On homogeneity of vapor bubbles' oscillation and corresponding heat transfer characteristics and boiling sound in microbubble emission boiling (MEB)

We investigate so-called "microbubble emission boiling (MEB)" on a horizontal circular heat transfer surface in a pool via experimental approach. We indicate the correlation among the temporal and spatial behaviors of the vapor bubbles, the averaged heat transfer characteristics, and the accompanying boiling sound. We show that the vapor bubbles oscillate in a non-uniform manner in the radial direction immediately after the MEB transition. As the MEB develops by increasing the power input to the heaters, the vapor bubbles exhibit synchronous oscillation on the heat transfer surface as if they oscillate homogeneously. The homogeneity of the vapor bubble oscillation in the radial direction is quantified by the cross-correlation between the local oscillations. We illustrate significant variations of the heat transfer characteristics and the boiling sound driven by the homogeneous vapor bubble oscillation after the transition to the fully developed MEB. (c) 2022 Elsevier Ltd. All rights reserved.