Tailoring wettability to push the limits of condensation

Abstract

Wetting plays a crucial role in achieving efficient condensation in applications such as atmospheric water harvesting, air conditioning and refrigeration, and thermal power plants. Despite decades of research, the industrial implementation of dropwise condensation, which is often superior to filmwise condensation, has been limited, mostly due to the poor durability of promoter coatings and the challenge of achieving dropwise condensation for non-aqueous working fluids. Both areas have seen noteworthy advancements over the past few years, some of which we highlight in this review article. For example, recognizing that contact angle hysteresis, not contact angles per se, are responsible for enabling dropwise condensation, ultra-smooth liquid-like polymer coatings and lubricant-infused surfaces were developed for use with water and non-aqueous working fluids. There are also several new developments for passive and active droplet removal. Advances in coating durability include a better understanding in the failure mechanisms and physics-informed designs of new coating processes and chemistries.