Scaling Laws for CFD-DEM Simulations of CLC

In this chapter, the parcel approach and various scaling laws are described for computationally efficient simulations of CLC process using CFD-DEM. In particular, the simplified scaling law of Glicksman et al. (Powder Technol 77:177–199, 1993), the scaling law of Link et al. (Powder Technol 189:202–217, 2009), and the terminal velocity ut-based scaling law of Banerjee and Agarwal (Energy Fuels 30:8638–8647, 2016) are described, and their relative usefulness is evaluated and demonstrated by simulating an experimental spouted fluidized bed with draft plates using the CFD-DEM method. The particle velocity is an important quantity for characterizing the fluidization behavior in a spouted fluidized bed; it is used to compare the performance of the different scaling approaches. Comparing the particle velocities in the vertical z-direction at various heights, it is found that all the scaling methodologies can capture the general trends in the particle velocities at different heights. However, the terminal velocity ut-based scaling law outperforms the other scaling approaches and provides the best match with the experimental values. This makes sense because the scaled model using the ut-based approach of Banerjee and Agarwal maintains the same values as the experiment for all the nondimensional parameters used to ensure dynamic similarity. The ut-based scaling law also provides the largest reduction in the number of particles in the system in all cases, and hence the largest reduction in computing cost. The establishment of a scaling law that can maintain fidelity with experiment is a crucial step toward the development of CFD-DEM simulations of industrial scale fluidized beds for chemical looping combustion.