Interferometric Measurement of the Liquid-Phase Temperature Field around an Isolated Boiling Bubble

In this study, high-speed digital interferometry was used to measure heat transfer from the liquid phase to an isolated boiling bubble on a MEMS boiling sensor. The interferometric measurement results indicated variations in the macroscopic thermal field around the isolated boiling bubble, such as development of a superheated liquid layer on the heating wall, swelling of the superheated liquid layer in the bubble growth process, hot wake accompanied by a rising bubble, and thermal boundary layer around the bubble indicating condensation in subcooled boiling. However, the interferometry could not detect the positive temperature gradient driving the evaporation near the liquid-vapor interface during the bubble growth process, because the spatial resolution of about thirty microns was insufficient. The thickness of the boundary layer driving the evaporation was estimated to be a few dozen microns by a two-dimensional heat transfer simulation with the experimental results as calculation conditions. Finally, an improvement plan of the high-speed interferometer based on the result of the heat transfer analysis was presented.