Visualization of droplet departure on a superhydrophobic surface and implications to heat transfer enhancement during dropwise condensation

Droplet departure frequency is investigated using environmental scanning electron microscopy with implications to enhancing the rate of dropwise condensation on superhydrophobic surfaces. Superhydrophobic surfaces, formed by cupric hydroxide nanostructures, allow the condensate to depart from a surface with a tilt angle of 30 degrees from the horizontal. The resulting decrease in drop departure size shifts the drop size distribution to smaller radii, which may enhance the heat transfer rate during dropwise condensation. The heat transfer enhancement is estimated by modifying the Rose and Le Fevre drop distribution function to account for a smaller maximum droplet size on a superhydrophobic surface. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3460275]