Abstract
Fabric drying is an energy-intensive process, which generally involves blowing hot dry air across tumbling wet fabric to facilitate evaporation and moisture removal. Most of the energy supplied is used to overcome the enthalpy of vaporization for water. Although this process tends to be inefficient, it is fairly simple and forms the basis for the majority of existing clothes dryer technology today. To address the relatively low efficiency, a new method of drying called “direct contact ultrasonic fabric drying” is proposed. The process involves using high-frequency vibration introduced by piezoelectric transducers, which are in contact with wet fabric. The vibration is used to extract water droplets from the fabric mechanically. In this study, a total of 24 individual transducers are used in a module to dry a 142 cm2 sized fabric. The performance characterization of this single module has enabled successful scale-up of the system to a midscale prototype dryer, which can be used to ultrasonically dry clothing-sized fabric (∼750 cm2). The first-generation ultrasonic fabric dryer fabricated uses as little as 17% of the energy needed by traditional evaporation-based drying techniques. In addition to experimental data, this paper presents the results of a kinetic and scaling analysis that provides some important insights into ultrasonic drying.
