Positron Imaging Centre

Examples of Research Using Birmingham Facilities

PEPT Data from Spouted Fluidised Bed

The second image above shows a typical particle track. This track represents five seconds worth of particle motion within a spouted fluidised bed (image far left). We can use the raw particle track data to produce a number of plots. For example analysing the particle tracks allows the production of velocity vector plots (third image). By analysing the amount of time a particle spends within a particular region of the bed gives us the occupancy plot (fourth image); in certain condidtions this can be related to the density of the bulk.

Batch Operated Grain Roasting Drum

Here the drum is rotating at a lower speed with a 5kg load.

Here the drum is rotating at high speed with a 5kg load.

In this instance, PEPT studies used a scale model to gain insight into grain mixing and heat transfer. The rotating drum has internal flights to lift and mix the grain and heat is transferred from the circumferential wall to adjacent grains. The slippage between the bulk grain and the wall can be observed above.
PEPT analysis allows us to quantify the grain residence time at the wall (total time and mean residence time), as well as the residence time distribution. PEPT also reveals the total time at the wall unaffected by the fill level or rotation speed and shows that the average visit time decreases with increasing speed.

Twin screw extrusion

This video shows the flow of real particles through a twin-screw extruder. The technique used was Positron Emission Particle Tracking and more can be discovered at PEPTFlow. This video is an early result from the project that will increase the understanding of flow and mixing in twin-screw extruders. This technique is ground breaking and is the first technique capable following flow/particles under realistic processing conditions.