CFD analysis of liquid phase flow in a rotating packed bed reactor

Rotating packed bed (RPB) reactors can greatly intensify the gas–liquid mass transfer efficiency by their strong centrifugal acceleration. However, due to the complex structure of packing in RPB, it is extremely difficult to acquire information about the flow patterns and mixing behaviors inside the reactor by experiments. In this study, by means of computational fluid dynamics (CFD), a two-dimensional computational framework of RPB was developed to investigate the liquid phase flow within RPB numerically. The volume of fluid (VOF) multiphase model, sliding model (SM) and the Reynolds stress model (RSM), as implemented in FLUENT solver, were used to compute the velocity fields and to capture the interface between gas–liquid phases in RPB. The CFD simulations showed that once the liquid was injected into the packing area, it would be quickly split and synchronized with the motion of the rotating packing. The average liquid droplet diameter at high rotating speeds was significantly smaller than that at low rotating speeds, and the droplet diameter in the RPB with static baffles was smaller than that without baffles. The maldistribution of liquid in local areas of the packing could be weakened by increasing rotating speeds. In addition, the increase of rotating speed and inlet velocity of liquid could decrease the mean residence time (MRT) of liquid flow within RPB reactors.