Experimental And Numerical Study On Mechanism Of Mixing And Interfacial Reaction In Impinging Jets Reactors

Impinging jets reactors have shown great application value and broad development prospects in energy,chemical,material,biological and other fields due to excellent process enhancement effect.In this paper,the characteristics of flow,mixing and interfacial reaction in T-jet and cross-shaped impinging jets reactors were investigated by means of experiments and numerical simulation.The influence mechanism of complex flow structure on mixing and interfacial reaction in impinging stream reactors was systematically studied.The main contents are summarized as follows:1.The flow field structure and product concentration distribution in a T-jet reactor were visualized by planar laser induced fluorescence(PLIF)technique and phenolphthalein color reaction.The characteristics of flow,mixing and interfacial reaction in a T-jet reactor were investigated at 20<Re<420.At low Re,the reactants only react at the fluid separation interface by molecular diffusion in segregated flow,and the degree of reaction is low;In steady engulfment flow,the vortices in the flow field make the fluids entrain each other.The laminar structure is formed at the fluid interface,which increases the contact area of reactants,and the mixing effect and reaction degree are significantly improved;In unsteady engulfment flow,periodic vortex merging causes the fluid interface to twist and stretch repeatedly.The reactants are fully mixed and reacted,and the product concentration is high and the distribution is uniform.2.The characteristics of flow,mixing and interfacial reaction in a cross-shaped reactor were studied experimentally.The evolution of flow structure and the distribution of reaction products in the circulation region of engulfment flow were investigated.The influence of vortex structure of engulfment flow on mixing effect and interfacial reaction was analyzed.In steady engulfment flow,a central vortex is formed in the flow field of the reactor.There is a spindle circulation zone in the center of the chamber,which has higher mixing and reaction degree than other regions.The vortex structure in the center of the reactor chamber periodically merges and breaks in unsteady engulfment flow and the concentration distribution of reaction products also changes periodically.3.Based on the above experimental study,the flow and reaction characteristics in T jet and cross-shaped reactors were numerically simulated.The simulation results are basically consistent with the experimental results,and the mechanism of the influence of complex flow structure on interfacial reaction in impinging stream reactor was revealed.The results show that,in T-jet reactor,the formation of vortices in engulfment increases the contact area of reactants,enhances the reaction rate and degree,and expands the distribution range of reaction products.In cross-shaped reactor,the reactants have a very long residence time in the circulation zone,different reactants can be fully contacted and reacted,and the reaction products are concentrated and difficult to flow out.