SURFACE EMBOSSING TECHNIQUE FOR CONDENSATE MANAGEMENT IN AIR- COOLING HEAT EXCHANGERS

Recent advances allow us to inexpensively impart micro-scale grooved surface features on heat exchanger construction material (surface embossing), which we exploit to reduce condensate retention. We report a study of wetting behavior and drainage performance on a series of embossed surfaces with different groove dimensions. Static contact angles, critical sliding angles, droplet aspect ratios, etc. are reported with detailed surface topographical information. Our results show that unless the spacing between grooves is very large (>100µm), the parallel-groove surface feature normally increases the apparent contact angle of a droplet placed onto the surface. A consistent reduction of critical sliding angle was observed on surfaces after embossing, and droplets exhibit an elongation behavior. These may be due to contact line discontinuities and contact-line pinning induced by groove structure on the surface. Smaller channel spacing, larger depth, and steeper sidewalls are observed to be favorable for drainage enhancement. Future work is discussed after a summary of the results