Study of raw cotton and fine debris movement in a pneumatic conveying system and reduction of impurity concentration in bunker cotton

Abstract

This article analyzes the movement of raw cotton and small debris in the pneumatic conveying system used by cotton pickers. The numerical study was conducted using the Ansys Fluent software package, which offers extensive turbulence modeling capabilities, including RNG k-ε, SST k-ω, LES, and other models. These features allow for a detailed examination of the turbulent fluctuations affecting particle trajectories. The numerical calculations revealed that when small debris approaches cotton bundles, some particles cling to and penetrate deeply between the cotton fibers, while others bend around the cotton bundles and continue moving. The study's results indicate that to reduce the contamination of raw cotton with small debris during its passage through the pneumatic conveying system, it is advisable to lower the debris concentration in the air-cotton mixture. Furthermore, it was found that using a U-shaped receiving chamber in the pneumatic conveying system significantly decreases the concentration of cotton debris in the air, leading to a 20–25% reduction in impurities in the bunker raw cotton collected by a vertical spindle cotton harvesting machine.