Mass transfer characteristics of bubbly flow in microchannels

•The mass transfer characteristics of bubbly flow were first studied.•The mass transfer coefficients were determined by an online measurement method.•The mass transfer coefficients of bubble forming and flowing stages were studied.•The effect factors on mass transfer coefficient were discussed.•The empirical correlations were established to predict mass transfer coefficients.

The mass transfer characteristics of bubbly flows in co-flowing and T-junction microchannels are described in this study. A CO2N2 gas mixture and a monoethanolamine–ethylene glycol solution were used as the gas and liquid phases, respectively, to generate gas/liquid bubbly microflows. The bubble dimensions changed obviously during the bubble-forming and bubble-flowing stages. The overall mass transfer coefficients (KL) at these stages were determined by developing an online measurement method through which time-dependent changes in bubble volume were analyzed. Investigation of the effects of phase flow rate and concentration of the two phases on KL showed that KL was in the range of 1×10−4–4.9×10−3 m/s. In addition, empirical correlations were established to predict KL for different mass transfer stages.