Determining effects of induction electrode geometry on charging efficiency of droplets in pesticide electrostatic spraying applications

Electrode properties in the induction charging method, usually used in electrostatic pesticide spraying, can have a significant impact on the charging efficiency. The study aimed to investigate the effect of several specifications of the ring-shaped electrode such as diameter, length, cross-section shape, material, and the number of used electrodes, on the charging efficiency of spray droplets. Also, the effect of insulating the electrode electrically on removing the electric leakage resulting from electrode wetting and increasing the charging efficiency was studied. Results showed that neither the electrode material nor its cross-section shape affects the charging efficiency. Reducing the diameter and increasing the length of the ring-shaped induction electrode improves the charging operation by inducing more electric charges on the liquid jet. However, they cause electrode wetting and later electrical leakage at low values of the electrode voltages. Using more than one electrode to charge the spray droplets can increase charging efficiency. Generally, the insulated electrode with an insulator layer reduces the charging efficiency of spray droplets by about 24∼38% at 1∼6 kV electrode voltage compared with the exposed electrode. Nevertheless, it increases the charging efficiency (by 28% at 16 kV) by allowing the use of high values of the high voltage applied to the induction electrode without facing the electrical leakage between the electrode surface and grounded liquid that causes the earthing of the high voltage electrode and stopping of the charging operation.