Three-phase Leidenfrost effect

To date, the Leidenfrost effect has been a two-phase phenomenon: either an evaporating liquid or a sublimating solid levitates on its vapor. Here, we demonstrate that an ice disk placed on a sufficiently hot surface exhibits a three-phase Leidenfrost effect, where both liquid and vapor films emanate from under the levitating ice. Curiously, the critical Leidenfrost temperature was about 400 ${}^{\circ }\mathrm{C}$ hotter for ice than for a water drop. As a result, the effective heat flux was an order of magnitude larger when quenching aluminum with ice rather than water over a wide temperature range of 150–550 ${}^{\circ }\mathrm{C}$. An analytical model reveals the mechanism for the delayed film boiling: the majority of the surface's heat is conducted across the levitating meltwater film due to its 100 ${}^{\circ }\mathrm{C}$ temperature differential, leaving little heat for evaporation.

Figure 1

(a) Schematic of the experimental setup. (b) Diagram of the three-phase Leidenfrost effect, where $H_{\text{i}}$, $H_{\text{l}}$, and $H_{\text{v}}$ are the thicknesses of the ice disk, meltwater layer, and vapor layer, respectively. The solid-liquid interface is fixed at the melting temperature, $T_{\text{m}}=0{}^{\circ }\mathrm{C}$, while the liquid-vapor interface is at the boiling point, $T_{\text{b}}=100{}^{\circ }\mathrm{C}$. Radial semi-plug Couette flows are generated in the liquid layer (pressure gradient $\mathrm{\Delta }{P}_{\text{l}}/R$, velocity $u_{\text{l}}$) and vapor layer ($\mathrm{\Delta }{P}_{\text{v}}/R$, velocity $u_{\text{v}}$). A subset of the heat conducted across the vapor layer (${\dot{Q}}_{\text{v}}$) is transferred into the liquid layer (${\dot{Q}}_{\text{l}}$) to melt the ice (${\dot{m}}_{\text{melt}}{L}_{\text{f}}$), while the remainder evaporates the meltwater (${\dot{m}}_{\text{v}}{L}_{\text{v}}$).

Figure 2

Side-view imaging of an ice disk of initial radius $R=25\mathrm{mm}$, height $H_{\text{i}}=12\mathrm{mm}$, and volume $V=23.56{\mathrm{cm}}^3$ being placed on an aluminum stage heated to different temperatures. Four different regimes of heat transfer occurred depending on the temperature: (a) Suppressed boiling, (b) nucleate boiling, (c) transition boiling, and (d) three-phase Leidenfrost effect. See Figs. S2–S4 for equivalent imaging of the other three sizes of ice disks and Videos S1–S4 in Ref. [35] to see the dynamic melting of all of the ice disks.

Figure 3

(a) Melting lifetime of ice disks (${\tau }_{\text{i}}$) on an aluminum substrate, which the inset compares to the previously reported evaporation lifetimes of water droplets (${\tau }_{\text{l}}$) on an aluminum substrate (Biance et al. 2003 [1]). (b) Effective heat flux supplied into the ice disks ($q_{\text{i}}^{″}$) or water droplets ($q_{\text{l}}^{″}$), as calculated from Eq. (1). See Fig. S5 in Ref. [35] for additional comparisons of ${\tau }_{\text{i}}$ and $q_{\text{i}}^{″}$ to those for water on a variety of surfaces [23, 25, 26, 30, 31].

Figure 4

(a) Theoretical estimation of the heat fluxes conducted across the vapor layer [Eq. (5)] and meltwater layer [Eq. (2)], for ice disks exhibiting the three-phase Leidenfrost effect at $T_{\text{s}}=550{}^{\circ }\mathrm{C}$. The theoretical $q_{\text{l}}^{″}$ is compared against the experimental approximation, obtained by plugging the measured ${\tau }_{\text{i}}$ into Eq. (1). (b) Comparison of the theoretical and experimental values of ${\tau }_{\text{i}}$, again for the case of the three-phase Leidenfrost effect at $T_{\text{s}}=550{}^{\circ }\mathrm{C}$. The theoretical ${\tau }_{\text{i}}$ is obtained by plugging the prediction for $q_{\text{l}}^{″}$ into Eq. (1).