Measurement of spray droplet evaporation rate constant by laser diffraction

A technique for measuring the droplet evaporation rate constant for a spray is shown, and a novel laser diffraction technique is applied to the investigation of spray vaporizations. Local spatial size and distribution were measured in volume elements within a quasi two dimensional spray injected from the fan spray nozzle. The diffracted total light energy and its relative diffracted light energy were defined and, in order to determine the evaporation rate constant, the detected relative light energy was compared with the total light energy diffracted by the vaporizing spray in the hot gas stream. For ethanol cloud sprays, the evaporation rate constants were 0.04-0.1 sq mm/s (373 K-573 K). It is shown that this method is suitable for estimating the evaporating rate constant of liquid spray clouds.