Condensation and collapse of bubbles in region of microbubble emission boiling

To illustrate the bubble dynamics in microbubble emission boiling (MEB), a high-speed video camera (Fastcam SA5) was employed to observe the boiling phenomena on a heating surface with a diameter of 10 mm at the liquid subcooling of 15-60 K. An equivalent radius was induced to analyze the bubble behavior in different boiling regions. It is showed that the bubble behavior of MEB differs from that of nucleate boiling and film boiling obviously. In the regime of MEB, a large irregular bubble commonly forms on the heating surface and collapses immediately, but not departures from the heating surface. The period of bubble ebullition is shorter, with a faster change rate in volume. A dimensionless analysis shows that the inertia control increasingly dominates the process of bubble collapse with the increase of wall superheat and heat flux. © All Rights Reserved.