Impact of inlet design on mass transfer in gas-liquid rectangular microchannels

The length of the gas bubbles as well as of the liquid slugs in Taylor flow in rectangular microchannels was studied. At constant flow ratios of the gas and the liquid phase, we were able to vary the unit cell length, and therefore the gas bubble length as well as the liquid slug length by factor 4 solely by changing the inlet geometry. Based on literature and experimental data, we state a new correlation to predict the gas bubble length, the liquid slug length as well as the pressure drop for rectangular microchannels. The observed decrease in slug length for the investigated case corresponds to an increase in the Sherwood number and therefore of the mass transfer by a factor of 1.6. Short unit cell lengths, meaning enhanced mass transfer within the liquid slug and increased interfacial area, can be achieved for given flow rates using a small gas inlet channel compared to the main channel and injection in flow direction.