Abstract:Microreactors are widely applied in fields including chemical synthesis, pharmaceutical production, and energy material applications. However, passive microreactors are generally limited by inherent design constraints, including significant pressure drops and a high clogging risk, which restrict their practical application in reaction systems involving high viscosity and solid particles. To address this problem, this study enlarges the microchannel dimensions to the centimeter scale and develops a novel active microreactor driven by a motor-driven stirring shaft to achieve mixing. This design is suitable for high-viscosity and solid-particle-containing reaction systems, offering the advantages of high mixing performance and high production throughput. Three impeller configurations were designed within a 100 mm diameter flow domain: a straight blade (26 mm high), a straight blade with baffles (incorporating four transverse baffles), and a propeller (110 mm pitch). By combining computational fluid dynamics (CFD) simulations with experimental validation, the effects of time, inlet velocity, and stirring speed on mixing performance were investigated, with segregation index (XS) and mixing efficiency (η) as evaluation metrics. Simulations utilized the RNG k-ε turbulence model and sliding mesh technique on a water/glycerin system, with a grid size of 1.5 mm determined via grid independence tests. Analysis of mass transfer enhancement mechanisms showed that the straight blade impeller induces a radial jet via localized shear; the straight blade impeller with baffles suppresses circumferential vortices to convert momentum into radial/axial flow; and the propeller forms an axial-driven through-flow ring. Mixed fluid reached the outlet fastest with the propeller (0.9 s), followed by the straight blade (1.2 s) and the straight blade with baffles (1.3 s). Subsequently, the mixing efficiency (η) rose rapidly and then stabilized. Mixing performance was ranked as: straight blade with baffles> straight blade>propeller. Quantitative analysis indicated that the straight blade impeller reached a peak efficiency of 90.74% at 358 r/min, while the straight blade impeller with baffles further improved this to 93.70%. Although the propeller performed poorest at low speeds, its efficiency surpassed that of the straight blade at high speeds (956 r/min). Simulations also indicated that η decreased as inlet velocity increased (0.1 to 1.0 m/s) due to reduced residence time. To validate the simulation results, a mixing platform was constructed using the iodide-iodate reaction (c(H+)=0.012 55 mol/L). Experiments verified the simulation reliability and analyzed the effects of inlet velocity and stirring speed on the segregation index (XS). Results showed that stirring speed had a significantly greater impact on mixing effectiveness than inlet velocity. Notably, increasing stirring speed from 0 to 280 r/min significantly reduced Xs from 0.978 to 0.268. The study concludes that the strategy of combining centimeter-scale scale-up with forced mechanical shearing effectively resolves the mixing challenges of high-viscosity systems, providing theoretical data and design criteria for industrial applications. Close-