Experimental analysis of mass transport and mixing in a single screw extruder for semolina dough

In this paper a fluid dynamics analysis of a single screw extruder for semolina dough is reported. Experimental evidence is provided of the absence of a backflow velocity component and that the screw effect on hydrated semolina consists mainly in transporting and compacting the feed semolina particles. The absence of the supposed backflow component is due to the particulate of feed semolina particles and to the effect of the pre-die bell, which is investigated.