Rheometer could determine viscosity during manufacture

Scientists at Sheffield University are moving closer to commercialising a sensor that could improve how liquid viscosity is measured in manufacturing.

The researchers are working with several companies from different industries to develop a production version of their novel rheometer, which enables engineers to monitor how a liquid’s viscous components change in real time during a manufacturing process.

‘We’ve been told it could be used for any process that involves a fluid flowing,’ research leader Dr Julia Rees, who is a senior lecturer in the university’s department of applied mathematics, told The Engineer.

‘The food industry springs to mind but it can also be used for personal-care products such as creams and cosmetics. It can be used in processes that involve polymers and also for the oil industry.’

The sensor will enable companies to monitor the viscosity of liquids while they are still in the manufacturing process, rather than having to take samples and test them separately.

It works by measuring several of the individual parameters that can be used to calculate viscosity, such as shear rate — how much the speed of the liquid changes over a given interval.

‘Traditionally, to measure viscosity you’d have to do a separate experiment for each shear rate,’ said Rees. ‘We came up with the idea of a T-junction channel, so the fluid comes up the main channel and when it turns the corner its velocity is zero but further away from the corner it moves more quickly.

‘By making it turn the corner, you induce a wide range of shear rates in a single geometry. It enables you to design a sensor that gives responses in real time, so that feature coupled with fast mathematical algorithms will permit real-time monitoring.’

In October 2011, The Engineer reported on how the Sheffield team had developed a laboratory prototype of the system. The researchers are currently working on a mark-two prototype that will use more robust materials than the initial version and will include a temperature control system to keep the sample inside the sensor at the same temperature as the rest of the liquid.

Rees said the device would need to be optimised to meet the specific standards of the different industries that might use it, but added that, generally, a standard design could be used for different applications.