Hydrodynamic and mass transfer behaviors of NH ₃ microbubbles in ionic liquids

Abstract

Ionic liquids enable efficient ammonia‐containing gas separation, but conventional absorption towers suffer from limited interfacial area and mass transfer efficiency. Microchannels overcome this owing to their large specific surface area. This study investigated the hydrodynamic and mass transfer behaviors of ammonia microbubbles in T‐junction microchannels with [Bmim][BF ₄ ]. Experimental results revealed that ammonia bubble generation proceeded by a squeezing‐dominated mechanism. The intense vorticity field in the bubble growth stage drove rapid bubble expansion and played a key role in overall mass transfer. The volumetric mass transfer coefficient initially increased and then declined with increasing Q _g , which was determined by the competition between bubble‐induced flow disturbance and channel obstruction. A constricted gas‐inlet structure was proposed to enhance the mass transfer performance, and a predictive model was subsequently developed with prediction errors within ±15%. These findings provide fundamental support for the design and optimization of microchannel reactors for ionic liquid‐based gas separation.