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I.i. Inculet - One of the best experts on this subject based on the ideXlab platform.

  • Induction charging of flat sprays for space charge generation
    Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248), 2001
    Co-Authors: I.i. Inculet, G.s.p. Castle
    Abstract:

    Space charges play a key role in many industrial and agricultural applications such as Electrostatic Painting or application of insecticides in orchards and row crops. For generation of large sized space charge clouds, induction charging is the preferred method. Whereas corona charging often involves voltage in the order of 100 kV, induction charging may be achieved with voltages of less than a few thousand volts. The paper presents a novel construction of a spray unit with induction charging suitable for injecting large volumes of ionic space charge into a region. The experimental unit comprises: a flat spray liquid atomizing nozzle with high pressure air; two large size induction electrodes, and, an air curtain surrounding the electrodes to prevent the fine droplets from landing on the electrodes. The two large, flat induction electrodes sandwiching the flat spray have shown to generate excellent induction charging on the spray droplets achieving charge to mass ratios in the order of 4 mC/kg and ionic charge densities of 2 mC/m/sup 3/. The studied variables were: pressure and flow of water supply at the nozzle and the pressure and flow of the curtain The atomized charged spray cloud of droplets with a mean volume diameter of several micrometers, evaporates at certain distances from the nozzle forming a mixed charged cloud of both water ions and finer water droplets.

  • Mathematical modeling of powder paint particle trajectories in Electrostatic Painting
    IEEE Transactions on Industry Applications, 2000
    Co-Authors: T.e. Base, I.i. Inculet
    Abstract:

    The trajectories of charged powder particles in an Electrostatic powder coating system were modeled considering electrical and fluid forces. The mathematical model employed an iterative technique wherein the charge simulation method was used to compute the electric field strength and the method of characteristics was used to compute the charge density in the gun-to-target region. The fluid flow between the Electrostatic gun and the target was modeled using interpolated experimental data assuming stagnation point flow. Particle trajectories were simulated for size range 10-40 /spl mu/m and charge-to-mass ratios of -0.1 to -1 /spl mu/C/g. The simulation results showed good agreement with experimental data (charge and mass measurements) at several collection points on the Painting target and provided valuable information concerning particle deposition.

  • Innovations in Electrostatic processes in industrial applications
    CCECE '97. Canadian Conference on Electrical and Computer Engineering. Engineering Innovation: Voyage of Discovery. Conference Proceedings, 1997
    Co-Authors: I.i. Inculet
    Abstract:

    Over 35 years, the branch of the electrical science called "Electrostatics" has provided the foundation for extraordinary, new industrial developments measured in billions of U.S. dollars. The common link of all these industrial applications is the engineering of the unique forces which may be generated in an electric field. The author describes five new concepts in the generation and use of electric field forces and their application in agriculture, in filtration, in Electrostatic Painting of non-conductive surfaces and consolidation of foundations. The new concepts are believed to offer considerable promise for industrial applications.

  • The Electrostatic fields and discharge hazards of insulating sheets close to a conductor: a review
    IEEE Transactions on Industry Applications, 1997
    Co-Authors: G.s.p. Castle, I.i. Inculet
    Abstract:

    Dielectric sheets and films are used in various forms in a large number of industrial applications. The important Electrostatic properties of such sheets are reviewed to highlight the significance of the surface potential, the electric field within and adjacent to the sheet, and the electric energy stored. Selected industrial examples in the fields of electrophotography, Electrostatic Painting and materials handling are discussed. A case study of a specific industrial problem involving charge retention on plastic boxes treated in an AC corona discharge is described.

