Numerical Investigation of the Two-Fluid Model and Computational Fluid Dynamics–Discrete Element Method in Supercritical Methanol Fluidized Beds

Abstract

This work focuses on the comparison of simulated methanol fluid–particle fluidization behavior using the two-fluid model (TFM) and computational fluid dynamics–discrete element method (CFD-DEM) in subcritical methanol (SbM) and supercritical methanol (SCM) fluidized beds (FBs). The solid-phase constitutive correlations are modeled using the low density ratio-based kinetic theory of granular flow. The fluidization states of methanol fluid–particle mixtures using the TFM and CFD-DEM are compared with four thresholds reported in the literature. The outcome of the comparison shows that simulations using the TFM and CFD-DEM capture the coexistence of wave-like flow and churn-like flow along bed height in SbM FBs, and particle aggregates and fluid voids flow in SCM FBs. Agreement in methanol fluid pressure is observed, while discrepancy in volume fractions and velocities is found from the TFM and CFD-DEM in SbM and SCM FBs. Predicted methanol fluid fluctuating quantities of turbulent kinetic energy, dissipation rate, and granular temperatures show sensitivity to the two-equation turbulence model and collisional properties. The predicted expansion bed height and volume fractions agree well with experimental data in superficial carbon dioxide fluid and ambient water FBs.