Hydrodynamics and mass transfer of the coaxial jet mixer in flow injectionanalysis

A coaxial jet mixer that was previously proposed for rapid and efficient mi xing under laminar now conditions has been studied both theoretically and e xperimentally. ia mathematical model that consists of a set of Navie-Stokes equations that determine the now velocities and three diffusion-convection reaction equations that determine the reactant and product concentrations has been developed. Equations are solved with the help of finite difference techniques for different now conditions. The quality of sample and reagent mixing is characterized by the mean product concentration and the amount o f product produced. Theoretical results are compared with experimental ones for the mixing of bromothymol blue (a pH indicator) in the outer capillary with NaOH in the inner capillary of the jet mixer.