Controlling Condensation and Boosting Heat Transfer via Droplet Jumping - An Electrostatic Spraying Strategy

To address the technical challenge of frequent condensation on radiant cooling panels (RCPs) in high-humidity environments, this study innovatively employed an electrostatic spraying technique (ES-SHP) to fabricate a superhydrophobic coating with a multi-scale micro/nano-rough structure on aluminum substrates. The droplet jumping behavior and anti-condensation performance of the ES-SHP surface were systematically investigated and compared against those of a conventional superhydrophobic surface (Conv-SHP) and a bare aluminum plate (Bare-Al) under simulated practical RCP operating conditions, considering both horizontal-downward and vertical surface orientations. Results demonstrate that the ES-SHP surface most effectively sustains the Cassie state of droplets, harnessing​ the surface energy released during coalescence to induce vigorous jumping. This mechanism achieves self-cleaning and delivers excellent anti-condensation performance. Furthermore, a threshold effect of airflow velocity (0-3 m/s) on the anti-condensation performance was revealed. Additionally, it was found that the condensation rate in the horizontal-downward orientation was slightly higher than that in the vertical orientation, which is attributable to differences in mass transfer gradients. This work establishes the electrostatic spraying strategy as a viable pathway for developing durable and reliable condensation control solutions for radiant cooling systems.