Rotating packed bed (RPB) reactors, with strong centrifugal acceleration up to several hundred times gravitational acceleration, can greatly intensify the gas−liquid mass transfer efficiency. With the improvement of high performance computer clusters and simulation models, a more precise and comprehensive simulation on the gas−liquid flows in RPBs has been achieved by a three-dimensional model. The volume of fluid (VOF) multiphase model, sliding model (SM), and different turbulence models were used to compute the velocity fields and capture the evolution of the gas−liquid interface in the RPB reactor. The liquid flow behavior, droplet size, liquid phase distribution, specific surface area, and mean residence time (MRT) of the liquid phase within the RPB were studied. Compared with two-dimensional simulations, the threedimensional simulation model can not only describe the liquid breakage and coalescence processes within RPB reactors more clearly, but also obtain results in more satisfactory agreement with experimental data.

Micromixing in rotating-packed-bed (RPB) reactors is of great significance for their process-intensifying performance. On the basis of the iodide−iodate reaction system, a two-dimensional computational framework of RPB was developed to investigate the micromixing efficiency in a RPB. The volume-of-fluid multiphase model, laminar finite-rate model, and the Reynolds stress model were adopted to simulate the volumetric fraction of the liquid phase, the concentration distributions, and the effects of rotating speed and liquid flow velocity on the micromixing performance of a RPB. The computational fluid dynamics results showed that the micromixing and reaction processes occurred mainly in the inlet region of RPB packing, which further confirmed the end effect of the packing. An increase of the rotating speed and liquid flow velocity could remarkably enhance the micromixing efficiency in a RPB. On the basis of the incorporation model, the micromixing time in a RPB was estimated as 0.05−0.30 ms, indicating a remarkably quick micromixing performance.

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When a water droplet moves in atmosphere with pollutant, internal circulation is formed due to surface shear stress. This enhances internal mass transfer greatly, and improves the spray droplet SO 2 absorption. In this paper, the internal circulation and diffusion of SO 2 in a water droplet were numerically studied. The distribution of tangential velocity at the interface and the effect of interior circulation on sulfur dioxide transfer are analyzed under different Reynolds numbers. The numerical results indicate that there are two symmetrical vortexes inside the droplet when there is a relative motion between gas and liquid phase. The distance between the vortex core and the droplet center is around 2/3R d , and the vortex velocity increases with the Reynolds numbers. The study shows sulfur dioxide absorption by the droplet is controlled by two mechanisms, w are (1) the radial diffusion due to concentration gradient; and (2) mass transport induced by internal circulation. The characteristic times of radial diffusion and vortex formation are compared. The comparison indicates that the internal circulation dominates sulfur dioxide mass transfer inside the water droplet. The internal circulation influences the sulfur dioxide mass transfer greatly with the increase of Reynolds number. On the other hand, the effect of deformation rate on mass transfer is insignificant because of the characteristic time are of the same order with the same Reynolds number.