The property of flow and the transfer of dye through the yarn assembly in a package dyeing process is modelled and simulated to provide a kinetic understanding of the package dyeing process. A novel approach to the modelling of flow in porous media and dye transfer through the package has been presented. The flow properties in package dyeing process have been described by coupling the Navier-Stokes equations with Brinkman equations. The Navier-Stokes equations were also combined with Darcy's law for comparison. The dye concentration in dyebath and on fibres throughout the package has been defined by the mass transfer model, which involved the factors of dispersion, convection, and various adsorption isotherms. The simulation results of the flow model present the velocity and pressure distribution of the flow in the tube and yam assembly. The influence of package factors, such as package size, shape, density, and process parameters, such as flow rate, flow direction, dye/fibre type, and dye concentration in the mixing tank on the outcome of the dyeing process have been examined based on the mass transfer model. The relevant adsorption isotherms can be selected for different dye/fibre combinations, to simulate the dye dispersion process through the package. The relationship between various dye dosing profiles and the degree of levelness achieved is also demonstrated. The use of computational methods to simulate the dyeing process is proved to be a powerful tool providing a kinetic understanding of the flow phenomena and dye transfer in package dyeing process. The predicted behaviour of the liquor flow in both tube and porous package, as well as the dye concentration distributions across the package under different conditions, appear to be in qualitatively good agreement with available experimental data. These models can also be used to design package dyeing apparatus, and select suitable material for the construction of tubes taking into account the static pressure predictions under different flow rates. The selection of correct type of flow meter, and pressure sensors based on their simulated range can also be carried out.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:580623 |
| Date | January 2004 |
| Creators | Zhao, Xiaoming |
| Publisher | Heriot-Watt University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0017 seconds