Water-Repellent Slippery Surfaces for HVAC&R Systems

Minimizing water retention on the air side of aluminum surfaces is important in the design and operation of efficient heat exchangers for heating, ventilation, air-conditioning and refrigeration (HVAC&R) systems. Accumulation of water degrades the performance of heat exchangers by lowering the heat transfer rate and increasing the pressure drop. As a result, power consumption in such systems increases. In this work, a method of fabricating liquid-infused slippery surfaces with honeycomb-like superhydrophobic micro-/nano-structure substrate via an anodization process is developed. The slippery surface exhibits superhydrophobicity with a contact angle of 155° and a sliding angle smaller than 5°. The delay of ice formation is observed during condensation/frosting experiment. Frost-melt retention experiments show that the liquid-infused slippery surface reduces the water retention by 90% compared to an untreated specimen. The longevity of the slippery surface is also explored. The water retention ratio does not show a significant change after 60 frosting/defrosting cycles, and is still only one third that of the baseline. The slippery surface has potential in HVAC&R applications.