Mixing enhancement of wheat granules in a hopper bottom lab-scale mixer using discrete element simulations

Abstract

In the agricultural industry, the conservation of wheat grains in silos after stocking is a hard task. This is because when stocking a large crop, hot aeration from the bottom of the silo is not sufficient to preserve the crop and avoid losses due to the manifestation of moisture between grains and grains-wall. As a concern, engineers, as well as inspectors, challenged day-to-day issues whenever packing such granular material. A screw could be a good solution to improve the dryness of the particles and mix the bed material in case of stocking different types of grains. Mainly, the complexity does emanate from the model used to predict accurately the mixing performance. Emerging generation of simulation codes using the discrete element method (e.g., EDEM®, LIGGGHTS, etc.) have brought an intact solution to the problem of particulate flow and particles inhomogeneity. The present work has sought to develop predictive models for average mixing index and particles velocity distribution assessments in mixing of wheat granules in a small-scaled hopper base screw mixer. A screw-mated-horizontal-ploughs has been utilized to improve the agitation of grains rather than a simple screw. 1, 2 and 4 mated ploughs to the screw axle has been used, also the tilt angle of the 4 mated ploughs case has been varied as follows; 20°, 45° and 70° then evaluated. Next, findings regarding bed homogeneity are calculated using the Lacey method [1] for quantitative analysis and visual observations have been read out for qualitative assessment. Particles inhomogeneity is at its minimum when more ploughs mated to the screw were used.

The effect of Triple Particle sizes on the mechanical behaviour of granular materials using Discrete element method (DEM)

“…Instead of the conventional cost-effective trial-and-error method, the DEM is an excellent tool for modeling the mechanical properties of bulk material and a full process of particle blending [30].…”

Study the particle size impact on the mechanical behaviour of granular material by discrete element method

“…Instead of the conventional cost-effective trial-and-error method, the DEM is an excellent tool for modeling the mechanical properties of bulk material and a whole process of particle blending [36].…”

“…Newton's second law of motion describes the translational and rotational motion of every particle in the DEM system [37,38]. During the simulation circle, The normal and tangential forces generated among particles and between particles and the wall are computed using a calculation loop that involves apply-ing Newtonian equations of motion repeatedly to generate each particle's acceleration, velocity, and disp-lacement values, as described by the following equa-tions [36]:…”

“…The DEM parameters in Table 1, based on the previous work, were used in our work to achieve accurate results [36,44].…”

Numerical study on the impact of particles filling pattern and screw parameters on the mixing uniformity of wheat grains in a screw mixer

“…In our previously conducted study that used a new screw design by adding ploughs mated to the screw and evaluating the mixture uniformity using the classic index of mixing so-called Lacey index [6]. We have seen that less volume would be available for filling grains, also changing the number of cells alters the Lacey index results.…”