Comparative analysis of CFD models of dense gas-solid systems

Many gas-solid CFD models have been put forth by academic researchers, gove rnment laboratories, and commercial vendors. These models often differ in t erms of both the form of the governing equations and the closure relations, resulting in much confusion in the literature. These various forms in the literature and in commercial codes are reviewed and the resulting hydrodyna mics through CFD simulations of fluidized beds compared. Experimental data on fluidized beds of Hilligardt and Werther (1986), Kehoe and Davidson (197 1), Darton et al. (1977), and Kuipers (1990) are used to quantitatively ass ess the various treatments. Predictions based on the commonly used governin g equations of Ishii (1975) do not differ from those of Anderson and Jackso n (1967) in terms of macroscopic flow behavior but differ on a local scale. Flow predictions are not sensitive to the use of different solid stress mo dels or radial distribution functions, as different approaches are very sim ilar in dense flow regimes. The application of a different drag model, howe ver significantly impacts the flow of the solids phase. A simplified algebr aic granular energy-balance equation is proposed for determining the granul ar temperature, instead of solving the full granular energy balance. This s implification does not lead to significantly different results, but it does reduce the computational effort of the simulations by about 20%.