X. Lu, D.J. Holland, Investigation of drag models for the two fluid simulation of Geldart group A powders, Powder Technology, Volume 304, December 2016, Pages 41-54, ISSN 0032-5910, http://dx.doi.org/10.1016/j.powtec.2016.07.063.
Abstract: Electrical capacitance tomography and magnetic resonance imaging were used to investigate two drag models used when simulating Geldart group A powders with the two fluid model. Experiments were performed using cylindrical fluidised beds 50 mm in diameter with a silica-alumina catalyst support particle of diameter 63 μm. A dense phase, bubbling fluidised bed and a dilute phase, circulating fluidised bed were studied. Simulations were performed using the open source software MFIX. The two drag models considered were the revised Gibilaro model and the Energy Minimisation Multiscale model. Both of these models have previously been shown to be effective at describing the fluidisation of Geldart group A powders. The comparison of the simulations with experimental measurements presented here demonstrates that the revised Gibilaro model can be used to predict the voidage and particle velocity distribution in the dense fluidised bed with a high degree of accuracy, however when used to simulate the circulating fluidised bed it underestimates the solids circulation rate by approximately a factor of 4. The Energy Minimisation Multiscale drag model is able to predict the circulating fluidised bed solids circulation rate to within about 50%, however it does not predict the correct voidage distribution in the dense fluidised bed. These results indicate that neither model is able to predict the fluidisation behaviour across the entire range of fluidisation conditions.
Keywords: Fluidised bed; Two fluid model; Magnetic resonance imaging; Electrical capacitance tomography