Sensitivity Analysis and Effect of Simulation parameters of CPFD Simulation in Fluidized Beds

Abstract

Fluidized bed technology is broadly applied in industry due to its distinct advantages. CFD simulation of fluidized beds is still challenging compared to singlephase systems and needs extensive validation. Multiphase particle-in-cell is a recently developed lagrangian modeling technique and this work is devoted to analyze the sensitivity of grid size, time step, and model parameters, which are the essences of accurate results. Barracuda VR 17.1.0 commercial CFD package was used in this study. 500μm sand particles and air was used as the bed material and fluidization gas respectively. Five different grids, having 27378, 22176, 16819, 9000 and 6656 computational cells were analysed, where five different time steps of 0.05, 0.01, 0.005, 0.001 and 0.0005 were used for each grid. One velocity step was maintained for 8 seconds. The bed pressure drop at packed bed operation was high for simulations with reduced time steps while equal pressure drops were observed during fluidization for all time steps. Time steps of 0.0005s and 0.001s and 0.005s produced equal result of 0.15 m/s for minimum fluidization velocity, irrespective of the grid size. The results from time steps of 0.05 and 0.01 are converged to the results from time steps of 0.005 and 0.001 by increasing simulation time per one velocity step.