Calm Before The Storm

When a liquid drop comes close to a hot surface with a temperature above the liquids' boiling point, we expect to observe a behavior that resembles the liquid boiling. However, if the surface temperature is significantly higher than the boiling point, the evaporation rate of the liquid drop becomes high enough that it creates a vapor cushion below the droplet preventing any contact between the liquid and the substrate. This phenomenon, known as Leidenfrost effect, represents a very low rate of heat transfer from the hot surface. During my research at UIC, I’ve studied the behavior of individual droplets after contacting superheated microstructured surfaces. With the goal of understanding and recognizing the dominant heat transfer mechanisms during the droplet impact, I’ve fabricated microstructures to systematically study the boiling transitions inside an impacting liquid droplet. This video is explaining a very interesting incident at which the droplet shows an explosion behavior after it contacts a substrate with a dense pattern of fabricated microstructures. During this explosion, even though the droplet shows a similar behavior to when it boils, boiling is suppressed, and the explosion is not a sign of efficient heat transfer. Recognizing this behavior is vital to avoid any possible calamities in power plants and industries in which cooling hot surfaces is critical.