Experimental magnetic field-driven segregation mechanisms in Geldart D magnetically fluidized beds: From uniform to gradient fields

Several fluidized bed chemical processes, including Chemical Looping, exhibit improved efficiency due to layered organization of the particle bed.Layered organization is obtained by controlling the segregation behavior of admixture particle beds.This work presents the first experimental analysis of the segregation behavior of Geldart D particles under externally imposed uniform and gradient magnetic fields in magnetically fluidized bed reactors.Under uniform magnetic fields, higher gas velocities are observed to reduce the maximum segregation index, limiting the effectiveness of such magnetic fields. Gradient magnetic fields overcome this limitation by introducing an additional directional force: when applied in co-flow with the gas, they increase segregation indices by up to 44% compared to uniform fields, yielding more robust, complete, and less velocity-dependent layering. Conversely, contra-flow gradients weaken or even suppress segregation, depending on field strength and orientation.These experimental results demonstrate the advantages of using gradient magnetic fields for improved layered organization within magnetically fluidized bed reactors opening the door toward achievement and control of layered organization within magnetically fluidized bed reactors. • First experimental systematic study, to the best of our knowledge, of Geldart D particle segregation under uniform magnetic fields. • First experimental systematic study, to the best of our knowledge, of particle segregation under gradient magnetic fields. • Development of an experimental - theoretical framework to understand the impact of the applied magnetic fields on the bed’s behavior. • Robust particle layering observed in mixtures with low mass density difference, enabling precise spatial structuring for process intensification in chemical looping. • The use of gradient magnetic fields leads to a more robust and complete segregation compared to the use of uniform magnetic fields.