A new design of transfer chute, with a low cost-to-benefit ratio, to solve a problem so intrinsic with chutes designed before it
The academic team at The University of Manchester have developed a new design of transfer chute, with a low cost-to-benefit ratio, to solve a problem so intrinsic with chutes designed before it.
These specially designed chutes utilise a series of obstacles, which automatically prevent a granular avalanche from accelerating as it flows downwards. As a result, the velocity and thickness at the outflow are precisely the same as the inflow, regardless of the chute length and for a wide range of inclination angles. This gives unprecedented control of granular free-surface flows.
Gravity-driven transfer chutes are used extensively in industry to move granular materials between different processing units. The granular avalanches that develop on these chutes result in a stream of particles leaving the chute that is often poorly mixed or segregated. These failures can have dramatic consequences for the final product, and can lead to higher manufacturing costs, increased waste, and product recalls.
This design of chute avoids separation of the granular materials, and maintains carefully-mixed bulk formulations, as they are transported through the supply chain from producer to packager. Without this design, household goods can end up over- or under-strength, resulting in a final product that does not taste or perform as intended, leading to complaints and loss of brand confidence.
The novel chute design gives significant competitive advantages, such as a well-mixed outflow, a minimisation of material scrappage and wastage, and reduced plant downtime. The novel design can be retrofitted to existing chutes without additional space required, making it a cost-effective remedy to current designs.
An experiment showing the time evolution of the jet to the steady state. As the oncoming material flows over the top of the bump it is able to detach from the base and follow ballistic trajectories, before landing and coming into contact with the chute once again.
An experiment showing the time-dependent evolution of the shock towards steady state. As the oncoming material from the inflow collides with the layer of static particles upstream of the bump there is a sharp decrease in bulk velocity and associated increase in flow thickness. This shock propagates upstream until it reaches an equilibrium position.
A lab prototype has been developed and demonstrated that particle-size segregation may be used against itself to mix grains, rather than separate them, fulfilling an unmet need in industry.
