Abstract Summary (Max 250 words)
Micro-fluidized beds (MFBs) are attractive intensified gas–solid contactors because of their high heat and mass transfer potential. However, strong wall confinement in small-diameter columns often promotes severe slugging, which deteriorates gas–solid mixing and limits stable operation. In this work, the mixing behavior of baffled micro-fluidized beds was investigated to evaluate the role of internal baffles in suppressing slugging and improving operability. A stereolithography-based 3D-printed reactor with an internal diameter of 4 mm and a height of 300 mm was studied in four configurations: an unbaffled column and columns containing 5, 10, and 30 internal baffles. Experiments were carried out with two Geldart B particles, Alpha-SiCB289 and OlivineB97.5, over a range of gas velocities. Mixing and flow dynamics were characterized using pressure fluctuation analysis, wavelet-based multiscale decomposition, time–frequency hotspot mapping, and high-speed imaging. The results show that internal baffling effectively fragments large slugs into smaller flow structures, suppresses mesoscale oscillations associated with unstable gas–solid mixing, and promotes a more homogeneous flow pattern. Flow regime analysis further indicates that baffling significantly broadens the bubbling and turbulent operating windows while narrowing the slugging regime. In addition, the minimum fluidization Reynolds number decreased by 23% for Alpha-SiCB289 and 37% for OlivineB97.5. These findings demonstrate that internal baffling is an effective strategy for improving gas–solid mixing in micro-fluidized beds and provide useful design guidance for intensified thermal and reaction processes.