  • Electrostatic Painting of nonconductive surfaces with water-base paints
    IEEE Transactions on Industry Applications, 1996
    Co-Authors: I.i. Inculet, R.g. Klein
    Abstract:

    Electrostatic corona Painting on nonconductive surfaces normally requires a ground-connected conductive precoating of the surface in order to dissipate the continuously incoming ionic charge from the corona gun. If the surface charge does not flow to ground, the resulting surface electric field will repel a substantial amount of the incoming paint. The authors present a new Painting method consisting of generating ultrasonically atomized electrically charged water particles behind the nonconductive surface to be painted. The paint spraying is carried out with a mechanical spray gun maintained at ground potential. The water base paint becomes charged by induction under the influence of the space charge behind the nonconductive surface to be painted. As the resulting charge on the water base paint particles is of opposite polarity to that of the ultrasonically atomized electrically charged water particles cloud, all propelling electric fields converge toward the surface to be painted. The results show excellent transfer efficiencies.

A.a. Elmoursi - One of the best experts on this subject based on the ideXlab platform.

  • Electrostatic Painting of plastics using metal backing
    IEEE Transactions on Industry Applications, 1993
    Co-Authors: A.a. Elmoursi, D P Garner
    Abstract:

    This work explains theoretically and experimentally the fundamental differences between spraying metal and plastic panels Electrostatically. Mechanisms of charge dissipation from plastic surfaces are discussed and a simple method is proposed for determining the Electrostatic sprayability of plastic substrates. Using a 1-D analytical model, it is shown that the effect of charge accumulation can be minimized by appropriately placing a grounded metal backing behind the plastic substrate. Experiments were conducted in a spray booth environment and the results showed good agreement with those predicted theoretically. Special metal backings with indentations and gaps were used to study the effect of a mismatch between the plastic substrate and its metal backing on the quality of the paint finish.

  • Electrostatic Painting of plastics using metal backing
    Conference Record of the 1992 IEEE Industry Applications Society Annual Meeting, 1992
    Co-Authors: A.a. Elmoursi, D P Garner
    Abstract:

    The authors explain theoretically and experimentally the fundamental differences between spraying metal and plastic panels Electrostatically. Mechanisms of charge dissipation from plastic surfaces are discussed, and a simple method is proposed for determining the Electrostatic sprayability of plastic substrates. Using a one-dimensional analytical model, it is shown that the effect of charge accumulation can be minimized by appropriately placing a grounded metal backing behind the plastic substrate. Experiments were conducted in a spray booth environment, and the results showed good agreement with those predicted theoretically. Special metal backings with indentations and gaps were used to show that a mismatch between the plastic substrate and its metal backing can have a visually observable effect on the quality of the paint finish.

  • Electrostatic Painting of plastics ii electric field effects
    Journal of Coatings Technology, 1992
    Co-Authors: A.a. Elmoursi, D P Garner
    Abstract:

    On etudie les facteurs impliques dans le peinturage electrostatique des matieres plastiques en examinant les effets d'un champ electrique a l'aide d'une modelisation et d'une simulation experimentale. Les resultats experimentaux sont en bon accord avec les resultats prevus par le modele analytique.

  • Electrical characterization of a charged workpiece grounded-sprayer Electrostatic Painting system
    IEEE Transactions on Industry Applications, 1991
    Co-Authors: A.a. Elmoursi, C.e. Speck
    Abstract:

    In situations where paint resistivity is low, as it is with waterborne paints, it is not possible to use conventional Electrostatic Painting systems without isolating the sprayer, the fluid handling system, and the paint containers. An alternative technique is to apply high voltage to the workpiece and ground the sprayer. The electrical characteristics of such a system are evaluated and compared with those of the conventional Electrostatic spraying system using computer simulations. It is shown that a charged workpiece grounded-sprayer system can achieve a transfer efficiency that is comparable to that of a conventional Electrostatic system. The results also predict an enhancement in the film build along curved surfaces and strong wraparound. These predictions have been confirmed experimentally. Furthermore, the analysis indicates that there is no improvement in the paint deposition for recessed surfaces.

  • Electrostatic Painting of plastics i electrical properties of plastics and primers
    Journal of Coatings Technology, 1991
    Co-Authors: D P Garner, A.a. Elmoursi
    Abstract:

    Afin de mieux comprendre les problemes lies a la mise en peinture electrostatique des plastiques, on examine l'aptitude de differents polymeres (polyurethanne/polyuree, olefines thermoplastiques, melanges aromatiques/nylon et nylon/polyphenyleneoxyde, urethannes thermoplastiques, polycarbonates) a dissiper les charges electriques. On a egalement examine six primaires conductrices. On a determine la resistivite dans la masse et en surface des plastiques pour differentes conditions d'humidite.

