Investigation of fabric movement in a tumble dryer for the development of drying methods for wool fabrics to save energy

Tumble dryers are widely used for drying garments, but felting shrinkage can be caused to wool garments during the tumble drying process. To dry wool fabrics or garments in tumble dryers, the flat dry function has been introduced in the dryers; however, the energy efficiency is very low. The current study investigated fabric movement at different rotation speeds in the tumble dryer and their resultant performances in terms of specific moisture extraction rate, evenness of drying, fabric shrinkage, and fabric smoothness. For shrink-resist-treated wool fabrics, tumble drying at the rotation speed to keep fabric movement in projectile motion accompanied with occasional tumbling could achieve better energy efficiency, drying uniformity, and fabric smoothness. For untreated wool fabrics, introducing vertical movement to the flat dry in the tumble dryer can improve the heat exchange between the fabric and hot air, resulting in an increase in energy efficiency of approximately 30% compared with motionless flat drying. Wool fabric shrinkage can be controlled at less than 2% with the smooth appearance of fabric at grade 3.5 after drying under the recommended drying condition. This study could help tumble dryer manufacturers design optimal drying methods for wool fabrics with the potential for the reduction of energy consumption.