impact of liquid-liquid hydrodynamic focusing on the efficiency of heterogeneous microreactors: numerical solution

Most of the reactions that occur in microreactors take place on the surface, so it is important to keep the reactants close to the reactive wall. one effective technique in this field is the single-phase hydrodynamic focusing. however, this method has a drawback: a high percentage of reactants penetrate into the sheath fluid. to address this issue, the concept of the two-phase hydrodynamic focusing is introduced in this study. the main idea is to use a highly viscous sheath fluid to create a barrier against reactant penetration into the sheath flow. to demonstrate the effectiveness of this method, a 3d numerical simulation was performed with an irreversible second-order reaction. the results show that the two-phase hydrodynamic focusing increases reaction rates, particularly in downstream regions where the sherwood number can increase by several orders of magnitude with the use of a highly viscous sheath of liquids. additionally, it was observed that the use of the two-phase hydrodynamic focusing improves the efficiency, which is defined as the ratio of the solute in the sample flow to the total solute in each cross-section.