Flow pattern of liquid multiphase flow in microreactor with different guideline structures and surface modification

Abstract

A parallel multiphase flow in microchannel offers simple phase separation at the exit and hence, reduces the post-treatment requirements. Guideline structure and surface modification by silanization was therefore, introduced to stabilize and maintain organic-aqueous two phase parallel flow in a glass microchannel. The effects of guideline structure and surface modification on water-toluene flow pattern were investigated using computational fluid dynamics (CFD). The CFD simulation can well predict the flow patterns observed from the experiment. In straight microchannel, with the presence of guideline structure, the interface became more stable with curve shape. The role of guideline structure on the flow development was analyzed. With surface modification, the stable interface was pinned near the center of the microchannel with guideline structure. The fluids required less time to reach the stable flow pattern and could be maintained in their corresponding paths since feeding. Flow rate and flow ratio were varied to investigate the flow behaviors. The instabilities were observed at higher and lower flow rates. At higher flow rate, the interface stability could be obtained by adjusting the flow rate ratio. The parallel-slug flow pattern transition, which occurs at low flow rate, could be altered by surface modification. The effects of channel width and curve radius were demonstrated. In curved microchannel, the guideline could not stabilize the interface at the simulation flow conditions. In contrast, the surface modification could fix the interface at the channel center and maintain the parallel flow pattern at high flow rate.