Performance evaluation of helical tangential porous tube-in-tube microchannel mixer: Effect of cross-sectional area ratio and volumetric flow rate ratio

Abstract

The tube-in-tube microchannel mixer (TMM) is a passive micromixer primarily applied in chemical engineering and pharmaceutical fields. This study investigates the performance optimization of a helical tangential porous tube-in-tube microchannel mixer (HTP-TMM) using computational fluid dynamics (CFD) simulations. A critical structural parameter, the cross-sectional area ratio (R_a), defined as the ratio of the annular microchannel cross-sectional area to the total micropore cross-sectional area, was introduced. The effects of various R_a and volumetric flow rate ratios (R_f) on mixing efficiency, turbulent kinetic energy, pressure drop, and mixing energy cost were evaluated across flow rates ranging from 10 to 300 mL/min. Results indicate that R_a = 1.5 demonstrates higher mixing efficiency and turbulent kinetic energy at low flow rates. Decreasing R_f improves mixing efficiency and turbulent kinetic energy, with optimal mixing performance occurring at R_f = 1. Additionally, larger R_a and smaller R_f values induce higher pressure drops, with maximum recorded values of 23,449 Pa for R_a = 2 and 19,990 Pa for R_f = 1, both within acceptable ranges for practical applications. Moreover, varying R_a minimally affects mixing energy cost, while increasing R_f raises mixing energy cost. These findings provide valuable guidance for TMM design and application in chemical engineering.