Enhanced performance of an air-assisted electrostatic nozzle: Role of electrode material and its dimensional considerations in spray charging

The development of reliable means of charging for finely divided particulate matter is among the major portion of the research activities in electrostatic spraying. This paper presents the role of electrode material and engineering aspects in spray charging with emphasis on theoretical considerations of selection of electrode material and its dimensional shape and size. It reveals the charge-to-mass ratio dependency on variables such as electrode material, shape and geometrical specifications, which is in good agreement with the theoretical considerations. For the particular designed electrostatic nozzle, it is found that optimum electrode position is in the range of 2.0-3.0 mm from the nozzle tip. The copper electroplated with nickel as a charging electrode material can be plausible alternative for spray charging as excellent charge-to-mass ratio 2.8 mC/kg is attained for improved efficacy and efficiency of the electrostatic spraying processes. Possible limitations requiring further research includes the design for maximum charge injection rate, which is thought to be limited by corona breakdown, again a trade-off in air media between charging electrode and liquid sheet.