CityU researchers solve 266-year old challenge of thermal engineering

25 February 2022

A research team led by scientists from City University of Hong Kong has designed a new material that achieves efficient liquid cooling at extremely high temperatures, 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 team was led by Professor Wang Zuankai from the Department of Mechanical Engineering of the City University of Hong Kong, Professor David Quéré from the PSL Research University, France, and Professor Yu Jihong, Director of the International Center of Future Science, Jilin University and Senior Fellow of the Hong Kong Institute for Advanced Study at the City University of Hong Kong. Their findings were published in Nature.

The Leidenfrost effect, discovered in 1756, refers to the levitation of drops on a surface that is significantly hotter than the liquid's boiling point. It produces an insulating vapour layer and dramatically reduces heat transfer performances at high temperature, which makes liquid cooling on the hot surface ineffective.

Researchers constructed a multitextured material with key elements that have contrasting thermal and geometrical properties. The rational design for the material superimposes robust, conductive, protruding pillars that serve as thermal bridges for promoting heat transfer; an embedded thermally insulating membrane designed to suck and evaporate the liquid; and underground U-shaped channels that evacuate the vapour.

It successfully inhibits the occurrence of the Leidenfrost effect up to 1,150 °C and achieves efficient and controllable cooling across the temperature range from 100°C to over 1,150°C.

“This multidisciplinary research project is truly a breakthrough in science and engineering, since it mixes surface science, hydro- and aero-dynamics, thermal cooling, material science, physics, energy and engineering,” said Wang. “Searching for novel strategies to address the liquid cooling of high-temperature surfaces has been one of the holy grails in thermal engineering since 1756.”