Numerical Study On The Micromixing Performance Of Single Countercurrent-Flow Microchannel Reactor

Due to their intensive micromixing and,thus high mass/heat transfer efficiency,microchannel reactors have been widely used in many chemical processes,especially in extraction and multiphase reactions.As a new type of process intensification technology,microchannels provide a powerful tool for micro scale processing.The performance of most microchemical devices strongly depends on the efficiency of micromixing.In this work,a novel microchannel reactor named single countercurrent-flow microchannel reactor(S-CFMCR)was proposed and numerical as well as experimental studies were carried out to investigate the fluid flow characteristics and the influencing factors of micromixing inside S-CFMCR.The major findings are as follows:(1)The fluid dynamical characteristics were studied extensively and the visualization of velocity and turbulent kinetic energy inside the reactor had been demonstrated by ANSYS Fluent software.We also researched the macromixing performance of the reactor comprehensively in which we took mixing intensity as the performance index.The conditions of the formation of convection were explored and the fluid field was divided into three regions:convection zone,vortex zone and exit zone.(2)The effects of operating conditions as well as geometric parameters of S-CFMCR,e.g,inlet Reynolds number(Rej),volumetric flow ratio(R),inlet diameter(d)and outlet length(L),on the micromixing performance have been investigated both numerically and experimentally based on "Villermaux/Dushman" method.The experimental data and numerical results agreed well and indicated that the micromixing of this reactor was intensified with rising Re at Rej<1200;however,no further intensification of micromixing could be observed after the increasing Rej reached 1200.The optimal operating condition of R is R=1.At micro scale,a better micromixing performance will be achieved with increasing d and decreasing L.It also showed that the pressure drop within the microchannel increased significantly with decreasing L.