Spherical cap bubbles in low density liquids

Abstract

Measurements have been made of the rising velocities and the shapes of spherical cap bubbles in a column 15 cm in dia. The liquids used were water, aqueous solutions of polyvinyl alcohol (PVA) with viscosities up to 216 cP and ethyl alcohol; the gases were air, nitrogen and carbon dioxide. With carbon dioxide mass transfer coefficients were also obtained. Relationships between the measured quantities and the properties of the various liquids are considered. Liquid viscosities up to 50 cP have no effect on either the rising velocity or the shape of spherical cap bubbles. The addition of 0·5 per cent PVA to water results in a sharp drop in the mass transfer coefficient. Further additions cause it to increase and almost return to its original value.