A Theorical And Experimental Study On Mixing-Reaction Processes

Mixing-reaction process is very important in industries, but its mechansim,especially that related to micromixing, is still little known. For this reason,the mechanism of mixing-reaction in microscale was experimentally and thcorically studied in this work by the approach of unified application of hydromechanics, basic principles of chemical reaction engineering and the optical technique. New ideals and concepts were developed, by which the understanding of the real mechanism of mixing-reaction can be broutght to a new and deeper stage. The whole work is summerized to give the following points:1. High Speed Stroboscopic Microscopic Photography, a new technique firstly developed in our laboratory was successfully used for the observation of the deformation history of fluid elements during submicro- and micromixing pro-cesses. A number of valuble pictures showing the morphological chang of microfluid elements during mixing in turbulent field with or without chemical re-action were obtained. It was found that the submicro— and micromixing processes are composed of three successive stages: (1) turbulent dispersion in the initial-convective subrange, (2) laminar alongation deformation in the viscous-diffusion subrange and (3) molecular diffusion in viscous-diffusion subrange. By comparing the micromixing in stirred tank and that in tubular reactor, we found that the latter is inferior to the former due to the restrainment of turbulent macromixing.2. On the basis of turbulent theory and the above results, a micromixing mechanism was proposed and a new general mixing—reaction model, which...