Behavior of a bubble growing on a hydrophobic spot under sub-atmospheric pressures

Abstract

In the present study, to investigate the mechanism of transition to intermittent boiling, we have conducted a visualization study of pool boiling on biphilic surfaces at subatmospheric pressures. Experiments were conducted on copper surfaces with a single hydrophobic spot at their centers. The hydrophobic spots were made by PTFE spray coating, and their contact angles were 120–130°. Bubble behavior on the spot was captured using a high speed camera (with 1000 fps). Compared to that at atmospheric pressure, considerably different bubble behaviors were observed under sub-atmospheric conditions. It was suggested that dynamics of the three-phase contact line of bubble was closely related with the transition to intermittent boiling.