Performance Evaluation and modeling of a Poundo-yam Single Screw Extruder

Abstract

A low speed single screw poundo-yam extruder was designed, constructed and mathematically modeled. The performance evaluation of the extruder was carried out using slices of white yam (Dioscorea rotundata) and the effects of screw speed ( )1 x and quantity of added water ( ) 2 x on the extrudate throughput ( ) 0 y and residence time ( )r y were investigated using a 2 3 full factorial design, with 3 levels of screw speed (13,15, and 17 rpm) and 3 levels of quantity of added water (300, 400, and 500 mls/kg of tuber slices). Empirical relationships were developed to established the effects of screw speeds and level of added water on the throughput and extrudate residence time within the barrel. Results indicated that screw speed and the amount of added water affect the extrusion process, the extrudate output, and the extrudate residence time. Both factors have positive influences on extrudate output. However, screw speed is more influential than quantity of added water. On the effects of the two factors on extrudate residence time, it was found that both factors have negative influences. However, quantity of added water has less negative influence than screw speed.