Bubble Formation from a Submerged Microcapillary Nozzle in Novec 649

Bubble formation in liquids is ubiquitous in nature and in various industrial processes, playing a crucial role in water electrolysis, chemical reaction, and boiling. This study investigates bubble formation from submerged microcapillary nozzles in Novec 649, an advanced dielectric fluid with a low global warming potential and toxicity. The behaviors and detachment parameters of the bubbles are analyzed under various gas flow rates and nozzle diameters. We create a bubbling regime map for bubble formation in Novec 649 and develop a scaling law to predict the transition from bubbling without coalescence to bubbling with coalescence by using Weber and Bond numbers. Force analysis reveals that in Novec 649, drag and liquid inertia forces are more significant in bubble detachment compared to bubble formation in water, attributed to its higher density and lower surface tension. Additionally, we develop a new force balance model and a new explicit approximate model to predict the bubble detachment diameter in Novec 649, considering the impact of the waiting time and liquid velocity around the bubble. These models outperform previous models for the experimental data of Novec 649. This study contributes to enhancing our understanding of the dynamics of bubble formation in novel liquids.