Efficient condensation on spiked surfaces with superhydrophobic and superhydrophilic coatings

TL;DR

This paper presents a novel surface design combining superhydrophilic and superhydrophobic coatings on spiked structures to enhance steam condensation efficiency and liquid removal, independent of gravity, with implications for heat transfer devices.

Contribution

It introduces a new surface modification strategy using micro-scale spikes and dual coatings to optimize condensation and liquid removal, advancing phase-change heat transfer technology.

Findings

Hydrophobic spikes promote dropwise condensation.

Hydrophilic grooves facilitate liquid spreading.

Capillary suction effectively removes condensate.

Abstract

Steam condensation on the surface of a solid is a widely observed mode of energy transfer in nature and various industrial applications. The condensation efficiency is closely related to the material properties and geometric morphology of the solid surface, as well as the method of liquid removal. Despite many surface modification strategies at the micro and nano levels having been employed to enhance steam condensation, understanding how to regulate steam condensation and liquid removal on complex surface morphologies remains incomplete. Here, we report a method that uses superhydrophilic and superhydrophobic coatings as well as spiked surfaces to achieve efficient steam condensation and rapid removal of the liquid. We reveal that on a copper plate with millimeter-scale spikes, hydrophobic spiked surfaces facilitate the dropwise condensation, while hydrophilic bottom grooves promote liquid spreading, and the suction in capillary gaps can promptly remove the condensate liquid. This method achieves a high condensation efficiency without relying on gravity. Additionally, we demonstrate that the condensation on spiked surfaces has a significant suction effect, as it continuously attracts the steam flow, thereby altering the flow direction. This finding provides a new approach for efficient steam condensation technology and opens up a promising pathway for providing circulation power and improving condensation efficiency in phase-change heat transfer devices such as heat pipes.