CSIRO develop mixing technology for efficiency increase

Australian scientists have produced a new mixer that is five times more energy efficient than traditional industrial mixing for everything from explosives to cosmetics. The CSIRO Rotated Arc Mixer (RAM) mixer can also mix thick fluids well.

"The RAM overcomes many mixing problems. For example, static mixers used in cosmetics manufacture have baffles, plates and constrictions that result in regions that clog and cause material build-up," Inventors Dr Guy Metcalfe and Dr Murray Rudman of CSIRO Thermal & Fluids Engineering said.

"Stirred tank mixers used in the dairy industry, can suffer from large stagnant regions (badly mixed regions leading to waste raw material) and high energy consumption. Stirred-tank mixers are also normally characterised by regions of high shear (turbulence)."

Dr Rudman says that the regions of high shear may destroy delicate products or reagents, such as the biological reagents involved in fermentation in food processing.

Similarly, regions of high shear may produce poor mixing in explosives resulting in inferior explosive performance.

The basic configuration of the RAM is an outer cylinder that rotates around a fixed inner cylinder, which has flow apertures cut at strategic locations depending on the material being mixed.

As the outer cylinder rotates, fluid is moved axially through the inner cylinder. The viscous drag from the outer cylinder, which acts on the fluid in the region of each flow aperture, sets up a secondary (transverse) flow in the fluid.

"The key to the RAM mixer's success is these forces that produce very effective chaotic mixing of highly viscous fluids in either batch or continuous (through-flow) modes," Dr Metcalfe said.

For further information please contact CSIRO