Vapor-phase engineering

To maintain dropwise condensation, a significant portion of prior research has relied on low surface-energy coatings to achieve hydrophobicity. However, these coatings tend to degrade and show lower thermal performance over time. Instead of modifying the solid-liquid surface energy through surface coatings, we shifted our focus to manipulating the liquid surface energy via vapor-phase engineering. We used amphiphilic surfactants to induce distinct behaviors during different condensation modes. Under dropwise condensation mode, the adsorbed amphiphiles enhanced shedding by promoting repulsion between condensed droplets. Moreover, the amphiphilic surfactants could also dynamically interact with condensed film, and alter the filmwise condensation into the more efficient dropwise condensation mode. Our novel approach shows that vapor-phase engineering can be a promising alternative to surface coatings to enhance condensation heat transfer performance.