The Minimum Leidenfrost Temperature on Smooth Surfaces

TL;DR

This paper investigates the minimum temperature at which stable Leidenfrost vapor layers can exist on smooth surfaces, revealing a nearly material-independent threshold around 140°C linked to hydrodynamic stability.

Contribution

It introduces a high-speed electrical measurement technique to determine vapor layer thickness and identifies a universal minimum temperature for vapor layer stability.

Findings

Minimum Leidenfrost temperature is approximately 140°C.

Vapor layer thickness at stability threshold is 10-20 μm.

Threshold is nearly independent of material and fluid properties.

Abstract

During the Leidenfrost effect, a thin insulating vapor layer separates an evaporating liquid from a hot solid. Here we demonstrate that Leidenfrost vapor layers can be sustained at much lower temperatures than those required for formation. Using a high-speed electrical technique to measure the thickness of water vapor layers over smooth, metallic surfaces, we find that the explosive failure point is nearly independent of material and fluid properties, suggesting a purely hydrodynamic mechanism determines this threshold. For water vapor layers of several millimeters in size, the minimum temperature for stability is $\approx 140^{\circ}$C, corresponding to an average vapor layer thickness of 10-20$\mu$m.