An automated imaging and control system for the continuous determination of size and relative mass of single compositionally dynamic droplets

A novel droplet imaging system (DIS) has been developed which, when interfaced with an electrodynamic balance (EDB), offers unique capabilities for characterizing size, mass, density, and composition of single, compositionally dynamic droplets. The DIS employs a standard closed‐circuit video camera as a droplet sensor. Real‐time hardware image processing techniques are employed to extract cross‐sectional area and position information from the video signals. The position information is used to generate a control signal which is proportional to the droplet mass. The DIS capabilities are demonstrated for evaporating water and coal‐water slurry droplets. The results presented clearly demonstrate that this system can be applied to easily detect compositional variations from one droplet to another. Accurate estimates of droplet composition can be obtained with little knowledge of the starting composition. The DIS has a wide range of applications and is particularly valuable when applied to the study of multicomponent droplets where the physical and chemical behavior often times depends on the droplet composition.