Spray Mode and Monodisperse Droplet Properties of an Electrospray

Abstract

As a method of fluid atomization via application of a high voltage, electrospraying forms more uniform droplets than other spraying modes. This approach involves various spraying modes depending on the applied voltage. Most previous studies on electrospraying focused on the cone jet mode, which has limited applications since the applied voltage has a narrow range. To overcome this limitation, it is necessary to consider alternative spray modes, which require an in-depth understanding of their characteristics. To compare different spray modes, an investigation was conducted based on experimental parameters and fluid properties. In this study, a total of nine modes were identified, and the droplet characteristics in four modes were compared. The maximum deviation of the Sauter mean diameter (SMD) between the spray modes was approximately 1.7 times, and the SMD standard deviation was up to 2.8 times. In addition, the conditions required to realize Coulomb fission and monodisperse distribution depending on the Rayleigh critical charge (RSD < 6.76) were compared and examined.

Experimental Investigation of Electrospraying Properties Based on Ring Electrode Modification

“…The top surface was flattened using a milling machine. 41 The cover was made of acrylic and had a ring and double cover to minimize changes in the internal environment. The board height was modified by attaching a support jack.…”

“…The ring height was adjusted by placing a support within the cover. 41 A variable high-voltage power supply (Korea Switching, B150; 30 kV, 15 mA) was used as the voltage supply of the nozzle and the ring. The cathode was connected to the nozzle and ring, whereas the anode was connected to the substrate.…”

“…The experiments were performed at an ambient temperature of 25 °C and a relative humidity of 40 ± 10%. 41 indicating a stable spraying mode. Several cones were generated when the applied voltage increased to 5.45 kV or higher.…”

“…The substrate was produced in a cylindrical shape using aluminum (D, 45 mm; H, 10 mm). The top surface was flattened using a milling machine . The cover was made of acrylic and had a ring and double cover to minimize changes in the internal environment.…”

“…Ali reported that the applied voltage required for cone-jet generation increases with the flow rate, contradicting the results of Liao, who concluded that the cone jet is independent of the flow rate. According to Kim, the cone-jet mode might be delayed depending on the distance between the nozzle and the substrate. Tang and Kebarle confirmed that the applied voltage in the cone-jet mode is delayed based on the nozzle diameter.…”