An electrostatic suspension method for testing spark breakdown, ignition, and quenching of powders

Colver, Gerald M.; Kim, S.W.; Yu, Tiantang

doi:10.1016/0304-3886(96)00008-3

Cited by 14 publications

(8 citation statements)

References 9 publications

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“…Uniformity of the powder suspension within the electrostatic cell was proven in several papers that investigated electrostatic fluidization in detail (see Ref. [5]). It has to be noted that the particlesi nt he cell are in constant vertical motion betweent he two electrodes:c harging on one electrode, moving under electrostatic force to the other,c hanging polarity of the charge at impact and then moving back.…”

Section: Gauge Calibrationmentioning

confidence: 98%

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Measurement of Particle Density During Explosive Particle Dispersal

Goroshin

Frost

Ripley

et al. 2015

Propellants Explo Pyrotec

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A gauge based on laser light attenuation has been developed to determine the temporal history of particle number density during the explosive dispersal of inert particles. The optical scheme of the gauge employs narrow band pass and spatial optical filters that protect the optical sensors from ambient light and laser light scattered by particles. The gauge is used in field experiments to measure particle density at two locations in close proximity to spherical metalized explosive charges containing a packed bed of either iron, nickel, or glass particles saturated with nitromethane. The heavy iron particles penetrate the blast wave in the near field, whereas the lighter particles remain behind the blast wave. Comparisons with multiphase calculations indicate that the particle density field inferred from the light intensity signals is consistent with the computations until the point at which the combustion products containing soot arrives at the gauge, blocking the laser light.

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Section: Gauge Calibrationmentioning

confidence: 98%

“…The powders were dispersedi nto au niform suspension using an electrostatic particulate suspension set-up designed by Prof. Gerald Colver at Iowa State University [5].Aschematic of the set-up and the arrangement of the equipment in the laboratory setting are shown in Figure 4.…”

Section: Gauge Calibrationmentioning

confidence: 99%

Measurement of Particle Density During Explosive Particle Dispersal

Goroshin

Frost

Ripley

et al. 2015

Propellants Explo Pyrotec

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“…The cloud of particles is formed by accelerating particles between parallel plate electrodes. 17 For this experiment the molybdenum particles are placed on the anode, causing the particles to become negatively charged. The particles are then attracted to the positively charged top plate.…”

Section: Characteristics Of Electrostatic Particulate Suspensionmentioning

confidence: 99%

Nonthermal Plasma-Assisted Synthesis of Molybdenum Carbide Thin Film Catalysts

Campbell

Nelson

Heitzman

et al. 2007

J Undergrad Research UIC

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Optimization of the nonthermal plasma-assisted method of synthesizing molybdenum carbide thin films on molybdenum particle substrates was initiated using a previously existing experimental setup. The yield of the apparatus used has increased by 20% as the result of redesign. The molybdenum carbide produced through nonthermal plasma has been characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). It is tentatively observed by using the TEM that an ethylene concentration of 3% gives the best molybdenum carbide surface layer. The quality of the product is unclear, indicating that further characterization is necessary. This novel method of catalyst production has been tested in very preliminary experiments with a water-gas shift reactor and the CO conversion was 0.5%, suggesting, again, that further optimization is necessary. Introduction and Background MotivationGroup VI transition metal carbides have received a great deal of attention, since it was shown that they have catalytic behavior similar to the noble metals.1 Molybdenum carbide has been shown to possess catalytic activities for many different reactions, including water-gas shift (WGS) 2 , methane conversion to aromatics 3 , and reforming reactions, such as isomerization and cracking. 4Molybdenum carbide also has exceptional chemical and thermal stability and resistance to poisons like sulfur and nitrogen oxides. 5 The literature suggests that having a nanolayer of catalyst encompassing a support increases the catalytic activity.6,7 The objective of this experiment is to form an even coating of molybdenum carbide on a molybdenum metal substrate and test its catalytic ability in a water-gas shift reactor.The WGS is a reaction of industrial importance and possible fuel cell powered vehicles applications.5 It is the reaction of water and carbon monoxide to produce carbon dioxide and hydrogen:The catalyst for this reaction is often Cu-Zn-Al, Pt or other group VIII noble metals 2,5,8 , which are rare and expensive.Molybdenum is significantly more abundant and less expensive than group VIII metals. Clean surfaces of molybdenum carbide are more reactive than platinum catalysts for reforming reactions 4 and perform better than the commercial Cu−Zn−Al catalyst used in WGS. 2Using molybdenum carbide as a catalyst to replace Pt could lower operation costs and make fuel cell powered vehicles more feasible. However, a reliable, efficient, and inexpensive process for the production molybdenum carbide is necessary and is the focus of this work. Previous Synthesis TechniquesResearch groups have formed molybdenum carbide via self-propagating high-temperature synthesis 9 , carburization of M oO 3 4 , and metal-organic chemical vapor deposition 3 . These techniques, however, require high temperatures, long reaction times, and give low yields. Brezinsky has attempted to synthesize M oC utilizing microwave synthesis 10 , and that project has evolved into the current project utilizing nonthermal plasma. The plasma reactor began as a ...

