Microbubble emission boiling on a horizontal upward-facing rectangular surface in subcooled flow.

Abstract

It is known that there exists a boiling condition of subcooled liquid at which many microbubbles are emitted from a heated surface in the transition boiling regime. We call this phenomenon "microbubble emission boiling" (MEB). MEB occurs easily in systems where the subcooled liquid removes the bubbles naturally, and not against their own motion from the surface soon after their generation. Consequently the subcooling and the velocity of the liquid should be very important factors concerning the occurrence of MEB. In this study, our purpose was to clarify the effects of the degree of liquid subcooling and its approaching velocity to the surface on the occurrence of MEB and the intensity of microbubble emission by measuring temperature fluctuations of the surface and pressure fluctuations in the liquid above the surface.