Designing air-independent slippery rough surfaces for condensation

摘要

Enhancing condensation heat transfer is significant for power generation, heat exchangers, water harvesting, and air-conditioning. While superhydrophobic surfaces (SHS) are widely studied for condensation, this type of surface suffers from several weaknesses: (1) the hydrophobic surface chemistry does not favor nucleation, (2) the air lubricant has poor thermal conductivity, and (3) the air pocket may be displaced at an elevated humidity or subcooling. Patterned SHS can enhance vapor nucleation in the hydrophilic domains, but the superhydrophobic domains still rely on the air lubricant, resulting in the same weakness as SHS. Recently, the liquid infused surfaces have been developed by replacing the air lubricant with liquid lubricant, leading to more robust lubrication for liquid repellency. However, the original design of liquid infused surfaces shows a flat lubricant-water interface, which cannot provide a large contact area for heat transfer. Here, we successfully designed and manufactured the air independent slippery rough surfaces (SRS) by conformal liquid lubrication on the rough solid surfaces. The surface chemistry of the SRS is governed by the liquid lubricant, not the solid textures, and the roughness is determined by the lubricated microtextures. Droplets are highly mobile on this air-independent slippery rough surface in the absence of air lubricant. Our comprehensive models provide rational design and optimization for the air-independent slippery rough surface that is highly desired in condensation heat transfer. (C) 2019 Elsevier Ltd. All rights reserved.