| Drying commonly refers to the process of thermally removing volatile substance from a solid product. The through-air dryer is the most commonly used equipment for drying unbacked tufted carpet. A thorough understanding of the mechanisms that govern the drying process can not only facilitate the design of faster industrial carpet dryers, but also allow for the proper control of high energy-efficient dryers. Research on the drying of tufted carpet can lead to improved production rates and lower operational cost.; This research consists of two major topics, carpet air permeability and through-air drying process. In study of carpet air permeability, the effects of several carpet construction and process parameters on air permeability of unbacked cut-pile nylon carpet with woven polypropylene primary backing were investigated using a modified Frazier air permeability tester (FAPT) and a laboratory through-air dryer (LTAD). The process parameters considered were moisture regain of the carpet and temperature. The construction parameters included primary backing weft density (pick/cm), carpet thickness, pile height, areal density (weight per unit area), tufting density (stitches per unit area), and yarn linear density. A model, based on an equation that includes viscous and inertial terms, was developed to predict pressure drop over the carpet at a given apparent velocity.; The effects of several carpet construction and process parameters on drying rate and time for unbacked tufted nylon carpet were studied using the magnetic resonance imaging system (MRI) and the LTAD. The process parameters included initial moisture distribution within the carpet, airflow direction, airflow rate and air temperature. The construction parameters were primary backing weft density, carpet thickness, areal density, tufting density, and yarn linear density.; A theoretical transient two-dimensional drying model, based on the MRI results, was developed to describe detailed mass, momentum and heat transfer within the yarn and airflow during through-air drying process. To obtain the numerical solution, the model was simplified by considering the major transport mechanisms, and the implicit finite difference method was used. The three unknown transport properties, effective diffusivity and heat and mass transfer coefficients, were obtained by the best fit to the experimental data. The numerical drying results were compared with the experimental MRI and LATD results to validate the accuracy of the drying model. |
