Use of α-shapes for the measurement of 3D bubbles in fluidized beds from two-fluid model simulations

•The alpha-shapes method allows reconstruction of 3D bubbles in fluidized bed reactors.•This method becomes more efficient than digital image analysis (tomography) to measure bubble properties.•A volume-based equivalent bubble diameter was employed to compare BSD between pseudo-2D and 3D beds.•Simulated bubble hold-up and bed expansion did not change between bed configurations.•The increase of simulated bubble velocity from 2D to 3D beds agrees with the empirical correlation of Davidson and Harrison.

A geometrical technique based on shape construction was employed to reconstruct the simulated domain of 3D bubbles in a gas–solid fluidized bed, from two-fluid model (TFM) simulations. The Delaunay triangulation of the cloud of points that represent volume fraction iso-surfaces in transient TFM simulations was filtered by means of the so-called α-shapes, allowing a topologically accurate description of 3D bubbles within a fluidized bed. Consequently, individual 3D bubble properties such as size and velocity were measured. Simulated bubble characteristics were further compared to those measured on pseudo-2D bed facilities by image techniques in order to illustrate the effect of the bed geometry on the bubbling behavior under mimicked operational conditions.

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