The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform

John R. Grace - One of the best experts on this subject based on the ideXlab platform.

  • monitoring Electrostatics and hydrodynamics in gas solid bubbling fluidized beds using novel Electrostatic Probes
    Industrial & Engineering Chemistry Research, 2015
    Co-Authors: John R. Grace
    Abstract:

    The ability of recently developed novel Electrostatic Probes to monitor particle charge density and hydrodynamics in freely bubbling two- and three-dimensional fluidized beds of glass beads and polyethylene particles is demonstrated. Particle charge density and bubble properties in the beds were altered by abruptly changing superficial gas velocity or by impulsively adding antistatic agent to the bed. The Probes were then utilized to quantitatively monitor the particle charge density and bubble rise velocity. The current signals from the Probes responded quickly and significantly to abrupt changes in the superficial gas velocity. By analyzing time-series signals from the Probes, the particle charge density and the bubble rise velocity deduced from the Probes were found to be of similar order of magnitudes and changed consistently with those obtained from Faraday cup and video measurements. Charge densities from the Faraday cup decreased when an antistatic agent was added, as registered by the probe.

  • Monitoring Electrostatics and Hydrodynamics in Gas–Solid Bubbling Fluidized Beds Using Novel Electrostatic Probes
    2015
    Co-Authors: John R. Grace
    Abstract:

    The ability of recently developed novel Electrostatic Probes to monitor particle charge density and hydrodynamics in freely bubbling two- and three-dimensional fluidized beds of glass beads and polyethylene particles is demonstrated. Particle charge density and bubble properties in the beds were altered by abruptly changing superficial gas velocity or by impulsively adding antistatic agent to the bed. The Probes were then utilized to quantitatively monitor the particle charge density and bubble rise velocity. The current signals from the Probes responded quickly and significantly to abrupt changes in the superficial gas velocity. By analyzing time-series signals from the Probes, the particle charge density and the bubble rise velocity deduced from the Probes were found to be of similar order of magnitudes and changed consistently with those obtained from Faraday cup and video measurements. Charge densities from the Faraday cup decreased when an antistatic agent was added, as registered by the probe

G Barbezat - One of the best experts on this subject based on the ideXlab platform.

  • characterization of supersonic low pressure plasma jets with Electrostatic Probes
    Plasma Sources Science and Technology, 2004
    Co-Authors: Malko Gindrat, J L Dorier, Ch Hollenstein, A Refke, G Barbezat
    Abstract:

    Measurement of key plasma jet properties, such as the Mach number, electron density and temperature, in a low pressure environment, were performed using double Langmuir Probes and Mach Probes. In particular, under-expanded jets are studied in detail by performing complete mappings of plasma jet properties at chamber pressures of 10 and 2 mbar. These results show that the measured physical properties are consistent with the jet flow phenomenology, such as the presence of periodic expansion and compression zones, the effect of the pressure and the location of the shocks. It is shown, in particular, that for a highly under-expanded jet at 2 mbar, the Mach number reaches 2.8 in the first expansion zone followed by a strong drop to subsonic flow revealing the presence of a Mach reflection. The flow is accelerated further and a periodic structure of compression/expansion cells is observed until the local static pressure is in equilibrium with the surrounding pressure. These results contribute to the understanding of the supersonic plasma jet behaviour at low pressure and can be used to quantify the deviation from local thermodynamic equilibrium. The extensive mapping of the measured physical properties of the jet will also serve as input for modelling.

  • characterisation of low pressure plasma jets by Electrostatic Probes
    Réunion Annuelle de la Société Suisse de Physique, 2003
    Co-Authors: Malko Gindrat, J L Dorier, Ch Hollenstein, G Barbezat
    Abstract:

    Note: Reunion Annuelle de la Societe Suisse de Physique, Bâle, Suisse, Mars 2003, Bull. SPG/SSP 20, 231, 57 (2003) Reference CRPP-CONF-2003-020 Record created on 2008-05-13, modified on 2017-05-12

Jennifer Mcmillan - One of the best experts on this subject based on the ideXlab platform.

