Preliminary Investigation of Novel Direct Contact Ultrasonic Fabric Drying

Thermal evaporation of moisture from clothes is the main technique used in clothes dryers today. Most of the energy supplied is spent to provide the latent heat of evaporation of water (2.5MJ/kg). This paper presents a novel direct contact ultrasonic system to mechanically remove water from wet fabric. The vibrations from the transducers are transferred by direct contact to the water inside the narrow pores of the clothes. Breaking the capillary adhesion of moisture at the interface between air and water allows water to exit the clothes as cold mist. The cold mist also carries with it most impurities such as minerals or detergents. This cannot be achieved in thermal dryers where water evaporates and leaves the impurities behind. Mechanical extraction of water is expected to be more efficient since thermal processing is not required. The majority of the supplied energy is used to mechanically separate water from the fabric. Initial testing has revealed that it is possible to dry a 1 cm² piece of fabric from full saturation to a mere 0.4 % moisture content in just 14 seconds.