Figure 1
From: Enhanced condensation heat transfer using porous silica inverse opal coatings on copper tubes
Schematic depictions of different modes of condensation. (a) Filmwise condensation (FWC) where the condensate forms a continuous liquid film on a chemically clean (high surface energy) surface. The wall is maintained at a lower temperature (\(T_{{\text{w}}}\)) than the surrounding saturated vapor (\(T_{{{\text{sat}}}}\)). The temperature and velocity profiles are shown for laminar film condensation where the flow-rate based Reynolds number is < 30. (b) Dropwise condensation (DWC) on hydrophobic (low surface energy) surface. It is essential for dropwise condensation that some promoter material, for example organic compound, be present on the surface. Periodic removal of large droplets clears the surface for renewed droplet nucleation and growth. (c) Inverse opal condensation (IOC) on a porous inverse opal structure. Condensate seeps into the porous structure by displacing the air in the pores. Preferential condensate transport through high hydraulic conductivity micro cracks improves the heat transfer rate. (d) Condensation on a slippery liquid-infused porous surface (SLIPS). The porous interstices are impregnated with a chemically matched oil. Compared to DWC, droplets depart with smaller radius and higher frequency in SLIPS condensation.
