Dropwise condensation on hydrophilic surfaces

Droplet nucleation and condensation are ubiquitous phenomena in nature and industry. Over the past century, research has shown dropwise condensation heat transfer on non-wetting surfaces to be an order of magnitude higher than filmwise condensation heat transfer on wetting substrates. However, the necessity for non-wetting to achieve dropwise condensation is unclear. Here we report stable dropwise condensation on a smooth, solid, hydrophilic surface (a = 38°) having low contact angle hysteresis (< 3°). We show that the distribution of droplet sizes for coalescing droplets agrees well with the classical distribution on hydrophobic surfaces. Our findings demonstrate that achieving stable dropwise condensation is not governed by surface intrinsic wettability, as assumed for the past eight decades, but rather it is dictated by contact angle hysteresis