Superhydrophobic cooling coils with uniformly generated micro/nanostructures for enhanced condensate droplet repellency

Abstract

Despite advances in superhydrophobic cooling coil technology, challenges such as delayed condensate drainage and flooding still frequently occur in air-conditioning systems. Herein, we developed superhydrophobic cooling coils featuring uniformly generated micro/nanostructures. Our method enables scalable treatment of 6061 aluminum cooling coils measuring 25 × 24 × 9 cm or larger, including those with irregular geometries. To our knowledge, this work reports the first systematic study to generate micro/nanostructures uniformly on large-scale superhydrophobic cooling coils that are free of unetched regions. These uniform micro/nanostructures prevent the formation of nanoscale Wenzel wetting states and leverage fin pitch to limit the maximum condensate droplet diameter before self-repellency to 1 mm, thereby minimizing flooding risk. We demonstrate that such coils can maintain continuous and complete condensate droplet repellency for 6 h during atmospheric condensation of humid air. This approach holds strong potential for scalable integration into air-conditioning systems to enhance dehumidification and overall thermohydraulic performance.