Relevant parameters involved in tribocharging of powders during dilute phase pneumatic transport

Experimental Investigation of Electrostatic Charge Generation for Granules

“…For example, Yao and Wang [14] who carried out triboelectric tests based on pneumatic transport of PVC particles, reported that the angular particles allow a stronger charge transfer. In addition, this result was supported by experimental work on horizontal pneumatic flow done by Saleh [13], who found that the highest charge was reached with particles of irregular shape. Fig.2(b) illustrates the relationship between specific charge to length-ratio and area after sliding.…”

“…Nomura et al [12] studied in depth the humidity effect on the tribocharging of powder; they found that the absolute value of the saturated specific tribocharging of the powder decreased with increasing humidity, and the absorption hysteresis of the powder produced a large effect on the charging characteristic of powder. Saleh et al [13] investigated the effect of several parameters, such as the chemical nature of the transport pipe, the particle mean size, the solids flow rate, the air velocity, and relative humidity, on the tribocharging of fine glass particles during pneumatic conveying. Greater electrostatic effects were observed for larger particles, high air velocities, high solids flow rate, and low relative humidity.…”

Triboelectrification: A review of experimental and mechanistic modeling approaches with a special focus on pharmaceutical powders

“…However, despite their higher specific surface area, the smaller particles have often been reported to acquire a smaller charge than coarser particles. Saleh et al suggested this phenomenon due to surface deformation during elastic plastic collisions, increasing the contact surface area proportional to the square of particle size 83,84 . Mountain et al suggested this phenomenon in the finer particles due to lower inertia and less tendency to impact the container wall 85 .…”

Electrostatic Separation

“…It is known that humidity has a crucial influence on triboelectric charging processes [39,84,[138][139][140][141][142][143]. Better results are usually obtained at comparatively low humidities.…”

“…The most common method is a combination of a Faraday cage connected to an electrometer [65,131,132,138,140,[203][204][205]. Charged particles, e.g., collected directly after passing the electric field, induce a current within the Faraday cage that is proportional to the particle charge and this can directly be measured by the electrometer.…”