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SCREW CONVEYOR PERFORMANCE: COMPARISON OF
DISCRETE ELEMENT MODELING WITH LABORATORY EXPERIMENTS
Philip J. OWEN and Paul W. CLEARY
Screw conveyors are used extensively in agriculture and processing industries for elevating and/or transporting bulk materials over short to medium distances. They are very effective for conveying dry particulate solids, giving good control over the throughput. Despite their apparent simplicity, the transportation action is very complex and designers have tended to rely heavily on empirical performance data. In our previous work, we explored how screw conveyor performance is affected by its operating conditions (such as: the rotational speed of the screw, the inclination of the screw conveyor, and its volumetric fill level). In that work, the predicted mass flow rate was in excellent agreement with experimentally measured values for the horizontal and vertical configurations across the full range of screw rotation rates. Although the throughput predictions for the screw conveyor inclined at 30° and 60° followed the same qualitative trend, there were moderate differences between the DEM and experimental results. In this paper, we use the Discrete Element Method (DEM) to examine how variations of particle properties (such as: particle shape, particle-particle and particle-wall friction) influence the performance of the screw conveyor. The primary focus of our study is comparing predicted mass flow rates with experimentally measured values. The secondary focus is to study how other performance measures (such as: particle speeds and power
consumption) vary due to changes in the properties of the particles.