  • Applications of Electrostatic Probes in fluidized beds
    Powder Technology, 2020
    Co-Authors: Majid Jahanmiri, Francisco J. Sanchez Careaga, Cedric Briens, Franco Berruti, Jennifer Mcmillan
    Abstract:

    Abstract The Electrostatic charge in a fluidized bed can be applied to provide local information on the bed hydrodynamics. Electrostatic Probes can withstand adverse conditions that would be an issue for other measurement Probes, such as high temperatures (limited by metal), high velocities (e.g. 2 m/s), high bed densities (1500 kg/m3), and large-scale equipment. The objective of this study was to investigate various applications of Electrostatic Probes in fluidized beds. Results obtained with an array of 45 Probes arranged in 5 rows provided the local bubble gas flux and bubble velocity. They could also be used to detect any slugging. When liquid was sprayed into the gas-fluidized bed, the Electrostatic Probes could provide the penetration of the gas-liquid spray jet, detect bogging and measure the free moisture, i.e. the amount of liquid that was not trapped within wet agglomerates. The Electrostatic Probes measurements were validated with alternate measurement methods.

Rimma M Bektursunova - One of the best experts on this subject based on the ideXlab platform.

  • asymptotic theory of spherical Electrostatic Probes in large debye length plasmas containing negative ions
    Physics of Plasmas, 1999
    Co-Authors: Rimma M Bektursunova
    Abstract:

    The problem of a spherical Electrostatic probe in negative ion containing oxygen plasmas is treated by the matching asymptotic expansions technique [A. H. Nayfeh, Perturbation Methods (Wiley, New York, 1973)]. Assuming that the energy relaxation length is much smaller than the local characteristic length, explicit results are obtained in the asymptotic limits, (rp/rD)2≪1,(rp/rS)2≪1, where rD is the Debye radius, rS is the recombination length and rp is the probe radius. The perturbation region divides naturally into a thin space charged sheath, a transitional sheath, and a quasineutral chemically equilibrium plasma. The potential and charged particle density distributions are obtained. The calculated probe characteristic is presented in an analytical form.

Malko Gindrat - One of the best experts on this subject based on the ideXlab platform.

  • characterization of supersonic low pressure plasma jets with Electrostatic Probes
    Plasma Sources Science and Technology, 2004
    Co-Authors: Malko Gindrat, J L Dorier, Ch Hollenstein, A Refke, G Barbezat
    Abstract:

    Measurement of key plasma jet properties, such as the Mach number, electron density and temperature, in a low pressure environment, were performed using double Langmuir Probes and Mach Probes. In particular, under-expanded jets are studied in detail by performing complete mappings of plasma jet properties at chamber pressures of 10 and 2 mbar. These results show that the measured physical properties are consistent with the jet flow phenomenology, such as the presence of periodic expansion and compression zones, the effect of the pressure and the location of the shocks. It is shown, in particular, that for a highly under-expanded jet at 2 mbar, the Mach number reaches 2.8 in the first expansion zone followed by a strong drop to subsonic flow revealing the presence of a Mach reflection. The flow is accelerated further and a periodic structure of compression/expansion cells is observed until the local static pressure is in equilibrium with the surrounding pressure. These results contribute to the understanding of the supersonic plasma jet behaviour at low pressure and can be used to quantify the deviation from local thermodynamic equilibrium. The extensive mapping of the measured physical properties of the jet will also serve as input for modelling.

  • characterisation of low pressure plasma jets by Electrostatic Probes
    Réunion Annuelle de la Société Suisse de Physique, 2003
    Co-Authors: Malko Gindrat, J L Dorier, Ch Hollenstein, G Barbezat
    Abstract:

    Note: Reunion Annuelle de la Societe Suisse de Physique, Bâle, Suisse, Mars 2003, Bull. SPG/SSP 20, 231, 57 (2003) Reference CRPP-CONF-2003-020 Record created on 2008-05-13, modified on 2017-05-12