The axial dispersion of liquid solutions and solid suspensions in planar oscillatory flow crystallizers

In this research paper the residence time distribution (RTD) was monitored for a range of fluid oscillation, frequency, amplitude and flow rate in two oscillatory flow reactors (OFR) provided with 2D smooth periodic constrictions (2D-SPC) with different designs. It was studied the axial liquid dispersion using axial dispersion model and the mixing efficiency using tank-in-series model for continuous mode. Two cases, with and without fluid oscillation, were studied and determined the optimum conditions to ensure a close plug flow, an efficient mixing and a low axial liquid dispersion. The optimum operation conditions for the two 2D-SPC designs were found. Moreover, the effect of open cross-sectional area (a) on mixing and axial dispersion was also investigated. For low cross-sectional area values the mixing is higher. It was observed that fluid oscillation increases the mixing intensity even at lower flow rates, and the axial dispersion increases as the flow rate increases.

Download Full-text

Experimental axial dispersion for oscillatory flow through a baffled tube

Chemical Engineering Science ◽

10.1016/0009-2509(90)87127-e ◽

1990 ◽

Vol 45 (5) ◽

pp. 1349-1358 ◽

Cited By ~ 24

Author(s):

T. Howes ◽

M.R. Mackley

Keyword(s):

Oscillatory Flow ◽

Axial Dispersion ◽

Flow Through

Download Full-text

Oscillatory flow and axial dispersion in packed beds of spheres

Chemical Engineering Science ◽

10.1016/j.ces.2004.07.061 ◽

2005 ◽

Vol 60 (1) ◽

pp. 111-122 ◽

Cited By ~ 7

Author(s):

B.D. Crittenden ◽

A. Lau ◽

T. Brinkmann ◽

R.W. Field

Keyword(s):

Oscillatory Flow ◽

Axial Dispersion ◽

Packed Beds

Download Full-text

Numerical Analysis of Axial Dispersion in an Intermittent Oscillatory Flow.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B ◽

10.1299/kikaib.59.3078 ◽

1993 ◽

Vol 59 (566) ◽

pp. 3078-3085 ◽

Cited By ~ 2

Author(s):

Hideki Fujioka ◽

Gaku Tanaka ◽

Masahiro Nishida ◽

Kazuo Tanishita

Keyword(s):

Numerical Analysis ◽

Oscillatory Flow ◽

Axial Dispersion

Download Full-text

Augmentation of Axial Dispersion by Intermittent Oscillatory Flow

Journal of Biomechanical Engineering ◽

10.1115/1.2798008 ◽

1998 ◽

Vol 120 (3) ◽

pp. 405-415 ◽

Cited By ~ 7

Author(s):

G. Tanaka ◽

Y. Ueda ◽

K. Tanishita

Keyword(s):

Stationary Phase ◽

High Frequency ◽

Oscillatory Flow ◽

Effective Diffusivity ◽

Axial Dispersion ◽

High Frequency Oscillation ◽

Gas Transfer ◽

Straight Tube ◽

Gas Dispersion ◽

Molecular Diffusivity

The efficiency of axial gas dispersion during ventilation with high-frequency oscillation (HFO) is improved by manipulating the oscillatory flow waveform such that intermittent oscillatory flow occurs. We therefore measured the velocity profiles and effective axial gas diffusivity during intermittent oscillatory flow in a straight tube to verify the intermittency augmentation effect on axial gas transfer. The effective diffusivity was dependent on the flow patterns and significantly increased with an increase in the duration of the stationary phase. It was also found that the ratio of effective diffusivity to molecular diffusivity is two times greater than that in sinusoidal oscillatory flow. Moreover, turbulence during deceleration or at the beginning of the stationary phase further augments axial dispersion, with the effective diffusivity being over three times as large, thereby proving that the use of intermittent oscillatory flow effectively augments axial dispersion for ventilation with HFO.

Download Full-text