Validation of Eulerian modeling of gas-solid fluidized beds using nonlinear analysis

Abstract

In the present work, the new advanced method has been used for validation of two-fluid method (TFM) for modeling of the hydrodynamics of gas-solid fluidized beds. While many investigations were addressed validation of the CFD codes, less effort has been made to validate the nonlinear dynamics of fluidized beds with nonlinear methods. In this work new advanced nonlinear methods of recurrence plot (RP) and recurrence quantification analysis (RQA) have been used to validate the hydrodynamics modeling of the gas-solid fluidized beds. Pressure fluctuations of inside the bed were selected for comparing the nonlinear dynamics of fluidized bed in experiments and simulations. Pressure fluctuations were measured in a rectangle fluidized bed containing Geldart’s group B particles with sampling frequency 400 Hz. Simulations were done with the same operating condition and pressure fluctuations were recorded with the same sampling frequency. The superficial air velocity range was 0.25–0.73 m/s (bubbling regime) and two aspect ratios 1 and 1.5 were used. The results of experiments and simulations were analyzed by RP and RQA. The values of laminarity, determinism, and recurrence rate for both experiments and simulations are close to each other. The experimental and simulation results showed high values for determinism and laminarity which show predictable and periodic behaviors of both systems. High values of determinism and laminarity are one of the most important characteristics of bubbling regime in which bubbles are periodically produced and move in the bed. In the entire gas velocity, the values of determinism and laminarity were not changed significantly that shows that no regime change occurred in the bed.