Design and modelling of dust capturing system in thermally stratified flowing conditions

Abstract

An improved understanding of the spreading and deposition of particles in a thermally buoyant flow environment i.e. melting hall is a key prerequisite to plan new strategies for dust capturing and reduced diffuse emissions. Accurate modeling of dust spreading and deposition requires accurate prediction of turbulence, particles dynamics, and particle-flow interactions. Widely used Reynolds-averaged Navier-Stokes (RANS) turbulence model, such as k-epsilon model, have shortcomings when modeling transient flow phenomena in thermally buoyant flow conditions. To overcome this shortcoming, a filtered VLES model (Very Large Eddy Scale model) have been applied where turbulent structures larger than a given filter size (typically grid size) is captured by the governing flow equations and smaller structures are modelled with a modified filtered k-epsilon model. This modeling approach provides more details description of the stratified flow and small turbulence structures. Both Drift-Flux Model (DFM) in a Eulerian framework and discrete phase model (DPM) in a Lagrangian framework have been applied to model the particle phase. Three coupled modelling approaches VLES-DPM, k-epsilon-DPM, and VLES-DFM are applied to understand the dust spreading and deposition. These methods are also used for designing a dust capturing system. The parameters which influence the dust capturing efficiency are also identified. The result from these three approaches are compared and the study showed that the VLES-DFM produces similar results to the VLES-DPM with lower computational time. Furthermore, the studies show that dust capturing efficiency depends on hood shape, particle size, particle density, hall-wind, and suction rate.