Inhibiting the Leidenfrost effect above 1,000 °C for sustained thermal cooling

A research team led by scientists from City University of Hong Kong (CityU) has recently designed a structured thermal armor (STA) that achieves efficient liquid cooling even over 1,000°C, fundamentally solving a 266-year-old challenge presented by the Leidenfrost effect. This breakthrough can be applied in aero and space engines, as well as improve the safety and reliability of next-generation nuclear reactors.

The research has been led by Professor Yu Jihong, Senior Fellow of the Hong Kong Institute for Advanced Study at CityU, the Director of the International Center of Future Science, Jilin University and Professor Wang Zuankai from CityU's Department of Mechanical Engineering (MNE), Professor David Quéré from the PSL Research University, France.

Abstract

The Leidenfrost effect, namely the levitation of drops on hot solids¹, is known to deteriorate heat transfer at high temperature². The Leidenfrost point can be elevated by texturing materials to favour the solid–liquid contact^{2,3,4,5,6,7,8,9,10} and by arranging channels at the surface to decouple the wetting phenomena from the vapour dynamics³. However, maximizing both the Leidenfrost point and thermal cooling across a wide range of temperatures can be mutually exclusive^3,7,8. Here we report a rational design of structured thermal armours that inhibit the Leidenfrost effect up to 1,150 °C, that is, 600 °C more than previously attained, yet preserving heat transfer. Our design consists of steel pillars serving as thermal bridges, an embedded insulating membrane that wicks and spreads the liquid and U-shaped channels for vapour evacuation. The coexistence of materials with contrasting thermal and geometrical properties cooperatively transforms normally uniform temperatures into non-uniform ones, generates lateral wicking at all temperatures and enhances thermal cooling. Structured thermal armours are limited only by their melting point, rather than by a failure in the design. The material can be made flexible, and thus attached to substrates otherwise challenging to structure. Our strategy holds the potential to enable the implementation of efficient water cooling at ultra-high solid temperatures, which is, to date, an uncharted property.