Influence of permeability and pressure on the dye concentration profile in acrylic yarn bobbins in bidirectional flow by simulation

摘要

A two-dimensional process of dyeing yarn coils was modelled in COMSOL Multiphysics to evaluate the dyeing characteristics according to a pilot-scale process. The proposed mathematical model was able to reproduce the experimental data and great importance was identified for the dyebath flow through the axial exit of the coil in relation to the radial outlet, about 2.8 times greater. To maintain the same flow, the permeability of the bobbin decreased tenfold between the radial and two-dimensional flow. Changes in the pressure gradient greatly influence the velocity field. The velocity and concentration fields found reinforce the preferential use of dyeing bobbins that do not have gaps between them, forcing the dyeing bath to follow the radial flow.