Experimental Study on Bubble Dynamics and Mass Transfer Characteristics of Coaxial Bubbles in Petroleum-Based Liquids

[Image: see text] Petroleum-based liquids are from an important petroleum-based polymer, whose application and preparation involve multiple operations related to gas–liquid two-phase flow. Due to insufficient research on gas–liquid two-phase flow, there is a gap in bubble dynamics and mass transfer characteristics in petroleum-based liquids. Accordingly, we have systematically investigated the bubble formation process, bubble rising dynamics, and mass transfer of coaxial bubbles. Herein, the contour of bubbles was obtained for analyzing the bubble formation process. It was found that the increase of gas flow rate contributed to the increase of bubble generation size, while the liquid viscosity had an inhibitory influence on the increase of bubble generation size. Moreover, the variation of bubble rising velocity was considered and the force analysis of the rising bubble was provided. A new model of drag coefficient applicable to petroleum-based liquids was proposed. Finally, variations in the amount of dissolved oxygen in the liquid were measured to analyze the mass transfer characteristics. The increase in nozzle inner diameter and gas flow rate both promoted mass transfer, but the increased liquid viscosity hindered mass transfer.