Mass Transfer and Diffusion of a Single Bubble Rising in Polymer Solutions

Based on the planar laser-induced fluorescence with inhibition (PLIF-I) experiments, the mass transfer and diffusion phenomena in the wake of single air bubbles (equivalent diameter ∼ 1–1.4 mm) rising in various aqueous polymer solutions (PAAm: 0.1–0.5 wt %; Breox: 2–9.1 wt %) are investigated. For each fluid medium, liquid-side mass transfer coefficient and the diffusion coefficient were determined and analyzed by considering multiple factors: the rheological properties of the fluid, the concentration of the solute, the hydrodynamics of the bubble, and the contamination effect. The results were compared with cases implemented in nonpolymer solutions to clearly identify the characteristics of mass transfer in the polymer media. In addition, a new method is proposed to determine the diffusion coefficient in the bubble wake. The present research proves that PLIF-I is a promising tool for investigating local gas–liquid mass transfer, even in complex liquid media.