Next Article in Journal
Fast Models of Hydrocarbon Migration Paths and Pressure Depletion Based on Complex Analysis Methods (CAM): Mini-Review and Verification
Next Article in Special Issue
Effect of Surface Topography on Particle Deposition from Liquid Suspensions in Channel Flow
Previous Article in Journal
Viscosity-Enhanced Fluid Drift around Hairy Structures
Previous Article in Special Issue
Multi-Scale Modeling of the Dynamics of a Fibrous Reactor: Use of an Analytical Solution at the Micro-Scale to Avoid the Spatial Discretization of the Intra-Fiber Space
Open AccessArticle

Effect of Vertical Vibration on the Mixing Time of a Passive Scalar in a Sparged Bubble Column Reactor

Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK 74078, USA
*
Author to whom correspondence should be addressed.
Received: 14 November 2019 / Revised: 20 December 2019 / Accepted: 3 January 2020 / Published: 4 January 2020
(This article belongs to the Special Issue Coupled Flow and Heat or Mass Transport)
The present study used a sparged bubble column to study the mixing of a passive scalar under bubble-induced diffusion. The effect of gas superficial velocity (up to 69 mm/s) and external vertical vibrations (amplitudes up to 10 mm, frequency <23 Hz) on the mixing time scale were investigated. The bubble-induced mixing was characterized by tracking the distribution of a passive scalar within a sparged swarm of bubbles. Void fraction and bubble size distribution were also measured at each test condition. Without vibrations (static), the bubble column operated in the homogenous regime and the mixing time scale was insensitive to void fraction, which is consistent with the literature. In addition, the temporal evolution of the static column mixing was well approximated as an error function. With vertical vibrations at lower amplitudes tested, the bubble-induced mixing was restrained due to the suppression of the liquid velocity agitations in the bubble swarm wake, which decelerates mixing. Conversely, at higher amplitudes tested, vibration enhanced the bubble-induced mixing; this is attributed to bubble clustering and aggregation that produced void fraction gradients, which, in turn, induced a mean flow and accelerated the mixing. The vibration frequency for the range studied in the present work did not produce a significant effect on the mixing time. Analysis of the temporal evolution of the concentration of the passive scalar at a fixed point within the column revealed significant fluctuations with vibration. A dimensionally reasoned correlation is presented that scales the non-dimensional mixing time with the transient buoyancy number. View Full-Text
Keywords: bubble column; homogeneous bubble swarm; bubble-induced mixing; bubble size; void fraction; diffusion; passive scalar; specific input power; vibration; mixing time bubble column; homogeneous bubble swarm; bubble-induced mixing; bubble size; void fraction; diffusion; passive scalar; specific input power; vibration; mixing time
Show Figures

Graphical abstract

MDPI and ACS Style

Mohagheghian, S.; Ghajar, A.J.; Elbing, B.R. Effect of Vertical Vibration on the Mixing Time of a Passive Scalar in a Sparged Bubble Column Reactor. Fluids 2020, 5, 6.

AMA Style

Mohagheghian S, Ghajar AJ, Elbing BR. Effect of Vertical Vibration on the Mixing Time of a Passive Scalar in a Sparged Bubble Column Reactor. Fluids. 2020; 5(1):6.

Chicago/Turabian Style

Mohagheghian, Shahrouz; Ghajar, Afshin J.; Elbing, Brian R. 2020. "Effect of Vertical Vibration on the Mixing Time of a Passive Scalar in a Sparged Bubble Column Reactor" Fluids 5, no. 1: 6.

Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop