Atomization and Sprays

CONE-JET AND MULTIJET ELECTROSPRAYS: TRANSPORT AND EVAPORATION

RESUMO

A numerical model for droplet transport and evaporation of electrosprays in a capillary-plate configuration is compared to droplet size and velocity measurements. Two distinct electrospray modes are investigated: the cone-jet mode with a narrow droplet size distribution and a spraying angle smaller than 45 deg, and the intermittent multijet with a broad size distribution and a spraying angle of approximately 180 deg at the capillary exit. LiCl/isopropanol solutions are deposited on a heated plate. The temperature of the plate is adjusted between 20 and 215°C. The spray droplet transport and evaporation is examined with a phase doppler anemometer (PDA), which is able to track the velocity and size of droplets in the spray. The measurements are compared to the model predictions. For the first time, combined droplet transport and evaporation in the intermittent multijet electrosprays is calculated. Cone-jet and intermittent multijet calculations are in quantitative agreement with the measurements. The applicability of the different spraying modes to thin-film deposition and particle production is discussed with reference to electrospray transport and evaporation behavior.