The scaling-up effect on the concentration field and mass transfer of gas–liquid Taylor flow in micro/mini-channel reactors

The concentration fields during the bubble formation stages and the regular flowing stages were measured and discussed in three microchannels. It was shown that mass transfer coefficients during the bubble formation stage were 2–3 times larger than that during the regular flow stage. The influence of the disturbance induced by the bubble formation could extend to certain distances, which decreased with the increase in the channel size. During regular flow stage, three mass transfer regimes were observed, which was shown to be dependent on the circulation patterns inside the liquid slug. The channel size significantly influences the occurrence of these regimes. From the analysis of the evolution characteristics, a simple map based the Fo number was proposed for the distinguish of these regimes. The values of the mass transfer coefficient are compared to two models derived from the penetration theory. The validity of the models and scope of application are discussed and proposed.