This proposal aims to investigate the wetting properties of a novel, highly durable, superhydrophobic and water repellent coating that improves the performance of air dehumidification processes employed in spacecrafts. Air humidity continually increases due to crew members’ breathing out of their own metabolic moisture. High air humidity not only affects thermal comfort, but it also causes bacteria growth and damages on-board electronics. Air dehumidification is important for air humidity control and water recycling. Current dehumidification devices in spacecrafts (such as in Space Shuttle [1] and ISS [2]) are based on condensing heat exchangers (CHXs). However, the prolonged use of CHXs makes the hygroscopic coating applied onto their fins dissolve or peel off. Thus, it is carried away by the airflow into the water/air separator which is clogged [3], as reported several times by ISS crew [4, 5]. As a result, separator needs often maintenance, which is hard due to its complex structure, or replacement, but this requires waiting for the next launch operation, limiting the sustainability and efficiency of these systems. Here, we propose the use of novel fluorine-free and non-hazardous coating based on nanoparticles of either Ca(OH)2 [6] or hydroxyapatite [7] combined with highly adhesive resin [8] and durable polysiloxane matrix. This coating is expected to: i) enhance roughness and superhydrophobicity and ii) induce high mechanical and chemical durability [9]. The new coating is compatible with different materials and is expected to increase the performance of CHXs. Wetting behaviour will be examined by Kerberos, an innovative device capable of subjecting sessile drops at different tilting angles to varying centrifugal forces in order to explore their spreading/sliding behaviour [10, 11, 12]. In order to mature this coating, research is needed to understand the adhesion properties of nanoparticles, and quantify the performance in the context of air dehumidification.
