Effects of humidity, conveying velocity, and particle size on electrostatic charges of glass beads in a gaseous suspension flow

Effects of an electrostatic field in pneumatic conveying of granular materials through inclined and vertical pipes

“…It may be expected that charges induced on a pipe wall made of a conductive material may be more easily conducted away while those induced on an insulating material may tend to be accumulated. Zhu et al (2004) have reported that the presence of electrostatic charges residing on pipe walls may have some perturbation effects on ECT measurements when low gas Glass beads (Fasso et al, 1982) Polystyrene (Wolny and Kazmierczak, 1989) Glass beads (Nieh and Nguyen, 1988) Glass beads (Nieh andNguyen, 1988) Glass beads (Nieh and Nguyen, 1988) Present work Glass beads (Nieh and Nguyen, 1988) Polystyrene (Gajewski, 1989) Polyamide (Sharmene Ali et al, 1999) 0 400 800 1200 1600 2000 2400 2800 Particle size (μm) Fig. 4.…”

“…4. Map of particle charge-to-mass ratio as a function of particle size Fasso et al, 1982;Gajewski, 1989;Nieh and Nguyen, 1988;Sharmene Ali et al, 1999;Wolny and Kazmierczak, 1989. Table 3 Charge-to-mass ratios of particles conveyed through various types of pipes (Ally and Klinzing, 1985) Pipe velocities are used.…”

Applications of Electrified Dust and Dust Devil Electrodynamics to Martian Atmospheric Electricity

“…In a variety of experimental techniques and over a broad range of grain sizes (µm-mm) the electrification has been seen to be of order 0.1 mC m −2 (Poppe et al 2000;Lowell 1986;Merrison et al 2004;Nieh and Nguyen 1988). In many granular electrification studies the electrified surface area is taken as the (total) surface area of the grain; since the contact area is not known, this possibly explains the lower level of electrification seen in such cases e.g.…”

“…Another common cause for observing reduced electrification in charge collection systems is charge leakage via surface water, which is related to ambient humidity (Nieh and Nguyen 1988). In dust collection experiments electrostatic aggregation can also de-electrify suspended dust, especially when in high concentrations and after long suspension times .…”

On the electrostatic equilibrium of granular flow in pneumatic conveying systems

“…The relative humidity (RH) of the ambient air is an important factor to be considered in any electrostatics experiment. 2,15,33,34 In the present work, both air from the ambient atmosphere (RH ϭ 88%) and dry air (RH ϭ 5%, by passing air through a silica gel column) were used. Experimental data were acquired at the vertical pipe and for all tests conducted for the same pipe (new/old).…”