Measurements and analysis of oxygen bubble distributions in LiCl–KCl molten salt

Abstract

Transparent system experimental studies have been performed to provide measurement and analysis of oxygen bubble distributions at different sparging rates in LiCl–KCl molten salt at 500°C using a high-speed digital camera and an oxygen sensor. The results reveal that bubble sizes and rise velocities increased with an increase in oxygen sparging rate. The bubbles observed were ellipsoidal in shape, and an equivalent diameter based on the ellipsoid volume was calculated, ranging from 0.00263m to 0.00407m. Results also show that the bubble equivalent diameters are normally distributed. A Fanning friction factor correlation was used to predict a bubble's rise velocity. The oxygen mass transfer coefficients were calculated using the oxygenation model; these values were on the order of 10−4m/s and followed a decreasing trend corresponding to an increasing bubble size and sparging rate. The diffusivities were calculated based on two different approaches—one based on physics of the bubbles and the other on systematic properties. The diffusivity values calculated from bubble physics are 1.65×10−9m2/s to 8.40×10−9m2/s, which are within the range suggested by literature for gases in liquids of a similar viscosity.