Photograph of two CSIRO researchers observing a rotating tube producing chaotic mixing.

Industrial mixer creates a stir

CSIRO's Rotated Arc Mixer mixes fluids that cannot be efficiently mixed with other technologies.

  • 13 December 2007 | Updated 4 April 2013

CSIRO fluid engineers have invented an industrial mixer that is five times more energy efficient than traditional  mixers.

The Rotated Arc Mixer (RAM) is also able to mix a range of fluids that other technologies are unable to mix efficiently.

The problem

Current mixing technologies, such as static mixers, can clog and develop material build-up that can result in production downtimes.

Stirred tank mixers, often used in the diary industry, can suffer from large stagnant regions that do not get mixed properly.  

Some mixers are simply too rough and may destroy delicate ingredients. For example, sugarcane requires a delicate mix to preserve and encourage growth of crystals.

What CSIRO did

CSIRO fluid engineers:

  • imagined what the ideal mixer might be like
  • developed mathematical models to see how it would perform
  • built the real thing.

Instead of  beaters, blades or stirrers, RAM has two cylinders, one inside the other. 

The outer cylinder  rotates around the inner cylinder, which is fixed and has apertures cut into it at strategic locations.

As the outer cylinder rotates, fluid moves axially through the inner cylinder.

Drag from the outer cylinder acts on the fluid at each aperture in the inner cylinder, setting up a secondary cross-flow in the fluid.

Flow rate, rotation rate and the size of the apertures can be varied to suit different applications.

RAM lowers mixing energy costs around five times and successfully mixes fluids other technologies cannot mix efficiently.

Outcomes

RAM is able to mix:

  • polymers
  • paints and coatings
  • cosmetics
  • fermentations
  • foods
  • explosives.

RAM is just as effective mixing batches or continuous flows.

Advantages of RAM include:

  • mixing twice as well as equivalent commonly used static mixers
  • consuming five times less energy
  • no stagnant areas
  • ease of cleaning
  • no internal surfaces for material to get caught on
  • easy scale-up as flow fields are the same irrespective of size
  • mixing very thick fluids.

Activity and application

RAM is also being developed as a tool for controlled heating or cooling of fluids, particularly viscous fluids.

This application would be particlularly valuable to the food industry.

RAM has undergone successful trials in several industries and has been licensed to equipment manufacturers supplying the food industry.

Discover CSIRO's capabilities in Simulating the flow of liquids, gases and particles.