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Computational fluid dynamics (CFD) was used to investigate the hydrodynamic parameters of two internal airlift bioreactors with different configurations. Both had a riser diameter of 0.1 m. The model was used to predict the effect of the reactor geometry on the reactor hydrodynamics. Water was utilized as the continuous phase and air in the form of bubbles was applied as the dispersed phase. A two-phase flow model provided by the bubbly flow application mode was employed in this project. In the liquid phase, the turbulence can be described using the k-ε model. Simulated gas holdup and liquid circulation velocity results were compared with experimental data. The predictions of the simulation are in good agreement with the experimental data.

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-The effects of aeration velocity and liquid properties on the pertinent hydrodynamic and mass transfer parameters in a split-cylinder airlift reactor (with and without packing) were examined. Four different oil-in-water micro-emulsion systems containing kerosene, heavy naphtha, light naphtha and diesel as the oil at the concentration of 7% (v/v) were used in the experiments and the results were compared with pure water. The experimental results showed that the gas (air) hold-up and the volumetric gas-liquid oxygen transfer coefficient values for the micro-emulsion systems were usually greater than those of pure water. The packing installation increased the overall gas-liquid volumetric mass transfer coefficient by increasing the flow turbulence and Reynolds number, compared to the unpacked column. The packing increased the gas hold-up and decreased the bubble size and liquid circulation velocity. Furthermore, two empirical correlations were developed to predict the overall gas hold-up and volumetric oxygen transfer coefficient. A good agreement was observed between the experimental and correlated data.

Volumetric mass transfer coefficients kLa for CO2 absorption into n‐alkane/water emulsions were determined at oil volume fractions of 0–100 % in a stirred tank at a stirring speed of 1000 min−1. The oil was n‐heptane, n‐hexadecane, or n‐dodecane. The decrease of kLa with increasing volume fraction of dispersed oil can be uniformly correlated to the emulsion viscosity with the power of −0.72. Only the addition of n‐heptane caused a strong increase of the mass transfer coefficient. Upon addition of the surfactant sodium dodecyl sulfate to n‐heptane emulsions, kLa decreased as for the other oils. The increase can therefore be attributed to the spreading of n‐heptane on the bubble surface enabling gas‐oil contact, whereas spreading is inhibited by the ionic surfactant.

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