Optimization of Biogas Production from Co-digestion of Livestock Manure and Pumpkin Waste using the Response Surface Methodology (RSM)

Alfalfa is one of the main forage plants used for animal feed. Four percent of the total cultivated area in Iran is dedicated to this crop. Due to the fact that alfalfa has several harvests during its growth period, mowers have a special role for farmers. The purpose of this study was to evaluate and optimize the performance of cylindrical mower by designing two new blade types, and investigating the effect of blade type, forward speed and blade rotational speed on parameters such as fuel consumption, cutting height, harvest loss and damage index. The modeled blades were designed in Solidworks software environment and the force stresses were analyzed in Ansys software. Data analysis was performed using response surface method and Design Expert 12 software. The results of analysis of variance showed that the forward speed, blade rotational speed and the interaction between forward speed and rotational speed had a significant effect on tractor fuel consumption. But blade length and other mutual effects ofthis factor had no significant effect on tractor fuel consumption. Also, none of the independent parameters had any significant effect on cutting height, harvest loss and damage index. The relationship between independent and dependent variables was modeled in the form of regression equations. The optimal value for forward speed was 15 km/h, for rotational speed was 1596 rpm and for the blade lengh was 6.15 cm.