Analyzing Convective Heat and Mass Transfer in Through-Air Drying of Fabrics

In studying the through-air drying (TAD) of tissues and towels, the drying and heating of TAD fabrics as part of the overall system is considered for the first time. For a simple, single-layer TAD fabric structure, convective drying and heating is modeled using well- known heat and mass transfer models developed in general chemical engineering practice. The models are circular pipe flow, flow over cylinder, and packed bed. All three models predict a long fabric drying period and a quick fabric heating period. The constant temperatures of the fabrics during the fabric drying period predicted by all three models are nearly the same, and are close to the adiabatic saturation temperature of the inlet air, depending only on the temperature and supply humidity and not on the air flow rate. The drying rates predicted by the packed bed and flow over cylinder models are significantly higher than that by the circular pipe flow model. Further verification of the suitability of using either the packed bed or the flow over cylinder model to simulate fabric drying and heating during through-air drying is suggested.