Numerical investigation on droplet collision phenomena in moisture separators using population balance model under Lagrangian framework

Abstract

Droplet collision is an important phenomenon in the industry field. In this work, a new droplet collision model is proposed using moment method coupling with population balance model (PBM) under Lagrangian framework. First, by solving PBM equation with coalescence kernel, the droplet size distribution is obtained. Second, droplets are classified into represented droplets according to the moment parameters. Third, trajectories of represented droplets are simulated by a motion model under the Lagrangian framework. In the results part, three cases (e.g. two-dimensional wave-plate steam water separator, three-dimensional cyclone separator and three-dimensional swirl-vane separator) are performed to verify the accuracy of the new model. A variety of calculation conditions such as inlet velocity varies from 3 m/s to 11 m/s and inlet volume fraction varies from 0.018 % to 0.119 % are set under environment condition of normal temperature and pressure. The pressure distribution, velocity distribution and separation efficiency in the flow field are calculated. The comparison between the calculated results and the experimental values shows that the calculated model has high accuracy. This model shows good potential to describe the droplet collision behavior and the detail information of the particle size distribution for droplet-laden flows.