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“…Colver et al (1996Colver et al ( , 2001Colver et al ( , 2003, Goroshin and Lee (1999), Goroshin et al (2003Goroshin et al ( , 2005 and Lee et al (2001) have attempted to determine fundamental combustion parameters, such as the laminar burning velocity, the flammability limits or the quenching distance of dust-air mixtures for different metallic particle suspensions. They reported that the quenching distances were similar under normal gravity and microgravity.…”

Section: Introductionmentioning

confidence: 98%

“…To get rid of the influence of particle settling to the walls, several researchers (Colver et al 1996(Colver et al , 2001(Colver et al , 2003Goroshin and Lee 1999;Goroshin et al 2003Goroshin et al , 2005Lee et al 2001;Jarosinski and Podfilipski 1999;Jarosinski et al 2000;Kobayashi et al 1994;Hanai et al 1998;Pu et al 1998) have performed experiments under microgravity conditions. Colver et al (1996Colver et al ( , 2001Colver et al ( , 2003, Goroshin and Lee (1999), Goroshin et al (2003Goroshin et al ( , 2005 and Lee et al (2001) have attempted to determine fundamental combustion parameters, such as the laminar burning velocity, the flammability limits or the quenching distance of dust-air mixtures for different metallic particle suspensions.…”

Section: Introductionmentioning

confidence: 99%

Study of the Mechanisms of Dust Suspension Generation in a Closed Vessel Under Microgravity Conditions

Bozier

Veyssiere²

2010

Microgravity Sci. Technol.

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An experimental method has been developed to investigate the mechanisms of dust suspension generation in a closed vessel under microgravity conditions. The objective is to characterize the evolution as function of time of the aerodynamic flow field and the dust distribution inside the vessel, in particle concentration conditions representative of actual dust explosions. Cornstarch suspensions in air have been chosen for this purpose. Special adaptation of high frame rate video records with laser sheet tomography allowed performing PIV measurements under microgravity conditions, in the unsteady flow generated during the dispersion process. It was demonstrated that cornstarch particles, in spite of their relatively large size, were suitable to be used as tracers for PIV measurements. Video registrations, at high frame rate (5,000 fps) at discrete instants in the time interval 0-10 s, of the dispersion of cornstarch particles under microgravity conditions allowed to explore the time interval 600 ms to 10 s for which there were no experimental data until now. It appears that after 500 ms, velocity and rms velocity fields become similar for g = 0 and g = 1. For characteristic times beyond 7-8 s, these fields evolve very slowly. Recordings at slower frame rate (125 fps) continuously during the whole process, showed the tendency of particles to become uniformly distributed in the vessel. The variations of particle concentration were followed using B. Veyssière (the signal of light intensity diffused by the particles. Large fluctuations of the diffused light are detected during the dispersion process. However, for g = 0, the average value of the diffused light intensity remains quasi-constant as function of time, whereas for g = 1, it decreases quickly until approximately 4 s, and then decreases much slowly and becomes slightly smaller than in the case g = 0. To get further information about the subsequent evolution of the suspension, observation of the dispersion process beyond 10 s should be done in future experiments.

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An electrostatic suspension method for testing spark breakdown, ignition, and quenching of powders

Cited by 14 publications

References 9 publications

Measurement of Particle Density During Explosive Particle Dispersal

Measurement of Particle Density During Explosive Particle Dispersal

Nonthermal Plasma-Assisted Synthesis of Molybdenum Carbide Thin Film Catalysts

Study of the Mechanisms of Dust Suspension Generation in a Closed Vessel Under Microgravity Conditions

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