Growth dynamics of reaction-produced bubbles in viscous Newtonian and non-Newtonian liquids in a microchannel

Gas-forming gas–liquid systems are common in pharmaceutical, chemical, and energy processes. Microchannel reactors offer an effective platform for intensifying such multiphase systems. In this study, bubble growth dynamics in viscous Newtonian (glycerol) and non-Newtonian (xanthan gum) fluids within a rectangular microchannel were investigated experimentally and theoretically. Carbon dioxide bubbles were generated via the reaction of sulfuric acid with sodium bicarbonate. A high-speed camera was used to observe bubble evolution. Results showed that increasing concentrations of either glycerol or xanthan gum reduced bubble growth rates, whereas total flow rate had a negligible effect. A theoretical model was developed to describe bubble growth with chemical reactions in both fluid types, and its predictions agreed remarkably well with experimental data. The insights obtained can be helpful for the design and optimization of gas–liquid microchannel reactors for relevant applications.