where Uba is the terminal bubble velocity.

The liquid superficial velocity (JL) can be easily calculated for external-loop reactors, and for internal loop reactors, JL may be taken as half the liquid velocity in the riser. The viscosity may also play a role in the rate of mixing. An increase in liquid viscosity will increase the energy dissipation in the loop and result in an increase in mixing time and Bo. In non-Newtonian fluids, however, the behavior may be different, as shown in Figure 24. It has been reported that in the case of the addition of polymers that confer pseudoplastic behavior to the liquid, low concentrations produce a decrease of the mixing time (65,129). This can be explained in terms of the drag reduction due to the presence of polymers in the boundary layer near the walls. Fields et al. (129) found that the mixing time increased for concentrations of the natural polymer, xanthan gum, above the critical concentration. (The critical concentration is a theoretically calculated value at which appreciable overlapping of polymer molecules occurs and which marks the onset of a rapid increase of the apparent viscosity [130]).

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Brew Your Own Beer

Discover How To Become Your Own Brew Master, With Brew Your Own Beer. It takes more than a recipe to make a great beer. Just using the right ingredients doesn't mean your beer will taste like it was meant to. Most of the time it’s the way a beer is made and served that makes it either an exceptional beer or one that gets dumped into the nearest flower pot.

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