Mixing time of a non-Newtonian liquid in an unbaffled agitated vessel with an eccentric propeller

Abstract

Experimental study of mixing time of non-Newtonian shear-thinning fluids within the transitional regime (3 × 102 < Re < 3 × 103) of liquid flow is presented. The purpose of this study was to analyze the effect of eccentricity and pumping mode of the impeller as well as of position of the tracer dosage point into the agitated liquid on mixing time. The measurements were conducted in an unbaffled agitated vessel with inner diameter D = 0.7 m equipped with an up-or down-pumping propeller located centrically (e/R = 0) or eccentrically (e/R ≠ 0) in the vessel. Experiments were carried out by means of computer-aided unsteady-state thermal method for three positions of the tracer dosage point. The experimental data show that eccentric position of the propeller in an unbaffled vessel causes a decrease of the mixing time compared to that obtained in a vessel with a centrically located propeller. Mixing time depends also on the pumping mode of the propeller as well as on the position of the tracer dosage point.

Numerical investigation of hydrodynamic behavior of shear thinning fluids in stirred tank

“…Hence, the mixing of highly viscous nonNewtonian fluid is usually carried out at low Reynolds number in laminar or the early transition regime [3]. Even for the low viscous non-Newtonian fluids, the study of mixing is restricted to laminar and transition regimes [4][5][6][7][8]. Nouri and Whitelaw [9] and Koutsakos and Nienow [10] investigated the effect of non-Newtonian liquid properties on the mixing performance of stirring vessels.…”

“…Khapre, B. Munshi / Journal of the Taiwan Institute of Chemical Engineers 000 (2015) [1][2][3][4][5][6][7][8][9][10][11][12] …”

Investigation of mixing time in liquid under influence of rotating magnetic field

“…Most investigations have examined the mixing time and power consumption of agitation systems resulting in empirical correlations Manjula et al 2009;Szoplik and Karcz, 2008;Woziwodzki et al, 2010;Zadghaffari et al, 2006).…”

The simplest stirred tank for laminar mixing: Mixing in a vessel agitated by an off‐centered angled disc

“…Seminal work in eccentric stirred tanks agitated with a horizontal disc (with no blades) or with an axial impeller (four‐bladed) in a flat bottom tank was conducted by Alvarez et al and Sánchez‐Cervantes et al The flow structure in these systems was described using planar laser‐induced fluorescence (p‐LIF) experiments. Although several studies have been recently published on the subject of eccentrically agitated stirred tanks, a detailed characterization of mixing and axial flow enhancement in eccentrically agitated laminar tanks is not yet available.…”