Intensification Of The Micromixing And Liquid-Liquid Mass Transfer Performance By Pore-Array Tube-in-Tube Microchannel

Microchemical is a novel type of process intensification technology.Because of the small dimension of the micro devices,the characteristics of small volume,large specific surface area,high heat transfer and mass transfer efficiency promote its extensive applications in the field of rapid mixing,emulsification,mass and heat transfer as well as reaction processes.However,the throughput of the single microchannel is very low,which need to parallel the multiple channels to meet the demand of large industrial applications.In this work,we developed a novel pore-array intensified tube-in-tube microchannel(PA-TMC)with high throughput based on the previous studies,which could achieve low-cost manufacturing.The micromixing performance,liquid-liquid mass transfer performance and the micromixing performance as the liquid distributor of the high shear mixers(HSM)were systematically investigated.Firstly,the micromixing performance of PA-TMC with different structural and operating parameters were studied by the Villermaux/Dushman System and CFD simulations.Both results indicated that the pore size and annular size played a significant role in enhancing the micromixing level,and the design of PA-TMC should avoid the overlap of flow fields from the adjacent pores and too much pressure-drop in the annular.The micromixing time was estimated with incorporation model and a new energy efficiency was proposed to estimate the lower limit of the reactor efficiency,which would have promising applications to provide guidance on the design of the reactor for the single phase reaction process.The optimal micromixing time could reach 10^-4 s in PA-TMC.The comparison with other reactors showed that the PA-TMC was an efficient and high-throughput microchannel to meet the industrial applications with excellent micromixing performance and energy efficiency.Secondly,the liquid-liquid mass transfer performance of PA-TMC were characterized by the overall mass transfer coefficient(K_La)and the mass transfer efficiency(E)with water-benzoic acid-kerosene system,and the CFD was used to simulate the two-phase flow patterns.The results indicated that the overlap of the adjacent pores along radial and axial gave an optimal pore size at 0.3 mm and the better mass transfer performance with the lower row number.K_La decreased sharply with the increase of annular size and length,while E only increased with the annular length.The helical coil could enhance the fluid turbulence in the annular channel and improve the mass transfer performance,but the effects became smaller and smaller with the decrease of the helical pitch.The artificial neural network(ANN)was employed to correlate K_La with the investigated parameters,which provided a guidline for the desgin of the PA-TMC.The K_La and throughput of PA-TMC were respectively 3.6?153 min^-1 and 24?72 L/h,which demonstrated a considerable mass transfer performance and high-throughput compared with other mass transfer devices.Finally,we coupled the high-throughput of PA-TMC with the HSM(PA-HSM)for the first time to intensify its micromixing performance.The results displayed that the coupling distance,pore size and pore number had a great influence on the micromixing performance.The micromixing performance of PA-HSM was almost independent of the rotor speed of HSM when PA-TMC acted as a premixer,while the micromixing performance was improved significantly with the increase of rotor speed when PA-TMC acted as a distributor.The optimal pore size still existed at 0.3 mm under high rotor speed,but the smaller of the pore number the better of the micromixing perfromance.The micromixing time could reach 10^-4 s based on the incorporation model.The ANN was applied to correlate the micromixing time with the investigated parameters,and the comparison between the model and experimental data showed that it was an efficient method in fitting experimental data in PA-HSM by training a suitable neural network.