C.e. Speck - One of the best experts on this subject based on the ideXlab platform.

  • Electrical characterization of a charged workpiece grounded-sprayer Electrostatic Painting system
    IEEE Transactions on Industry Applications, 1991
    Co-Authors: A.a. Elmoursi, C.e. Speck
    Abstract:

    In situations where paint resistivity is low, as it is with waterborne paints, it is not possible to use conventional Electrostatic Painting systems without isolating the sprayer, the fluid handling system, and the paint containers. An alternative technique is to apply high voltage to the workpiece and ground the sprayer. The electrical characteristics of such a system are evaluated and compared with those of the conventional Electrostatic spraying system using computer simulations. It is shown that a charged workpiece grounded-sprayer system can achieve a transfer efficiency that is comparable to that of a conventional Electrostatic system. The results also predict an enhancement in the film build along curved surfaces and strong wraparound. These predictions have been confirmed experimentally. Furthermore, the analysis indicates that there is no improvement in the paint deposition for recessed surfaces.

G.s.p. Castle - One of the best experts on this subject based on the ideXlab platform.

  • Estimation of droplet charge forming out of an electrified ligament in the presence of a uniform electric field
    Journal of Physics: Conference Series, 2015
    Co-Authors: Husam Osman, G.s.p. Castle, K. Adamiak, Joseph C. Simmer
    Abstract:

    The charge on a liquid droplet is a critical parameter that needs to be determined to accurately predict the behaviour of the droplet in many Electrostatic applications, for example, Electrostatic Painting and ink-jet printing. The charge depends on many factors, such as the liquid conductivity, droplet and ligament radii, ligament length, droplet shape, electric field intensity, space charge, the presence of adjacent ligaments and previously formed droplets. In this paper, a 2D axisymmetric model is presented which can be used to predict the electric charge on a conductive spherical droplet ejected from a single ligament directly supplied with high voltage. It was found that the droplet charging levels for the case of isolated electrified ligaments are as much as 60 times higher than that in the case of ligaments connected to a planar high voltage electrode. It is suggested that practical atomization systems lie somewhere between these two extremes and that a better model was achieved by developing a 3D approximation of a linear array of ligaments connected to an electrode having variable width. The effect on droplet charge and its radius was estimated for several cases of different boundary conditions.

  • Induction charging of flat sprays for space charge generation
    Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248), 2001
    Co-Authors: I.i. Inculet, G.s.p. Castle
    Abstract:

    Space charges play a key role in many industrial and agricultural applications such as Electrostatic Painting or application of insecticides in orchards and row crops. For generation of large sized space charge clouds, induction charging is the preferred method. Whereas corona charging often involves voltage in the order of 100 kV, induction charging may be achieved with voltages of less than a few thousand volts. The paper presents a novel construction of a spray unit with induction charging suitable for injecting large volumes of ionic space charge into a region. The experimental unit comprises: a flat spray liquid atomizing nozzle with high pressure air; two large size induction electrodes, and, an air curtain surrounding the electrodes to prevent the fine droplets from landing on the electrodes. The two large, flat induction electrodes sandwiching the flat spray have shown to generate excellent induction charging on the spray droplets achieving charge to mass ratios in the order of 4 mC/kg and ionic charge densities of 2 mC/m/sup 3/. The studied variables were: pressure and flow of water supply at the nozzle and the pressure and flow of the curtain The atomized charged spray cloud of droplets with a mean volume diameter of several micrometers, evaporates at certain distances from the nozzle forming a mixed charged cloud of both water ions and finer water droplets.

