Universality of oscillating boiling in Leidenfrost transition

Abstract

The Leidenfrost transition leads a boiling system to the boiling crisis, a state in which the liquid loses contact with the heated surface due to excessive vapor generation. Here, using experiments of liquid droplets boiling on a heated surface, we report a phenomenon, termed oscillating boiling, at the Leidenfrost transition. We show that oscillating boiling results from the competition between two effects: separation of liquid from the heated surface due to localized boiling and rewetting. We argue theoretically that the Leidenfrost transition can be predicted based on its link with the oscillating boiling phenomenon and verify the prediction experimentally for various liquids.

From Bouncing to Floating: The Leidenfrost Effect with Hydrogel Spheres

“…The existence of this threshold for floating is supported by the fact that, down the lowest velocities we can reliably probe (∼100 μm=s), we observe no floating for a plate temperature of 155°C. These data warrant comparison with the dynamic Leidenfrost transition observed for liquid droplets impacting a heated substrate, where a similar separation between contact and noncontact plays out as a function of impact speed and temperature [4,5,23]. Physically, one suspects that with the extremely low velocities we probe here, the mechanism is dependent upon whether or not sufficient viscous stress can build up in the vapor layer to prevent the sphere from touching-similar to what happens for liquids impacting at low velocities [23].…”

“…2(d)]. Interestingly, similar oscillations have been observed for liquids [5,23], but in those experiments no energy harvesting is observed and instead droplets are quickly destroyed by the vigorous contact boiling.…”

“…These data warrant comparison with the dynamic Leidenfrost transition observed for liquid droplets impacting a heated substrate, where a similar separation between contact and noncontact plays out as a function of impact speed and temperature [4,5,23]. Physically, one suspects that with the extremely low velocities we probe here, the mechanism is dependent upon whether or not sufficient viscous stress can build up in the vapor layer to prevent the sphere from touching-similar to what happens for liquids impacting at low velocities [23]. Important distinctions exist, however, that preclude exact comparison.…”

Experimental Study of Diesel-Fuel Droplet Impact on a Similarly Sized Polished Spherical Heated Solid Particle

“…In general, the larger the Weber number, the higher the wall-surface temperature required to initiate rebounding and consequently TL increases [62], [63]. It is of interest to note that similar behaviour has been observed in [64], although the impact velocity was employed in the phase diagram rather than Weber number. However according to [60], the Leidenfrost temperature shows a weak dependence on the Weber number, yet it can be approximated as a constant value of T*≈2.1 (TW≈165°C).…”

How ambient conditions affect the Leidenfrost temperature

“…The prediction of the Leidenfrost temperature T L is however still an unsolved problem. It is known that T L depends on the type of liquid 21 as well as the roughness 22,23 and thermal conductivity 21,[24][25][26][27] of the plate. We also know that it increases with increasing impact velocity of the drop.…”