Case studies
Process modelling and automation
Modelling jelly flow to cut waste and save money - an investigation of faucet flows and tailing in the food industry
The Centre for Food Innovation been modelling the flow characteristics of jelly as it flows into moulds to solve a common problem in food manufacture.
Dripping or jetting fluids from nozzles into various containers or moulds is common in the food industry, particularly in the confectionery sector. The research has been examining the extrusion process of a starch/gelatine jelly mix to establish how the flow can be better controlled to give a clean mould fill with as little waste as possible.
In the process examined, the extruded mixture is pushed via positive pressure gradient through a nozzle, creating a jet flowing into a mould. A reversal, or cut in the pressure gradient, breaks the jet flow and the filled mould moves on. The whole process is then repeated with the next mould.
The problem
In the examined system, it is sometimes observed that during this reversal or cut in the pressure gradient, the jet thins but does not break. This forms a tail of jelly between moulds, creating waste and a messy process line. Elimination of the tailing would result in a cleaner and more efficient process.
Researchers established that the tailing was due primarily to the jelly mixture behaving as a non-Newtonian viscoelastic fluid. A state that lies between a simple liquid and a simple crystalline solid and showing intermediate properties of elasticity and viscosity with a time dependant strain property.
The solution
In order to improve the process and reduce the tailing and amount of waste, the research team have built a model system in which they can change various parameters. For example, they have tested the effect of changing the nozzle shape and the pressure profiles to see what effect this has on the problem. All of this is possible without interfering with the real production line.
Early results, which as yet need to be confirmed with viscoelastic component included, suggest that breaking the jet closer to the nozzle and having a sharp discontinuity in applied pressure can dramatically improve the tailing problem.
The benefits
The development of model systems allows complex engineering and fluid flow problems to be investigated and modified without interfering with the actual production line. It also allows a range of factors to be changed to see their individual effects on the desirable characteristics of the system. Such an approach allows complex problems to be broken down to their contributory parts and the best approach to process improvement to be determined.
The research team are currently working on the inclusion of non-Newtonian viscoelastic effects using the Maxwell model.
If you have fluid flow and deposition activities in your product process, then the predictive modelling system could be used to suggest ways to improve your system. If existing models cannot be adapted to suit your setup, new models can be developed to take into account all the relevant parameters of your particular system.
