Time series analysis of a binary gas-solid conical fluidized bed using radioactive particle tracking (RPT) technique data

Abstract

In current work, the radioactive particle tracking (RPT) technique has been used to investigate the behavior of gas-solid conical mono and binary fluidized bed. The dynamics of the bed has been analyzed using both time-averaged and fluctuation quantities at different gas inlet velocities and bed compositions. The binary bed was composed of glass beads of two different diameters 1 mm and 0.6 mm. The bed of 0:100, 50:50 and 100:0 by wt % of both the particles were investigated. Time-averaged quantities like mean axial velocities, RMS velocities, and granular temperature indicate that behavior of conical bed at the top and bottom sections are significantly different. Gas-solid interactions mainly dominate the bottom section while particle-particle interaction plays a critical role at the top section. Further, time series and chaos analysis of RPT data were performed. Hurst exponent, autocorrelation coefficient, and mixing index were calculated through time series analysis. The results indicate that better mixing is observed in conical bed even at low velocity compared to cylindrical fluidized-bed. It also reveals a regime transition around 5.7 m/s gas inlet velocity. Finally, Kolmogorov entropy and correlation dimension calculated through chaos analysis of RPT data confirm flow regime transition at gas inlet velocity around 5.7 m/s, for all the examined bed compositions.