Homogenization of liquids inside a new soft elastic reactor: Revealing mixing behavior through dimensional analysis
Résumé
A novel mixing device (Soft Elastic Reactor – SER) that induces mixing by vibration of the tank wall is
presented and characterized using dimensional analysis. This type of mixing system, which does not have
an agitator inside the tank, is interesting for specific mixing applications, although it is still seldom used
due to the lack of knowledge about how it works. First, the set of dimensionless numbers governing the
mixing time of the SER was established. Then, the shapes of mixing curves and the onset of different mixing
regimes as a function of the fluid property (i.e., viscosity) and operating conditions (i.e., penetration
depth and vibration frequency) were experimentally obtained. Results showed that a constant number of
beatings is required to achieve the desired degree of homogeneity under a laminar regime, while a sharp
decrease in the number of strikes can be observed when the laminar regime is over. The shape of the mixing
curves for the SER was compared to those of conventional mixers in which agitation is ensured by the
revolution around a vertical axis of a centered agitator. Similarities between the mixing curves are discussed:
it appears that regardless of the mixer type, the key parameter governing the desired degree
of homogeneity is the number of excitation cycles, i.e., either the number of agitator revolutions for classical
mixers or the number of strikes for the SER.