Owing to their superior mass and heat transfer performance, microreactors have emerged as a research hotspot in novel intensified equipment in recent years. This study experimentally investigates the gas–liquid flow behavior and mass transfer characteristics in microchannel reactors for viscous systems, focusing on the effects of superficial gas and liquid velocities, viscosity, and spiral turbulence elements on T-type microchannel reactors (T-MCRs). Four flow regimes are identified in the T-MCR, where viscosity significantly influences regime distribution and Taylor bubble morphology. In contrast, the spiral-wired T-MCR (T-MCR-SW) is dominated by “serpentine Taylor flow”. Increased viscosity leads to elevated pressure drop and reduced CO₂ saturation in both reactors, with the T-MCR-SW exhibiting a notably higher pressure drop. The impact of gas–liquid flow rates on CO₂ saturation varies with reactor type and viscosity. The total volumetric mass transfer coefficient (K_La) of the T-MCR-SW is substantially higher than that of the T-MCR, but its pressure drop is nearly doubled. Thus, a balance between mass transfer efficiency and energy consumption must be considered for practical applications. This work provides valuable insights for the design and optimization of microreactors in viscous systems.

Microreactors offer remarkable advantages in intensifying mixing/mass transfer and hold promising prospects for industrial applications. In this study, T-shaped microreactors (TMRs) integrated with baffle, orifice-plate, and venturi structures (featuring different contraction angles) were designed. Based on the Villermaux–Dushman reaction system, three-dimensional computational fluid dynamics (CFD) models were established to simulate the fluid flow and mixing-reaction processes in these microreactors. The results demonstrate that peaks in velocity, turbulent kinetic energy, and turbulent dissipation rate consistently emerge in the confluence region of the two fluid streams. In the operating range of this study, the baffle configuration exhibits the highest micromixing performance but also induces the largest pressure drop, followed by the orifice-plate structure. Notably, the venturi structure not only enhances micromixing efficiency but also results in a minimal increase in pressure drop and eliminates flow dead zones. Specifically, the venturi structure with a 45° contraction angle achieves a balance between energy consumption and micromixing efficiency. Using the agglomeration model, the micromixing times of the microreactors with various structures were determined to range from 0.025 to 0.234 ms.