Effect of interphase mass transfer on the coalescence of two bubbles under constant approach velocity

Abstract

The equations for the drainage of a full mobile liquid film between two bubbles under a constant approach velocity are extended to investigate the effect of interphase mass transfer on bubble coalescence. The diffusion boundary layer thickness in the bubble is considered to be on the same order of bubble radius because of the high diffusion rate of the gas phase, and as a result the solute concentration in the bubble is approximated to be constant. The numerical results indicate that the Marangoni effect induced by mass transfer prevents bubble coalescence for positive systems, while it promotes coalescence for negative systems, which is consistent with experimental results for bulk distillation processes. In addition, the effects of Marangoni number, surface Peclet number, and film Peclet number on film drainage rate are reported.