Coarse particle-laden flows and energy dissipation in inclined hydraulic conveying pipes

Abstract

Coarse particle-laden flows in inclined pipes are commonly encountered in a wide range of industrial processes. A fully coupled CFD-DEM model considering various fluid-particle interphase forces and turbulence-particle interactions is used to simulate coarse particles transported in inclined pipes. The energy dissipation is calculated from both the macro and micro perspectives. The effects of pipe’s inclination angle, particle concentration, conveying speed and particle diameter on the hydraulic transport characteristics and the energy dissipations are analyzed. The results showed that, with the increase in inclination angle, the deposited particles were gradually dispersed. Pressure drop and energy dissipation displayed a peak at 60°. Both the parameters increased with the increases in particle concentration and conveying speed in 60° inclined pipe. The energy dissipation was mainly due to the turbulent dissipation, wall friction, mean velocity field and particles’ gravity. The results further showed that the modulations in the fluid due to particle distribution could significantly change the energy dissipation caused by the fluctuating velocity, thus resulting in the maximum pressure drop and energy dissipation at 60°. The particle-fluid energy dissipation increased almost linearly with the increase in conveying speed, while it varied nonlinearly with the increase in inclination angle and particle parameters.