Elongated gas bubble dissolution under a turbulent liquid flow

Mass transfer between an elongated homogeneous gas bubble under a turbulent liquid flow in a duct is investigated experimentally. Elongated gas bubble dissolution is encountered in bioengineering tubular photobioreactors. Such reactors are interesting because they are compact, they have a low contamination risk and a low mechanical stress for a liquid phase containing fragile microalgae cells. It is demonstrated from experimental mass transfer measurements, that the interface of an immobilised elongated bubble can be approximated to a flat plane. Measured mass transfer experimental data, estimated using this simplification, appear to be well fitted by ShL = 1.76 × 10−5 × Re1.506 × Sc0.5, a correlation from Lamourelle and Sandall [8], given for a turbulent liquid flow in wetted-wall columns. A formula drawn from this hypothesis is proposed for mass transfer prediction in photobioreactors. For different applications, it is suggested that the results obtained for the studied geometry could be used to build mass transfer feedback control systems.

► Mass transfer between an elongated gas bubble and a turbulent liquid flow is studied.
► The elongated gas bubble mass transfer interface can be considered as flat.
► The molecular transfer rate and the bubble length are linearly related.