2015 Volume 48 Issue 7 Pages 518-522
While the chaotic degree can be efficiently increased by the temporal terms such as co-reverse periodic rotational impeller speed and time-periodic fluctuation of rotational impeller speed, the approach is nevertheless limited in practical applications because of the restriction of the motor and the speed reducer machine. Practically, the temporal approach has rarely been employed in the mixing operation in the process industries, except for washing machines. In contrast, the spatial way can also increase the chaotic degree by reducing the circumferential symmetry and shifting the complexity of the attractors or strange attractors in normal mixing equipment. In fact, the spatial way does not improve the mixing performance as impressively as the temporal way, but it has less demanding requirement on the machines. Consequently, the approach has been widely used in industry, however the comparison among the mixing performances of different spatial chaotic mixing methods has almost never been reported.
In this work, we measured the mixing times and power consumptions for several different spatial chaotic mixing methods, such as an off-center impeller, inclined impeller and inserting an object in identical agitated vessels agitated by the same impeller, and the comparison of mixing performances among these methods was conducted. As a result, it was found that the inserting of an object is the best method among the spatial chaotic mixing methods to achieve a short mixing time at a low power consumption.
