Coarsening‐induced disappearing droplets contribute to condensation

Abstract

Condensation heat transfer is widely used in water and energy systems. Despite being extensively studied, since 1973, the models for dropwise condensation have strongly relied on the droplet size distribution. In this study, we report that the classical models underestimate the heat transfer performance of dropwise condensation on a hydrophilic liquid-infused surface, on which the meniscusmediated coarsening droplets lead to a previously unachieved droplet coverage ratio down to 30%. We found that the time-averaged classical models have overlooked the coarsening-induced disappearing droplets. Moreover, these models cannot be used to determine the instantaneous heat transfer coefficient on the sheddinginduced water-free surface under steam condensation. Thus, a dynamic model is developed for dropwise condensation by considering the disappearing droplets induced by both coarsening and shedding, which shows good agreement with the experimental validation. Such a dynamic model provides a theoretical foundation to design surfaces for condensation, giving rise to an advanced design guideline for water and energy systems.

Recent advances of slippery liquid-infused porous surfaces with anti-corrosion

“…126,127 In addition to hydrophobic lubricants, a hydrophilic lubricant stands out as an effective choice of lubricant for SLIPS that are designed for water condensation and droplet removal. 128,129 Qi et al 130 prepared hydrophilic patterned SLIPS for efficient droplet transport and fog harvesting using hydroxy-terminated polydimethylsiloxane. The surface lubricant layer of SLIPS is the first barrier against corrosive media.…”

Fluid manipulationviamultifunctional lubricant infused slippery surfaces: principle, design and applications

“…111 In 2022, Guo et al developed a novel model of droplet condensation kinetics on hydrophilic SLIPS, which takes into account the droplet disappearance phenomenon caused by coarsening and provides a theoretical basis for designing condensing surfaces. 112…”

The case of the coarsening‐induced disappearing droplets

“…More recently, researchers have discovered that dropwise condensation can be promoted on hydrophilic liquid 6 or solid 7 surfaces. In this issue of Droplet , Xianming Dai and his co‐workers report a novel approach to address the challenges facing these classical models when applied to liquid‐infused hydrophilic surfaces 8 . Specifically, the authors note that the effect of coarsening‐induced disappearance of droplets cannot be captured using past modeling approaches.…”