CFD-DEM simulation of cyclone self-rotation drying: Particle high-speed self-rotation and heat transfer

Abstract

Cyclone self-rotation drying (CSRD) has been demonstrated to have the outstanding advantage of low energy consumption in drying field due to the ability of non-phase change separation of liquid in wet particles. Particle high-speed self-rotation are key factors that affect the energy consumption and efficiency of CSRD, but their laws and regulation methods are still unclear. In this study, under the framework of Eulerian-Lagrangian method, Eulerian model and Reynolds Stress Model (RSM) were adopted, and computational fluid dynamics (CFD) and discrete element method (DEM) coupled simulation was established to systematically investigate the effects of operating parameters on sludge particle self-rotation and heat transfer in a 200-mm-diameter CSRD device. The particle self-rotation and revolution speeds were found to decrease with increasing particle size and feeding rate. An average self-rotation speed of 5217.8 rad/s was observed for 1 mm particles at a gas velocity of 10 m/s and a feeding rate of 50 kg/h, when the gas velocity increased to 20 m/s, the self-rotation speed increased about 888.4 rad/s. These operating parameters were also found to affect particle residence time and temperature, smaller particles have better heat transfer performance. This study provides theoretical support for application and optimization of CSRD devices.