(429f) Effect of Fluid Viscosity Ratio On Mixing in a Static Mixer | AIChE

(429f) Effect of Fluid Viscosity Ratio On Mixing in a Static Mixer

Authors 

Caramellino, M. - Presenter, New Jersey Institute of Technology
Armenante, P. M. - Presenter, New Jersey Institute of Technology


In this work, a static mixer designed for laminar flow regime was used to study the mixing process of two miscible Newtonian fluids having different viscosities, i.e., water and solutions of different grades of hydroxypropyl methylcellulose (HPMC) polymers. The mixer was composed of 10 elements, each with a 90 degree rotation with respect to the previous one. Both Computational Fluid Dynamics (CFD) and experiments were used to characterize the mixing process as the two fluids moved through the elements of the static mixer. Planar Laser Induced Fluorescence (pLIF) was the experimental technique utilized here to quantify the mixing process. Accordingly, a fluorescent dye was added to one of the two fluids in order to track the position of the fluid elements. The distribution of the dye was obtained at planes at the exit sections of each mixer element and the striation thickness measured. The effect of various viscosity ratios ( up to 1000) as well as different flow rate ratios between the high and low viscosity fluids were investigated.

The number of mixing elements used clearly affected the quality of the mixing process, as indicated by the striation thickness. Both experiments and simulations showed that an increased number of mixer elements is necessary to mix fluids having large viscosity differences. In addition, when the small amount of the low viscosity fluid was added to the high viscosity one, the mixing task became significantly more difficult.