Stability and uniformity of gas–liquid two-phase flow in shear-thinning fluids in parallelized microchannels

The stability of gas–liquid two-phase flow and uniformity of bubble size in shear-thinning fluids within symmetrical parallelized microchannels are investigated experimentally. Air and sodium carboxymethyl cellulose (CMC) aqueous solutions with 0.3% SDS are used as the dispersed and continuous phases, respectively. The process of gas pressure buildup and rapid release is observed under conditions of exceeding the critical gas and liquid flow rates. Various slug bubble shapes are identified in different concentrations of CMC solutions, gas and liquid flow rates. The results show that the increase of liquid flow rates and the decrease of CMC concentration are beneficial for the stability of bubble formation and uniformity of bubble size in the parallelized microchannels. Finally, semi-empirical formulas are proposed, based on the rheological property of CMC aqueous solutions, to estimate the bubble length.