Visualisation study on the droplet size variation in water electrospray

The electrospray is one of the most attractive spray techniques to produce very fine and highly charged water droplets conically shaped. It uses highly concentrated free charges from high intensity electrical potential between two oppositely charged electrodes. In this paper, we investigated the flow motion and the water droplet size variation for different operating conditions such as flowrate, velocity, applied voltage, nozzle size, and electrode distance. From visualisation works, we analysed the most influencing parameter to the flow motion and droplet size, aiming at its application in various industries such as coatings, pharmaceuticals, or particle precipitation. In particular, we focused on its application to trap ultrafine particles since the negatively charged droplets can draw the positively charged ultrafine particle and agglomerate them. Experimental results show that the water droplet size increased as the flowrate, speed, nozzle diameter increased and as the applied voltage decreased.