Particle motion in mixed flow dryers: The effect of the wall inclination angle and friction

In Europe, the weather patterns require harvested grain crops to be dried before storage to prevent significant quality loss. The uneven movement of grains inside the drying equipment is a key issue affecting the drying process, causing under- or over drying the harvested crops and thus leading to quality degradation and ultimately to financial losses. To characterise the unevenness of material flow, we introduced a dimensionless displacement ratio. This dimensionless parameter was suitable for comparing the uniformity of the material movement processes within the dryer. Using experimental investigations and numerical simulations, we determined the effect of the lamella inclination angle, the friction between the grain-wall and grain-grain on the uniformity of the flow. The linear functions approximating the quantitative relationships were determined in all the cases. Our findings indicate a significant variation in the displacement ratio ξ corresponding to different lamella inclination angles and friction values demonstrating that the discrete element modelling approach provides further opportunities for determining the optimal operating parameters of mixed flow dryers.