Ultrathin Hexagonal\nBoron Nitride Coatings for Enhanced\nCondensation Heat Transfer

Dropwise condensation on hydrophobic surfaces, compared\nto filmwise\ncondensation on hydrophilic surfaces, is considered to be an effective\nmeans to enhance heat transfer. However, the development of technologies\nfor promoting dropwise condensation using hydrophobic coatings has\nremained challenging due to the potential trade-off between enhanced\nhydrophobicity and increased thermal resistance associated with thicker\ncoatings. In this study, we reported the realization of enhanced condensation\nheat transfer with ultrathin chemical vapor deposition of hexagonal\nboron nitride coatings, while maintaining robust dropwise condensation\nwith over 120 h. Our experimental results demonstrate a 4.6-fold improvement\nin the heat transfer coefficient compared with filmwise condensation\non bare substrates. These findings suggest that hexagonal boron nitride\nholds promise as a surface coating for promoting dropwise condensation\nof water vapor, potentially impacting various fields that rely on\nefficient heat transfer processes.