A
drying apparatus and method including heated
airflow and ultrasonic transducers. The ultrasonic transducers are arranged and operated for effectively breaking down the boundary layer to increase the
heat transfer rate. The ultrasonic transducers are spaced from the material to be dried a distance of about (λ)(n / 4), where λ is the
wavelength of the ultrasonic oscillations and n is an odd integer (i.e., 1, 3, 5, 7, etc.). In this way, the amplitude of the ultrasonic oscillations is maximized to more-effectively agitate the boundary layer. In addition, the ultrasonic transducers are operated to produce about 120-190 dB (preferably, about 160-185 dB) at the interface surface of the material to be dried. In one embodiment, the ultrasonic transducers are of a pneumatic type. In another embodiment, the ultrasonic transducers are of an electric type. And in other embodiments,
infrared and / or UV light devices are included for further boundary layer disruption.