Numerical insights into design and performance of centrifugal dryers for plastic pelletizing systems

This study presents a detailed numerical analysis of a centrifugal dryer in polymer pelletizing systems, focusing on the effects of rotor geometry and speed on mechanical drying performance. Employing a coupled Discrete Element Method (DEM) and Moving Particle Semi-implicit (MPS) approach to simulate particle interactions and fluid dynamics, we investigated rotor flight angles (10°, 45°, and 70°), number of flights (10–25), and speeds (1,280, 1,600, and 920 rpm). Performance metrics included pellet discharge count, discharge time for 1,000 pellets, residence time distribution, and energy consumption. Results indicate that a 45° flight angle consistently promotes stable discharge, efficient pellet transport, and narrow residence time distributions. The configuration with 45°, 14 flights, and 1,280 rpm achieved the highest throughput with well-controlled residence times (1.94–6.95 s) and moderate energy use (16.21 Wh), balancing efficiency and energy consumption. In contrast, 10° configurations lacked sufficient lift, while 70° angles caused recirculation and particle trapping. Increasing flight count improved confinement and uniformity but led to inefficiencies at high speeds. Rotor speed improved performance up to an optimal point beyond which instability and energy loss occurred.