Effects of agitation and aeration in mixing time determination for viscous suspensions using Double Indicator System

Abstract

Mixing time is the time taken to achieve a predefined level of homogeneity of the mixture in a reaction vessel using a tracer. It is one of the key parameters to evaluate the mixing efficiency in agitated systems. In order to make this definition valid, the tracer should be in the same physical phase (e.g. liquid) as the bulk material. In this study, determination of mixing time was done by Double Indicator System for Mixing Time (DISMT), which is a colorimetric method that indicates homogeneity in the reaction mixture composition. Here, we attempted the determination of mixing parameters by varying energy input configurations, i.e., with only mechanical agitation, with only aeration, and combination of agitation and aeration using different liquid broths, viz., water, 5%(w/v) of Sucrose,Starch,Polyethylene glycol, and Glycerol. DISMT experiments were conducted using food colors as indicators and confirmed the use of these food colors as tracers. In addition, the dependence of mixing time on gas (air) hold up was also elucidated experimentally.