Pressure Fluctuation Associated with Bubble Motion in Microbubble Emission Boiling from a Vertical Surface.

High heat flux far exceeding CHF in microbubble emission boiling (MEB) should be considered a result of violent growing and collapsing behavior of coalescent bubbles in that regime, which introduces subcooled liquid to the surface to make steady solid-liquid contact even in the high surface temperature region. This bubble behavior generates a moment of high pressure in the vicinity of the surface. In this study, a measurement of the pressure fluctuation in the liquid near the surface was performed synchronously with a recording of the bubble motion by a high speed video camera. The experimental results reveal that the peak value of the pressure fluctuation corresponds to the bubble collapse. The image processing method was also applied to the video pictures to analyze the bubble motion and some information was obtained.