Circumferential grooves are used on all rolls of crushing mills. The grooves
are intended to provide a better grip on the cane or bagasse and better drainage for
the large volumes of juice expressed. The second purpose has received little technical
attention. Crushing investigations that attempt to model the process using
advanced computational methods might need to account for these juice flows. A
simple model of the flow of expressed juice through the grooves has been used to
investigate the likely flow rates and pressures involved and their contribution to
reabsorption.
The model suggests that the pressures required even for large, high capacity
mills are quite small. However, the estimated flow towards the delivery side of a roll
pair makes a significant contribution to the reabsorption. Different groove dimensions
do not seem to make much difference to the flow to the delivery side when the
excess of bagasse volume over escribed volume is used for comparison. Juice
grooves or other drainage aids are probably unnecessary and the pressures calculated
are too low to inhibit mill feeding. Groove flow contributions to reabsorption will
need to be accounted for in computational models that attempt to predict extraction
performance.