Experimental Study of the Mixing Time in a Jet-Mixed Gas-Liquid System

In the present work, the impeller in the conventional gas-liquid mixed vessels was replaced by a fluid jet as the mixer. Using an experimental setup, the effect of several parameters on the mixing time as a measure of the liquid-phase mixing intensity, which is one of the required transport characteristics for designing gas-liquid mixed systems, was studied. The results show that gas injection decreases the mixing time in comparison with the ungassed condition, but the mixing time is not necessarily decreased by increasing the gassing rate. On the basis of the amount of the jet Reynolds number and gassing rate, and thus the created circulation pattern, the mixing time may be decreased or increased. Also, the location of the probe for cases in which there are more dead zones in the vessel have a considerable effect on the measured mixing time. With increasing uniformity of the velocity domain, the influence of the probe location was reduced. Also, by increasing the jet flow rate and decreasing the nozzle diameter, the length of the jet, the amount of entrained bulk fluid, and the intensity of recirculation flow increased, and thus the mixing time decreased.