Preliminary Investigation on Hydrodynamics

Characteristics of Oscillatory Flow Technology

in Minichannels

Kirubanandan. Shanmugam,

Graduate Research Student,

Minifluidics Research Laboratory,

Dept. of Process Eng.

Dalhousie University.

Dr. Adam. A. Donaldson,

Principal Investigator and Assistant Professor,

Minifluidics Research Laboratory,

Chemical Engineering,

Dept. of Process Eng.

Dalhousie University.

Oscillatory Flow in Process Equipment

• Radial mixing through vortex shedding propagation

A.P. Harvey, M.R. Mackley, T. Seliger. “Operation and optimization of an oscillatory

flow continuous reactor” Ind Eng Chem Res, 40 (23) (2001), pp. 5371–5377

Mini-fluidic Contactors for Enhancing Mixing

• Mixing/Heat transfer enhanced through static mixing

geometries

Objectives of Work

• Can we induce an oscillating field into a mini-fluidic

system?

• Challenges:

• Avoiding cavitation on suction-based systems

• Scale of geometries limit the use of moving baffles

Context of Work Compared to Passive Mixers

• Heat transfer analysis through scaling of conventional

correlations – representative of mixing

(Not to scale)

• Assumed properties of water

Nu vs. Energy Dissipation

Reo/Re ranging from:

0.2 at high Re

to 4 at low Re

Dfx ooo

)2(Re

Comparison to Other Geometries?

dh ~ 0.67 mm

dh ~ 1mm

Corning

“Heart”

reactor

Data from Plouffe P., Anthony R., Donaldson A., Roberge D.M.,

Kockmann N., Macchi A., ICNMM 2012

Preliminary Trial

• Development and characterization of a

“high-frequency” oscillating pressure field generator

(0 to 30 hz) with significant displacement capabilities

• experimental analysis of Oscillatory flow in existing

experimental set up.

Experimental System in Development

• Design of coupled high-speed switching

device for alternating the pressure field

• Resistance model & characterization of

flow (fluid displacement vs. time under

oscillatory conditions)

Results – 69 RPM, 1.17 Hz

Results – 175 RPM, 2.93 Hz

Results

• Generated Oscillatory flow at two different

frequencies (1.17 hz and 2.93 hz)

• Re0 = 8731, based on the L/d estimated for both flow

paths between sensors and pressure-based flow

assumptions.

Challenges

• Current valve design has packing issues with

continuous rotation

• Noisy signal for quantified analysis

• Flow path bypassing when valve rotating. Appears to

reduce when rotation initiated (based on pressure

field).

Conclusion

• Rotating valve assembly was able to generate an

oscillatory pressure field that could potentially apply

in the low energy dissipation region

• A number of challenges still exist in it’s use,

specifically in terms of inducing net flow, avoiding

leaks, and characterization at higher oscillation

frequencies with the signal noise.

Questions

Description of Conventional Correlations

References

1. P.Stonestreet and A.P.Harvey. “A mixing based design methodology for

continuous oscillatory flow reactors" Trans.I.Chem.Engg. 80, pp 31-44, 2002.

2. A.P. Harvey, M.R. Mackley, T. Seliger. “Process intensification of biodiesel

production using a continuous oscillatory flow reactor” Journal of Chemical

Technology and Biotechnology, 78 (2–3) (2003), pp. 338–341.

3. A.P. Harvey, M.R. Mackley, T. Seliger. “Operation and optimization of an

oscillatory flow continuous reactor” Ind Eng Chem Res, 40 (23) (2001), pp. 5371–

5377.

4. Norbert Kockmann and Dominique M.Roberge. “ Scale-up concept for modular

micro structured reactors based on mixing, heat transfer and reactor safety”

Chemical Engineering and Processing, 50, 1017-1026,2011.

5. M.R. Mackley and P.Stonestreet. “Heat Transfer and Associated Energy

Dissipation for Oscillatory flow in Baffled tubes” Chemical Engineering Science,

50,14,2211-2224,1995.