Heat and mass transfer depending on the porous structure of textiles

• Applicants: Professor Dr.-Ing. Götz T. Gresser; Professor Dr.-Ing. Ulrich Nieken
• Subject Area: Technical Thermodynamics
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 453311482

Textiles are products with a wide range of uses and high functional requirements for its mechanical and thermophysiological properties. In contrast to other materials, textiles with diverse fiber, yarn and surface topologies, have a complex “multi-scaled” porous structure. The heat and mass transfer properties of textiles are dominated by the present pore system, which can be described by the porosity, pore diameter and specific surface area. The aim of this research project is to develop and verify new methods of mathematical modeling and numerical simulation for the quantitative prediction of heat and mass transfer in textile porous media using the example of knitted fabrics. Based on the fiber properties and production parameters of the spinning process (yarn) and knitting process (knitted fabric), mathematical pore models of yarn and knitted fabric are developed and parameterized. For modeling and simulating of the effective heat and mass transfer of knitted fabrics based on the material properties and the pore geometry, a multi-stage procedure is proposed. The kinetics of the transport processes and the spatially resolved, multi-phase fluid distribution are examined in a detailed model. For the coarsening, the method of asymptotic homogenization is applied to the heat and mass transfer; in the yarn from the fiber to the fiber bundle and in the knitted fabric from the single stitch to the entire textile. The homogenized model, based on the findings of the detailed simulation, allows the calculation of heat and mass transfer with reduced computation time. The results of the simulations are validated in every step by experimentally determined heat and mass transfer.By predicting the effective pore system and the resulting heat and mass transfer, a new method for the production of knitwear arises in the sense of a "design-follow-function" approach.

• DFG Programme: Research Grants