Heat and mass transfer in a semi-porous textile composite

This research provides the thermal characteristics for two different drying processes for semi-porous textile composites. A mathematical model has been created for a batch drying process characterized by a parallel flow field boundary condition. The conservation of total mass, species, momentum, and energy are written for a moist porous fiber layer attached to a solid-backing layer. The numerical solution of the one-dimensional and transient conservation principles provides for the temperature, volumetric saturation, and gas phase pressure distributions in the porous solid and the temperature distribution in the solid-backing. The drying process for this model analysis is described by a two regime heat and moisture transport process.; The theoretical model results are compared to experimental data obtained from a laboratory controlled batch drying process. The batch dryer used to dry modular carpet tiles is characterized by the parallel air flow type boundary condition. The modular carpet tile is instrumented with thermocouples at various levels of its thickness to provide temperature-time history curves of the porous fiber and solid-backing materials. The porous specimen is instantaneously weighed in order to provide the overall moisture content of the material during drying.; In order to study the transport phenomena in a porous material subjected to a continuous industrial drying process, the mathematical model derived for the batch drying process is applied to the high heat flux multiple jet impingement type dryer. In this case, it is assumed that the penetration of the flow field into the porous solid is small (assumed valid due to the presence of the solid-backing) with the only modification to the theory occurring at the drying surface heat and mass transfer rates. This dryer type is described by turbulent jet impingement heat and mass transfer coefficients. The enhanced transport coefficients at the drying surface are estimated with the use of the Kolmogoroff theory of isotropic turbulence.; The model results of the continuous industrial drying process are compared to independent experimental temperature and global moisture content measurements taken in a currently operating industrial dryer. Temperature measurements are made both in the moist porous fiber layer as well as in the solid-backing layer.