Numerical study on pollutant removal performance of vortex ventilation with different pollution source locations
This study presents the flow trajectory and pollutant distribution of a vortex ventilation system with different pollution source locations. First, the horizontal flow path and vertical structure of vortex ventilation are analyzed using the Burgers–Rott vortex model to predict the basic flow trajectory of pollutants in vortex ventilation system, and to provide a reference for the layout of pollution source locations in the following research. Thereafter, the flow characteristics of pollutants with different source locations in the vortex ventilation are studied numerically. The results indicate that, owing to the flow characteristics of the column vortex, the pollutant released from different pollution source locations has three flow modes: inflow mode, upward flow mode and downward flow mode, showing that the locations of pollution source have a significant impact on the flow mode and distribution of pollutants. Moreover, the ventilation effectiveness (VE) for pollutant removal and the mean residence time (MRT) of pollutants are used to evaluate the vortex ventilation. The results demonstrate that when the pollution source is located in the vortex tube, the ventilation system shows good performance in both VE and MRT; when the pollution sources are located outside the vortex tube, none of the sources show satisfying VE, whereas the MRT performance is good for severe sources. Finally, vortex ventilation systems are qualitatively divided into five regions for preliminarily predicting the pollutant removal performance for different pollution source locations.