BASIC DESIGN CRITERIA OF EXPELLING MACHINE FOR EXTRACTING WHEAT GERM OIL

Abstract

An expelling machine for extracting wheat germ oil was designed and fabricated. The study included the investigation of the design criteria relating to hopper dimension and screw shaft parameters (outer diameter, pitch, thread depth, thread width, thread length, lead, lead angle, tapered angle, and number of turns on the screw shaft). The expelling machine was tested and evaluated at five screw speeds (25, 35, 45, 55, and 65 rpm) and four levels of press head clearance (0.5, 1, 1.5, and 2 mm) to determine the best machine capacity; percentage of oil recovery; percentage of residual oil; and specific energy consumption. The results showed that, the maximum machine capacity was 39 kg/h of raw material at 2mm outlet clearances, and 65 rpm of screw speed. The best operating pressing conditions for the wheat germ oil recovery was 45.7% at the 25 rpm of screw speed and 0.5 mm press head clearance, when the required specific energy was 0.0232 kWh/kg feed .