  • The Electrostatic fields and discharge hazards of insulating sheets close to a conductor: a review
    IEEE Transactions on Industry Applications, 1997
    Co-Authors: G.s.p. Castle, I.i. Inculet
    Abstract:

    Dielectric sheets and films are used in various forms in a large number of industrial applications. The important Electrostatic properties of such sheets are reviewed to highlight the significance of the surface potential, the electric field within and adjacent to the sheet, and the electric energy stored. Selected industrial examples in the fields of electrophotography, Electrostatic Painting and materials handling are discussed. A case study of a specific industrial problem involving charge retention on plastic boxes treated in an AC corona discharge is described.

  • The Electrostatic properties of insulating sheets close to a conductor: a review
    IAS '95. Conference Record of the 1995 IEEE Industry Applications Conference Thirtieth IAS Annual Meeting, 1995
    Co-Authors: G.s.p. Castle, I.i. Inculet
    Abstract:

    Dielectric sheets and films are used in various forms in a large number of industrial applications. The important Electrostatic properties of such sheets are reviewed to highlight the significance of the surface potential, the electric field within and adjacent to the sheet and the electric energy stored. Selected industrial examples in the fields of electrophotography, Electrostatic Painting and materials handling are discussed. A case study of a specific industrial problem involving charge retention on plastic boxes treated in an AC corona discharge is described.

  • Q/M distribution in pulsed corona powder coating spray cone
    IAS '95. Conference Record of the 1995 IEEE Industry Applications Conference Thirtieth IAS Annual Meeting, 1995
    Co-Authors: I.i. Inculet, G.s.p. Castle
    Abstract:

    The advantages of using a high voltage pulsed corona superimposed on a lower voltage DC bias Electrostatic field have been well-documented for the case of Electrostatic precipitation of high resistivity dusts. The high voltage, short pulses achieve adequate charge-to-mass ratios, while reducing the total ionic current landing on the dust layer and thus minimizing the deleterious back corona effects. To throw further light on this corona charging process, which up to the present has not been put to wide use by the Electrostatic Painting industry, the authors present a preliminary experimental study applied to powder coating. Measurements are presented for the Q/M ratios of the charged powder fractions collected in an ensemble of 5 double Faraday pails mounted in a cross behind the target plane. The results indicate, on average, a substantial increase in the charge-to-mass ratio of powder, combined with a reduction of the total ionic current which bombards the Painting target.

J. L. Oteo - One of the best experts on this subject based on the ideXlab platform.

  • Processing and properties of carbon nanofibers reinforced epoxy powder composites
    Journal of Nanoparticle Research, 2011
    Co-Authors: C. Palencia, M. A. Mazo, A. Nistal, F. Rubio, J. Rubio, J. L. Oteo
    Abstract:

    Commercially available CNFs (diameter 30–300 nm) have been used to develop both bulk and coating epoxy nanocomposites by using a solvent-free epoxy matrix powder. Processing of both types of materials has been carried out by a double-step process consisting in an initial physical premix of all components followed by three consecutive extrusions. The extruded pellets were grinded into powder and sieved. Carbon nanofibers powder coatings were obtained by Electrostatic Painting of the extruded powder followed by a curing process based in a thermal treatment at 200 °C for 25 min. On the other hand, for obtaining bulk carbon nanofibers epoxy composites, a thermal curing process involving several steps was needed. Gloss and mechanical properties of both nanocomposite coatings and bulk nanocomposites were improved as a result of the processing process. FE-SEM fracture surface microphotographs corroborate these results. It has been assessed the key role played by the dispersion of CNFs in the matrix, and the highly important step that is the processing and curing of the nanocomposites. A processing stage consisted in three consecutive extrusions has reached to nanocomposites free of entanglements neither agglomerates. This process leads to nanocomposite coatings of enhanced properties, as it has been evidenced through gloss and mechanical properties. A dispersion limit of 1% has been determined for the studied system in which a given dispersion has been achieved, as the bending mechanical properties have been increased around 25% compared with the pristine epoxy resin. It has been also demonstrated the importance of the thickness in the nanocomposite, as it involves the curing stage. The complex curing treatment carried out in the case of bulk nanocomposites has reached to reagglomeration of CNFs.