Modeling and Analyzing of Specific Mechanical Energy in Animal Feed Extrusion Process

Abstract

<abstract><title><italic>Abstract.</italic></title> A new mathematical model was proposed to describe the specific mechanical energy (SME) in the animal feed extrusion process based on dimensional analysis methodology (DAM). The effects of feed moisture content (21.3% to 29.7%), screw speed (140 to 240 rpm), and extrusion temperature (133°C to 167°C) on SME were studied by response surface methodology (RSM). The dimensional model was established with experiment data. The average deviation of the model correlation was 0.66%. The sequencing of parameter sensitivities of the SME model was T₀ > T_b > P > ρ > Q > w > n. A positive correlation between extrusion temperature and SME and a negative correlation between screw speed, moisture content, and SME were found in both the dimensional model and RSM. It was found from RSM that the moisture content (p < 0.1) and screw speed (p < 0.1) had significant influences on SME, while the influence of extrusion temperature was not significant. The final predicted minimum SME was obtained at 29.7% moisture content, 140 rpm screw speed, and 133°C extrusion temperature. The predicted value of the DAM model was close to that of the RSM model at these conditions.