice polymère de micro et nano-objets (charge) conducteurs ou semi-conducteurs. De plus, pour des applications plus spécifiques de la récupération d’énergie, la charge du film polymère par des micro et nano-objets conducteurs sera également étudiée. Idéalement, il serait très intéressant de réaliser un matériau multifonctionnel, sensible à la fois à une stimulation mécanique (propriétés de détection et/ou de récupération d’énergie par couplage électromécanique)

Multiphysics coupling with electret application to the Harvesting energy

Les matériaux actifs, tels que les matériaux piézoélectriques et électrostrictifs, sont couramment utilisés dans la conception de dispositifs exploitant leurs propriétés respectives. La propriété principale de ces matériaux réside dans le fort couplage entre les comportements électrique et mécanique (piézoélectricité). Dans la majorité des cas, ces matériaux sont utilisés séparément. L’utilisation combinée de ces matériaux permet la réalisation de dispositifs innovants basés sur l’effet électrostrictifs: l’apparition d’une polarisation électrique induite par une contrainte mécanique et réciproquement l’apparition d’une déformation mécanique sous l’action d’un champ électrique. Les applications « support » concernent les capteurs et les actionneurs. L’étude de ce couplage passe par la caractérisation de ces matériaux, puis par la mise en place de modèles décrivant finement leurs comportements et enfin par le développement d’outils pour la conception. L’objectif de la thèse est de remplacer le matériau céramique, rigide et à faible déformation, par un film polymère nanocomposite électroactifs, présentant des grandes déformations et forces d'actionnement sous champ électrique modéré grâce à l'incorporation dans la matrice polymère de micro et nano-objets (charge) conducteurs ou semi-conducteurs. De plus, pour des applications plus spécifiques de la récupération d’énergie, la charge du film polymère par des micro et nano-objets conducteurs sera également étudiée. Idéalement, il serait très intéressant de réaliser un matériau multifonctionnel, sensible à la fois à une stimulation mécanique (propriétés de détection et/ou de récupération d’énergie par couplage électromécanique).In the last decades, direct energy conversion devices for medium and low grades waste heat have received significant attention due to the necessity to develop more energy efficient engineering systems. A great deal of research has in recent years been carried out on harvesting energy using piezoelectric, electrostatic, electromagnetic , and thermoelectric ,transduction, with the aim of harvesting enough energy to enable data transmission. For this purpose, piezoelectric elements have been extensively used in the past; however they present high rigidity and limited mechanical strain abilities as well as delicate manufacturing process for complex shapes, making them unsuitable in many applications. Thus, recent trends in both industrial and research fields have focused on electrostrictive polymers for electromechanical energy conversion. This interest is explained by many advantages such as high productivity, flexibility, and processability. Hence, electrostrictive polymer films are much more suitable for energy harvesting devices requiring high flexibilities, such as systems in smart textiles and mobile or autonomous devices. Electrostrictive polymers can also be obtained in many different shapes and over large surfaces. . In the last years, electrostrictive polymers have been investigated as electroactive materials for energy harvesting. However for scavenging energy a static field is necessary, since this material is isotope, there is no permanent polarization compare to piezoelectric material. A solution for avoid this problem; concern the hybridization of electrostrictive polymer with electret. Finally, the implementation of electrostrictive materials is much simpler for small-scale systems (MEMS). Hence, several studies have analyzed the energy conversion performance of electrostrictive polymers, both in terms of actuation and energy harvesting

The effect of erosion on hydraulic machine performance

info:eu-repo/semantics/publishe

Location of seawater pumped storage hydropower plants: Case of Morocco

Energy transition consists of developing new energy strategies to diversify the power grid portfolio. However, these strategies depend in one hand to the available energy sources and technology maturity. Energy storage is one option to manage the power flow, grid interconnections and increase the social welfare for communities. Marine energy not yet well deserved to produce energy in Africa. In this potential study, we focus to locate suitable sites for seawater pumped storage systems in Morocco. The results were promising with high energy storage potentials. For medium hydropower storage plants, 11 sites were selected and for very high heights, 4 sites were selected. The available energy storage is at about 300 MWh depending on site geography and the chosen surface. The main tool used for this work, is the GIS with the open-source software QGIS and the academic version of Visual PROMETHEE software. Energy storage ranking showed that hydrogen can be a good option to store energy in the coming decades where flywheel has a cost competitive advantage regarding the other options. Compressed air and pumped storage stay on the middle of GAIA results.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Flexible thermoelectric device to harvest waste heat from the laptop

International audienc

Magnetoelectric coupling in Fe3O4/P(VDF-TrFE) nanocomposites

International audienceNanocomposite films composed of nanoparticles Fe3O4 embedded in copolymers of vinylidene fluoride and trifluoroethylene P(VDF-TrFE) (70/30) have been elaborated. The effect of Fe3O4 content on the cristallinity ratio, dielectric and magnetoelectric properties of the nano-piezo-composites was studied and discussed. Dielectric characterization showed an increase of the permittivity and a decrease of the resistivity with the increasing ratio of nanofillers. Thermal analysis revealed a decrease of the cristallinity of the composite. Poling process was found to be difficult for Fe3O4 contents higher than 1%, because of the low breakdown fields and diminished resistivity with increasing Fe3O4 content. As a consequence, magnetoelectric measurements were conducted only on nanocomposites with Fe3O4 contents lower than 0.5% in the case of poled samples. The optimal value of the first order magnetoelectric (ME) coefficient αpαp was obtained for a nanoparticles content of 0.3% wt

