Acoustically Enhanced Evaporation of a Polydisperse Stream of Micro Water Droplets

Abstract This work investigates the effect of focused acoustic field on a stream of polydisperse micro water droplets generated by a nebulizer. The acoustic field is induced by a customized axially stepped-thickness piezoelectric circular cylindrical transducer. Exposure of the droplets to the acoustic field while passing through the transducer improves the relative movement between the air and droplets, which results in an enhanced heat transfer and facilitates evaporation. Larger droplets in the stream are affected more than small ones by the acoustic field. A noticeable reduction in the size of 90% of droplets has been observed. This improves and narrows the droplet size distribution in the stream, which is of practical importance for some drug delivery applications or humidification in lung supportive devices.