Evaluate the effect of drag force models on the fluidization process

Drag models are essential the simulation of liquid-solid fluidized beds, a type of multi-phase flow system utilized in various chemical and process industries. Accurate prognosis of the behavior of particles in fluidization is relevant to better performance and efficiency, which allows for accurate predictions regarding pressure decrease and fluidization conditions, i.e., fixed bed, bubbling, turbulent, or homogeneous regimes, are needed, and deeper insight into particle suspension and segregation behavior with possible applications to mixing operations and system stability. Five drag models; Schiller & Naumann model, Dallavalle model, Haider & Levenspiel model, Brown & Lawler model, and Di Felice model are presented, to understand the drag force in terms of its role in governing hydrodynamic behavior during fluidization process, and choose the best probe model. Comparisons between the numerical results for the five models are done; to select appropriate model based on flow regime, porosity, bed height, and particle Reynolds number. The comparisons indicate, the Schiller & Naumann, Dallavalle, and Haider & Levenspiel models exhibit similar trends, in close accord with the experimental findings over the tested extent of velocities. Whereas the Brown and Lawler model tends to underpredict the bed height, particularly at higher inlet velocities. Discrepancy indicates a more conservative estimation drag force on the particle phase, which can lead to less intense fluidization dynamics. The Di Felice model gives the most conservative predictions overall, for the bed height over the velocity range. Selection of appropriate drag force model must correspond to the particular attributes of the fluidized bed stand with the specific characteristics of the fluidized bed under study, which is a liquid-solid fluidized bed.