A new method for measurement of droplet size distribution in superheated emulsions

Abstract

Superheated emulsion contains micron-sized superheated liquid droplets suspended in a host liquid medium. The superheated droplets nucleate to vapor bubbles when energetic radiation deposits a sufficient amount of energy within a very small localized region of the active liquid. Droplet nucleation is associated with a change in volume and also emission of an acoustic pulse, both of which can be detected electronically. When exposed to energetic radiation, the metastable superheated droplets nucleate independently of each other, and the number of drops nucleated and volume of vapor formed due to nucleation of these droplets are both acquired simultaneously as a function of time. These two data are then fitted simultaneously to obtain the droplet size distribution of the emulsion. The size distributions of R-114 (C2Cl2F4)- and R-12 (CCl2F2)-based emulsions are obtained by this method and compared with direct optical measurements.