Wettability, water shedding, slippery surface
Enhancing water shedding behavior on aluminum surfaces is important in the design of energy-efficient heat exchangers. In this work, a method for fabricating oil-infused aluminum for HVAC&R systems is described for the purpose of exploiting the slippery nature of such surfaces, thereby improving the overall surface wettability. The goal of this work is to determine the feasibility of using these surfaces to more effectively manage condensate/frost formation on the heat exchanger. A microstructured, porous aluminum fin stocks with heterogeneous polyfluoroalkyl silane coating are infused with a secondary liquid acting as a lubricant that enhances slippery, liquid repellant and self-healing behavior. The effects of the underlying oil-infused microstructure and hydrophobic coating on the behavior of droplets are studied. Although the slippery surfaces are observed to decrease the contact angle of droplets, they promote mobility of droplets by reducing the oil-water interfacial energy and friction force. From preliminary experiments, critical inclination angles of small droplets (volume ?30 µl) are reduced by more than 40° compared to baseline surfaces. Moreover, slippery surfaces delay the frost formation, and have only one fifth of the baseline water retention after self-defrosting. Therefore, such properties provide potential for improving the water drainage behavior for HVAC&R systems.