Chemical Engineering Research & Design, Vol.149, 65-80, 2019
Bubble behavior in gas-solid bubbling fluidized beds based on EMMS model: Comparison of 2D, Q2D, and 3D simulations
In this work, bubbling fluidized beds in two-, quasi-two-, and three-dimensional geometries are simulated by the Eulerian-Eulerian two-fluid model (TFM) coupled with an energy minimization multi-scale model. The parameters bubble diameter, bubble vertical velocity, shape factor, and aspect ratio, as well as bed height, are investigated. Simulation results show that vertical velocities of two- and quasi-two-dimensional bubbles are in good agreement with empirical correlations. Equivalent bubble diameter predicted in all dimensions of beds is also in reasonable agreement with empirical correlations. According to the comparison between simulation results (bubble diameter and vertical velocity) and empirical correlations, two- and quasi-two-dimensional simulations have better performance in predicting bubble behaviors. As for shape factor of three-dimensional bubbles, the peak value of frequency decreases with superficial gas inlet velocity, and the tendency is more significant than that of two- and quasi-two-dimensional bubbles. Slightly positively skewed distributions of aspect ratio are acquired, and the peak value decreases with superficial gas inlet velocity, especially for two- and three-dimensional bubbles. Additionally, bed height of two- and three-dimensional beds shows no major difference and is higher than that of the quasi-two-dimensional bed. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.