Experimental investigation on evaporation of a single droplet levitated in acoustic field

In this paper, the evaporation of a single droplet (water, ethanol) levitated by ultrasonic was investigated experimentally at various environmental temperatures from 100°C to 400°C. The evaporation history of the droplets was recorded by a high-speed camera. The initial droplet diameter ranges from 0.1 mm to 1.0 mm. We calculated the surface area, volume, aspect ratio, and the equivalent-diameter of a single droplet during evaporation. The evaporation constant of each droplet was estimated, and the effects of ambient temperature, initial droplet diameter, and liquid droplet physicochemical properties on evaporation characteristics were discussed. It is found that when the ambient temperature is below the critical temperature, the higher the ambient temperature results in a higher evaporation rate; the droplet evaporation conforms to the D2 law. Under the same conditions, the lower latent heat of the droplet leads to a higher evaporation rate.