Qinghai Jiang;Kai Wu;Yu Su

School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China;School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, Chin

animal feed;pelletization;modeling;compression force;response surface methodology;analysis of variance;PELLETED ANIMAL FEED;WHEAT-STRAW;ENERGY-CONSUMPTION;NUTRITIONAL-VALUE;PHYSICAL QUALITY;TEMPERATURE;MOISTURE;PARAMETERS;DIE;PERFORMANC

A multi-hole pelletizing device (MPD) was proposed to simulate the granular extrusion process of animal feed due to its cheap, fast, and controllable features. The compression mechanism was analyzed and discussed according to the compression force-time curve. This study applied response surface methodology (RSM) with a central composite design (CCD) to develop predictive models for the compression force F-out and the pellet properties which includes pellet density rho(p), pellet moisture content M-cp, and pellet tensile strength D-p based on the MPD. The effects of feedstock moisture content M-cf (10%-18% w.b.), feedstock particle size S-f (8 meshes -24 meshes), die temperature T-d (70 degrees C-110 degrees C) and compression speed V-c (5 mm/min to 25 mm/min) were investigated. Response surface models developed for the compression force and pellet properties have adequately described the pelleting process (R-2>0.95). The results showed the significant effects of all factors and most of the squared and interaction terms on the compression force and pellet physical properties. It can be concluded from the present study that moisture content and die temperature, followed by compression speed and feedstock particle size are the interacting process factors influencing compression force and pellet properties.