Optimization of Heat and Mass Transfer Process in Single Screw Floating Fish Feed Extruder

Abstract

To optimize the extrusion conditions of locally developed single screw floating fish feed extruder. A factorial experiment in completely randomized design was employed to study the effect of extrusion variables: feed moisture content (20, 30, and 40% wet basis), screw speed (158.5, 245, 334 rpm), die size (4, 6, 8, mm) while checking for their effect on Product temperature of the feed produced. Product temperature is strongly related to the extrusion process parameters under study. Product temperature decreased with increasing moisture content.  Optimum condition was found at 74.11⁰C at the feed section, 80.83⁰C at compression section and 85.15⁰C at metering section, screw speed at 330.5 rpm, feed rate at 0.6 kg/min, die size at 7.47 mm, moisture content at 39.87%, particle size at 1.1., and the  coefficient for the final model is 0.93 which indicated that the model is good. The extruder was found to be cost efficient for floating fish feed production. Thus, model-fitting using response surface methodology was performed to examine their effect on product temperature. Quadratic coefficients fit the extrusion data very well, better than linear models. The equations relating the various dependent and independent variables were established to predict the performance of the machine.