Enhancing Photovoltaic/Thermal system performance through innovative cooling tube design and water flow management

This research addresses the challenge of elevated temperatures impacting the performance of photovoltaic (PV) panels, considering both the dimensions of the cooling tube and the flow of water. A comprehensive analysis of various water flow rates is conducted using three tubes (tube 1, tube 2, and tube 3) with cross-sections of 100.27, 148.27, and 202.27 mm2 and 15, 11, and 9 loops, respectively. The numerical results reveal a significant 41.66% reduction in PV cell temperature, decreasing from 60 °C to 35 °C using tube 3 at a flow rate of 7.5 L/min, reflecting high electrical performance and efficiency. Meanwhile, at a flow rate of 1.5 L/min, tube 1 delivers optimum hot water at the outlet with a temperature of 55.6 °C. The proposed design significantly contributes to PV cell efficiency, emphasizing the impact of cooling tube dimensions on the overall efficiency of the PV/T system. This study introduces an innovative approach using a flat oval tube to minimize temperature elevation and simultaneously generate hot water. The innovative PV/T system demonstrates potential advancements in thermal management and lays the foundations for future sustainable energy applications

Improvement of the magneto-electric effect of composites loaded with different magnetic particles for current sensor applications

This article proposes a methodology to improve the magneto-electric effect of a poly(vinylidene fluoride-co-trifluoroethylene) P(VDF-TrFe) copolymer, doped with nanoparticles of nickel (Ni) and nickel iron (NiFe). The preparation of the composite films were achieved through the solvent casting approach. First, P(VDF-TrFe) powders and (Ni and NiFe) nanoparticles are dispersed in dimethyl formamide (DMF) as a solvent to form a homogeneous solution. Then, the solution obtained is deposited on a flexible substrate by a spin coating process. After that, the NiFe doped composites are corona polarized, to improve the magneto-electric response of these composites. The purpose of this work is to investigate the influence of the magnetic charges added in the P(VDF-TrFe) copolymer, and to reveal the effect of corona charging (polarization) on the magneto-electric behavior of the used composites. The obtained results in this article show that both the doping and the electric polarization (piezo coefficient) significantly affect the generated alternating current during the application of an alternating magnetic field. However, the magneto-electric response of composites increases by doping and charging via corona poling effect and also by increasing the excitation frequency and the magnetic field amplitude. In addition, the magneto-electric responses of all composites after corona polarization were also discussed. This indicates that the magneto-electric coefficient and the current can be increased with polarized composites. A good response is observed for P(VDF-TrFe) + 3% Ni with a piezoelectric coefficient d33 = 21.2 (pC/N

Modeling, optimization and characterization of titanium dioxide thin film prepared by the spin-coating method using the experimental design for an application of photocatalytic degradation of methylene blue

This work focuses on modeling and optimizing the deposition of a TiO2 film on ITO glass using the spin-coating method and experimental design. The parameters studied include the concentration of the solution, speed and duration of rotation, drying temperatures and time, and calcination temperature and time. Results show that optimal conditions are achieved at 457 g/l concentration, 1020 rpm speed, 43 s duration of rotation, 100 °C drying temperature for 30 s, and 500 °C calcination temperature for 2 h. XRD, FTIR, EDX, and SEM analyses of the TiO2/ITO film indicate crystallization in the anatase phase with a 29.3 nm crystal size and around 80% deposition quality, with good surface adhesion and a thickness of approximately 30 nm. The photocatalytic activity of the thin film for the decomposition of methylene blue (MB) in water was also studied. Results showed a 70% degradation of MB after 4.5 h, which was confirmed by absorption spectra and discoloration of MB. Additionally, the degradation reaction of MB by TiO2 followed the pseudo-first-order, with good agreement between the kinetic study and a high degradation rate constant (k1deg = 0.2919 (h−1)), indicating a rapid process. Finally, a photodegradation mechanism of MB was reported

Pyroelectric effect in lead zirconate titanate/polyurethane composite for thermal energy harvesting

We deal with the thermal energy which is one of the ambient energy sources surely exploitable, but it has not been much interest as the mechanical energy. In the last decades, direct energy conversion devices received particular attention because of the need to develop flexible systems, autonomous and self-powered. The energy harvesting aims to make the systems, autonomous in terms of energy and to contribute to sustainable development by the total respect of the environment. In this paper, our aim is to use thermal energy and show that it's an important source for producing the electrical energy through pyroelectric effect: first, elaborate charged polyurethane (PU) with different proportions (20%, 30% and 40%) of lead zirconate titanate (PZT), then to use those PZT/PU composites as a pyroelectric energy harvesting systems. Secondly, the optimization of energy harvesting and storage. The PZT/PU composite prepared is considered as one of the most promising composites for energy harvesting systems, due its various advantages, such as mechanical flexibility, high temperature sensitivity, low cost as well as its high electro-active functional properties. The current generated by all samples for temperature fluctuations over a period of time in the order of 140 s have been rectified and stored in a charge capacitor of 1μF. The stored energy can reach a maximum value in the order of 14μW for a composite loaded with 40% PZT. Therefore, these composites show an interesting potential to be used in various applications. These results shed light on the thermoelectric energy conversion by a new composite of PZT/PU having the pyroelectric property