Numerical and experimental study on spout elevation in spout-fluidized beds

Numerical Simulation of the Aerosol Particle Motion in Granular Filters with Solid and Porous Granules

In this work, a study was carried out to compare the filtering and hydrodynamic properties of granular filters with solid spherical granules and spherical granules with modifications in the form of micropores. We used the discrete element method (DEM) to construct the geometry of the filters. Models of granular filters with spherical granules with diameters of 3, 4, and 5 mm, and with porosity values of 0.439, 0.466, and 0.477, respectively, were created. The results of the numerical simulation are in good agreement with the experimental data of other authors. We created models of granular filters containing micropores with different porosity values (0.158–0.366) in order to study the micropores’ effect on the aerosol motion. The study showed that micropores contribute to a decrease in hydrodynamic resistance and an increase in particle deposition efficiency. There is also a maximum limiting value of the granule microporosity for a given aerosol particle diameter when a further increase in microporosity leads to a decrease in the deposition efficiency.

Two-dimensional numerical simulation of chimney fluidization in a granular medium using a combination of discrete element and lattice Boltzmann methods

We present here a numerical study dedicated to the fluidization of a submerged granular medium induced by a localized fluid injection. To this end, a two-dimensional (2D) model is used, coupling the lattice Boltzmann method (LBM) with the discrete element method (DEM) for a relevant description of fluid-grains interaction. An extensive investigation has been carried out to analyze the respective influences of the different parameters of our configuration, both geometrical (bed height, grain diameter, injection width) and physical (fluid viscosity, buoyancy). Compared to previous experimental works, the same qualitative features are recovered as regards the general phenomenology including transitory phase, stationary states, and hysteretic behavior. We also present quantitative findings about transient fluidization, for which several dimensionless quantities and scaling laws are proposed, and about the influence of the injection width, from localized to homogeneous fluidization. Finally, the impact of the present 2D geometry is discussed, by comparison to the real three-dimensional (3D) experiments, as well as the crucial role of the prevailing hydrodynamic regime within the expanding cavity, quantified through a cavity Reynolds number, that can presumably explain some substantial differences observed regarding upward expansion process of the fluidized zone when the fluid viscosity is changed.

Recent Advances of Spout-Fluid Bed: A Review of Fundamentals and Applications

The spout-fluid bed (SFB) is a very successful synthesis of the spouting and fluidization. The hydrodynamics of SFB are more complex than both fluidized beds and spouted beds. Up-to-date information on the fundamentals and applications of SFBs has been briefly presented, based on the limited work reported, in the new spouted bed book edited by Norman Epstein and John R. Grace (Spouted and spout-fluid beds: fundamentals and applications, 2011). In the past three years, nearly 30 papers have been published in international journals. They reported interesting studies on hydrodynamic characteristics, numerical simulations and new applications of SFBs. This article reviews the major research and development on SFB from the year 2010 and recommends further research topics. This review is intended not only as an important supplement to the SFB chapter of the spouted bed book but also helpful guidance for future research.