A process scaling approach for CFD-DEM modelling of thermochemical behaviours in moving bed reactors

Intensive heat and mass transfer between continuum fluids and discrete particulate materials plays a critical role in many chemical reactors. The residence and chemical reactions of particulate materials could span over hours. To understand and improve the operation of these reactors, discrete particle models are very helpful and computationally demanding. Different to the previous coarse grain model in reducing computational cost by reducing total particle number with large representative particles, a scaling approach by changing process parameters and thus the time scale is established to significantly reduce computational cost for the combined computational fluid dynamics (CFD) and discrete element method (DEM) modelling of moving bed reactors. The scaled model is first derived based on the governing equations of mass, momentum and energy for two-phase flow and then applied to a moving bed reactor. The results in terms of flow, heat and mass transfer and chemical reactions with different time scaling factors demonstrate that two-order acceleration in terms of computational time can be achieved while reliably representing the same physical process. The possible use of the scaling approach to other systems is discussed. The scaling approach represents a critical step forward towards establishing virtual real-time thermochemical reactors with discrete particle models.