The study of a single droplet impact and spread on a heated surface is motivated by its strong
relevance to spray cooling technology. The generic view on the study of the spray cooling process
exhibits the synthesis of fluid mechanics, heat transfer and surface thermodynamics. Due to the
complex phenomena involved, no comprehensive theoretical models are available. The few works that
appeared in the literature so far have been largely empirical; the applicability of several correlations
proposed is limited. This book chapter reports an experimental study of fundamental aspects of the
dynamic characteristics of a single droplet impacting on a heated surface. In this experiment, the entire
dynamic process of a droplet from the moment of collision with the substrate surface including the
rebound was visualized and analyzed using a high-speed CCD camera. The experimental study focused
mainly on the spread of a liquid droplet under the influences of substrate temperature varying from
26°C to 240°C, the inclination angle of substrates at 0°, 30°, and 60°, the wettability of substrates with
contact angles from 30° to 90°, the viscosity of liquids ranging from 0.00089 up to 0.9161 kg/m.s, and
surfactants of different concentrations.
Keywords: Droplet spreading, sessile droplet heat transfer, spray cooling.
