Comparison of boundary conditions for predicting the collection efficiency of cyclones

Gas-particle flow in three cyclones was numerically modeled using the Eulerian–Lagrangian approach. A tangential lift-off boundary condition was developed and included in the CFD simulations of cyclone performance via a user-defined function. Particles were considered as detached from the surface if they met the criterion of tangential lift-off; otherwise they were captured by the surface. Prediction of the collection efficiency in cyclones was conducted using the three different boundary conditions: (1) bottom trap only; (2) cone and bottom trap; and (3) the tangential lift-off, which is a combination of trap and reflect. Comparison with experimental data in literature indicates that the tangential lift-off boundary condition yields more accurate predictions than other boundary conditions.