Thermo-responsive nanostructured surface: Beeswax for enhanced condensation performance across solid, liquid, and transition states

The present work proposes a breakthrough technology that is focused on biocompatible bio-coating for increased efficiency of condensation in energy systems. By infusing anodized aluminum nanocavities with natural and histological beeswax, a cost-effective, scalable, and efficient solid-infused surface (SIS) is developed. Unlike a passive additive, the beeswax bio-coating modulates the surface behavior actively by adjusting contact angles and reducing contact angle hysteresis to less than 5° at operating conditions. This creates an efficient droplet formation and motion, even under high vapor flow, with a 44% improvement in the heat transfer coefficient (HTC) with respect to bare aluminum at a 16°C subcooling temperature and a 330 kW/m2 peak in heat flux at 24°C. In contrast to most studies focused on enhancing condensation with phase change materials (PCMs), in this work, the dynamic role of the beeswax coating, specifically its state transition—from solid to mushy to liquid—and its impact on droplet dynamics and thermal behavior, is emphasized. It outperforms conventional hydrophobic surfaces, especially under high subcooling conditions where flooding usually reduces efficiency. Durability tests reveal that beeswax-coated samples exhibit sustained enhanced performance even for 10 days of immersing in a wet environment or 100 hours of continuous condensation tests. Overall, the beeswax coating not only represents a breakthrough in enhancing condensation efficiency but also opens new avenues for future developments in desalination, thermal management, and renewable energy technologies.