Numerical and experimental modelization of the two-phase mixing in a small scale stirred vessel.

The numerical prediction of mass transfer rates of gas components within the liquid phase in a stirred two-phase flow reactor is presented. Experiments have been conducted to determine the flow regime and the number and sizes of the bubbles formed under different conditions. The dynamic field of the two-phase flow was obtained through numerical simulations. Bubbles with the experimentally measured diameter were released from the free surface and tracked numerically to compute the particle Reynolds number, which is used to determine the mass transfer rates. The unbaffled reactor provides mass transfer rates 30% larger than the baffled reactor for the bubbly flow. Mass transfer rates drop about 65% when the emulsion is formed. Therefore, above the critical rotation rate at which the emulsion forms for the unbaffled reactor, the baffled configuration provides larger mass transfer rates. The results indicate that even for the most unfavorable case mass transfer is not the limiting step, as 90% of the equilibrium concentration is reached in 10 s. [ABSTRACT FROM AUTHOR]