Modeling nonelectrostatic and electrostatic powder coating

The influence of particle size on separation and dustiness in powder mixtures during nonelectrostatic and electrostatic coating

“…In addition, the lighter fine powders were more likely to be blown out as dust by the air used to disperse the powder mixture into the coating chamber. A higher transfer efficiency of coarse powder than fine powders has been reported by others [3,13,21]. In a previous study, the difference in individual transfer efficiency was the biggest cause of separation in mixtures of NaCl and starch [15].…”

“…The charged powders are accelerated by electrostatic force according to Coulomb's law to deposit onto the nearest grounded target [1]. Gravitational force, which depends on the powder mass, and electrostatic force cause powders to deposit on food products, resulting in an increase in transfer efficiency [3,9,21] and a reduction of dust [3,11,13]. Even though electrostatic coating is more efficient than nonelectrostatic coating in individual coating, it can increase separation when mixtures are coated.…”

Electrostatic Coating Technologies for Food Processing

“…During electrostatic coating, using particles with the same size produces less separation because small powders have greater chargeto-mass ratios and so land closer to the nozzle, whereas large powders develop lower charge-tomass ratios and so deposit further away from the nozzle (Somboonvechakarn & Barringer 2009). This can be seen theoretically as well as experimentally (Yousuf & Barringer 2007 …”

“…In computer simulations, electrostatic transfer efficiency increased by 10% for small powders, as particle density increased from 1,200 to 2,200 km/m 3 . Powders with lower density have lower mass and inertia and are more likely to remain in the air as dust than more dense powders of the same particle size (Yousuf & Barringer 2007). Experimentally, electrostatic transfer efficiency increased only 4%, as powder density increased from 1,600 to 2,200 kg/m 3 (Biehl & Barringer 2003).…”

“…Differences in particle size (Somboonvechakarn & Barringer 2009, Wang et al 2005, Ye & Domnick 2003, density (Somboonvechakarn & Barringer 2011, Yousuf & Barringer 2007, and particle surface charge (Yousuf & Barringer 2007) cause separation of the different powders in a food powder mixture during coating. This separation is not desirable in powder coating due to the uneven appearance and distribution of flavors produced on the target.…”