On single bubble mass transfer in a volatile liquid

Abstract

We consider single bubble mass transfer of an non-condensible gas into a volatile liquid phase in industrial conditions, as observed for example in hydrocarbons liquid phase oxidation processes. Instantaneous bubble size, shape and velocity are measured using image processing with a particle tracking method. The mass transfer rate nitrogen into hot and pressurized liquid cyclohexane is deduced from the bubble volume decrease rate and is compared to literature correlations valid under isothermal conditions. Experiments are performed in a pressurized reactor for P=20bar, 30°⩽T⩽150°C and bubble Reynolds number Re=O(10–100). The analysis of bubble rise dynamics shows that the gas-liquid system studied can be considered as a clean system. The mass transfer results are found to follow isothermal correlations predictions excepted for ambient temperature for which liquid evaporation in bubbles is shown to be coupled with mass transfer. This phenomena seems to be a consequence of having a high Lewis number.