ABSTRACT
Simulation can be achieved by setting up a model, of a real situation (system) and then performing experiments on the model. It is widely used as a research and management tool in Engineering analysis, design and industry because of the complexity of agricultural systems. In this thesis, simulation models for stationary grain threshers were developed for predicting threshing performance, through careful selection of various threshing parameters and operating conditions in selected stationary grain threshers with a throw-in feedrate system. The formulated models were verified and validated with established experimental data from stationary mechanical sorghum and millet threshers. All the models were found to correlate and fit well with the experimental data with R-square values greater than 0.91 at 0.001 level of significance. A higher correlation was also achieved with the overall threshing efficiency model with Rsquare value of 0.99 at 0.001 level of significance when compared with the existing models. A computer simulation programme was also developed and used at three factor interaction of the process variables to obtain variables for optimum (minimum) grain loss for millet- and sorghum threshers. The utility of this programme is demonstrated in selecting least or minimum grain loss for various combination of process variables. The result obtained from the simulation revealed that a minimum grain loss of 0.09% was obtained for the millet thresher and 0.35% for the sorghum thresher at 9% grain moisture content, cylinder speed of 5 m/s and feedrate of 0.03 kg/s. These compare favourably with a minimum grain loss of 0.10% and 0.46% respectively, for millet and sorghum obtained from actual measurements at the same values of the parameters.