Conduction-convection coupled heat and moisture transfer in the open-width pre-drying for elastic fabrics

A novel open-width pre-drying scheme is presented in this study, which utilizes a large drum and hot air as dual heat sources for elastic fabrics. The aim is to prevent the migration of absorbed dye liquor at elevated temperatures and ensure that the elastic fabric attains optimal moisture content. This approach effectively addresses significant challenges in open-width drying, such as fabric deformation, curled edges, and the absence of specialized equipment. These issues have historically hindered the development and application of efficient drying technologies for elastic fabrics. To support this approach, a heat and mass transfer model is established to simulate the pre-drying process, incorporating moisture transfer within the fabric and the transitions between various moisture states. The model also defines boundary conditions based on the fabric's position within the pre-drying setup. The accuracy of the proposed model is validated against experimental data under various conditions, revealing maximum relative deviations of 34.7 % in moisture content and 2.2 % in temperature, along with high correlation coefficients of 0.99 and 0.96. This confirms effectiveness of the model in capturing moisture transfer and heat exchange dynamics during the pre-drying process. The drying process follows a three-stage pattern influenced by parameters such as drum temperature and fabric feed speed. It is recommended to maintain lower drum temperatures while ensuring higher jet temperature, and to optimize drying time by adjusting fabric feed speed. These insights are essential to enhancing drying efficiency and quality in the open-width pre-drying for elastic fabrics.