Influence of ultrasound on heat and mass transfer

Abstract

This paper reports several studies made at West Virginia University in which ultrasound was introduced into some heat and mass transfer systems. The frequency of ultrasound used was 20 and 50 kc/s with sound intensities up to 170 dB. The heat transfer systems investigated included: (1) solar heating of water; (2) heat conduction in metals; and (3) heat convection. It was found that the introduction of ultrasound into a system increased the heat transfer coefficient from 2 to 4 times. The mass transfer systems investigated included: (1) the stimulation of crude oil flow through porous sandstone; (2) the filtration of solids from an oil slurry: and (3) drying of powdered coal with the aid of ultrasound. It was found that the introduction of ultrasound into these different systems substantially increased the liquid flow rate through the porous media used for the processes. Also, it was noted that the constant drying rate was increased when the intensity of the airborne ultrasound used was above 130 dB. [Work supported by Coal Research Bureau, West Virginia University.]